J Fail. Anal and Preven.(2010)10: 399-407 existence of martensite, which occurs at the inner part of known inducing corrosion on metals, especially pitting austenite by means of strain-induced martensitic phase corrosion. However, it has been reported that a relatively hydrogen diffusion coefficient and permeability of mar- to the pitting corrosion of carbon steels [6]. In thUrs effect transformations, increases the hydrogen uptake because the high concentration of F will provide an inhibitor tensite is higher than austenite [4]. Therefore, the concentration of F is 6.4 g/ and may explain why martensitic transformation products could act as a suitable was no obvious evidence of pitting corrosion on the medium for hydrogen to entry and transport in the stainless stainless steel belt. steel [5] lon Chromatography Hydrogen Absorption lon chromatography was used to semi-quantitatively ana According to the technological parameters, hydroge lyze the main anions in the solutions concentration in the original 304 stainless steel belt is encounter,i.e, the deoxidation solution, the electrolytic 6 ppm, whereas the value for the failed one which used deburring solution, and the deplating solution. In addition only one month exceeds 17 ppm. The hydrogen absorption to the sulfate SO4- which was detected in all three solu- analysis thus showed the use had increased the hydroger imes of the normal tions, the fiuoride anion F was particularly found in the content to nearly thre deoxidation solution, as seen in Fig. 4. Commonly, So, 2- increase in hydrogen may result from hydrogen evolution is a main component in the electroplating solution and is reactions during the engineering production process and present as sulfuric acid. The F is a halide ion that is will favor the onset of hydrogen embrittlement SEM and EDS Analysis Surface of failed Steel Belts Figure 5 displays the SEM micrographs of the surface of the normal surface morphology. Regularly distributed micro cracks and pits can be clearly found in Fig. 5b and c 02040608.010.012014 and are absent in Fig. 5a. Additionally, there are linear Fig 4 Chromatographic analysis result of deoxidation solution cracks parallel to the fracture, and some of these cracks Fig§ SEM micrograph of defects in fractured belt bracket surface: (a) morphology of belt bracket surface, (b) enlarged local region, and (e) enlarged ()三existence of martensite, which occurs at the inner part of austenite by means of strain-induced martensitic phase transformations, increases the hydrogen uptake because the hydrogen diffusion coefficient and permeability of mar￾tensite is higher than austenite [4]. Therefore, the martensitic transformation products could act as a suitable medium for hydrogen to entry and transport in the stainless steel [5]. Ion Chromatography Ion chromatography was used to semi-quantitatively ana￾lyze the main anions in the solutions that the steel belts encounter, i.e., the deoxidation solution, the electrolytic deburring solution, and the deplating solution. In addition to the sulfate SO4 2 which was detected in all three solu￾tions, the fluoride anion F was particularly found in the deoxidation solution, as seen in Fig. 4. Commonly, SO4 2 is a main component in the electroplating solution and is present as sulfuric acid. The F is a halide ion that is known inducing corrosion on metals, especially pitting corrosion. However, it has been reported that a relatively high concentration of F will provide an inhibiting effect to the pitting corrosion of carbon steels [6]. In this case, the concentration of F is 6.4 g/l and may explain why there was no obvious evidence of pitting corrosion on the stainless steel belt. Hydrogen Absorption According to the technological parameters, hydrogen concentration in the original 304 stainless steel belt is 6 ppm, whereas the value for the failed one which used only one month exceeds 17 ppm. The hydrogen absorption analysis thus showed the use had increased the hydrogen content to nearly three times of the normal value. Such an increase in hydrogen may result from hydrogen evolution reactions during the engineering production process and will favor the onset of hydrogen embrittlement. SEM and EDS Analysis Surface of Failed Steel Belts Figure 5 displays the SEM micrographs of the surface of the failed stainless steel belts and compares that surface to the normal surface morphology. Regularly distributed micro cracks and pits can be clearly found in Fig. 5b and c and are absent in Fig. 5a. Additionally, there are linear Fig. 4 Chromatographic analysis result of deoxidation solution cracks parallel to the fracture, and some of these cracks Fig. 5 SEM micrograph of defects in fractured belt bracket surface: (a) morphology of belt bracket surface, (b) enlarged local region, and (c) enlarged side of fracture 402 J Fail. Anal. and Preven. (2010) 10:399–407 123