Abstract
Abstract
Welding-induced distortion is a common problem in industry. Many methods have been proposed in recent years to minimize such distortion, among which transient thermal tensioning has been shown effective for simple structures such as fillet joints or T-joints. Owing to the complexity of the welding process, effective implementation of the transient thermal tensioning method requires determining appropriate process parameters. The current paper presents a study on controlling the welding-induced distortion of large box beam structures that are made by joining four side plates simultaneously with multiple arc welds. The transient thermal tensioning method is applied through differential preheating zones moving along with the welding torches. A finite element model is developed to examine the sensitivity of various preheating parameters, including the average preheating temperature, temperature differential, and the preheating location. It is found that the differential preheating control is effective in adjusting the welding-induced twist distortions. However, excessive temperature differential could generate other types of distortions such as the bow distortion. In order to maintain the overall dimensional accuracy of a large box beam structure, location differential with the same preheating temperature should be applied to control the twist errors. The findings in the present study have been validated with experimental results from a real production environment.