Abstract: In the process of measuring high-level residual stress by the hole-drilling method, the stress calculation is overestimated due to plastic deformation caused by stress concentration around the hole. The plasticity locally induced by the introduction of the hole is analyzed and a procedure is proposed to take into account its effects on measurements of the residual stress. And then the residual stress of welded joint is measured by the modified strain release coefficients. When the stress is less than 175 MPa, the material undergoes elastic deformation, and the strain release coefficient satisfies the elastic deformation theory, which is independent of the stress. However, when the stress value reaches 175 MPa, plastic deformation occurs due to the stress concentration effect around the hole, which a stress value of 317.2 MPa is formed on the section perpendicular to the tensile direction around the hole. Although the plastic deformation around the hole has little effect on the strain release coefficient A, the strain release coefficient B decreases with the increase of stress. Based on the finite element calculation results, the equation between the parameter of the distortion-energy and the strain release coefficient is constructed to eliminate the plastic effect around the hole, and the measurement accuracy is greatly improved.

Key words: welding residual stress, hole-drilling method, strain release coefficients, plasticity effects, finite element analysis