Effect of Microstructure of Parent Metal and Weld Metal of Austenitic Stainless Steel Pipe on Ultrasonic Testing

Microstructure characteristics of parent metal and weld metal of austenitic stainless steel pipe in different welding process were studied using metallographic test. And microstructure characteristics of parent metal and weld metal of austenitic stainless steel pipe and carbon steel pipe with the same welding process were also studied. Detecting sensibility and signal noise ratio both from artificial groove defect of weld and edge were quantitatively tested with ultrasonic method. The propagation property differences of ultrasonic wave were analyzed by comparing the data tested from austenitic stainless steel pipe and carbon steel pipe. The results showed that, by the two different welding methods, the microstructure of parent metal and weld metal of austenitic stainless steel pipe was same, and the effect difference on ultrasonic testing was not obvious. By the same welding method, the weld microstructure of 304 austenitic stainless steel pipe and 20 carbon steel pipe was markedly different, and the communication effect of ultrasound in austenitic stainless steel pipe weld was not good, which led to test difficultly. Because both detecting sensibility and signal noise ratio of critical longitudinal wave twin probe were very high, so the satisfactory effect to find the surface defects could be obtained.