NTERNATIONAL ELSEVIER Tribology International 39(2006)191-197 www.elsevier.com/locate/trboint Wear behaviour of alumina based ceramic cutting tools on machining steels A Senthil Kumar., A. Raja Duraia, T. Sornakumar partment of Manufacturing Engineering, College of Engineering, Anna University, Chennai 600 025. India Department of Mechanical Engineering, Thiagarajar College of Engineering, Madurai 625 015, Indi Received 7 April 2003: received in revised form 16 September 2004: accepted 12 October 2004 Available online 10 May 2005 Abstract The advanced ceramic cutting tools have very good wear resistance, high refractoriness, good mechanical strength and hot hardness Alumina based ceramic cutting tools have very high abrasion resistance and hot hardness. Chemically they are more stable than high-speed steels and carbides, thus having less tendency to adhere to metals during machining and less tendency to form built-up edge. This results in good surface finish and dimensional accuracy in machining steels. In this paper wear behaviour of alumina based ceramic cutting tools is investigated. The machining tests were conducted using SiC whisker reinforced alumina ceramic cutting tool and Ti(C, N mixed alumina ceramic cutting tool on martensitic stainless steel-grade 410 and en 24 steel work pieces. Flank wear in Ti(C, N mixed alumina ceramic cutting tool is lower than that of the Sic whisker reinforced alumina cutting tool. SiC whisker reinforced alumina cutting tool exhibits poor crater wear resistance while machining. Notch wear in Sic whisker reinforced alumina cutting tool is lower than that of the ti[C, NI mixed alumina ceramic cutting tool. The flank wear, crater wear and notch wear are higher on machining martensitic stainless steel than on machining hardened steel. In summary Ti[C, N] mixed alumina cutting tool performs better than SiC whisker reinforced alumina cutting tool on machining martensitic stainless steel C 2005 Elsevier Ltd. All rights reserved. Keywords: Alumina; Wear; Ceramic cutting tools; Steel 1. Introduction based alloys at high speeds. The advantages of using ceramic cutting tools are that the hard materials with Ceramic cutting tools can be toughened by particulate complex shapes can be machined in one step and grinding toughening, fibre toughening, whisker toughening, trans- quality surface finish can be obtained by turning the hard formation toughening etc [1]. Ceramic cutting tools have work materials. The performance of ceramic cutting tools in unique chemical and mechanical properties and these tools machining of stainless steel is not fully evaluated can offer increased metal removal rates, extended tool life Martensitic stainless steel, like most plain carbon steels and have the ability to machine hard workpiece materials can be hardened by heat treatment. Ronald L Klueh et al. [2] like stainless steel and hardened steel. When properly reported that advanced ferritic/martensitic stainless steel is applied these tools can provide the manufacturing engineer used in thermal power plants, nuclear power plants and in with a means of reducing machining costs and increasing other productivity Improvements have been made in tool proper- properties, and high creep strength. Machining of hard les, such as fracture strength, toughness, thermal shock materials was mostly done by ceramics and cubic boron resistance, hardness and wear resistance by microstructure nitrides and they stand out for their high material hardness engineering. These developments have now enabled the hot hardness at elevated temperature, wear resistance and ceramic tools to be used in the machining of various types of chemical stability []. These attributes enable high cutting steel, cast iron, non-ferrous metals and refractory nickel speeds, as well as machining hard materials. Silva et al. [4 observed that the recent cutting tool materials such as ceramic and PCBn(polycrystalline boron nitride) have stimulated investigations conc 0301-679 front matter o 2005 Elsevier Ltd. All rights reserved doi:10.1016 j tribon2005.01.021
Wear behaviour of alumina based ceramic cutting tools on machining steels A. Senthil Kumara,*, A. Raja Duraia , T. Sornakumarb a Department of Manufacturing Engineering, College of Engineering, Anna University, Chennai 600 025, India b Department of Mechanical Engineering, Thiagarajar College of Engineering, Madurai 625 015, India Received 7 April 2003; received in revised form 16 September 2004; accepted 12 October 2004 Available online 10 May 2005 Abstract The advanced ceramic cutting tools have very good wear resistance, high refractoriness, good mechanical strength and hot hardness. Alumina based ceramic cutting tools have very high abrasion resistance and hot hardness. Chemically they are more stable than high-speed steels and carbides, thus having less tendency to adhere to metals during machining and less tendency to form built-up edge. This results in good surface finish and dimensional accuracy in machining steels. In this paper wear behaviour of alumina based ceramic cutting tools is investigated. The machining tests were conducted using SiC whisker reinforced alumina ceramic cutting tool and Ti[C,N] mixed alumina ceramic cutting tool on martensitic stainless steel-grade 410 and EN 24 steel work pieces. Flank wear in Ti[C,N] mixed alumina ceramic cutting tool is lower than that of the SiC whisker reinforced alumina cutting tool. SiC whisker reinforced alumina cutting tool exhibits poor crater wear resistance while machining. Notch wear in SiC whisker reinforced alumina cutting tool is lower than that of the Ti[C,N] mixed alumina ceramic cutting tool. The flank wear, crater wear and notch wear are higher on machining martensitic stainless steel than on machining hardened steel. In summary Ti[C,N] mixed alumina cutting tool performs better than SiC whisker reinforced alumina cutting tool on machining martensitic stainless steel. q 2005 Elsevier Ltd. All rights reserved. Keywords: Alumina; Wear; Ceramic cutting tools; Steel 1. Introduction Ceramic cutting tools can be toughened by particulate toughening, fibre toughening, whisker toughening, transformation toughening etc [1]. Ceramic cutting tools have unique chemical and mechanical properties and these tools can offer increased metal removal rates, extended tool life and have the ability to machine hard workpiece materials like stainless steel and hardened steel. When properly applied these tools can provide the manufacturing engineer with a means of reducing machining costs and increasing