EXPERIMENTAL STUDY OF RESIDUAL STRESSES IN Q550GJ HIGH-STRENGTH STEEL WELDED BOX SECTIONS

In order to investigate the distribution of residual stress in Q550GJ high strength steel welded box sections， 6 specimens of Q550GJ with various dimensions were designed and manufactured according to its mechanical properties． The partition method was adopted to test the residual stress of these specimens． The distributions of the residual stresses in these specimens were obtained through the test data． The effects of the plate width-thickness ratio and plate thickness were studied． The analysis results showed that there were bigger residual tensile stress in the middle of the flanges and near the welded regions of the web，there were almost the same residual compression stress in the middle of the overhanging regions of the flanges and the web，and the residual stress of other regions for the specimen was transferred from the tensile stress to the compression stress． The residual compression stress was becoming smaller as the increasing of the width-thickness ratio，the changes in the residual tensile stress were not significant，and they were a trend of increasing． The biggest residual tensile stress was lower than the yield stress of the steel． Under the same width-thickness ratio，the residual tensile stress and compression stress were decreased with the increasing of the thickness of the welded specimen．