铝合金LB-VPPA复合热源焊焊缝成形机理

以Al-Zn系铝合金LB-VPPA（激光-变极性等离子弧）复合焊接焊缝成形机理为研究对象，分析了LB与VPPA耦合效应对复合热源特性及其焊缝成形的影响规律.结果表明，LB与VPPA相互耦合不仅提高了激光吸收率，在变极性等离子弧根部形成一烁亮区，并且在VPPA反极性期间此效应更为显著.适当减小VPPA电流幅值，增加离子气流量，匹配合适的激光功率，可获得总热输入小，穿透力更强的热源，从而能够克服单VPPA平焊位置不易形成穿孔熔池的难点.8 mm厚Al-Zn系铝合金LB-VPPA复合热源焊在I_z=115 A、I_f=155 A、离子气流量q=3.0 L/min、激光功率P=1 000 W时可获得良好的焊缝成形.

Mechanism of weld formation in laser beam-variable polarity plasma arc hybrid heating source welding of aluminum alloys

By being taken weld formation mechanism as research object, and the influence of LB(Laser Beam) and VPPA(Variable Polarity Plasma Arc) coupling effects on heat source characteristics and weld formation mechanism were analyzed in LB-VPPA hybrid welding of Al-Zn aluminum alloys. The results show that laser absorptivity is increased by the coupling effects of LB and VPPA. A shining zone exists at the root of VPPA, especially during direct current electrode positive period. The heat source with the advantage of smaller heat input and higher penetration depth can be achieved by combining slightly smaller VPPA current, higher orifice gas flow rate and suitable laser power, which can overcome the difficulty of keyhole weld formation on flat position in VPPA welding. Better welded joints are achieved by LB-VPPA hybrid heating source welding on Al-Zn aluminum alloys with thickness of 8 mm at VPPA direct current electrode negative current of 115 A, VPPA direct current electrode positive current of 155 A, orifice gas flow rate of 3.0 L/min and laser power of 1 000 W.