productivity. Improvements have been made in tool properties, such as fracture strength, toughness, thermal shock resistance, hardness and wear resistance by microstructure engineering. These developments have now enabled the ceramic tools to be used in the machining of various types of steel, cast iron, non-ferrous metals and refractory nickel based alloys at high speeds. The advantages of using ceramic cutting tools are that the hard materials with complex shapes can be machined in one step and grinding quality surface finish can be obtained by turning the hard work materials. The performance of ceramic cutting tools in machining of stainless steel is not fully evaluated. Martensitic stainless steel, like most plain carbon steels can be hardened by heat treatment. Ronald L Klueh et al. [2] reported that advanced ferritic/martensitic stainless steel is used in thermal power plants, nuclear power plants and in other demanding environments for its high temperature properties, and high creep strength. Machining of hard materials was mostly done by ceramics and cubic boron nitrides and they stand out for their high material hardness hot hardness at elevated temperature, wear resistance and chemical stability [3]. These attributes enable high cutting speeds, as well as machining hard materials. Silva et al. [4] observed that the recent cutting tool materials such as ceramic and PCBN (polycrystalline cubic boron nitride) have stimulated investigations concerning the possible 0301-679X/$ - see front matter q 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.triboint.2005.01.021 Tribology International 39 (2006) 191–197 www.elsevier.com/locate/triboint * Corresponding author
A. Senthil Kumar et al. Tribology International 39(2006)191-197 substitution of grinding operations by machining, in greater thermal conductivity than oxide alumina ceramic ing of hardened steels. It was also indicated that, tools, while machining hardened steel. Brandt and Mikus in general, mixed alumina ceramic tool exhibited better [10] observed that the crater wear of alumina based ceramic performance than some of the PCBn tools. When success- tools was predominantly dependent upon superficial plastic fully applied, ceramic cutting tools can increase the metal deformation while machining steel. This superficial plastic removal rate by several times over that obtained with deformation of the ceramic cutting tool was greatly affected conventional tool materials [5]. An understanding of the by chemical reaction with workpiece material Gwidon W wear mechanisms is a prerequisite for proper utilization of Stachowiak et al. [ll]observed that SiC whisker reinforced these tool materials. The wear mechanisms such as abrasive, alumina cutting tool suffers from chemically activated wear adhesive, tribochemical wear and wear by plastic defor- due to the high chemical affinity of SiC with iron and during mation and fracture are observed in ceramic cutting tools. machining sic whiskers are removed from alumina matrix During machining, a contact pair between tool and work- Gatto and luliano [12] observed the presence of whiskers piece/chip is formed and is subjected to conditions pull out mechanism due to temperature effects on tool-chip promoting intense abrasion, adhesion, diffusion, plastic interface while machining Inconel 718 with SiC whisker deformation etc over a portion of the cutting tool. This reinforced ceramic tool. Richards and Aspinwall [13] results in different forms of tool wear like flank wear, crater observed that the tool life of mixed alumina ceramic tool wear, notch wear etc. The total tool wear observed in the was severely limited due to excessive depth of cut (DOC ceramic cutting tool can be divided into two main broad notching, while machining Nickel based alloys. Narutaki categories such as(a) mechanically activated wear which et al. [14] observed that Sic whisker reinforced alumina includes abrasion, adhesion, plastic deformation and ceramic tool showed good performance when compared to fracture and(b) chemically activated wear also called mixed alumina ceramic tool in respect of notch wear at tribochemical wear which includes diffusion or dissolution moderate speed, while machining Inconel 718 wear. Usually the wear in a cutting tool is a complex Zhao Xingzhong et al. [15] reported that wear tests were phenomenon and can be attributed to several of the above carried out under dry friction conditions on a block-on-ring wear modes/mechanisms. The combined effect of the wear tribometer in order to simulate the real cutting practice of mechanisms or the predominance of any of them depends ceramic cutting tools. The investigated materials include a upon the type of cutting tool material, the type of workpiece composite ceramic Al2O3-Ti[C, N] and stainless steel (AIS material and cutting conditions. In general ceramic cutting 02). The results showed that the metals were easily tool materials are more wear resistant than cemented transferred on to the ceramic surface in the rubbing process, carbide tools In our present work, the wear behaviour of and the ceramic microfracture fragments were also lumina based ceramic cutting tools on machining marten- embedded into metal surfaces. Zhao Xingzhong et al. [16] sitic stainless steel and hardened steel is investigated also reported that wear tests were carried out using a pin-on- disc tribometer which could simulate a real cutting process, in order to investigate the wear behavior of Si3N4 ceramic 2. Literature review when cutting stainless steel. These test results showed that the wear of Si3 N4 ceramic was caused mainly by adhesion The wear behaviour of ceramic cutting tools has to be between the rubbing surfaces; the wear increased with load properly understood for their effective utilizatio anzhen et al. [17 machining hard materials. El-Wardany et al. [6]observed resistance ability of A2 O3+SiCp+SiCw ceramic tool was hat the occurrence of plastic deformation of the ceramic greater than Al2O3+ SiCw ceramic tool, when machining cutting edge, triggered surface roughness deterioration, and stainless steel. Liu Yourong et al. [18] reported that the main eventually, edge fracture, while machining hardened steel wear mechanism for cutting the stainless steel using ceramic using ceramic cutting tool materials. Lo Casto et al. [7 cutting tool was related to adhesion and diffusio reported that alumina-zirconia inserts are very sensitive to by high cutting temperature. Liu Yourong et al. [19] also notch wear, whereas Sic whisker reinforced alumina