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铝-钢异种金属脉冲旁路耦合电弧MIG熔钎焊界面反应的热力学分析

Thermodynamic analysis of interfacial reaction by pulsed DE-GMAW for aluminum-steel dissimilar metals

  • 摘要: 采用脉冲旁路耦合电弧MIG熔钎焊方法用ER5356铝合金焊丝在镀锌钢板上进行平板堆焊试验.通过调整焊接参数获得最佳焊接成形,结果表明脉冲旁路耦合电弧MIG熔钎焊方法可以实现铝和铁异种金属材料的连接.采用SEM,EDS等测试手段观察和分析连接界面区的微观组织,在连接界面区形成Fe2Al5,FeAl3金属间化合物层.通过Thermo-Calc软件对Fe2Al5,FeAl3金属间化合物的吉布斯自由能进行计算,得出在高温Fe2Al5的吉布斯自由能比FeAl3的吉布斯自由能小,在低温FeAl3的吉布斯自由能比Fe2Al5的吉布斯自由能小,说明在焊接过程中Fe2Al5金属间化合物先生成,再在冷却过程中FeAl3金属间化合物生成或析出.

     

    Abstract: ER5356 aluminum alloy wire was welded on galvanized steel sheet by pulsed DE-GMAW process.The best weld morphology was obtained by adjusting the welding parameters.The results indicate that fusion-brazing between aluminum alloy and galvanized steel was achieved by pulsed DE-GMAW process.The microstructure of the interface in joint was observed and analyzed with SEM and EDS,and Fe2Al5 and FeAl3 intermetallic compound layers formed in the interface.The Gibbs free energies of Fe2Al5 and FeAl3 intermetallic compounds were calculated with Thermo-Calc software,and it was found that the Gibbs free energy of Fe2Al5 was smaller than that of FeAl3 at high temperature,but the Gibbs free energy of FeAl3 was smaller than that of Fe2Al5 at low temperature.The results show that Fe2Al5 intermetallic compound formed first during welding,and subsequently FeAl3 intermetallic compound formed and precipitated upon cooling.

     

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