Abstract：Many white spot imperfections were observed on the inner surface of 1Cr18Ni9Ti stainless-steel pipes produced by cold rolling process, so that the products could not be delivered normally. In order to confirm the reasons for the formation of white spots, the surface morphology, metallographic structure, grain size and micro area composition of this batch of steel pipes were analyzed and detected using scanning electron microscopy + energy disperse spectroscopy, metallographic microscope, and laser-induced breakdown spectroscopy. The results showed that the surface carburization occurred on both inner and outer surface of the pipe, and the carburization in white spot imperfection was much more serious than other areas. The severe intergranular corrosion was caused during pickling and passivating. Many grains on the surface were dropped off, deteriorating the roughness on partial surface, and forming white spot imperfections. The inadequate degreasing on pipe surface caused carburization in heat treatment process, which was the major reason for white spot imperfections.
2022, Vol. 40 
