真空浸炭におけるエッジ部過剰浸炭の疲労強度に対する影響

抄録

To study the effect of excess carburizing at edge on fatigue strength of vacuum-carburizing steels, the relationship between the apex angles and fatigue strength was investigated with the four-point bending tests loading maximum stress at top edge. It was found that the strength of atmosphere-carburized specimens hardly depends on edge angles. The strength of vacuum-carburized specimens with near 150 deg edge is higher than that of atmosphere-carburized specimen. However, decreasing apex angles significantly lowers the fatigue strength of vacuum-carburized specimen due to excess carburizing resulting in carbide precipitation. Fatigue strength of vacuum-carburized specimen with the same edge section profile. Excess carburizing at edge occurs in diffusion period which is one of the unavoidable phenomena in vacuum- carburizing.