ショットピーニング条件が浸炭鋼における無害化可能な表面欠陥寸法に及ぼす影響

抄録

The objective of this study was to find the shot peening (SP) conditions for to increase the size of defects that can be is rendered harmless in vacuum-carburized steel. After introducing semi-circular slits of 0.1, 0.2, and 0.3 mm depth into vacuum-carburized SCM420H steel, SP was performed under two different conditions to vary the depth of compressive residual stress (crossing point). One SP condition is a common condition for carburized steel and is called CSP. The other condition provided a deeper crossing point and is referred to as DSP. The crossing points for CSP and DSP were 0.20 mm and 0.25 mm, respectively. These specimens were subjected to plane bending fatigue tests at a stress ratio of R = -1. For CSP and DSP, the depth of slit that could be rendered the defect harmless was 0.10 mm and 0.20 mm, respectively. These results indicate that deep compressive residual stresses can increase the harmless defect size that can be rendered. The fracture mechanics study enabled the prediction of differences in the defect sizes that could be rendered become harmless under different SP conditions.