激光深熔焊接车身安全件的热循环研究

在热电偶标定测试的基础上，通过实验获得了焊缝热影响区的实际热循环曲线。将高温等离子体简化为点热源，薄板焊接时的热源简化为线状热源后，采用叠加原理建立激光焊接高强度镀锌钢热循环的数学模型。对模型进行了解析计算，获得了热影响区的理论热循环曲线。对比研究后认为，热循环数学模型能反应激光深熔焊接的实际热循环过程。焊缝显微组织中存在少量的马氏体的事实表明，激光焊接高强度镀锌钢的热循环特点是加热冷却速度快。

Research on Thermal Cycling of Deep Penetration Laser Welding to Safety Part of Vehicle Body

Based on the thermojunction assignment test, actual thermal cycling curve of welded seam heat-affected zone is obtained. After simplifying high-temperature plasma as dot heat reservoir, heat reservoir of light gauge welding as linear heat reservoir and adopting principle of superposition, mathematical model to laser welding zinc coated high strength steel is established and analyzed, meanwhile theoretical thermal cycling curve of welded seam heat-affected zone is obtained. By contrasting the two results, it demonstrates that thermal cycling mathematical model can explain actual thermal cycling process of deep penetration laser welding. Microscale martensite is existed in welding seam microscopic structure, which indicates that thermal cycling characteristic of laser welding is quick heating and cooling velocity.