大型GCr15钢锻坯黑皮粗糙度对超声波检测结果的干扰

Interference of Black Surface Roughness of GCr15 Steel Large Forging Stocks on Ultrasonic Testing Results

某批大型GCr15钢锻材超声波检测出纵向超声波密集型缺陷,缺陷当量高于GB/T6402-2007质量等级3级的要求,究其原因为GCr15钢锻坯表面黑皮粗糙度较高,使得超声波探伤结果出现正向系统误差,实际探伤结果高于真实缺陷当量。笔者提出了一种μ值修正法,对于GCr15钢锻材毛坯件,可通过μ影响系数1/10β粗糙背散射声压40来消除毛坯表面黑皮粗糙度的干扰。结果表明:通过该方法修正,可使得毛坯面的超声波检测结果与机加工面的检测结果相一致。

Longitudinal ultrasonic intensive defects were tested for a batch of CA2r15 steel large forging stocks and the equivalent defect diameter was higher than the requirement of GB/T 6402-2007 for the third quality grade. Because the black surface roughness of the GCr15 steel forging stocks was rather high, the ultrasonic testing results appeared forward system error and the actual testing results was higher than the real equivalent defect diameter. A method of μ-value correction was proposed, and for GCr15 steel forging stocks, the interference of black surface roughness on ultrasonic testing results could be eliminated by correcting with μ= 1/10^β/40. The results show the calibration to eliminate the interference of black surface roughness was rather good.