厚壁CCASS材料特性及其对超声检测的影响

Investigations on Material Properties of Thick-wall CCASS and Their Effects on Ultrasonic Testing

对壁厚98 mm的离心铸造奥氏体不锈钢(Centrifugally Cast Austenitic Stainless Steel,CCASS)试样的纵波声速、衰减系数和幅度谱等声学特性进行了测试分析,并采用TRL相控阵探头进行扇形扫描和B扫描检测。结合试样的宏观、微观组织对实验结果进行了分析讨论。研究表明:试样晶粒粗大,内部组织存在分层,介质的非均质性明显,导致超声检测信号噪声水平高、幅度谱波动大,纵波声速和衰减系数在一定范围内变化,相控阵扇形扫查和B扫查成像效果较差。利用CIVA软件得到的模拟结果为解释上述实验现象提供了依据。

The acoustic properties of Centrifugally Cast Austenitic Stainless Steel （CCASS）, longitudinal wave velocity, attenuation coefficient and amplitude spectrum, were tested and analyzed with the 98 mm thickness specimen. S-scan and B-scan were conducted using the TRL phased array probe. The results were discussed in virtue of the macro- and microstructure. It shows that coarse grains, mnlti-layers and obvious heterogeneity in the sample led to the high level noise and large fluctuation of amplitude spectrum. The longitudinal wave velocity and attenuation coefficient also varied to some content. Thus, poorer imaging of S-scan and B-scan were obtained. Simulation results obtained from the CIVA software were in accordance with the results above ~