超高强贝氏体钢的冲击性能和组织特征

Impact properties and microstructural characteristics of ultra-high strength bainitic steel

通过系列冲击和回火实验,研究了TMCP工艺条件下100kg级煤机用钢的冲击性能和显微组织的演变规律。结果表明,实验钢的组织以马氏体和下贝氏体为主。钢板的韧脆转变温度在-70℃^-50℃之间,钢板断裂为韧性断裂。钢板的冲击功横向比纵向高50J左右。经300℃回火后组织仍然具有较明显的板条特征,基体位错密度大幅下降,少量碳化物已有析出;回火温度到600℃时,板条特征不明显,为典型上贝氏体组织。回火后钢板的冲击功下降约30%。

Toughness and microstructure evolution of lOOkg-class coal machine with high-strength steel were studied through series impact and tempering test under TMCP conditions. The results show that the microstructure was mainly composed of martensite and lower-hainite. Ductile-brittle transition temperature of the present steel is in range of -70℃～-50℃, and ductility fracture feature can be observed at the tensile fracture surfaces. Transverse impact energies are higher than longitudinal ones by about 50J. Lathy microstructure and less carbides precipitated is still observed after tempering at 300℃, and dislocation density is also highly reduced; The upper-bainite dominant microstructure are obtained due to the absent of lathy microstructure after tempering at 600℃ Impact energies of the steel plates are decreased by about 30% after tempering.