reported that the temperature on the rake face of Si3N4 ceramic cutting tool exhibit slightly better performance ceramic cutti ng tools and Ti[C, N] mixed alumina ceramic despite the accompanying chemical wear mechanism. Hong cutting tools on turning stainless steel was much higher than Xiao [8] conducted tool wear studies on various ceramic on turning plain carbon steel. The above observations are tools and observed that oxide ic cutting tools and important in understanding the wear behaviour of the mixed ceramic cutting tools are more suitable for machining ceramic cutting tools on machining hard materials hardened steel than other ceramic tools because of their superior fank wear resistance. It was also observed that 3 Experimental procedure crater wear was significant in Sic whisker reinforced alumina ceramic tool while machining hardened alloy steel The machining tests were performed on martensitic Brandt 9]observed that the mixed alumina ceramic tool has ainless steel-grade 410 hardened to 60 HRC and EN steel etter flank wear resistance due to higher hot hardness and hardened to 45 HRC work piece materials. Two types of
substitution of grinding operations by machining, in the finishing of hardened steels. It was also indicated that, in general, mixed alumina ceramic tool exhibited better performance than some of the PCBN tools. When successfully applied, ceramic cutting tools can increase the metal removal rate by several times over that obtained with conventional tool materials [5]. An understanding of the wear mechanisms is a prerequisite for proper utilization of these tool materials. The wear mechanisms such as abrasive, adhesive, tribochemical wear and wear by plastic deformation and fracture are observed in ceramic cutting tools. During machining, a contact pair between tool and workpiece/chip is formed and is subjected to conditions promoting intense abrasion, adhesion, diffusion, plastic deformation etc over a portion of the cutting tool. This results in different forms of tool wear like flank wear, crater wear, notch wear etc. The total tool wear observed in the ceramic cutting tool can be divided into two main broad categories such as (a) mechanically activated wear which includes abrasion, adhesion, plastic deformation and fracture and (b) chemically activated wear also called tribochemical wear which includes diffusion or dissolution wear. Usually the wear in a cutting tool is a complex phenomenon and can be attributed to several of the above wear modes/mechanisms. The combined effect of the wear mechanisms or the predominance of any of them depends upon the type of cutting tool material, the type of workpiece material and cutting conditions. In general ceramic cutting tool materials are more wear resistant than cemented carbide tools. In our present work, the wear behaviour of alumina based ceramic cutting tools on machining martensitic stainless steel and hardened steel is investigated. 2. Literature review The wear behaviour of ceramic cutting tools has to be properly understood for their effective utilization in machining hard materials. El-Wardany et al. [6] observed that the occurrence of plastic deformation of the ceramic cutting edge, triggered surface roughness deterioration, and eventually, edge fracture, while machining hardened steel using ceramic cutting tool materials. Lo Casto et al. [7] reported that alumina–zirconia inserts are very sensitive to notch wear, whereas SiC whisker reinforced alumina ceramic cutting tool exhibit slightly better performance despite the accompanying chemical wear mechanism. Hong Xiao [8] conducted tool wear studies on various ceramic tools and observed that oxide ceramic cutting tools and mixed ceramic cutting tools are more suitable for machining hardened steel than other ceramic tools because of their superior flank wear resistance. It was also observed that crater wear was significant in SiC whisker reinforced alumina ceramic tool while machining hardened alloy steel. Brandt [9] observed that the mixed alumina ceramic tool has better flank wear resistance due to higher hot hardness and greater thermal conductivity than oxide alumina ceramic tools, while machining hardened steel. Brandt and Mikus [10] observed that the crater wear of alumina based ceramic tools was predominantly dependent upon superficial plastic deformation while machining steel. This superficial plastic deformation of the ceramic cutting tool was greatly affected by chemical reaction with workpiece material. Gwidon W Stachowiak et a1. [11] observed that SiC whisker reinforced alumina cutting tool suffers from chemically activated wear due to the high chemical affinity of SiC with iron and during machining SiC whiskers are removed from alumina matrix. Gatto and Iuliano [12] observed the presence of whiskers pull out mechanism due to temperature effects on tool–chip interface while machining Inconel 718 with SiC whisker reinforced ceramic tool. Richards and Aspinwall [13] observed that the tool life of mixed alumina ceramic tool was severely limited due to excessive depth of cut (DOC) notching, while machining Nickel based alloys. Narutaki et al. [14] observed that SiC whisker reinforced alumina ceramic tool showed good performance when compared to mixed alumina ceramic tool in respect of notch wear at moderate speed, while machining Inconel 718. Zhao Xingzhong et al. [15] reported that wear tests were carried out under dry friction conditions on a block-on-ring tribometer in order to simulate the real cutting practice of ceramic cutting tools. The investigated materials include a composite ceramic Al2O3–Ti[C,N] and stainless steel (AISI 302). The results showed that the metals were easily transferred on to the ceramic surface in the rubbing process, and the ceramic microfracture fragments were also embedded into metal surfaces. Zhao Xingzhong et al. [16] also reported that wear tests were carried out using a pin-ondisc tribometer which could simulate a real cutting process, in order to investigate the wear behavior of Si3N4 ceramic when cutting stainless steel. These test results showed that the wear of Si3N4 ceramic was caused mainly by adhesion between the rubbing surfaces; the wear increased with load and speed. Chuanzhen et al. [17] reported that the wear resistance ability of Al2O3CSiCpCSiCw ceramic tool was greater than Al2O3CSiCw ceramic tool, when machining stainless steel. Liu Yourong et al. [18] reported that the main wear mechanism for cutting the stainless steel using ceramic cutting tool was related to adhesion and diffusion promoted by high cutting temperature. Liu Yourong et al. [19] also reported that the temperature on the rake face of Si3N4 ceramic cutting tools and Ti[C,N] mixed alumina ceramic cutting tools on turning stainless steel was much higher than on turning plain carbon steel. The above observations are important in understanding the wear behaviour of the ceramic cutting tools on machining hard materials. 3. Experimental procedure The machining tests were performed on martensitic stainless steel-grade 410 hardened to 60 HRC and EN steel hardened to 45 HRC work piece materials. Two types of 192 A. Senthil Kumar et al. / Tribology International 39 (2006) 191–197
