Ni-Cr-Mo-V鋼の破壊じん性特性に及ぼすS量の影響

概要

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The forging process of large products sometimes requires more than a month for repeated heating to high temperatures. The heating of steels up to an extremely high temperature during forging causes precipitation of sulfide inclusions at the grain boundaries which makes the grain boundaries weaken. The phenomenon is called overheating which sometimes reveals a loss of ductility and toughness in tensile and impact tests. In this study, the effect of overheating on the fracture toughness was investigated using Ni-Cr-Mo-V steels with various sulfur contents. It was revealed that the overheating led to a decrease in fracture toughness J_<Ic> and tearing modulus T_J of the materials, depending on sulfur content, heating temperature and cooling rate. The degradation was caused by the crack initiation and propagation through the grain boundaries weakened due to the manganese sulfide precipitates. Quenching and tempering heat treatments improved the toughness properties of the overheated steels.
社団法人日本材料学会の論文
1984-05-15