电弧增材制造工艺及数值仿真研究进展

对电弧增材制造的工作原理、基本概念及取得的成果与进展进行综述。论述了电弧增材制造的工艺参数对增材件力学性能的影响;总结了电弧增材构件的成形性、微观组织等特点;概述了数值模拟在电弧增材中的应用,以及仿真模型中不同工艺参数对其温度场与应力场的影响规律;对电弧增材制造未来的发展做出总结展望。

不锈钢/铝合金异种金属激光-MIG熔钎焊工艺研究

分别采用激光-MIG复合焊和单MIG焊,实现了2mm厚的304不锈钢和6061铝合金对接接头的熔钎焊,对比了不同焊接热源对接头显微组织、界面层化合物及力学性能的影响。结果表明,采用激光-MIG复合焊可以获得性能良好的不锈钢-铝对接接头。激光-MIG复合焊接头的界面层化合物为FeAl_2和Fe_4Al_(13),厚度约为5μm;而单MIG焊接头的界面层化合物厚度约为3μm,主要为Fe_4Al_(13)。激光-MIG复合焊接头的抗拉强度为105MPa,比单MIG焊接头提高了10.8MPa,达到铝合金母材的33.9%。接头试样拉伸断裂均起裂于钎焊界面处,并向余高处扩展,且由脆性断裂转变为韧性断裂。

QP980-DP980异种先进高强钢激光焊接头微观组织及力学性能

采用光纤激光焊实现了异种汽车用先进高强钢QP980与DP980的拼焊连接,对异种焊接接头的微观组织、硬度分布进行了观察和测试,对焊接接头的拉伸性能进行了测试,对断口形貌进行了观察和分析。结果表明,焊缝区域的组织全为马氏体组织,且硬度最高(535 HV);两侧焊接热影响区均可分为完全相变区、不完全相变区和回火区三个区域。两侧热影响区中的完全相变区由于冷却速度快全部为马氏体组织,硬度提高;不完全相变区部分形成马氏体,成为马氏体和铁素体的混合区,回火区由于回火马氏体的出现使其硬度下降。QP980侧的回火区由回火马氏体、铁素体和残余奥氏体组成;DP980侧的回火区由回火马氏体和铁素体组成。接头拉伸断裂发生在DP980侧热影响区,抗拉强度达到DP980母材的98.9%,断后伸长率约为DP980母材的70.9%,断裂模式为韧性断裂。

Microstructural evolution and its effect on mechanical properties in different regions of 2219-C10S aluminum alloy TIG-welded joint

Microstructural evolution and its effect on mechanical properties in different regions of 2219-C10S aluminum alloy tungsten inert gas(TIG)welded joint were analyzed in detail.In weld zone(WZ),α+θeutectic structure formed at grain boundaries with no precipitates inside the grains.In partially melted zone(PMZ),symbiotic eutectic or divorced eutectic formed at grain boundaries and needle-likeθ′phases appeared in the secondary heated zone.In over aged zone(OAZ),the coarsening and dissolution ofθ′phases occurred and mostθ′phases transformed intoθphases.In general heat affected zone(HAZ),θ′phases coarsened.Factors such as the strengthening phases,the grain size,the Cu content in matrix and the dislocation density can affect the mechanical properties in different regions of the joint.Moreover,a model describing the relationship between mechanical properties of the material and the volume fraction of precipitates,the average diameter of precipitates and the concentration of soluble elements was proposed.