A study on the compensation of secondary distortion effect in the cutting process of a welded structure

Abstract

Lug structures are commonly used in heavy industries. Welded lugs with holes could be hooked onto and transported by a crane. After setting up, the lugs are typically cut away using a flame cutting process. As undesirable damage is caused by concentrated heat input, the band saw cutting process is more appropriate. However, re-establishment of equilibrium within the remaining part of the structure causes secondary distortion owing to the redistribution of the residual stresses. Additionally, in the cutting procedure, the stiction problem always occurs because of the squeezing of the saw blade between the materials. A compensation method, which uses an additional procedure before the cutting process, is proposed in this study. The top side of the lug is thermally heated to induce the redistribution of residual stress and make the amount of distortion same as that in the final state after cutting. Comparing the results from experiment sets, the stiction problem in the band sawing of a lug was alleviated using this additional procedure. The additional heating procedure did not intensify the final welding distortion. The compensation effect of thermal heating was confirmed in this study.