Welding Defects Research and Control of Underframe Longitudinal Girder in Aluminum Alloy Carbody

The welding defects such as crack and porosity were analyzed aiming at the welding construction character istic of aluminum alloy longitudinal girder.Effective loading section area of backing weld was too small to stand larger stress after welding,which caused the crack.And the crack problem was solved by enlarging backing welding section area.The porosity was caused by the high humidity and no cleaning air on the welding area,and the crack can be solved by controlling welding time and environment condition.Also,porosity can take place in the form of linear porosity and be removed.