钢板残余应力盲孔测量法试验及应用

盲孔法为目前应用最为广泛的金属结构残余应力测量方法. 为了在薄钢板残余应力检测时更合理使用盲孔法并获得最好的测量精度，设计制作钢板试样在拉伸(压缩)试验机上施加拉力或者压力，使用盲孔法重复测量钢板内应力多次并与其理论值进行比较，分析测量的准确性和重复性. 结果表明，最小可稳定感知的拉伸和压缩应力都大约为1 MPa，在各应力水平下测量值都存在一定大小的偏差和分散性. 随着拉应力的增大，测量的准确度和重复性也都提高，并在大于60 MPa以后趋于稳定；随着压应力绝对值的增大，测量的准确度和重复性也都提高，并在大于35 MPa之后达致稳定；当应力水平在?10 ~ 25 MPa之间时，测量的准确度和重复性都较差. 建立测量精度补偿修正模型，经过修正后盲孔法对于高应力(拉应力大于25 MPa，压应力小于?10 MPa)水平的测量准确度都可以显著提高；但对于低应力(拉应力小于25 MPa，压应力大于?10 MPa)水平的测量准确度与重复性仍都较低，建议在实际使用中通过增加测量次数以保证测量结果可信度. 将所建立的测量精度修正方法用于针对某公司热轧汽车大梁钢板分条前钢板残余应力的实际测量，测量发现产生分条翘曲缺陷的热轧钢板都存在横向残余应力大于纵向残余应力的现象，为研究分条翘曲问题提供了支撑.

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.