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本文从成分、组织结构和性能关系的角度,用金属学和热处理基础理论的新发展新成果,综合归纳出提高超高强度钢强韧性的十种有益组织结构和三类强韧化工艺,简述了它们的强韧化机理及不足之处。指出较佳的强韧组织结构是:低碳的回火板条马氏体+板条相间残余奥氏体薄膜+均匀分布的碳化物(无板条相间碳化物)和低碳下贝氏体+细、散、匀、圆的多相析出物;较佳的强韧化工艺是:淬火+自回火(或回火或时效)和高温形变热处理。并且,简述了合金元素的作用,指出合金化方向应是:低碳多元少量的综合合金化和微合金化,并认为合金化应兼顾到热处理工艺的简化。最后,提出了提高超高强度钢强韧性的三条途径:(1)合金强化的低碳马氏体;(2)多相析出强化的低碳下贝氏体;(3)N_b、V、Ti、B微合金化+高温形变热处理。
In this paper, from the perspectives of composition, structure and properties, ten new beneficial and microstructural structures and three types of strengthening and toughening techniques are proposed to improve the strength and toughness of ultra-high strength steels, using the newly developed and new achievements in basic theories of metallurgy and heat treatment. Described their toughening mechanism and inadequacies. It is pointed out that the better tough structure is: low-carbon tempering lath martensite + lath martensite residual austenite thin film + uniformly distributed carbides (no interlaminar carbides) and low carbon lower bainite + Fine, scattered, uniform, round multi-phase precipitates; the preferred toughening process is: quenching + self-tempering (or tempering or aging) and high temperature deformation heat treatment. In addition, the effect of alloying elements is briefly described. It is pointed out that the direction of alloying should be as follows: the alloying and micro alloying of a small amount of carbon with a small amount of carbon, and the simplification of the heat treatment process should be considered. Finally, three ways to improve the toughness of ultra-high strength steels are put forward: (1) low carbon martensite strengthened by alloy; (2) low carbon lower bainite strengthened by multiphase precipitation; (3) N_b, V, Ti , B micro-alloying + high temperature heat treatment.