A. Senthil Kumar et al. / Tribology international 39(2006)191-197 Table 1 4. Wear behavior of ceramic cutting tools The composition and properties of the alumina based ceramic cutting tool The main wear mechanisms in ceramic cutting tools are Details of tool Whisker IC, NI abrasion, adhesion, diffusion, plastic deformation and fracture. The cutting tools are subjected to high localised alumina(CC alumina(CC 650) stresses, high temperatures, sliding of the chip along the tool rake face and sliding of the machined surface along the tool Alo A2O370% TN22.5% flank. These conditions induce tool wear. which in turn TC7.5% adversely affects tool life, the quality of the machined Insert specificati CNN surface and its dimensional accuracy. 20408 20408 To1020 4 Flank wear Vickers hardness (HV10) Transverse rupture MPa Flank wear occurs on the relief face of the cutting tool and is generally attributed to the rubbing of the tool along Young’ s modulus Fracture tou the machined surface and higl h temperatures causing Thermal conductivity W/m Coefficient of ther. K-1x10-68 abrasive and/or adhesive wear, thus affecting tool materials properties as well as work piece surface. Abrasion, diffusion mal expansion and adhesion are the main wear mechanisms in flank wear Flank wear in the ceramic cutting tools is a mechanically alumina based ceramic cutting tool materials from sandvik activated wear usually by the abrasive action of the hard Coromant, Sweden; Ti[C, N] mixed alumina ceramic cutting workpiece material with the ceramic cutting tools. The tool inserts(CC 650) and SiC whisker reinforced alumina severity of abrasion increases in cases, where the workpiece materials contain hard inclusions or when there is a hard ceramic cutting tool inserts(CC 670) were used to machine the steels. The specification and properties of the tool wear debris from the workpiece or the tool, at the interface materials are given in Table 1. The machining tests were The flank wear is usually characterised by the abrasive conducted using these alumina based composite ceramic grooves and ridges on the flank face. Fig. I shows the SEM tools at different cutting speeds of 120, 170 and 270 m/min micrograph of the flank wear land of the SiC whisker reinforced alumina ceramic cutting tool. The variation of feed of 0.12 mm/rev and depth of cut of 0.5 mm in a flank wear of alumina based ceramic cutting tools with precision lathe. The machining studies were conducted in fiank wear, crater wear contour area and notch wear were martensitic stainless steel-grade 410 and EN 24 steel is dry environment without any cutting fluid, for 15 min The measured using a tool maker's microscope and crater wear presented in Fig. 2. This figure shows that the flank wear increases with the cutting speed. Flank wear in Ti[C,N depth was measured using a micro stylus dial gauge. The wear area e observed using a scanning electron mixed alumina cutting tool is lower than Sic whisker reinforced alumina cutting tool on machining the steels. The microscope to determine the wear mechanism of the higher flank wear in SiC whisker reinforced alumina cutting ceramic cutting tool materials. The tool holder used for tool can be attributed to the higher chemical affinity of machining is ISO CClNR 25 25M 12 0 silicon carbide towards iron. It can be noted from the figure that fank wear in both types of ceramic tools is higher on 50 Cutting speed (m/min Ti[C, N-alumina /EN24 TC, N-alumina /SS GRADE-410 SiC whisker-alumina/EN 24 -Sic whisker-alumina/SS GRADE-410 Fig. 1. SEM micrograph of the flank wear of Sic whisker reinforced Fig. 2. Flank wear vs cutting speed of the ceramic cutting tools after alumina ceramic cutting tool. machining 15 min
alumina based ceramic cutting tool materials from Sandvik Coromant, Sweden; Ti[C,N] mixed alumina ceramic cutting tool inserts (CC 650) and SiC whisker reinforced alumina ceramic cutting tool inserts (CC 670) were used to machine the steels. The specification and properties of the tool materials are given in Table 1. The machining tests were conducted using these alumina based composite ceramic tools at different cutting speeds of 120, 170 and 270 m/min, feed of 0.12 mm/rev and depth of cut of 0.5 mm in a precision lathe. The machining studies were conducted in dry environment without any cutting fluid, for 15 min. The flank wear, crater wear contour area and notch wear were measured using a tool maker’s microscope and crater wear depth was measured using a micro stylus dial gauge. The wear areas were observed using a scanning electron microscope to determine the wear mechanism of the ceramic cutting tool materials. The tool holder used for machining is ISO CCLNR 25 25 M 12 07. 4. Wear behavior of ceramic cutting tools The main wear mechanisms in ceramic cutting tools are abrasion, adhesion, diffusion, plastic deformation and fracture. The cutting tools are subjected to high localised stresses, high temperatures, sliding of the chip along the tool rake face and sliding of the machined surface along the tool flank. These conditions induce tool wear, which in turn adversely affects tool life, the quality of the machined surface and its dimensional accuracy. 