高强钢/铝及全铝车身用材料复合连接技术基础研究

Centering on the technical problem about steel/aluminum and aluminum auto-body welding, the program introduced Resistance Element Welding(REW), laser weld bonding(LWB) and laser-arc hybrid welding technology to spot welding and line welding of high-strength steel/aluminum and to the manufacture of tailor welded blanks. The fundamental research mainly focused on the steel/aluminum and aluminum auto-body hybrid welding technology. The coordinated control mechanism with intermetallic (IMC) layer and rivet self-locking structure was built by revealing the multi-interface heat and force dynamic evolution law of joining high-strength steel to aluminum with resistance spot welding; the interface microstructure and property coordination mechanism of the joint of high-strength steel/aluminum with LWB was established by the study about the disturbance effect decomposition and escape of adhesive to IMC and the stress relieving mechanism during the process of laser weld bonding; the structure compliance optimization design principle of tailor welded blanks was illustrated by researching the rule of the effect of heat resource of laser-arc hybrid welding to the integrality of welding structure. And then, some theoretical guidance was offered to the parts design and optimization for lightweight vehicles, including building coordinated control system of the welding structure of high-strength steel/aluminum which is based on hybrid welding technology, exploring new joining method for tailor welded blanks, forming the basic database for high-strength steel/aluminum and aluminum welding and exploiting the typical specimen of tailor welded blanks.

本项目围绕高强钢/铝混合及全铝车身材料连接技术难题，将电阻单元点焊、激光胶焊及激光-电弧复合焊接技术引入到高强钢/铝点连接、线连接及铝合金拼焊板制造之中，开展高强钢/铝及全铝车身用材料复合连接技术基础研究。通过研究高强钢/铝电阻单元点焊多界面电/热/力作用动态演变规律，揭示高强钢/铝点连接界面金属间化合物层、点焊熔核以及铆钉自锁结构的协调控制机理；通过研究激光胶焊中胶粘剂分解逸出对熔池及金属间化合物的扰动机制，构建高强钢/铝线连接界面组织与性能调控模型；通过研究铝合金拼焊板激光-电弧复合热源对焊接组织及结构完整性的影响规律，阐明铝合金拼焊板焊接接头组织和结构顺应性优化设计原则。在此基础上构建满足高强钢/铝及全铝车身用材料连接需求的复合连接技术体系，形成高强钢/铝及铝合金连接新方法及工艺性能数据库，开发出典型高强钢/铝及铝合金拼焊板结构件样件，为车身轻量化设计和制造提供理论基础。

本项目围绕汽车制造钢铝混合结构及全铝车高性能焊接制造需求，开展了高强钢与铝合金异种金属的焊接技术研究，揭示了钢铝异质界面Fe-Al金属间化合物的形成机理，通过电阻单元点焊、激光胶焊及焊铆复合连接技术有效消除了金属间化合物对焊接接头性能的不良影响，显著提高了高强钢与铝合金焊接接头的力学性能。采用激光-电弧焊接方法实现了同种及异种铝合金拼焊板的优质高效焊接，揭示了铝合金焊接接头组织演变规律及组织顺应调控机制，显著提高了铝合金焊接稳定性和可靠性。. 通过本项目的研究成功实现了铝合金与高强钢异种金属高性能连接，采用电阻单元点焊及激光胶焊两种焊接技术实现了DP/QP980与6系及5系铝合金的良好连接，电阻单元点焊单铆钉接头拉伸载荷到5.0kN以上，激光-电弧胶焊试件拉伸线载荷达到4.8N/cm。综合上述两种技术的优点，研制出高强钢与铝合金高能束焊铆复合连接技术，采用该创新技术成功实现了两种金属的高性能连接，单铆钉复合连接接头拉伸载荷到7.0kN以上。以上述技术为核心制备出汽车铝合金内门板与高强钢防撞梁模拟焊接结构件，为推动高强钢与铝合金焊接结构在汽车领域的实际应用起到了积极的促进作用。. 本项目采用激光-电弧焊接方法实现了5系及6系铝合金拼焊板的高性能焊接制造。5系及6系同种及异种铝合金激光-电弧焊接接头性能达到铝合金母材的85%以上，同种铝合金焊接接头的抗杯凸变形能力达到母材的90%以上。针对7系铝合金焊接接头性能低的问题，本项目提出了一种焊接-轧制复合成形制造技术，采用该技术成功实现了7系铝合金的优质高效焊接制造，焊接接头性能达到7系铝合金母材的85%以上。为推动铝合金拼焊板在汽车制造领域的应用奠定了理论基础。. 围绕高强钢/铝混合车身及全铝车身材料连接领域，在国内外知名期刊发表学术论文67篇，被SCI检索56篇，申请中国及国际发明专利11项，获得国家发明专利授权6项，获得中国专利奖银奖1项，培养博士研究生5人，硕士研究生7人。