轴承钢水浸探伤缺陷分析与改善实践

In this paper,the characteristics and main impact factors of macroscopic inclusion defects in steel were analyzed by combining ultrasonic detection,location analysis and metallography sample analysis,based on the production of GCr15 bearing steel produced by BOF-ARS(argon station)-LF-RH-CC process in Shaosteel,and corresponding improvement measures were proposed.The results show that it is difficult to remove the fine CaO-Al2O3-MgO inclusions,as the wettability of fine these inclusions generated at the ladle furnace increased with the increase of CaO and decrease of Al2O3 content,and the probability of agglomeration and formation of macroscopic inclusions increase during solidification.The change of acid-soluble aluminum in smelting process,the refining time of LF and the content of Ca in LF treated steel are significantly correlated with the results of water immersion test.When the loss of acid-soluble aluminum in smelting process increases,the refining time of LF is inappropriate and the content of Ca in steel is too high,the pass rate of water immersion ultrasonic test will decrease significantly.After the improvement,the amount of liquid inclusions in steel is greatly reduced,and no macro inclusions of millimeter level are detected in rolled steel with the carbon at the end of converter controlled not less than 0.1%,the LF refining time in the range of 50-90min,and the index of Ca content after LF treated less than 5.The purity of molten steel is effectively improved.