热处理对Q1030钢的亚结构及析出物的影响机理

Influence Mechanism of Heat Treatment on Martensite Substructure and Precipitates of Q1030 Steel

Q1030钢是低合金高强钢。利用两相区轧制的方式,再经过淬火和回火处理后,力学性能有了较大的提高。经分析得出,200℃回火后,低于5°的小角度晶界频率比较多;经400℃回火后,θ-碳化物沿着马氏体的{112}面析出和{111}面析出,在马氏体板条内呈梭子状弥散分布,对马氏体内位错起到有效的钉扎作用,从而阻碍了位错的运动和螺纹的扩展。此外,200℃到400℃回火后,屈服强度、延伸率和屈强比与淬火态的相比都明显升高,但抗拉强度变化不明显。

Steel Q1030 is a high strength low alloy steel. By using the method of two-phase-field rolling, followed by quenching and tempering treatment, the mechanical performance of the steel was greatly improved. The analysis results showed that the grain boundaries with a small angle less than 5° occurred more frequently after the tempering at 200 ℃while θ-carbide precipitated along {112} and {111} surfaces of the martensite and had a shuttle-like diffused distribution in the martensite lath after the tempering at 400 ℃, which effectively pinned the dislocation in the martensite, and thereby impeded the dislocation movement and the screw thread expansion. In addition, after the tempering at 200 ℃ to 400 ℃,the yield strength, elongation and yield ratio were increased significantly compared with those of the quenched, but the change of tensile strength was not obvious.