J Fail. Anal. and Preven. (2010)10: 399-407 have connected to form a larger one. Moreover, a peculiar Fractograph of Failed Steel Belts morphology of step-shaped crack group found on the sur face is the typical feature of hydrogen-induced stepwise In Fig. 7a, a flat cross section can be observed on the cracking(HISC). According to the EDS result shown in fracture. This fracture topography is generally a sign of Fig. 6, it can be seen that no chlorine and fluorine elements macroscopically brittle fracture and is consistent with the were found on the surface of the failed steel belts, which failure mechanism of hydrogen embrittlement. Addition- indicates that halide-induced pitting corrosion should not ally, a long dark strip with even smoother surface is seen be blamed for the emergence of the pits on the surface. on the bottom of the fracture, Fig. 7b. This is a typical Hence, it can be further identified that pits around the morphology of erosion, and then it can be inferred that the micro cracks were caused by hydrogen blistering(HB). To ultimate fracture of the steel belts may also involve the sum up, all the above observations are relevant to hydrogen high-pressure water washing procedure embrittlement of the stainless steel belt which reduced its Both obvious cleavage steps and dimples can be found properties and eventually resulted in fracture [71 n Fig 8a. However, the cleavage steps cover most of the cross section, while the dimples were found only in the part of the cross section, seen in Fig. 8b. This phenomenon is consistent with fracture of the steel belts by hydrogen embrittlement with the embrittlement process being initiated from the outer surfaces of the belt In order to qualitatively analyze the effect from the high-pressure washing water (20 MPa) imposed on the stainless steel belt, finite element method(FEM) software was employed to simulate the stress distribution on the belt fter washing. This is actually a two-dimensional (2-D transient elastic-dynamic analysis [8-10], and the meshed FEM model with element of PLANE 82 is presented in Fig. 9. The fractured part was further refined for accuracy Thickness of the belt is 0.5 mm. Poisson ratio and Youngs modulus were set as 0.3 and 2.06X 10- MPa, respectively Fig. 6 Result of EDs Displacement of the left and right sides(except the bracket) Fig. 7 SEM micrograph of fracture surface of belt bracket: b (a) facture surface of belt bracket and (b) enlarge the left NowY SO Moan set W, Dora Bim Mum stainless steel belt's fracture Springhave connected to form a larger one. Moreover, a peculiar morphology of step-shaped crack group found on the sur￾face is the typical feature of hydrogen-induced stepwise cracking (HISC). According to the EDS result shown in Fig. 6, it can be seen that no chlorine and fluorine elements were found on the surface of the failed steel belts, which indicates that halide-induced pitting corrosion should not be blamed for the emergence of the pits on the surface. Hence, it can be further identified that pits around the micro cracks were caused by hydrogen blistering (HB). To sum up, all the above observations are relevant to hydrogen embrittlement of the stainless steel belt which reduced its properties and eventually resulted in fracture [7]. Fractograph of Failed Steel Belts In Fig. 7a, a flat cross section can be observed on the fracture. This fracture topography is generally a sign of macroscopically brittle fracture and is consistent with the failure mechanism of hydrogen embrittlement. Addition￾ally, a long dark strip with even smoother surface is seen on the bottom of the fracture, Fig. 7b. This is a typical morphology of erosion, and then it can be inferred that the ultimate fracture of the steel belts may also involve the high-pressure water washing procedure. Both obvious cleavage steps and dimples can be found in Fig. 8a. However, the cleavage steps cover most of the cross section, while the dimples were found only in the middle part of the cross section, seen in Fig. 8b. This phenomenon is consistent with fracture of the steel belts by hydrogen embrittlement with the embrittlement process being initiated from the outer surfaces of the belt. In order to qualitatively analyze the effect from the high-pressure washing water (20 MPa) imposed on the stainless steel belt, finite element method (FEM) software was employed to simulate the stress distribution on the belt after washing. This is actually a two-dimensional (2-D) transient elastic-dynamic analysis [8–10], and the meshed FEM model with element of PLANE 82 is presented in Fig. 9. The fractured part was further refined for accuracy. Thickness of the belt is 0.5 mm, Poisson ratio and Young’s modulus were set as 0.3 and 2.06 9 105 MPa, respectively. Fig. 6 Result of EDS Displacement of the left and right sides (except the bracket) Fig. 7 SEM micrograph of fracture surface of belt bracket: (a) facture surface of belt bracket and (b) enlarge the left part Fig. 8 SEM micrograph of stainless steel belt’s fracture: (a) expended morphology of stainless steel belt’s fracture and (b) dimples showing expended direction J Fail. Anal. and Preven. (2010) 10:399–407 403 123