【摘要】 通过对一种785 MPa级低合金高强度船体钢Ac1附近临界区热处理试样的性能测试,研究了Ac1附近临界区处理对其性能及屈强比的影响,采用光学和透射电镜观察了试验钢的微观组织,分析了试验钢性能与微观组织结构的相关性。结果表明:Ac1附近临界区热处理改变了试验钢的微观组织结构,热处理后钢板组织为回火马氏体基体上分布细小马氏体/M-A组元、碳化物、少量残留奥氏体、细小弥散的纳米铜析出相;多元复相组织中的转变马氏体及残留奥氏体降低了试验钢的屈服点,提高了钢板的加工硬化率和均匀伸长率,降低了试验钢的屈强比;同时,细化的组织结构保证了材料的塑韧性。更多还原

【Abstract】 The influence of tempering temperature and time on mechanical properties and yield ratio of a 785 MPa high strength low alloyed steel( HSLA) quenched and tempered in intercritical temperature range was studied by tensile and impact tests,microstructure of the steel was observed by metallographic microscope and transmission electron microscopy,and the relationship between microstructure and mechanical properties was analyzed. The results show that the microstructure of the steel after tempering at the temperatures above Ac1 consisted of tempered martensite,fine martensite / M-A,carbide,a little retained austenite and dispersed fine nano-Cu precipitates. Because of the quenched martensite and retained austenite in the microstructure,the yield stress of the steel is reduced,the work hardening coefficient and uniform elongation are increased. Therefore,the yield ratio of the steel is decreased. Meanwhile,the plasticity and toughness of the steel is improved due to the fine microstructure.更多还原