4.1. Flank wear Flank wear occurs on the relief face of the cutting tool and is generally attributed to the rubbing of the tool along the machined surface and high temperatures causing abrasive and/or adhesive wear, thus affecting tool materials properties as well as work piece surface. Abrasion, diffusion and adhesion are the main wear mechanisms in flank wear. Flank wear in the ceramic cutting tools is a mechanically activated wear usually by the abrasive action of the hard workpiece material with the ceramic cutting tools. The severity of abrasion increases in cases, where the workpiece materials contain hard inclusions, or when there is a hard wear debris from the workpiece or the tool, at the interface. The flank wear is usually characterised by the abrasive grooves and ridges on the flank face. Fig. 1 shows the SEM micrograph of the flank wear land of the SiC whisker reinforced alumina ceramic cutting tool. The variation of flank wear of alumina based ceramic cutting tools with respect to cutting speed, after machining 15 min on martensitic stainless steel-grade 410 and EN 24 steel is presented in Fig. 2. This figure shows that the flank wear increases with the cutting speed. Flank wear in Ti[C,N] mixed alumina cutting tool is lower than SiC whisker reinforced alumina cutting tool on machining the steels. The higher flank wear in SiC whisker reinforced alumina cutting tool can be attributed to the higher chemical affinity of silicon carbide towards iron. It can be noted from the figure that flank wear in both types of ceramic tools is higher on Table 1 The composition and properties of the alumina based ceramic cutting tool materials Details of tool material Unit Whisker reinforced alumina (CC 670) Ti[C,N] mixed alumina (CC 650) Composition Al2O3 80% Al2O3 70% SiCw 20% TiN 22.5% TiC 7.5% Insert specification CNGN CNGN 12 04 08 T01020 12 04 08 T01020 Density g/cm3 3.74 4.26 Vickers hardness (HV10) 2000 1800 Transverse rupture strength MPa 900 550 Young’s modulus GPa 390 400 Fracture toughness MPa-m1/2 8.0 4.0 Thermal conductivity W/mK 18 24 Coefficient of thermal expansion KK1 !10K6 6 8.6 Fig. 1. SEM micrograph of the flank wear of SiC whisker reinforced alumina ceramic cutting tool. Fig. 2. Flank wear vs cutting speed of the ceramic cutting tools after machining 15 min. A. Senthil Kumar et al. / Tribology International 39 (2006) 191–197 193
A. Senthil Kumar et al. Tribology International 39(2006)191-197 0 Time(min) Time(min) I-xe-sc htkeriau/ 2 +-TIG H a/ SS GRADE-410 EN24 - +Ti[C, N]-alumina/SS GRADE- 410 -oSiC whisker-alumina/EN 24 /SS GRADE-410 Fig. 3. Flank wear of the ceramic cutting tools vs machining time on machining at 270 m/min Fig. 5. Crater wear contour area of the ceramic cutting tools vs machining time on machining at 270 m/min. machining martensitic stainless steel than on machining eN 4 steel Fig 3 shows the flank wear of these ceramic cutting temperatures. It is thus a tribochemical wear as a result of tools vs machining time on machining martensitic stainless chemical affinity between the work lee materials and steel and en 24 steel at 270 m/min. It can be observed that the cutting tool materials. Fig. 4 shows the crater wear depth the flank wear of these ceramic cutting tools is increasing of the ceramic tools Vs cutting speed after machining 15 min with time on machining for both martensitic stainless steel on stainless steel and hardened steel. Crater wear depth in and hardened steel. but the flank wear of Sic whisker both types of ceramic cutting tools increases with cutting forced alumina cutting tool is higher than Ti[C, N] speed on machining martensitic stainless steel and EN 24 alumina ceramic cutting tool on machining both steel Crater wear depth in SiC whisker reinforced alumina of work materials cutting tool is higher than Ti[C N mixed alumina ceramic cutting tool while machining both types of work materials 4.2 Crater wear The growth of the crater contour area can be observed by plotting the contour area as a function of cutting speed or Crater wear occurs on the rake face of the tool, changing time [20].Fig.5 shows the crater wear contour area of the the tool-chip interface geometry, thus affecting the cutting ceramic tools vs machining time on machining both types of process. The most significant factors influencing crater wear work materials. The growth of crater wear contour in Sic are the temperature at the tool-chip interface and the whisker reinforced alumina cutting tool is higher than chemical affinity between the tool and the work piece Ti(C, N] mixed alumina ceramic cutting tool. The higher materials. Additionally the factors influencing flank wear crater wear for SiC whisker reinforced alumina cutting tool also influence crater wear. The main wear mechanisms in can also be attributed to the higher solubility of silicon crater wear of ceramic tools are diffusion, adhesion and carbide in steel at high temperatures than that of titanium abrasion Crater wear involves a chemical reaction between e workpiece chip material and the ceramic tool material and the process is activated by high speeds and D.1 Cutting speed(m/min) -Ti[C, NI-alumina / EN2 -Ti(C, N]-alumina /ss grade-410 -CSic whisker alumina/EN24 Sic whisker alumina/ SS grade-410 Fig 4. Crater wear depth vs cutting speed of the ceramic cutting tools after Fig. 6. Photograph showing crater wear of SiC whisker reinforced alumina ceramIc cu
machining martensitic stainless steel than on machining EN 24 steel. Fig. 3 shows the flank wear of these ceramic cutting tools vs machining time on machining martensitic stainless steel and EN 24 steel at 270 m/min. It can be observed that the flank wear of these ceramic cutting tools is increasing with time on machining for both martensitic stainless steel and hardened steel. But the flank wear of SiC whisker reinforced alumina cutting tool is higher than Ti[C,N] mixed alumina ceramic cutting tool on machining both types of work materials. 4.2. Crater wear Crater wear occurs on the rake face of the tool, changing the tool–chip interface geometry, thus affecting the cutting process. The most significant factors influencing crater wear are the temperature at the tool–chip interface and the chemical affinity between the tool and the work piece materials. Additionally the factors influencing flank wear also influence crater wear. The main wear mechanisms in crater wear of ceramic tools are diffusion, adhesion and abrasion. Crater wear involves a chemical reaction between the workpiece chip material and the ceramic tool material, and the process is activated by high speeds and temperatures. It is thus a tribochemical wear as a result of the chemical affinity between the workpiece materials and the cutting tool materials. Fig. 4 shows the crater wear depth of the ceramic tools vs cutting speed after machining 15 min on stainless steel and hardened steel. Crater wear depth in both types of ceramic cutting tools increases with cutting speed on machining martensitic stainless steel and EN 24 steel. Crater wear depth in SiC whisker reinforced alumina cutting tool is higher than Ti[C,N] mixed alumina ceramic cutting tool while machining both types of work materials. The growth of the crater contour area can be