Methods to reduce residual welding stresses in mining excavator metal structures

Abstract

Residual stresses in metal structures of mining machinery caused by welding occur due to simultaneous uneven heating and cooling of local sections of structures, variable cooling rates in the different areas of the weld and deformations caused by metallurgical phase transformations. Residual stress in the welded joint can significantly increase the external load that can lead to structural failure. Research on the calculation, measurement and relief of residual stresses under welding is an important issue when predicting the service life of metal structure units of mining machinery and equipment. An accurate quantitative estimation of residual stresses in welded products, repair welds included, as well as the search for the fundamental principles of the elimination methods of residual deformations are of considerable practical interest, which is relevant for the authors of this paper. The study involved a general review of the latest researches in the field of estimation and measurement of residual stresses caused by electrogas welding. It has been proposed to use various techniques and analytical methods for quantitative estimation of welded joint residual stresses on the basis of fracture mechanics, which enabled to take preventative measures at early stages to reduce the cost of repair and maintenance of welded metal structures of mining excavators. The conducted study resulted in formulating the proposals on relief of residual welding stresses in the metal structures of mining excavators.