抄録
Medium manganese cast steels containing 0.35%C, 2.8-5.5%Mn were studied in order to find out what effects manganese content and heat treatment have on hardness and toughness. Medium manganese cast steels containing 0.35%C, 2.8-5.5%Mn became extremely hard exhibiting a uniform overall structure. In the steel containing 4.21% manganese especially, hardness up to HRC 47 and impact value up to 1.45kg⋅m/cm2 were obtained after the heat treatment consisting of annealing at 900°C followed by normalizing at 810°C and tempering at 230°C. This would assure practical service as an abrasion resistant material. However, some signs of grain boundary deterioration and embrittled matrices which were recognizedly low tempering temperature embrittlement were found in fractographic observation. By adding 1.60-2.68%Si and 0.55%Mo to improve embrittlement and with appropriate heat treatment, hardness of HRC 52 and impact value of 2.05kg⋅m/cm2 can be obtained.
