保护气体对高强铝合金的焊缝组织及气孔敏感性的影响

采用普通电弧焊对2519铝合金进行焊接,研究了Ar和He二元混合气体以及Ar、He和CO2三元混合气体对接头的气孔数目、焊缝组织的影响.研究表明,采用Ar和He二元混合保护气体可以明显减少接头气孔的数目和尺寸,促进焊缝中心组织由柱状晶向等轴晶转变,且细化焊缝组织,当He气达到70%时,接头气孔数目已显著减少,焊缝中心完全呈等轴晶状态,晶粒最为细小.往30%Ar 69%He二元混合气体添加1%的CO2后接头的气孔数目进一步减少,但是焊缝组织没有明显变化.添加了He气还可以减少热影响区宽度,减弱热影响区的软化程度.

Effects of shielding gas on microstructure and number of gas pore in high strength aluminum alloys weld

The effect of Ar and He dual mixed shielding gas and Ar, He and CO₂ ternary mixed shielding gas on the number of the gas pore and microstructure in the weld was studied in arc welding of 2519 aluminum alloy.Results indicate that, compared with using Ar alone, the number and the size of gas pore is reduced by using Ar andHe dualmixed shielding gas and the dual mixed shielding gas is also helpful for the transition of columnar crystal to equiaxed crystal.When the percentage of He reaches 70%, the number and the size of the gas pore are reduced significatly, and in weld centre it can get the smallest equiaxed crystal entirely.When filling 1% CO₂ into the dual mixed gas which the ratio of Ar:He is 30:69, the number of the gas pore is further reduced, but there is no evidence to prove that it can affect the microstructure of the weld. The width and the softening extent of the HAZ can also be reduced by filling He into Ar shielding gas.