基于大型炉体焊接残余应力测试的盲孔法研究

MEASUREMENT OF WELDING RESIDUAL STRESS IN THE HEAVY CONVERTER USING BLIND-HOAL METHORD

为提高炉体焊接残余应力测试精度,对传统的盲孔法进行改进,即在测点打孔后多次扩孔并增加孔深;通过对SM400ZL钢焊接残余应力测试时的应变释放系数A,B进行实验标定,得出多组应变释放系数值,计算可得残余应力的估算值,并对不同状况下的残余应力值进行比较．通过大拉力标定试验得出SM400ZL钢盲孔的孔边塑性变形对测量精度的影响和塑性修正公式．结果表明,改进的盲孔法能够更准确地测得焊接残余应力值,测量结果经塑性修正,最大误差减小到2%以下．测试方法和结果可直接在相关的工程实际中应用．

To enhance the measurement accuracy for welding residual stress in the converter, the traditional blind-hole method is improved by widening hole and increasing depth more than once after drilling hole on one measuring point. Strain relief parameters A and B for welding residual stress of Steel SM400ZL measured by the blind-hole method are verified by test, applying multi-group strain relief parameters for calculation. Welding residual stress estimations in different conditions are obtained, and compared with test results. In the force tensile test, it is found that the plastic deformation around the blind hole influences the measurement precision and plastic correction formulation. The tests show that the improved blind-hole method could measure the residual stress more accurately, and by plastic correction the largest measurement error is reduced with in 2%. The test method and results can be directly used in welding residual stress measurement of Steel SM400ZL.