observed by plotting the contour area as a function of cutting speed or time [20]. Fig. 5 shows the crater wear contour area of the ceramic tools vs machining time on machining both types of work materials. The growth of crater wear contour in SiC whisker reinforced alumina cutting tool is higher than Ti[C,N] mixed alumina ceramic cutting tool. The higher crater wear for SiC whisker reinforced alumina cutting tool can also be attributed to the higher solubility of silicon carbide in steel at high temperatures than that of titanium Fig. 3. Flank wear of the ceramic cutting tools vs machining time on machining at 270 m/min. Fig. 4. Crater wear depth vs cutting speed of the ceramic cutting tools after machining 15 min. Fig. 5. Crater wear contour area of the ceramic cutting tools vs machining time on machining at 270 m/min. Fig. 6. Photograph showing crater wear of SiC whisker reinforced alumina ceramic cutting tool. 194 A. Senthil Kumar et al. / Tribology International 39 (2006) 191–197
A. Senthil Kumar et al. / Tribology intenational 39(2006)191-197 Fig. 7. SEM micrograph showing crater wear region of SiC whisker ig. 9. SEM micrograph of SiC whisker failure on the rake face of SiC reinforced alumina ceramic cutting tooL. whisker reinforced alumina ceramic cutting tool. carbide and titanium nitride [21]. SEM micrographs were normal circumstances without any dissolution of whiskers taken to understand the wear behaviour of Sic whisker the matrix fails first and then the total failure will occur by reinforced ceramic cutting tool. Fig. 6 shows the photograph gradual pullout of the whisker from the matrix and it is of the Sic whisker reinforced alumina ceramic cutting tool known as whisker pullout mechanism. In this type of tool showing the crater wear region. From this figure it can be the alumina matrix is not much affected by the tribochem- noted that the crater wear of SiC whisker reinforced alumina ical wear but the reinforcement silicon carbide is subjected ceramic cutting tool is clearly visible. Fig. 7 shows the SEM to diffusion, when machining steel. In this case, the micrograph of the crater wear region of Sic whisker dissolution of SiC whisker is due to the affinity of silicon reinforced alumina ceramic cutting tool. In this figure the carbide towards iron, and the partially dissolved whisker magnified crater wear region on the rake face of SiC whisker weakens, thus leading to breakage of whisker at weak places reinforced alumina ceramic cutting tool can be seen. Fig8 and also pullout from the matrix due to the stress develope shows the SEM micrograph of the crater wear region on the in the process of machining rake face of the Sic whisker reinforced alumina ceramic cutting tool showing the whisker pullout from the alumina matrix. From this figure it can be noted that the SiC whisker 4.3. Notch wear tends to come out or pull out of the alumina matrix in the crater wear region of the Sic whisker reinforced alumina The notch wear is caused due to rubbing of the machined ceramic cutting tool. Fig 9 shows SEM micrograph of the surface at depth of cut line and also due to the removal of the rake face of the sic whisker reinforced alumina ceramic of the cutting tool material over the depth of cut line zone. cutting tool showing the failure of the Sic whiskers Under Notch wear is mostly observed in the ceramic have low toughness values, while machining hard The formation of segmented chips is one the Fig 8. SEM micrograph of Sic whisker pullout from the matrix in SiC whisker reinforced alumina ceramic cutting tool. Fig. 10. Optical micrograph of the martensitic stainless steel chip
carbide and titanium nitride [21]. SEM micrographs were taken to understand the wear behaviour of SiC whisker reinforced ceramic cutting tool. Fig. 6 shows the photograph of the SiC whisker reinforced alumina ceramic cutting tool showing the crater wear region. From this figure it can be noted that the crater wear of SiC whisker reinforced alumina ceramic cutting tool is clearly visible. Fig. 7 shows the SEM micrograph of the crater wear region of SiC whisker reinforced alumina ceramic cutting tool. In this figure the magnified crater wear region on the rake face of SiC whisker reinforced alumina ceramic cutting tool can be seen. Fig. 8 shows the SEM micrograph of the crater wear region on the rake face of the SiC whisker reinforced alumina ceramic cutting tool showing the whisker pullout from the alumina matrix. From this figure it can be noted that the SiC whisker tends to come out or pull out of the alumina matrix in the crater wear region of the SiC whisker reinforced alumina ceramic cutting tool. Fig. 9 shows SEM micrograph of the rake face of the SiC whisker reinforced alumina ceramic cutting tool showing the failure of the SiC whiskers. Under normal circumstances without any dissolution of whiskers, the matrix fails first and then the total failure will occur by gradual pullout of the whisker from the matrix and it is known as whisker pullout mechanism. In this type of tool, the alumina matrix is not much affected by the tribochemical wear but the reinforcement silicon carbide is subjected to diffusion, when machining steel. In this case, the dissolution of SiC whisker is due to the affinity of silicon carbide towards iron, and the partially dissolved whisker weakens, thus leading to breakage of whisker at weak places and also pullout from the matrix due to the stress developed in the process of machining. 4.3. Notch wear The notch wear is caused due to rubbing of the machined surface at depth of cut line and also due to the removal of the of the cutting tool material over the depth of cut line zone. Notch wear is mostly observed in the ceramic tools, which have low toughness values, while machining hard materials. The formation of segmented chips is one the important Fig. 7. SEM micrograph showing crater wear region of SiC whisker reinforced alumina ceramic cutting tool. Fig. 8. SEM micrograph of SiC whisker pullout from the matrix in SiC whisker reinforced alumina ceramic cutting tool. Fig. 9. SEM micrograph of SiC whisker failure on the rake face of SiC whisker reinforced alumina ceramic cutting tool. Fig. 10. Optical micrograph of the martensitic stainless steel chip. A. Senthil Kumar et al. / Tribology International 39 (2006) 191–197 195
