退火工艺对冷轧中锰中铝低密度钢组织与性能的影响

Effect of Annealing Process on Microstructure and Properties of Cold Rolled Medium Manganese Medium Aluminum Low Density Steel

钢铁材料的轻量化、增强增韧是目前先进金属材料的重点研究方向。在钢材固有合金元素的基础上,通过添加一些增强其性能的元素及低密度元素等,可以显著改善钢材的综合性能,并降低零件质量。随着汽车工业的快速发展,轻量化汽车用钢的研发和应用越来越深入和广泛。目前,Fe-Mn-Al-C系低密度钢主要借鉴了中/高锰钢成分设计、热处理工艺、组织性能调控的研究思路,形成性能优异、成本合理的高强韧性钢。本工作针对中锰中铝低密度钢(12.4%Mn,4.7%Al,0.1%C(均为质量分数,下同))的成分特点,通过对冷轧试样在A_(c1)与A_(c3)附近进行退火处理,调控基体相稳定性和组织构成。结果表明:γ奥氏体稳定性与原始组织形态、退火条件和拉伸应力有很大的关联,其组织转变遵从γ奥氏体→ε马氏体→α′马氏体规律;在850℃退火、保温15 min条件下,获得了抗拉强度、延伸率分别为854 MPa、44.3%,强塑积为37.8 GPa·%的优异性能。

Lightweight,strengthening and toughening of iron and steel materials are the key research directions of advanced metal materials.Based on the inherent alloy elements of steel,the comprehensive properties of steel can be improved and the weight of parts can be reduced by adding some strengthening elements and low density elements.With the rapid development of automobile industry,the development and application of lightweight automobile steel are more and more extensive.At present,Fe-Mn-Al-C low density steel mainly uses for reference the research ideas of composition design,heat treatment process,microstructure and properties controlling of medium/high manganese steel to form high strength and toughness steel with excellent performance and reasonable cost.According to the composition characteristics of medium manganese medium aluminum low density steel(12.4wt%Mn,4.7wt%Al,0.1wt%C),the stability and structure of the matrix were controlled by annealing the cold rolled samples near A_(c1) and A_(c3).The results show that the austenite stability is closely related to the original microstructure,annealing condition and tensile stress,and the transformation law follows the of austenite→ε-martensite→α′martensite,the excellent properties of tensile strength and elongation of 854 MPa,44.3%and strength plastic product of 37.8 GPa·%are obtained after annealing at 850℃for 15 min.