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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。
The performance of a 785 MPa low-alloy high-strength hull near the critical area Ac1 of the heat-treated specimens were tested to study the impact of Ac1 near the critical area on the performance and yield ratio, the optical and transmission electron microscopy of the experimental steel The microstructure of the test steel was analyzed and the correlation between the microstructure and the properties of the test steel was analyzed. The results show that the microstructure of the test steel is changed by heat treatment near the critical region of Ac1. The microstructure of the steel after heat treatment is characterized by the distribution of fine martensite / MA elements, carbides, a small amount of retained austenite on the tempered martensite matrix, fine dispersion Of the nano-copper precipitation phase; Multivariate complex phase transformation of the martensite and retained austenite reduced the yield point of the test steel to improve the work hardening rate and uniform elongation of the steel, reducing the test steel yield ratio At the same time, the refinement of the organizational structure to ensure the plasticity and toughness of the material.