A. Senthil Kumar et al. Tribology International 39(2006)191-197 15 -Ti[C N]alumina/SS GRADE 410 -ATi [C, N] alumina/EN t- Ti[C, N] mixed alumina SiC whisker alumina Fig. 13. Notch wear of Ti(C, NI mixed alumina ceramic tool vs time on Fig. 11. Notch wear vs cutting speed of the ceramic cutting tools after achining 15 min on aspects in notch wear mechanism of the ceramic inserts, as reinforced alumina ceramic cutting tool, it can be inferred these type of chips abrade a notch at the end of the cut zone. that the notch wear resistance of the former tool is lower Saw tooth type of chips are observed on machining than the latter. Even though the crater wear performance of martensitic stainless steel and it is presented in Fig. 10 Sic whisker reinforced alumina cutting tool is poor, it has These types of chips play an important role in the formation better notch wear resistance than the ti C, N mixed alumina of notch wear. In our machining studies, it is found that Sic tool. Generally, the wear scars produced by notch wear are whisker reinforced alumina ceramic cutting tool exhibits rough, as opposed to the smooth wear surfaces generated by slightly better performance in notch wear resistance than crater wear. Abrasion, adhesion and diffusion are the major Ti(C, N mixed alumina ceramic cutting tool on machinin wear mechanisms in notch wear. The tool with higher martensitic stainless steel and it is presented in Fig. 11 hardness and better fracture toughness is able to resist the From the above figure it can be noted that the notch wear in abrasive action of the work piece/chip and reduces the notch both of the ceramic cutting tools increases with cutting wear. Fig. 13 shows the notch wear of Ti[C N mixed alumina ceramic cutting tool vs time on machining speed. Fig. 12 shows the SEM micrograph of the notch wear hardened steel and martensitic stainless steel at 270 m/ of the Ti[C, N mixed alumina ceramic cutting tool on machining martensitic stainless steel, The notch wear in min Notch wear in TiC. N mixed alumina cutting tool is Ti(C, N] mixed alumina ceramic cutting tool is clearly seen higher on machining martensitic stainless steel than that on machining hardened steel and same trend is alse from this figure. As the Ti C, N mixed alumina ceramic utting tool has lower fracture toughness than Sic whisker bserved in Sic whisker reinforced alumina ceramic cutting 5 Conclusions The wear behaviour of alumina based ceramic cutting tools on machining of martensitic stainless steel-grade 410 (60 HRC)and EN 24 steel (45 HRC) is investigated. Flank wear increases with cutting speed in both the types of ceramic cutting tools. Flank wear in TiC. N] mixed alumina ceramic cutting tool is lower than Sic whisker reinforced alumina( and hardened steel. Crater wear in Ti[C, N mixed alumina ceramic cutting tool is lower than Sic whisker reinforced alumina cutting tool in the machining of martensitic stainless steel and hardened steel. The Sic whisker Fig. 12. SEM micrograph showing the notch wear of Ti[C, N mixed reinforced alumina cutting tool exhibits poor crater wear alumina ceramic cutting tool. resistance during machining. Notch wear in SiC whisker
aspects in notch wear mechanism of the ceramic inserts, as these type of chips abrade a notch at the end of the cut zone. Saw tooth type of chips are observed on machining martensitic stainless steel and it is presented in Fig. 10. These types of chips play an important role in the formation of notch wear. In our machining studies, it is found that SiC whisker reinforced alumina ceramic cutting tool exhibits slightly better performance in notch wear resistance than Ti[C,N] mixed alumina ceramic cutting tool on machining martensitic stainless steel and it is presented in Fig. 11. From the above figure, it can be noted that the notch wear in both of the ceramic cutting tools increases with cutting speed. Fig. 12 shows the SEM micrograph of the notch wear of the Ti[C,N] mixed alumina ceramic cutting tool on machining martensitic stainless steel. The notch wear in Ti[C,N] mixed alumina ceramic cutting tool is clearly seen from this figure. As the Ti[C,N] mixed alumina ceramic cutting tool has lower fracture toughness than SiC whisker reinforced alumina ceramic cutting tool, it can be inferred that the notch wear resistance of the former tool is lower than the latter. Even though the crater wear performance of SiC whisker reinforced alumina cutting tool is poor, it has better notch wear resistance than the Ti[C,N] mixed alumina tool. Generally, the wear scars produced by notch wear are rough, as opposed to the smooth wear surfaces generated by crater wear. Abrasion, adhesion and diffusion are the major wear mechanisms in notch wear. The tool with higher hardness and better fracture toughness is able to resist the abrasive action of the work piece/chip and reduces the notch wear. Fig. 13 shows the notch wear of Ti[C,N] mixed alumina ceramic cutting tool vs time on machining hardened steel and martensitic stainless steel at 270 m/ min. Notch wear in Ti[C,N] mixed alumina cutting tool is higher on machining martensitic stainless steel than that on machining hardened steel and the same trend is also observed in SiC whisker reinforced alumina ceramic cutting tool. 5. Conclusions The wear behaviour of alumina based ceramic cutting tools on machining of martensitic stainless steel-grade 410 (60 HRC) and EN 24 steel (45 HRC) is investigated. Flank wear increases with cutting speed in both the types of ceramic cutting tools. Flank wear in Ti[C,N] mixed alumina ceramic cutting tool is lower than SiC whisker reinforced alumina cutting tool on machining martensitic stainless steel and hardened steel. Crater wear in Ti[C,N] mixed alumina ceramic cutting tool is lower than SiC whisker reinforced alumina cutting tool in the machining of martensitic stainless steel and hardened steel. The SiC whisker reinforced alumina cutting tool exhibits poor crater wear resistance during machining. Notch wear in SiC whisker Fig. 11. Notch wear vs cutting speed of the ceramic cutting tools after machining 15 min on martensitic stainless steel. Fig. 12. SEM micrograph showing the notch wear of Ti[C,N] mixed alumina ceramic cutting tool. Fig. 13. Notch wear of Ti[C,N] mixed alumina ceramic tool vs time on machining at 270 m/min. 196 A. Senthil Kumar et al. / Tribology International 39 (2006) 191–197
