GCr15钢复合热处理及多元强韧化——等温工艺与优化复相组织强韧化

Compound Heat Treatment and Multicomponent Strengthening and Toughening of Bearing Steel GCr15

用金相法观察GCr15钢复合热处理中经不同温度、时间等温后显微组织的变化并测出其马氏体点M,据此试探等温参数,设计优化复合热处理工艺,获得了最佳强韧度,这是采诸工艺之长集多元强韧化的结果。进一步研究复相精细组织与其对应的性能,发现:无贯穿先奥氏体(A)晶粒的连冷形成粗针状马氏体(M);含适量(12～15％)下贝氏体(B_下)且其中碳化物(C)尚细小而铁素体(F_B)仍残存着过饱和固溶强化;以及受先连冷形成的M、B_下分割细化A和与其相关的成分均匀的A微区变小而导致形成细化的M都对M+B_下复相强韧化起重要作用。

by using metallographic method, the Ms of GCr15 for compound heat treatment has been determined, according to the Ms, isothermal parameters have been tested and the best of which has been found, thus optimum compound heat treatments have been designed. By using theseparameters, the steel obtains much achievements in strength and toughness, this is the results of incorporating merits of various processes and combining together with the multicomponent strengthening and toughening. Further microscopy study of OM and TEM on dual-phase structures of isothermal treatment shows that there is no coarse needle-like martensite across prior austcnite grain, it contains optimum amount (12～15%) of lower bainitc which consisting fine carbide and supersaturated ferrite that has the solution hardening effect and fine martensite formed from the refined austenite separated by forming martensite or lower bainite, and the relevant micro-heterogeneous austcnite all play important role in the strengthening and toughening of the dual-phase of martensiteflower hainite.