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针对HQ785试验钢,采用Gleeble-1500热模拟试验机进行了单向外加拉/压应力下的等温相变实验,等温温度分别是425℃和475℃,所加应力依次为20、40和60 MPa,通过光学显微镜和透射电镜对相变后的显微组织进行了观察与分析。结果表明,外加应力作用下的等温相变组织是粒状贝氏体,外加应力使无明显晶界的显微组织转变为晶界清晰的细小晶粒;粒状贝氏体中贝氏体铁素体的亚单元,随着外加拉应力的增加逐渐由条片向块状变化,随着外加压应力的增加逐渐由块状向条片变化。
Aiming at the HQ785 test steel, the isothermal transformation experiments under uniaxial tension / compression stress were carried out by using Gleeble-1500 thermal simulation tester. The isothermal temperatures were 425 ℃ and 475 ℃, respectively, and the stresses were 20, 40 and 60 MPa The microstructures after transformation were observed and analyzed by optical microscope and transmission electron microscope. The results show that the isothermal transformation under applied stress is granular bainite, and the stress is applied to transform the microstructure without obvious grain boundaries into fine grains with clear grain boundaries. The granular bainitic bainitic ferrite Of the subunits gradually change from the strip to the block with the increase of the applied tensile stress and gradually change from the block to the strip with the increase of the applied compressive stress.