Abstract：In order to increase the oxidation resistance of the material, a kind of austenitic heat-resistant stainless steel used in the automobile exhaust system contains more than 1.5%Si element. The silicate inclusions with diameter larger than 50 μm were formed by ferrosilicon deoxidation during AOD process. Due to the high alloy composition, the viscosity of the molten steel is high, therefore, the large particle silicate inclusions cannot be removed by LF bottom blowing gas stirring method. The inclusions in continuously cast strands was deformed greatly during rolling process, and the grade was exceeding level 2.0 in the austenitic heat-resistant stainless steel cold rolled plate for the exhaust system, which seriously affects the high temperature fatigue and creep resistance of the product and reduces the service life of the product. Aiming at the higher requirements of inclusions in heat-resistant stainless steel cold rolled sheet for automobile exhaust system, starting from the basic thermodynamic theory, according to the actual smelting process and the composition of molten steel, the thermodynamic conditions for the formation of SiO2, Al2O3and MgO·Al2O3 inclusions in the smelting process and the thermodynamic basis of Ca modified high melting point MgO·Al2O3 inclusions were calculated. LF refining process were improved according to the thermodynamic results, and the following conclusions were obtained. When the mass percent of Al in molten steel is more than 0.003%, the inclusions in molten steel are mainly Al2O3, and MgO·Al2O3 inclusions are easily formed. Ca can modify high melting point MgO·Al2O3 inclusions into low melting point composite inclusions. At 1 500 ℃, when the mass percent of Al in molten steel is 0.04%, the critical mass percent of Ca that begins to modify MgO·Al2O3inclusions is 0.000 4%. In actual LF refining production process, the technology of modifying large-size silicate inclusions into small-size plastic inclusions is adding 0.1 kg aluminum shot and 1.5 kg aluminum powder per ton steel, and feeding 3 m calcium wire per ton steel after aperiod of reaction. The total oxygen mass percent of austenitic heat-resistant steel cold-rolled sheet for automobile exhaust system produced after LF refining process adjustment is less than 0.002 5%, and the inclusions grade is less than level 1.0.
庄迎, 李国平. 排气系统用耐热不锈钢夹杂物控制理论与实践[J]. 钢铁, 2023, 58(3): 151-157.
ZHUANG Ying, LI Guo-ping. Inclusion control theory and practice of heat resistant stainless steel for exhaust system[J]. Iron and Steel, 2023, 58(3): 151-157.
[1] QU Rui,YUE Jian-peng,WANG Yu,et al.Analysis on fatigue fracture and vibration characteristics of vehicle exhaust system[J].Machine Tool and Hydraulics Hydromechatronics Engineering,2019,47(24):52. [2] 王银凤,石平.铁素体不锈钢在排气系统冷凝液中的腐蚀特性研究[J]. 热加工工艺,2019,48(16):37.(WANG Yin-feng,SHI Ping.Research on corrosion characteristics of ferritic stainless steel in condensate of exhaust system[J]. Hot Working Technology,2019,48(16):37.) [3] 任培东,宋仁伯.310S耐热不锈钢高温循环氧化性能[J]. 钢铁研究学报,2017,29(10):844.(REN Pei-dong,SONG Ren-bo.High temperature cyclic oxidation property of 310S heat-resistance stainless steel[J].Journal of Iron and Steel Research,2017,29(10):844.) [4] 胡国栋,冯锐,李书志,等.奥氏体耐热不锈钢中析出相研究进展[J]. 热加工工艺,2022,51(18):6.(HU Guo-dong,FENG Rui, LI Shu-zhi, et al.Research process of precipitates in austenitic heat resistant stainless steels[J].Hot Working Technology,2022,51(18):6.) [5] 张华煜,李国栋,秦凤明,等.309S耐热不锈钢蠕变行为及寿命预测[J].钢铁研究学报,2022,34(3):264.