先进镀锌高强钢中液态金属脆化的研究进展及挑战

Progress and challenge of liquid metal embrittlement in galvanized advanced high strength steel

先进高强钢广泛用于汽车车身结构,能够在保证车辆安全性的同时使整体车身减重,满足节能减排的要求,在汽车轻量化方面已凸显出巨大的应用潜力。通常汽车用高强钢板需要进行表面镀锌处理以提高车身结构的抗腐蚀能力。但镀锌高强钢板在点焊过程中容易产生液态金属脆化,降低焊接接头的承载性能。镀锌热成形高强钢在热成形过程中也会产生液态金属脆化,使其抗拉强度和伸长率明显降低。概述了先进镀锌高强钢板中的液态金属脆化现象及其产生原因和机制,并着重分析了液态金属脆化的影响因素。此外,结合最新的研究进展阐述了目前先进镀锌高强钢板中液态金属脆化面临的挑战并提出了可行的研究思路。

Attributing to its great application potential in automobile lightweight, advanced high strength steel(AHSS) is extensively used in car white body, which can meet the demands of saving fuel and reducing exhaust emission by reducing the car weight while ensuring its safety. To increase the service life of vehicle structure, it is required to protect AHSS from corrosion, mostly by zinc(Zn)-based coating. However, advanced high strength steel with Zn coating is prone to liquid metal embrittlement(LME) during welding, resulting in the reduction of load-carrying property of the involved welded joints. Liquid metal embrittlement also occurs in galvanized hot stamping steel during hot-press forming process, which can deteriorate its mechanical property and resultantly limit its application. The LME occurred in galvanized AHSS sheets and its forming mechanism were reviewed, and the factors to cause LME were also emphatically analyzed. Combined with the recent investigations of LME in Zn-coated AHSS, the challenges were discussed and correspondingly the feasible research approaches were put forward.