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通过绘制试验钢种的CCT曲线,确定了贝氏体转变区间,研究了贝氏体组织对低碳硅锰钢力学性能的影响。结果表明:400℃C盐浴等温淬火得到板条贝氏体组织,板条宽度均匀,晶界清晰,抗拉强度1140MPa,伸长率21%;450℃C时试验钢为50%板条贝氏体+50%粒状贝氏体的组织,且板条间距较400℃C时大,粒状组织晶界明显比板条状组织晶界模糊;500℃C高温下组织完全转变成粒状,为少量块状马氏体+岛状残余奥氏体,该组织状态下抗拉强度大大下降,只有800MPa,但塑性较好,为30%。综合考虑,板条及粒状贝氏体混合组织力学性能较好。
The bainite transformation interval was determined by drawing the CCT curve of test steel, and the effect of bainite structure on the mechanical properties of low carbon Si-Mn-Mn steel was studied. The results show that the bainite structure is obtained by isothermal quenching in 400 ℃ C salt bath. The width of the lath is uniform and the grain boundaries are clear. The tensile strength is 1140MPa and the elongation is 21%. The test steel is 50% 50% granular bainite, and the lath spacing is larger than that at 400 ° C. The grain boundaries of the granular structure are obviously obscured than the grain boundaries of the lath-like structure. The microstructure completely changes into granular form at the temperature of 500 ° C, Massive martensite + island-like retained austenite, the tensile strength of the state significantly decreased, only 800MPa, but better plasticity, 30%. Taken together, slab and granular bainite mixed tissue better mechanical properties.