B340LA变厚截面板变功率激光焊接试验研究

张屹 梁志超 张哲豪 陆润东 李福南 韦海英

摘    要：变厚截面材料是实现汽车轻量化的有效途径之一，但截面厚度变化的材料连接实现困难.1.2～2.0 mm厚的B340LA变厚截面板在长度和宽度方向上都存在厚度波动，并且不同厚度处的材料硬度存在最大20%的偏差.针对该材料的特性自行设计了专用焊接夹具，提出了阶跃式变功率的激光焊接方法.对比分析固定功率和阶跃式变功率两种激光焊接试验，结果表明：固定功率（900～1 400 W）条件下获得的焊缝形貌与熔透状态均在焊接方向表现出显著的差异性，且部分焊缝会出现塌陷等焊接缺陷;采用1 000 W、1 100 W和1 300 W分段功率的阶跃式变功率焊接，1.2～2.0 mm板厚方向上可得到一致的焊缝形貌和熔透状态，焊缝熔合区的硬度偏差小于9%.与固定功率激光焊接相比，阶跃式变功率激光焊接可实现B340LA变厚截面材料的有效连接.

关键词：激光焊接;变厚截面板;阶跃式变功率;熔透状态;焊缝形貌和组织

中图分类号：TG406                                文献标志码：A

Experimental Research on Variable Power Laser Welding

of the B340LA Tailor Rolled Banks

ZHANG Yi 1，2，LIANG Zhichao1，2，ZHANG Zhehao1，2，LU Rundong1，LI Funan2，WEI Haiying2？覮

（1. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body，Hunan University，Changsha 410082，China;

2. Hunan Province Key Laboratory for Intelligent Laser Manufacturing，Hunan University，Changsha 410082，China）

Abstract： The application of Tailor Rolled Blanks （TRB） is one of the most effective ways to achieve automobile lightening， however， it's difficult to join the materials with the variable thickness. The thickness of B340LA TRB ranges from 1.2 mm to 2.0 mm and fluctuates in both length and width directions. And its hardness has a maximal deviation of 20% at different thickness. The special welding fixture was designed based on characteristics of TRB， and step variable laser power was proposed. By a contrastive analysis of two laser welding tests， including constant laser power and step variable laser power， the results show that there are huge differences in the weld appearance and penetration status along the welding direction under the conditions of constant laser power（900～1 400 W），and the defect of surface depression occurs in a portion of weld. By step variable laser power with 1 000 W， 1 100 W and 1 300 W，approximately consistent weld appearance and penetration status were obtained in the direction of thickness from 1.2 mm to 2.0 mm， and the hardness deviation in fusion zone of weld is less than 9%. B340LA TRB can be joined more effectively by step variable laser power than by constant laser powers.

Key words： laser welding; tailor rolled blanks;step variable power laser;penetration status;weld appearance and microstructure

汽車轻量化技术作为降低原油消耗和尾气排放的重要措施，已经成为世界各汽车企业提高品牌竞争力的重要手段[1-3].汽车轻量化技术路线可以分为[4]：结构优化设计、轻量化材料的应用和先进制造工艺等三个主要方面.基于新材料的变截面结构是实现汽车轻量化的有效途径[5].但在应用过程中发

现，变厚截面材料的连接成为该类材料制造过程中亟需解决的关键问题之一. 解决连续变厚截面材料的焊接问题……