汽车用热基镀锌高强钢的研发进展

 日益复杂的服役环境,对汽车底盘及结构内件耐蚀性提出了更高要求,常规酸洗板已无法满足。以低合金高强钢(HSLA)、铁素体贝氏体钢(FB)和复相钢(CP)为代表的热基镀锌高强钢兼具热轧钢板的高成形性及镀层钢板的高耐蚀性,取代酸洗板用于汽车底盘和结构内件制造,不仅可以提高整车防腐性能,还可以降低零件修复、更换和再生产带来的能源消耗与碳排放,为汽车企业选材用材升级、降本增效提供了重要解决方案。汽车用热基镀锌高强钢对组织性能及表面质量的要求极其严格,国内外具备产品开发及稳定供货能力的企业很少。从化学成分、热轧、冷却、卷取和退火等工艺参数对微观组织及析出相的影响方面阐述了热基镀锌高强钢组织性能调控机理,以色差、漏镀和锌流纹等缺陷为例概述了热基镀锌高强钢表面问题产生的原因及相应的攻关方向。重点介绍了锌铝镁镀层在耐腐蚀方面的优势以及热基锌铝镁产品的主要应用途径。综述了国内外汽车用热基镀锌高强钢的生产及应用现状,指出进一步提升综合性能、改善表面质量和拓展极限规格是其发展方向。同时指出,需要持续关注热基镀锌高强钢生产和应用方面的问题,如色差、漏镀和锌流纹等表面问题,焊接飞溅、气孔和LME裂纹问题以及针对底盘特定腐蚀环境的耐蚀性数据积累及评价。

Research and development progress of hot-rolled galvanized high-strength steel for automobile

The increasingly complex service environment puts forward higher requirements for the corrosion resistance of automobile chassis and structural internals,which cannot be met by conventional pickling steel sheet. Hot-rolled galvanized high-strength steel represented by low-alloy high-strength steel (HSLA),ferritic bainitic steel (FB) and complex phase steel (CP) possesses both the high formability of hot-rolled steel and the high corrosion resistance of coated steel. Instead of pickling steel sheet,it can not only improve the anti-corrosion performance of the whole vehicle,but also reduce the energy consumption and carbon emission caused by repair,replacement and reproduction of parts. It provides an important solution for automobile enterprises to select materials,upgrade materials,reduce costs and increase efficiency. The hot-rolled galvanized high-strength steel for automobile has extremely strict requirements on microstructure,mechanical properties and surface quality. There are few enterprises with product development and stable supply capacity at home and abroad. The control mechanism of microstructure and properties of hot-rolled galvanized high-strength steel is expounded from the effects of process parameters such as chemical composition,hot rolling,cooling,coiling and annealing on microstructure and precipitation. The causes of surface problems of hot-rolled galvanized high-strength steel and the corresponding research direction are summarized,taking defects such as color difference,missing plating and zinc flow pattern as examples. The advantages of zinc-aluminum-magnesium (ZM) coating in corrosion resistance and the main application ways of hot-rolled ZM products are introduced. The production and application status of hot-rolled galvanized high-strength steel for automobile at home and abroad are reviewed. It is pointed out that further enhancing the comprehensive properties,improving the surface quality and expanding the limit specification are the development direction of hot-rolled galvanized high-strength steel. At the same time,it is also pointed out that continuous attention needs to be paid to the production and application of hot-rolled galvanized high-strength steel,including surface problems such as color difference,missing plating and zinc flow pattern,welding problems such as spatter,pores and LME cracks,as well as the accumulation and evaluation of corrosion resistance data for the specific corrosive environment of the chassis.