钴和钼对高钴铬钼轴承钢组织及力学性能影响

通过性能测试和组织观察,研究了钴和钼两种元素对高钴铬钼轴承钢组织和力学性能的影响规律。结果表明,钴和钼元素质量分数降低及匹配改变会使试验钢的综合力学性能降低。试验钢的淬火及回火组织为板条马氏体+残余奥氏体,在钴和钼元素的影响下,Cr_(eq)、Ni_(eq)差值变大,致使试验钢组织中残余奥氏体减少,产生δ-铁素体。并且,碳化物由质量分数1.17%的颗粒状M6C改变成质量分数低于0.15%的针状M_2C。试验钢的强度主要受碳化物影响,而在碳化物质量分数低于0.15%时,w(Co)/w(Mo)的值越小,位错密度越高,则试验钢的强度越高。试验钢的韧性主要受δ-铁素体影响,δ-铁素体面积分数大于6.3%,则试验钢会产生脆性,面积分数小于1.1%则试验钢的韧性较好。

Influence of Co and Mo on microstructure and mechanical properties of bearing steel with high content of cobalt,chromium and molybdenum

The influence of Co and Mo on the microstructure and mechanical properties of bearing steel with high con-tent of cobalt,chromium and molybdenum wereinvestigated by the testof performance and the observationof microstruc-ture. Main results showthat the reduction of Co and Mo contents and the change of Co to Mo ratio could cause the de-crease of comprehensive mechanical properties of test steels. The hardening and tempering microstructure of test steels were lath martensite and retained austenite,the difference between Creq and Nieq became larger under the influence of Co and Mo elements,which reduced the content of retained austenite and produced δ-ferrite. Moreover,the carbides changed from the 1.17%granulated M6C to the 0.15%acicular M2C. The strength of test steels was mainly affected by carbides,when the contents of carbides was less than 0.15%,With the decrease of w(Co)/w(Mo),the dislocation density increased,and the strength of test steels increased. The toughness of test steels was mainly affected byδ-ferrite. If the content ofδ-ferrite was more than 6.3%,the test steel would become brittle,if the contentwas less than 1.1%,the tough-ness of test steels would be excellent.