Weldability of Al-Mg Alloy 5083-O Thick Plates (Report 2)

Effect of Grain Refining on Hot Cracking of Welds

Abstract

The effect of grain refinement on hot cracking susceptibility of 5083/5183 weldments was examined using y-type cracking test and slit-type cracking test. Furthermore, the effective preventive methods of micro-cracks in multi-pass welding were also investigated. Test results obtained are summarized as follows:
1. Hot cracking susceptibility of 5083/5183 weldments was markedly reduced by addition of grain refiner Ti, B. In this case, it was more effective to add Ti, B to base plate rather than to electrode wire.
2. Both y-type cracking test for thicker plate and slit-type cracking test for thin plate might be applicable to the assessement of hot. cracking susceptibility of Al alloys.
3. In multi-pass welding, some micro-cracks were observed in the heat affected weld metal, especially in the region heated twice or three times by subsequent welding, or in the weld metal along the weaving line. Tohse micro-cracks are also prevented successfully by addition of grain refiner and control of welding conditions.