J Fail. Anal and Preven.(2010)10: 399-407 Fig. 1 Process, medium, and concentration of tin plating Electrolytic Deburring tration approximate 70-80p/L) ( flumes filled by acidic solution containing fluoride anion Activation Once water spray concentration approximate 95-120B/L) flumes acid and acidity cor proximate 95-120g/L (Alkali concentration approximate 45-50g/L) M Hot-water cleaning Once water spray 3 times blow drying planing (5 bathes Methanesulfonic acid and thorough survey through field investigations and sampling respectively. Figure 2b indicates that the failed position is nalyses on the causes and the mechanisms failure the bottom bracket of the belt moreover the fat fracture is was required to reduce the downtime and resulting increase a sign of macroscopically brittle failure processes, seen in in production costs. Consequently, ion chromatography (IC) Fig. 2c was used for determining chemical composition of plating solution, while hydrogen analyzer, photoelectric direct Matrix Materials Examination reading spectrometer, metallurgical microscope (MM) scanning electronic microscope(SEM) were applied to Chemical compositions of three types of the stainless steel detect the chemical compositions, metallographic structures belt samples, i.e., the original one, the failed one which used and macro micro morphologies of the failured stainless only one month, and the normal one which used longer than steel belts, respectively. Furthermore, finite element method 4 months, were inspected by photoelectric direct reading (FEM) as an auxiliary method was also employed to simu- spectrometer. The main content in matrix material is listed late the stress distribution on the steel belts under high in Table 1. It is found that the matrix material of the failure pressure washing water. The analysis results showed that the steel belt was 301 stainless steel which has higher carbon main cause of this failure was hydrogen embrittlement, content and less chromium than the 304 stainless steel which was introduced from the solutions used in deoxidation required from design. This contrasts the matrix of the belt and electroplating steps. Finally, mechanisms of the failure used for 4 months which was 316L stainless steel. The 316L were discussed and suggestions were proposed, which have steel has an excellent corrosion resistance but a relatively significant importance not only in failure prevention for steel higher cost. Commonly, as metastable austenitic stainless belts used under similar service conditions but also in steels [1], both 301 and 304 exhibit a severer hydrogen developing a better understanding of hydrogen embrittle- embrittlement aptitude than stable austenitic stainless steels ment in engineering practice. The service life of stainless [2]. This observation suggests that inappropriate materials steel belts was extended to the normal level by accepting selection may be one of the failure causes. hese suggestions. In order to judge whether the steel belts were given a surface treatment to increase of corrosion resistance chemical compositions of the polished original stainless Experimental Methods and Results steel belts, and the unpolished one were measured and are listed in Table 1 [3. It's obvious that both surfaces have Visual observation the similar chemical compositions, demonstrating that no surface treatment was conducted. Thus. the lack of The different macro morphologies of the original and required surface treatment to the steel belts is another ailed stainless steel belts are shown in Fig 2a and b. factor of the failurethorough survey through field investigations and sampling analyses on the causes and the mechanisms of this failure was required to reduce the downtime and resulting increase in production costs. Consequently, ion chromatography (IC) was used for determining chemical composition of plating solution, while hydrogen analyzer, photoelectric direct reading spectrometer, metallurgical microscope (MM), scanning electronic microscope (SEM) were applied to detect the chemical compositions, metallographic structures and macro & micro morphologies of the failured stainless steel belts, respectively. Furthermore, finite element method (FEM) as an auxiliary method was also employed to simu￾late the stress distribution on the steel belts under high pressure washing water. The analysis results showed that the main cause of this failure was hydrogen embrittlement, which was introduced from the solutions used in deoxidation and electroplating steps. Finally, mechanisms of the failure were discussed and suggestions were proposed, which have significant importance not only in failure prevention for steel belts used under similar service conditions but also in developing a better understanding of hydrogen embrittle￾ment in engineering practice. The service life of stainless steel belts was extended to the normal level by accepting these suggestions. Experimental Methods and Results Visual Observation The different macro morphologies of the original and the failed stainless steel belts are shown in Fig. 2a and b, respectively. Figure 2b indicates that the failed position is the bottom bracket of the belt. Moreover, the flat fracture is a sign of macroscopically brittle failure processes, seen in Fig. 2c. Matrix Materials Examination Chemical compositions of three types of the stainless steel belt samples, i.e., the original one, the failed one which used only one month, and the normal one which used longer than 4 months, were inspected by photoelectric direct reading spectrometer. The main content in matrix material is listed in Table 1. It is found that the matrix material of the failure steel belt was 301 stainless steel which has higher carbon content and less chromium than the 304 stainless steel required from design. This contrasts the matrix of the belt used for 4 months which was 316L stainless steel. The 316L steel has an excellent corrosion resistance but a relatively higher cost. Commonly, as metastable austenitic stainless steels [1], both 301 and 304 exhibit a severer hydrogen embrittlement aptitude than stable austenitic stainless steels [2]. This observation suggests that inappropriate materials selection may be one of the failure causes. In order to judge whether the steel belts were given a surface treatment to increase of corrosion resistance, chemical compositions of the polished original stainless steel belts, and the unpolished one were measured and are listed in Table 1 [3]. It’s obvious that both surfaces have the similar chemical compositions, demonstrating that no surface treatment was conducted. Thus, the lack of a required surface treatment to the steel belts is another factor of the failure. Fig. 1 Process, medium, and concentration of tin plating technics 400 J Fail. Anal. and Preven. (2010) 10:399–407 123