Hot Cracking Susceptibility of Twin Roll Cast Al-Mg Alloy Welds

The hot cracking susceptibility of two different Al-Mg alloys during welding at various applied strains was investigated. At each strain value, the amount of hot cracking susceptibility increased with increasing magnesium content. Thermal analysis results verified that hot cracking susceptibility indeed call be related to the solidification range. As suggested in the solidification range approach, the results of the present Study confirm that the extent of solidification and liquation cracking depend oil the magnitude of solidification range and the strain imposed during welding. The fracture surfaces of liquation and solidification cracks were investigated with EDS. Liquation crack surfaces were found to have high Mg content whereas solidification crack surfaces revealed iron rich phases. A quench test was designed to observe the effect of mid-plane segregation zone. It was observed that high segregation at the mid-section of the alloy having higher magnesium can increase the liquation cracking susceptibility during welding since it decreases the solidus temperature of the intergranullar liquid.