Abstract

During ultrasonic nondestructive testing of several stamped forgings made of nickel heat-resistant alloys of two grades, we discovered a new phenomenon of a local decrease in the amplitude of the bottom echo signal. The decrease was accompanied by the presence of large (more than 20 mm) zones with considerable (up to 1.5%) fluctuations in the propagation velocity of a longitudinal ultrasonic wave that were chaotically scattered over the surface of the semi-finished product. In this case, the material revealed no uneven grain-size distribution or coarse-grained structure, usually causing an increase in the coefficient of attenuation of ultrasonic waves in such alloys and causing a decrease in the amplitude of the bottom echo signal. The present paper describes the studies carried out to establish the physical reasons for the discovered macroscopic inhomogeneity of velocity and its relationship with the drop in the amplitude of the bottom signal.

中文翻译：

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镍耐热合金毛坯中超声振荡“异常”衰减的研究案例

摘要

在对几种由两种等级的镍耐热合金制成的冲压锻件进行超声无损检测期间，我们发现了底部回波信号幅度局部降低的新现象。减少伴随着大的（大于20 mm）区域的存在，纵向超声波的传播速度有相当大的波动（高达1.5％），这些波动混乱地散布在半成品的表面上。在这种情况下，该材料没有显示出不均匀的晶粒尺寸分布或粗晶粒结构，通常导致这种合金中超声波的衰减系数增加，并且导致底部回波信号的振幅减小。