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结合Gleeble3500热力模拟与工业试验,通过显微组织观察、硬度测试、拉伸试验与TEM研究了形变与冷却工艺对钒微合金化600 MPa级钢筋组织、力学性能及析出相的影响。结果表明:试验钢的铁素体转变范围广,无变形且冷速大于5℃/s时,组织中开始形成贝氏体与马氏体。相变前粗大的原奥氏体晶粒将促进贝氏体与板条马氏体形成;原奥氏体晶粒细小与低温形变有利于铁素体与岛状马氏体的形成。冷速较小时,试验钢经形变后的硬度值大于无形变后的硬度值。冷速较大时,试验钢无形变的硬度值大于形变后的硬度值。为了获得细小铁素体与珠光体以及细小弥散的氮化钒,最佳生产工艺为:终轧温度大于1000℃,冷速为3℃/s;或终轧温度为900℃,冷速为5℃/s。
Combined with Gleeble 3500 thermal simulation and industrial test, the effects of deformation and cooling process on microstructure, mechanical properties and precipitated phase of vanadium microalloyed 600 MPa steel were studied by microstructure observation, hardness test, tensile test and TEM. The results show that the bainite and martensite begin to form in the microstructure of the test steel with a wide range of ferrite transformation without deformation and a cooling rate greater than 5 ℃ / s. The former coarse austenite grains before the phase transformation will promote the formation of bainite and lath martensite. The small and low temperature deformation of the former austenite grain is favorable to the formation of ferrite and island martensite. When the cooling rate is small, the hardness of the test steel after deformation is greater than that of the non-deformation hardness. Larger cooling rate, the test steel without deformation of the hardness value greater than the hardness after deformation. In order to obtain fine ferrite and pearlite and finely dispersed vanadium nitride, the best production process is: finishing temperature is greater than 1000 ℃, cooling rate is 3 ℃ / s; or finishing temperature is 900 ℃, cooling rate is 5 ℃ / s.