(ZHANG Hua-yu,LI Guo-dong,QIN Feng-ming,et al. Greep behavior and life prediction of 309S heat-resistant steel[J]. Journal of Iron and Steel Research,2022,34(3):264.) [6] 陈启超,游程超,范晓明,等.GX40CrNiSi25-20奥氏体不锈钢的高温氧化性能研究[J].中国铸造设备与技术,2019,54(2):9.(CHEN Qi-chao, YOU Cheng-chao, FAN Xiao-ming,et al. Study on high temperature oxidation properties of GX40CrNiSi25-20 austenitic stainless steel[J]. China Foundry Machinery and Technology,2019,54(2):9.) [7] 付邦豪,陈超,成国光,等.430不锈钢冶炼过程的夹杂物[J].炼钢,2012,47(1):40.(FU Bang-hao,CHEN Chao,CHENG Guo-guang,et al. Inclusions in 430 stainless steel making during AOD-LF-CC process[J]. Iron and Steel,2012,47(1):40.) [8] 缪新德,于春海,石超民,等.轴承钢中钙铝酸盐夹杂物的形成及控制[J].北京科技大学学报,2007,29(8):771.(MIU Xin-de,YU Chun-hai,SHI Chao-min,et al.Formation and control of calcium aluminate inclusions in bearing steel[J].Journal of University of Science and Technology Beijing,2007,29(8):771.) [9] 成东全,陈兴润.硅含量对含钛不锈钢全氧和夹杂物的影响[J].炼钢,2019,35(5):23.(CHENG Dong-quan,CHEN Xing-run.Effect of silicon content on the total oxygen and inclusions of Ti-bearing stainless steel[J].Steelmaking,2019,35(5):23.) [10] 贺道中,周宇涛.高强度船板钙处理热力学计算分析——夹杂物变质研究和应用[J].特殊钢,2017,38(3):23.(HE Dao-zhong, ZHOU Yu-tao.Study and application on thermodynamic calculated analysis of calcium treatment and modification of inclusions in high strength ship plate steel[J]. Special Steel,2017,38(3):23.) [11] 张一民,孙彦辉,白雪峰,等.不锈钢中夹杂物三维形貌及其热力学计算[J].过程工程学学报,2020,42(1):14.(ZHANG Yi-min,SUN Yan-hui,BAI Xue-feng, et al.Three-dimensional morphology and thermodynamic calculation of inclusions in stainless steel[J].Chinese Journal of Engineering,2020,42(1):14.) [12] 沈春飞,蒋兴元,李阳,等.Mg处理钢生成细小尖晶石夹杂物的研究[J].炼钢,2009,25(5):52.(SHEN Chun-fei,JIANG Xing-yuan,LI Yang,et al.Research on tiny MgO·Al2O3 spinel inclusions in Mg treated steel[J].Steelmaking,2009,25(5):52.) [13] 陈兴润,成东全,潘吉祥,等.410S不锈钢脱氧及冶炼过程的夹杂物[J].中国冶金,2016,26(8):56.(CHEN Xing-run,CHENG Dong-quan,PAN Ji-xiang,et al.Deoxidization and inclusions in 410S ferritic stainless steel during smelting process[J].China Metallurgy,2016,26(8):56.) [14] 张鉴,成国光,王力军,等.冶金熔体的计算热力学[M].北京:冶金工业出版社,1998.(ZHANG Jian,CHENG Guo-guang,WANG Li-jun,et al. Computational Thermodynamics of Metallurgical Melts[M]. Beijing:Metallurgical Industry Press,1998.) [15] 陈家祥. 钢铁冶金学[M].北京:冶金工业出版社,1993.(CHEN Jia-xiang. Iron and Steel Metallurgy[M]. Beijing:Metallurgical Industry Press,1993.) [16] 张月鑫,张立峰,王举金,等.连铸坯全断面非金属夹杂物成分分布的预报[J].钢铁,2021,56(10):74.(ZHANG Yue-xin,ZHANG Li-feng,WANG Ju-jin,et al. Prediction of composition distribution of non-metallic inclusions in a billet[J].Iron and Steel,2021,56(10):74.) [17] 赵东伟,李海波,高攀,等.非钙处理铝脱氧车轮钢夹杂物形成及变形行为[J].钢铁,2016,51(1):25.(ZHAO Dong-wei,LI Hai-bo,GAO Pan,et al.Inclusion formation and deformation in Al-killed wheel steel without calcium treatment[J].Iron and Steel,2016,51(1):25.) [18] 高胜亚,姜敏,侯泽旺,等.钙处理对高碳铝镇静钢中夹杂物的影响[J].钢铁,2017,52(4):25.(GAO Sheng-ya, JIANG-Min,HOU Ze-wang, et al.Effect of calciumtreatment on non-metallic inclusions in high carbon aluminum lilled steel [J].Iron and Steel,2017,52(4):25.) [19] 李双江,姜周华,黄宗泽,等.精炼渣碱度对304不锈钢夹杂物的影响[J].钢铁,2010,45(12):26.(LI Shuang-jiang,JIANG Zhou-hua,HUANG Zong-ze,et al.Effect of refining slag basicity on inclusions in 304 stainless steel[J].Iron and Steel,2010,45(12):26.) [20] 王昆鹏,王郢,徐建飞,等.轴承钢二次精炼过程夹杂物演变规律[J].钢铁,2022,57(6):42.(WANG Kun-peng, WANG Cheng, XU Jian-fei, et al. Investigation on evolution of inclusions in bearing steel during secondary refining[J].Iron and Steel,2022,57(6):42.)
2023, Vol. 58 
