Zn-Al-Si钎料厚度对磁脉冲辅助半固态钎焊Cu/Al管接头组织性能的影响

Effect of Zn-Al-Si filler metal thickness on microstructure and properties of Cu/Al tube joints by magnetic pulse assisted semi-solid brazing

结合磁脉冲成形、半固态成形以及钎焊的复合优势,采用磁脉冲辅助半固态钎焊的方法来实现Cu/Al异质金属管件的连接。基于LS-DYNA对钎焊过程进行了多物理场耦合仿真,分析了钎料厚度对流变行为的影响,提出了综合考虑氧化膜去除效果及钎料流失缺陷的壁厚设计思路。利用附加能谱仪的电子探针显微分析仪和电子万能材料试验机研究了半固态Zn-15Al-1.0Si钎料的厚度对钎焊接头质量的影响。结果表明:在钎焊过程中,半固态钎料所受压、剪应力复合作用随着其厚度的增加而变弱,且在搭接区域中部最弱。钎料过厚,其与母材两侧难以形成良好的冶金结合,而钎料过薄,会导致接头钎料缺失的缺陷。在合适的放电参数条件下,当钎料固相率为0.6,厚度为300μm时,能获得以球晶组织为主的磁脉冲辅助半固态钎焊Cu/Al管接头。

Combining the advantages of magnetic pulse forming,semi-solid forming and brazing,the method of magnetic pulse assisted semi-solid brazing was used to realize the connection between Cu/Al tubes.Based on LS-DYNA,a multi-physics coupling simulation of the brazing process was carried out.The influence of filler metal thickness on its rheological behavior was analyzed,and a design idea of filler metal thickness was put forward,comprehensively considering the removal effect of oxide film and the defect of filler metal loss.The influence of the thickness of semi-solid Zn-15 Al-1.0 Si filler metal on the quality of brazing joints was studied by using an electron probe microanalyzer with an additional energy spectrometer and an electronic universal material testing machine.Results show that during the brazing process,the composite effect of pressure and shear stress on the semi-solid filler metal became weaker with the increase in its thickness,and was the weakest in the middle of the overlap area.When the filler metal was too thick,it was difficult to form a good metallurgical bond with both sides of the base material,while too thin filler metal could lead to the defect of missing filler metal in the joint.Under suitable discharge parameters,when the solid fraction and thickness of filler metal were 0.6 and 300μm,a magnetic pulse assisted semi-solid brazed Cu/Al tube joint with spherulitic structure as its main structure could be obtained.