Abstract:For the blowhole defects generated in continuous casting billets of high-sulfur Y12Cr13 free-cutting stainless steel, the position of defects was tested and analyzed by macroscopic examination and scanning electron microscope (SEM). Through theoretical calculations and related verification tests, the correlation between the gases of N2, H2 and CO in molten steel with blowhole defects was analyzed. The specific reasons were finally determined by the exclusion method. The comprehensive analysis test results showed that the blowhole defects in continuous casting billets of Y12Cr13 stainless steel were caused by CO bubbles generated due to the C-O reaction in the molten steel. The improvement measures of reducing free oxygen content in the molten steel could effectively reduce the blowhole defects in continuous casting billets.