Abstract：A 900 MPa seamless steel pipe experienced cracking during the drilling process. Through analyses of chemical composition, mechanical properties, and metallographic structure, no differences were found between the factory performance of the product. This failure was not caused by the structure abnormalities, component deviations, or low performance. On this basis, the finite element simulation was used to analyze the stress status of the pipe body, and an X-ray residual stress analyzer was used to measure the residual stress on the surface layer and different depths of the steel pipe. The reasons for cracking during use were further analyzed. The results indicated that the shear stress of steel pipes under service conditions was above 100 MPa. The maximum residual stress values all occurred at a depth of approximately 1 mm in the shallow layer, with a maximum of 784 MPa. The high residual stress in the shallow surface layer was the main reason for the formation of capillary and small cracks in local areas of the shallow surface layer after the production of steel pipes was completed. In the later stage of use, the combined action of external load and residual stress led to the secondary propagation of these small cracks, forming the main crack with multiple crack sources, and ultimately causing the longitudinal crack of the steel pipe.
2023, Vol. 41 
