何珺 梁萌 彭会芬 冯建航 姜延飞 宋开红 王荣伟 王井会

摘要 以ML08Al冷镦钢为研究对象，研究了不同回火形变处理条件下，材料组织和力学性能的变化。研究发现，经过1 150 ℃热轧后直接淬火，并于470～530 ℃进行回火形变处理，随回火温度降低，材料的强度略有增加，但塑性和韧性有所下降。回火后的显微组织由细小纤维状回火屈氏体和铁素体组成，且经过500 ℃回火形变处理的ML08Al钢具有最佳的力学性能（室温条件下，屈服强度为796 MPa，拉伸强度为812 MPa，延伸率为13.8%，断面收缩率为43.2%，冲击能量为186 J）。与热轧态的相比，延伸率和断面收缩率分别降低了55%和31%，抗拉强度与屈服强度分别提高了78%与124%，冲击能量提高了约8倍。即使在-60 ℃时，屈服强度为863 MPa，拉伸强度为880 MPa，延伸率为12.7%，断面收缩率为39.4%，冲击能量为147 J。理论计算结果表明：位错强化和细晶强化是导致ML08Al钢回火形变处理后强度提升的两个主要因素。

关 键 词 ML08Al钢;回火形变处理;强韧化;显微组织;热轧

中图分类号 TG142.1     文献标志码 A

Abstract Effect of tempforming on microstructure and mechanical properties of the steel was studied. It was found that this steel was composed of fine fibrous tempered troostite and ferrite through water quenching after 1 150 ℃ hot rolling and then tempforming between 470 ℃ to 530 ℃.With the Temperature decrease， the strength increase while the toughness and plasticity decrease. The sample tempformed at 500 ℃presented optimum mechanical properties， while yielding strength and tensile strength were about 796 MPa and 812 MPa， elongation and percentage reduction of area were about 13.8% and 43.2%， respectively， together with high impact energy of 186 J with V-type notch， at room temperature. The yielding strength and tensile strength were about 124% and 78% higher， and the impact energy was about 8 times higher， concomitant with elongation and percentage reduction of area about 55% and 31% lower than those of the hot rolled one. Even so， the steel exhibited yielding strength and tensile strength were about 863 MPa and 880 MPa， elongation and percentage reduction of area were about 12.7% and 39.4%， respectively， together with high impact energy of 147 J with V-type notch at low temperature of -60 ℃. Furthermore， theoretical analysis indicated that dislocation strengthening and refinement strengthening were mainly responsible for the increase in strength of the material.

Key words ML08Al cold forging steel; tempforming; strengthening and toughening; microstructure; hot rolled

0 引言

我國钢材产能和消费量已连续20多年保持世界第一，是名副其实的钢铁大国。但我们并非钢铁强国，大量高端产品仍需进口[1]。近年来，现代工业技术的发展对工程材料提出了越来越高的要求，且各种恶劣气候条件对材料也提出了极高的服役性能要求。因此，实现高强度与良好韧性的配合是金属材料领域一个永恒的主题[2-5]。

目前，常用的金属材料强韧化方法是采用复杂的合金化及微合金化手段，再辅以适当的热处理实现较好的强韧性配合。……