摘要
在降碳和安全的大背景下,汽车用超高强度钢的发展面临新的挑战。通过改变冷轧板的退火工艺,将退火组织转化为马氏体,可大幅提高热成形过程中材料完全奥氏体化的效率,从而缩短热成形所需的总加热时间。基于此,将新材料和新工艺相结合,提出了短流程热成形工艺。以免镀层热成形钢为例,研究了短流程热成形工艺下钢的微观组织演化及力学性能。结果表明,初始组织为马氏体和碳化物的免镀层钢,以100℃/s加热至930℃,保温30s以内可实现完全奥氏体化,并获得马氏体和3%~5%残余奥氏体的混合组织,且最终材料具备较高的强韧性,其抗拉强度可达1578 MPa,伸长率为7.8%。由此,热成形所需的总加热时间可缩短至1min以内,相比传统硼钢板热成形工艺所需的5min加热时间,短流程热成形新工艺在保证零件强韧性的同时将总加热时间缩短了80%以上,可有效助力节能降碳。
Under the background of carbon reduction and safety,the development of ultra-high strength steels for automobiles are facing new challenges.By changing the annealing process of the cold-rolled sheet,the annealed microstructure could be transformed into martensite.The efficiency of complete austenitization of the material in the hot forming process can be greatly improved,thereby shortening the total heating time required for hot forming.A short-flow hot forming process was proposed by combining new materials and new processes.Taking coating-free hot forming steel as an example,the microstructure evolution and mechanical properties of steel under short-flow hot forming process are studied.Results shown that the non-plating steel with the initial structure of martensite and carbide can be fully austenitized by heating at 100℃/s to 930℃and holding for 30 s,and martensite and 3%-5%retained austenite can be obtained.The final material owns high strength and toughness:with tensile strength of 1578 MPa,and elongation of 7.8%.Therefore,the heating time required for hot forming can be shortened to less than 1 min.Compared with the 5min heating time required for traditional hot forming process of boron steel plate,the short process hot forming technology reduces the total heating time by more than 80%while ensuring the strength and toughness of the parts,which can effectively help energy saving and carbon reduction.
作者
侯泽然
王建锋
卢琦
闵峻英
何志康
张显
汪锦成
林建平
HOU Zeran;WANG Jianfeng;LU Qi;MIN Junying;HE Zhikang;ZHANG Xian;WANG Jincheng;LIN Jianping(School of Mechanical Engineering,Tongji University,Shanghai 201804;China Science Lab,General Motors Global Research&Development,Shanghai 201206)
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2022年第16期43-50,共8页
Journal of Mechanical Engineering
基金
国家自然科学基金资助项目(52105395)
关键词
热成形钢
短流程
马氏体
快速加热
hot forming steel
short process
martensite
rapid heating
