Microstructure and properties of Al-Mg-(Sc, Zr) welded joint

摘要

Mechanical properties and microstructure of Al-Mg-(Sc, Zr) welded joint prepared by manual labor melt inert gas(MIG) welding method using Al-Mg and Al-Mg-Sc weld wire as filling materials were studied comparatively. The results show that the apparent recrystallization does not happen in heat-affected zone. It proves that Al-Mg-(Sc, Zr) alloy has a high capability of resistance to welding heat-soften. Using Al-Mg-Sc welding wire as filling material can obviously refine the grains of weld seam and improve its strength. The layer of small equal-axe grains in fusion area improves the joint strength between welded metal and base metal. The coefficients of welded joints when Al-Mg-Sc and Al-Mg welding wire are used as filling material are greater than 0. 90, respectively. The yield strength of welded joints with Al-Mg welding wire is only 187 MPa, one is as high as 287 MPa with Al-Mg-Sc welding wire, thus the working strength of the welded unit is greatly improved.