【摘要】 采用形变热处理新工艺加工超高强度低合金钢30Cr3SiNiMoVA(30Cr3)以降低工件畸变并获得良好的综合强韧性。通过光学显微镜和SEM观察分析微观组织的转变与特征,研究形变热处理过程中两次回火工艺对力学性能与组织的影响,发现30Cr3钢的强度受去应力回火影响明显。在回火过程中拉伸强度随着回火温度上升而提高,这要归因于大变形产生的位错促进了碳化物的析出从而提高了沉淀强化;但是回火温度超过400℃造成碳化物过度长大,弥散强化效果降低导致强度开始下降。根据对组织和性能的分析确定最佳的回火温度是400℃。更多还原

【Abstract】 Microstructure resulted from thermomechanial processing for an ultrahigh strength microalloyed steel 30Cr3SiNiMoVA( 30Cr3)was characterized using optical and scanning electron microscopy in order to optimize parameters in the processing to obtain required properties. Tensile properties and work hardening behavior were analyzed for the steel tempered at different temperatures in the thermomechanial routes. The microstructure of the steel after spinning deformation and tempering at 400 ℃ exhibits a better combination of strength and toughness owing to its fine tempered ferrite matrix and precipitation of dispersed carbide. Plastic deformation results in high density dislocations in microalloyed steel 30Cr3 by the thermomechanial treatment,which improves the precipitation of carbides in the matrix to rise the tension strength,however,overgrowth of the carbides after the tempering at temperature higher than 400 ℃ decreases the tension property because of the vanishing of carbide dispersion-strengthening. The optimized tempering temperature of 400 ℃ is recommended for thermomechanically treated 30Cr3 steel based on the experiment.更多还原