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采用光学显微镜和力学性能测试设备研究了不同热处理方式对550 MPa级高强度船板组织和性能的影响。结果表明:随正火温度的升高(低于860℃),组织的变化并不明显,均为铁素体+粒状贝氏体+M/A;继续升高温度,铁素体晶粒尺寸明显粗大,带状组织减轻;钢板的屈服强度、抗拉强度都下降,屈服强度不能满足标准要求。高温热处理再经回火后,组织中的M/A岛几乎完全分解;屈服强度、伸长率及低温冲击韧度明显提高,抗拉强度下降。在高出Ac3点0~40℃进行正火+650℃回火处理,钢板的综合力学性能最佳。
The effects of different heat treatment methods on the microstructure and properties of 550 MPa high strength ship deck were studied by optical microscope and mechanical property test equipment. The results show that with the increase of normalizing temperature (less than 860 ℃), the microstructure changes are not obvious, which are ferrite + granular bainite + M / A; the temperature continues to increase, the ferrite grain size Obviously coarse, strip organization to reduce; steel yield strength, tensile strength decreased, yield strength can not meet the standard requirements. After tempering at high temperature, the M / A island in the structure decomposed almost completely. The yield strength, elongation and impact toughness at low temperature obviously increased, and the tensile strength decreased. In the Ac3 point 0 ~ 40 ℃ for normalizing +650 ℃ tempering, the best mechanical properties of steel.