对接装配精度是制约车身零件激光对接焊技术应用的重要因素之一。采用激光填充热丝焊，对1.2 mm厚车用高强钢DP800在不同对接间隙条件下进行了对接间隙裕度的研究。通过优化焊接参数, 在间隙达到母材厚度的100%（1.2 mm）时得到表面成形良好的焊缝。焊后对焊缝的成分分布、金相组织及力学性能进行了分析。焊接结果表明，对接间隙变化对焊缝成分分布及金相组织无明显影响；焊缝的拉伸强度在对接间隙不大于母材厚度的83%（1.0 mm）时大于母材，在间隙为母材厚度的100%（1.2 mm）时达到母材强度的89.9%。采用激光填充热丝焊能显著降低激光对接焊车身零件对装配间隙的要求。

The fit up precision is one of the facts that restrict the applications of the laser welding of the vehicle body components in a butt joint. An experimental study on gap margin in laser butt welding of 1.2 mm thick high-strength automobile steel DP800 is performed with hot wire filler under various butt gaps. Sound weld beads are obtained by optimizing welding parameters when the butt gap is not more than 100% of the steel sheet thickness (1.2 mm). The chemical composition distributions, metallographic phase and mechanical property of the weld are analyzed after welding. The result shows that the butt gaps have little influence on the chemical composition distributions and metallographic phase of the weld; the tensile strength of the weld is higher than that of the bass metal when the butt gap is not more than 83% of the steel sheet thickness (1.0 mm), while it reaches 89.9% of the tensile strength of the base metal when the butt gap is 100% of the steel sheet thickness (1.2 mm). The requirement of high fit up precision of butt joint can be loosened dramatically using laser welding with hot wire.