A. Senthil Kumar et al. / Tribology intenational 39(2006)191-197 reinforced alumina cutting tool is lower than Ti[C,N] mixed [9 Brandt G. Flank and crater wear mechanisms of alumina based cutting alumina ceramic cutting tool on machining both types of tools when machining steel. Wear 1986: 1 12: 39-56 teel. The flank wear crater wear and notch wear are higher [10] Brandt G, Mikus M. An electron microprobe and cathodolumines- on machining martensitic stainless steel than that on cence study of chemical reactions between tool and workpiece machining hardened steel, which is due to the higher when turning steel with alumina-based ceramics. Wear 1987: 115: hardness of martensitic stainless steel than that of en 24 [11] Stachowiak GW, Stachowiak GB. Wear behaviour of ceramic cutting steel. In conclusion, Ti(C, N mixed alumina ceramic cutting tools. Key Eng Mat 1994 96: 137-64. tool performs better than Sic whisker reinforced alumina [12] Gatto A, luliano L. Chip formation analysis in high-speed machining ceramic cutting tool lining martensitic stainless steel nickel base super alloy with silicon carbide whisker-r alumina. Int J Mach Tools Manuf 1994: 34: 1147-61 and hardened steel [13] Richards N, Aspinwall D Use of ceramic tools for machining nickel based alloys. Int J Mach Tools Manuf 1989: 29: 575-88. [14] Narutaki N, Yamane Y, Hayashi K, Kitagawa T. High-speed References machining of Inconel 718 with ceramic tools. Ann CIrP 1993: 42. (1 Sormakumar T. Advanced ceral [15] Zhao X, Liu J, Zhu B, Miao H, Luo Z.Wear etal cutting applications. Key Eng Mat RL. Harries DR, editors. High 1996-314:1 steel Ceram Int 1997: 23(3): 197-202 steels for nuclear applications. West Conshohocken, [16] Zhao X, Liu J, Zhu B, Miao H, Luo Z. Tribological characteristics ia. USA: ASTM International: 2001 f Si3 Na ceramic sliding on stainless steel. Wear 1997: 206(1-2): 3 J Ceramics and CBN. Manuf Eng 1999: 122: 66. [4] Silva LR, Abrao AM. Machining of the hardened AISI 4340 steel [17] Chuanzhen H, Zhaoqian L, Xing A, Shusheng Z Cutting performan using ceramic and PCBn tooling. Sci Eng J 1999: 8: 85-92. of an advanced ceramic tool and its wear mechanism. Ind Ceram 5] Brandt G. Ceramic cutting tools, state of the art and development 1998:18(1):25-8 trends. Mater Technol 1999: 14: 17-22. [18] Liu Y, Liu J, Zhu B. Wear performance and mechanism of Si3N4 [6] El-Wardany Tl, Mohamed E, Elbestawi MA Material side flow in omposite ceramic cutting tool. Tribology 1997: 17(2): 105-14. finish turning of hardened steel with ceramic tools. Contact problems [19] Liu Y, Liu J, Zhu B, Luo Z Hezhuo M. Computer simulation of the and surface interactions in manufacturing and tribological systems. temperature distribution on the surface of ceramic cutting tools. Wear vol. 67. New York: ASME, PED; 1993. pp 159-170 1997;210(1-2):39-44. [7 Lo Casto S, Lo Valvo E, Lucchini E, Maschio S, Piacentini M [20] Amitabha B, editor. Metal cutting theory and practice. Calcutta: New Ruisi VF Ceramic materials wear mechanisms when cutting nickel Central Book Agencies(P)Ltd: 2000. based alloys 999225(1):227-33 [21] Lo Casto S, Lo Valvo E, Lucchini E, Maschio S, Piacentini M, aviour and wear mechanism of ceramic tools in Ruisi VF. Machining of steel with advanced ceramic cutting tools. alloy steel. Wear 1990: 139: 439-5 Key Eng Mat1996;114:105-34
reinforced alumina cutting tool is lower than Ti[C,N] mixed alumina ceramic cutting tool on machining both types of steel. The flank wear, crater wear and notch wear are higher on machining martensitic stainless steel than that on machining hardened steel, which is due to the higher hardness of martensitic stainless steel than that of EN 24 steel. In conclusion, Ti[C,N] mixed alumina ceramic cutting tool performs better than SiC whisker reinforced alumina ceramic cutting tool on machining martensitic stainless steel and hardened steel. References [1] Sornakumar T. Advanced ceramic–ceramic composite tool materials for metal cutting applications. Key Eng Mat 1996;114:173–88. [2] Klueh RL, Harries DR, editors. High chromium ferritic and martensitic steels for nuclear applications. West Conshohocken, Pennsylvania, USA: ASTM International; 2001. [3] Schneider J. Ceramics and CBN. Manuf Eng 1999;122:66. [4] Silva LR, Abrao AM. Machining of the hardened AISI 4340 steel using ceramic and PCBN tooling. Sci Eng J 1999;8:85–92. [5] Brandt G. Ceramic cutting tools, state of the art and development trends. Mater Technol 1999;14:17–22. [6] El-Wardany TI, Mohamed E, Elbestawi MA. Material side flow in finish turning of hardened steel with ceramic tools. Contact problems and surface interactions in manufacturing and tribological systems. vol. 67. New York: ASME, PED; 1993. pp. 159–170. [7] Lo Casto S, Lo Valvo E, Lucchini E, Maschio S, Piacentini M, Ruisi VF. Ceramic materials wear mechanisms when cutting nickelbased alloys. Wear 1999;225(1):227–33. [8] Hong X. Wear behaviour and wear mechanism of ceramic tools in machining hardened alloy steel. Wear 1990;139:439–51. [9] Brandt G. Flank and crater wear mechanisms of alumina based cutting tools when machining steel. Wear 1986;112:39–56. [10] Brandt G, Mikus M. An electron microprobe and cathodoluminescence study of chemical reactions between tool and workpiece when turning steel with alumina-based ceramics. Wear 1987;115: 243–63. [11] Stachowiak GW, Stachowiak GB. Wear behaviour of ceramic cutting tools. Key Eng Mat 1994;96:137–64. [12] Gatto A, Iuliano L. Chip formation analysis in high-speed machining of a nickel base super alloy with silicon carbide whisker-reinforced alumina. Int J Mach Tools Manuf 1994;34:1147–61. [13] Richards N, Aspinwall D. Use of ceramic tools for machining nickel based alloys. Int J Mach Tools Manuf 1989;29:575–88. [14] Narutaki N, Yamane Y, Hayashi K, Kitagawa T. High-speed machining of Inconel 718 with ceramic tools. Ann CIRP 1993;42: 103–6. [15] Zhao X, Liu J, Zhu B, Miao H, Luo Z. Wear behaviour of Al2O3– Ti[C,N] composite ceramic sliding against pure Al, Fe and stainless steel. Ceram Int 1997;23(3):197–202. [16] Zhao X, Liu J, Zhu B, Miao H, Luo Z. Tribological characteristics of Si3N4 ceramic sliding on stainless steel. Wear 1997;206(1–2): 76–82. [17] Chuanzhen H, Zhaoqian L, Xing A, Shusheng Z. Cutting performance of an advanced ceramic tool and its wear mechanism. Ind Ceram 1998;18(1):25–8. [18] Liu Y, Liu J, Zhu B. Wear performance and mechanism of Si3N4 composite ceramic cutting tool. Tribology 1997;17(2):105–14. [19] Liu Y, Liu J, Zhu B, Luo Z, Hezhuo M. Computer simulation of the temperature distribution on the surface of ceramic cutting tools. Wear 1997;210(1–2):39–44. [20] Amitabha B, editor. Metal cutting theory and practice. Calcutta: New Central Book Agencies (P) Ltd.; 2000. [21] Lo Casto S, Lo Valvo E, Lucchini E, Maschio S, Piacentini M, Ruisi VF. Machining of steel with advanced ceramic cutting tools. Key Eng Mat 1996;114:105–34. A. Senthil Kumar et al. / Tribology International 39 (2006) 191–197 197
