DIMENSIONAL INSTABILITY OF LD31 Al ALLOY WELDMENTS AT ROOM TEMPERATURE AND AFTER THERMAL CYCLES

The unstable dimensional distortion of LD31 aluminum alloy weldments at room temperature and after thermal cycles was studied by use of light interference and CMM(three-coordinate measuring machines). At the same time, distortion mecha- nism was analyzed from the viewpoint of mechanics and microstructure. Experimen- tal results show that there exists obvious difference of unstable dimensional distortion between LD31 welded specimens under two conditions mentioned above. Under room temperature, dimensional variation of welded specimens will decrease gradually and nally tends to be stable during 200h after welding. The relative elongation of welded specimen is 3.0 10