Abstract

The wettability and spreadability of the molten Al drop on the surface of bare steel and galvanized (GI) steel was studied. It was expected that the role of Zn coating during the laser welding–brazing process of Al/steel could be understood through this study. The bare steel without coating and the GI steel with different Zn coating thicknesses of 10 and 20 μm were used. Different laser power was considered. The welding time was 1000 ms. Deposited filler metal ER4043 was applied, and the feeding rate was 5 m/min. The transferring, wetting, and spreading process of the molten drop on the steel surface was observed and recorded by a high-speed video camera. The temperature field was measured by an infrared thermometer. The microstructure of the joint was observed and analyzed after welding. The GI steel with a 10-μm coating improved the wettability of Al/steel compared with the bare steel, but the GI steel with a 20-μm coating deteriorated the wettability and the weld appearance compared with the GI steel with a 10-μm coating. The evaporation of Zn coating could protect the steel surface from oxidation and absorb the excessive heat input. The formation of the brazing interface and Zn-rich zones was revealed based on the adsorption values of Al-Si/Fe and Al-Zn/Fe systems.

中文翻译：

---

激光焊接-钎焊锌涂层对铝/钢的润湿性，扩展性和微观结构的影响机理

摘要

研究了熔融铝滴在裸钢和镀锌（GI）钢表面上的润湿性和铺展性。可以预期，通过这项研究可以理解Zn涂层在Al /钢的激光焊接-钎焊过程中的作用。没有镀层的裸钢和具有Zn镀层厚度分别为10和20μ的GI钢 m被使用。考虑了不同的激光功率。焊接时间为1000ms。施加沉积的填充金属ER4043，进料速度为5 m / min。用高速摄像机观察并记录了熔融液滴在钢表面上的转移，润湿和扩散过程。用红外温度计测量温度场。焊接后观察并分析了接头的微观结构。用10-胃肠钢μ米涂层改善与裸钢相比铝/钢的润湿性，但与20-胃肠钢μ米涂层劣化的润湿性和焊接外观与具有10-胃肠钢相比μ米涂层。镀锌层的蒸发可以保护钢表面不被氧化并吸收过多的热量。根据Al-Si / Fe和Al-Zn / Fe系统的吸附值揭示了钎焊界面和富锌区的形成。