Experimental research on the blind hole-drilling method for measuring residual stress of steel plate

The blind hole method is the most widely non-destructive measurement method to measure the residual stress. In order to use the blind hole method more reasonable and achieve the higher measurement accuracy, the tensile and compressive force is applied to the steel sheet sample and the internal stress of the sample is measured through the blind hole method, then compare with the theoretical values and analyze the measurement accuracy. The experimental results show that the minimum resolution of the blind hole method is about 1 MPa; the residual stress values which are measured by the blind hole method have some deviation under the different internal stress levels; as the tensile stress increases, the measurement accuracy of the blind hole method are increased, which becomes stable after the tensile stress is more than 60 MPa; as the absolute value of the compressive stress increases, the measurement accuracy are increased, which becomes stable after the compressive stress is less than −35 MPa; when the stress is between −10 MPa and 25 MPa, the measurement accuracy is relatively poor. According to the experimental measurement results, the compensation correction mode for the blind hole method is established, and after correction the measurement accuracy of the blind hole method under high stress conditions (tensile stress greater than 25 MPa, compressive stress less than −10 MPa) could be significantly improved. However, under the low stress conditions (tensile stress is less than 25 MPa, compressive stress is greater than −10 MPa), after correction the improvement of the measurement accuracy is still limited. It is recommended to increase measurement number to ensure the measurement accuracy. The compensation correction mode is applied to the actual measurement of residual stress of hot rolled automobile beam steel plate, the experimental results show that the transverse residual stress is greater than the longitudinal residual stress exists in the hot rolled steel plate with sliver warping defects, which provide a support for solving the slicing warpage problem.