低碳低合金复相钢中的残留奥氏体及其机械稳定性

Retained Austenite in a Low Carbon-Low Alloy Multiphase Steel and its Mechanical Stability

作者应用光学显微镜、透射电镜、X射线衍射仪、拉伸试验机研究临界区热处理制度对低碳低合金复相钢中残留奥氏体量的影响和残留奥氏体的机械稳定性及其对拉伸性能的影响。研究结果表明,低碳低合金复相钢中残留奥氏体虽对临界区退火温度,退火时间、冷却方式很敏感。残留奥氏体的机械稳定性低,在拉伸变形过程中易发生应变诱发马氏体转变,其转变过程为:残留奥氏体(f.c.c.)→层错(h.c.p.)→马氏体(b.c.c.)。残留奥氏体对钢的拉伸性能有显著影响,提高σ_b、n_1、n、δ_(?),降低σ_(?)、σ_(?)/σ_b、δ_t、ψ,推迟颈缩形成。

The effect of intercritical annealing regime on amount of retained austenite and mechanical stability and its effect on tensile properties in a low carbon-low alloy multiphase steel have been studied by optical microscope, transmission electron microscope(TEM), X-ray diffractometer aad tensile test machine.The experimental results show that the amount of retained austenite in the low carbon-low alloy multiphase steel is sensitive to the intercritical annealing temperature, annealing time and cooling regime. The retained austenite is unstable mechanically, the strain induced martensite transformation occurs in it, the sequence of transformation is retained austenite(f. c. c.)→stacking fault(h. c. p. )→martensite(b. c. c. ). The effect of retained austenite on tensile properties of steel is remarkable, σ_b, n_(?), n and δ+u are enhanced, σ_(?), σ_(?)/σ_b, δ_t and ψ are decreaced and the resistance to the formation of necking is increaced.