MSA-25534: No of Pages 9 ARTICLE IN PRESS D Jianxin et aL. Materials Science and Engineering A xxx(2009)xxx-xXX AWT AWT AWT Al AWT AWT AWT AWT AWT AWT Fig 1. SEM micrographs of the cross-section surface of AWT+ AT multilayered ceramic materials( layer number N= 3)with thickness ratio p of (a)AWT stress-free material, b)p=0.5.(c)p=1.(d)p=2.(e)p=6,and(p=8. the finite element method (FEM). The microstructure of 3. Results and discussion the layered materials was investigated by scanning electron mIcroscopy. 3.1. Microstructural characterization of the AWT+ AT multilayered ceramic materials 2. 2. Cutting tests The SEM micrographs of the cross-section surface of the AWT+ AT multilayered ceramic materials with different thickness Cutting tests were carried out on a CA6140 lathe. the ratios(p) and number of layers(n) are shown in Figs. 1 and 2, ools used were the AWT+ AT multilayered ceramic tools respectively, where the bright layers correspond to AWT and the AWT stress-free tool having the following geometry: rake dark ones to AT composition. The layered architectures can be yo=-15, clearance angle ao=5, inclination angle As clearly seen, the Awt and at layers are all compact without voids cutting edge angle Kr=45 and are reasonably uniform and the interfaces are straight and The workpiece material used was nodular cast iron(QT420-10) well-distinguishable with a hardness of HB 190-210 in the form of round bar. No cutting Closer examination at higher magnification on the interface fluid was used in the machining processes. All tests were carrie structure of these multilayered ceramic materials is illustrated in out with the following parameters: depth of cut ap=0.5 mm, feed Fig 3. No cracks or delaminations can be detected at the interfaces rate=0. 1 mm/rev, cutting speed v=108 m/min Tool flank wear was measured using a 20x optional microscope 3.2. Residual stresses in AWT+ AT multilayered ceramic materials system linked via transducers to a digital read out The worn rake nd flank regions on the tools were examined using scanning elec he magnitude of residual stresses is proportional to the Cte tron microscopy(HITACH S-570). mismatch between constituent layers, and also depends on the AWT AWT AWT AWT AWT 2 Fig. 2. SEM micrographs of the cross-section surface of AWT+ AT multilayered ceramic materials( thickness ratio, p=l)with layer numbers of (a)N=3, (b)N=5, and (c)N=7. Please cite this article in press as: D Jianxin, et al, Mater Sci Eng. A(2009). doi: 10. 1016/j. msea. 2009.09.020Please cite this article in press as: D. Jianxin, et al., Mater. Sci. Eng. A (2009), doi:10.1016/j.msea.2009.09.020 ARTICLE IN PRESS GModel MSA-25534; No. of Pages 9 D. Jianxin et al. / Materials Science and Engineering A xxx (2009) xxx–xxx 3 Fig. 1. SEM micrographs of the cross-section surface of AWT + AT multilayered ceramic materials (layer number N = 3) with thickness ratio p of (a) AWT stress-free material, (b) p = 0.5, (c) p = 1, (d) p = 2, (e) p = 6, and (f) p = 8. the finite element method (FEM). The microstructure of the layered materials was investigated by scanning electron microscopy. 2.2. Cutting tests Cutting tests were carried out on a CA6140 lathe. The cutting tools used were the AWT + AT multilayered ceramic tools and the AWT stress-free tool having the following geometry: rake angle o = −15◦, clearance angle ˛o = 5◦, inclination angle s = −5◦, side cutting edge angle Kr = 45◦. The workpiece material used was nodular cast iron (QT420-10) with a hardness of HB 190–210 in the form of round bar. No cutting fluid was used in the machining processes. All tests were carried out with the following parameters: depth of cut ap = 0.5 mm, feed rate f = 0.1 mm/rev, cutting speed v = 108 m/min. Tool flank wear was measured using a 20× optional microscope system linked via transducers to a digital read out. The worn rake and flank regions on the tools were examined using scanning elec￾tron microscopy (HITACH S-570). 3. Results and discussion 3.1. Microstructural characterization of the AWT + AT multilayered ceramic materials The SEM micrographs of the cross-section surface of the AWT + AT multilayered ceramic materials with different thickness ratios (p) and number of layers (N) are shown in Figs. 1 and 2, respectively, where the bright layers correspond to AWT and the dark ones to AT composition. The layered architectures can be clearly seen, the AWT and AT layers are all compact without voids, and are reasonably uniform and the interfaces are straight and well-distinguishable. Closer examination at higher magnification on the interface structure of these multilayered ceramic materials is illustrated in Fig. 3. No cracks or delaminations can be detected at the interfaces. 3.2. Residual stresses in AWT + AT multilayered ceramic materials The magnitude of residual stresses is proportional to the CTE mismatch between constituent layers, and also depends on the Fig. 2. SEM micrographs of the cross-section surface of AWT + AT multilayered ceramic materials (thickness ratio, p = 1) with layer numbers of (a) N = 3, (b) N = 5, and (c) N = 7.