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Reduction of hot crack formation in laser beam welding of high strength aluminum alloys with local creation of residual stresses by forming

通过成形产生局部残余应力，减少高强度铝合金激光束焊接中热裂纹的形成

基本信息

批准号：
389369540
负责人：
Professor Dr. Thomas Graf
金额：
--
依托单位：
Institut für Umformtechnik (IFU)
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
资助国家：
德国
起止时间：
项目状态：
未结题

来源：
https://gepris.dfg.de/gepris/projekt/389369540?language=en
关键词：
Reduction hot crack formation laser

项目摘要

High-strength aluminum alloys are often used to implement lightweight construction concepts in the automotive/aerospace industry. In connection with laser beam welding processes, however, such alloys are highly susceptible to the formation of hot cracks, which severely reduce the strength of joints. The previous project showed that additional stresses caused by inhomogeneous plastic deformations during the forming process of the parts significantly influence the formation of centerline hot-cracks in the subsequent joining process. These findings imply that the formation of hot cracks during laser beam welding can be prevented by the specific creation of compressive residual stresses in the area of the joining zone. Based on the results of the preceding project, in the follow-up project the conditions of compressive residual stresses required for the prevention of hot cracks are to be specified quantitatively. For this suitable forming processes for the creation of defined residual stresses in joining zones will be identified.The aim is to develop forming methods for the local generation of compressive residual stresses that prevent the formation of hot cracks in laser-welded joining zones of high-strength aluminum alloys. Taking into account the entire process chain in car body manufacturing, these forming methods should enable the optimization of the welding process already during the preceding forming process. The cross-process-chain optimization approach is intended to ensure higher overall process reliability on the one hand and greater degrees of freedom in the implementation of lightweight design concepts with high-strength aluminum alloys on the other hand.

高强度铝合金通常用于实现汽车/航空航天工业中的轻质结构概念。然而，与激光束焊接工艺有关，这种合金非常容易形成热裂纹，这严重降低了接头的强度。先前的项目表明，在零件成形过程中由不均匀塑性变形引起的附加应力显著影响随后的连接过程中中心线热裂纹的形成。这些发现意味着，在激光束焊接过程中热裂纹的形成可以通过在接合区的区域中特定地产生压缩残余应力来防止。根据前一项目的结果，在后续项目中，应定量规定防止热裂纹所需的压缩残余应力条件。为此，将确定在连接区域产生确定的残余应力的合适成形工艺，目的是开发局部产生压缩残余应力的成形方法，以防止高强度铝合金激光焊接连接区域形成热裂纹。考虑到车身制造中的整个工艺链，这些成型方法应该能够在前一个成型过程中优化焊接工艺。跨工艺链优化方法旨在一方面确保更高的整体工艺可靠性，另一方面确保在使用高强度铝合金实现轻量化设计概念时有更大的自由度。