Research on Improving the Accuracy of Welding Residual Stress of Deep-Sea Pipeline Steel by Blind Hole Method

Abstract

For a typical pipeline-lifting deep-sea mining system, marine mining pipelines have higher requirements for steel welding. After the pipeline steel is welded, a large amount of residual stress will be generated inside the component because the heat treatment is not carried out, causing the pipeline to form stress corrosion cracks in the seawater environment. For high residual stress, the blind hole method has inaccurate measurement accuracy. Based on the theory of solid mechanics, this paper comprehensively considers the distance between the strain grid and the center of the hole. It introduces the ratio γ of the applied stress to the yield strength of the specimen. The strain relief coefficients under the values were investigated. The variation trend of the strain release coefficient distribution with the γ value of the three kinds of strain gauge flowers commonly used in China was discussed. Finally, the variation law of strain release coefficient with γ value was obtained by fitting. The strain release coefficient was corrected to improve the accuracy of the blind hole method for measuring high residual stress, which provides a reference value for the engineering application of the blind hole method. This has important theoretical significance and engineering value for guiding the welding construction of high-strength pipeline steel in a deep-sea environment.