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高碳铬轴承钢全流程夹杂物演变机理及关键控制工艺

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为研究GCr15轴承钢中夹杂物演变规律,利用Zeiss Ultra55型场发射扫描电镜配置的Aztec-Feature夹杂物自动分析系统对GCr15轴承钢EAF-LF-RH-CC全流程中各工序试样进行大范围(大于200 mm2)定量扫描分析,研究各工序夹杂物形貌、成分、数量、尺寸、分布等演变规律.结果表明,GCr15轴承钢EAF出站时夹杂物主要为纯A12O3夹杂;LF精炼过程中夹杂物转变为MgO-Al2O3及含有少量CaO的Al2O3-MgO-CaO复合夹杂;RH进站后夹杂物中CaO含量升高,逐渐形成Al2O3-CaO-MgO夹杂;最终GCr15轴承钢中间包内夹杂物平均成分为56Al2O3-22CaO-7MgO-8CaS.同时,LF-RH精炼阶段及软吹前期对GCr15轴承钢中夹杂物具有显著去除效果,去除率达95.6%;但随着RH软吹时间的增加,对钢中T[O]、[N]含量的进一步去除影响不大,甚至还会发生大型夹杂物的卷入,导致T[O]含量升高、夹杂物平均尺寸增大等问题.由FactSage平衡热力学计算分析可知,在轴承钢w(T[O])=7×10-6条件下,钢中w([Mg])和w([Ca])分别超过0.4×10-6和0.16×10-6时,钢液中可分别生成镁铝尖晶石和钙铝酸盐夹杂物.研究结果为轴承钢中该类夹杂物控制提供了参考和理论指导.
Evolution mechanism and key control processes of inclusions in high carbon chromium bearing steel during whole process
To study the evolution of inclusions in GCr15 bearing steel,the Aztec-Feature inclusion automatic soft-ware configured with Zeiss Ultra55 scanning electron microscope was used to statistically analyze samples in EAF-LF-RH-CC each process with over 200 mm2 scanning area.The evolution of inclusion morphology,composition,quantity,size and distribution,etc.in each process was analyzed.The result indicates that,the main inclusions in GCrl5 bearing steel are mainly Al2O3 in EAF exit.In the LF refining process,the main inclusions are MgO-Al2O3 and Al2O3-MgO-CaO with a little CaO.After RH start,the content of CaO in the inclusions increases,forming Al2O3-CaO-MgO inclusions.Finally,the average composition of inclusions in the tundish is 56A12O3-22CaO-7MgO-8CaS.At the same time,the LF-RH refining stage and the early stage of RH soft blowing have significant removal effect on inclusions in steel,with removal rate of 95.6%.However,with the increase of RH soft blowing time,it has little effect on the removal of T[O]and[N]in the steel,and even large inclusions may be involved,leading to T[O]and average size of inclusions increase.According to the calculation of FactSage equilibrium thermodynamics,when w(T[O])=7 × 10-6,w([Mg])≥0.4 ×10-6 and w([Ca])≥0.16 × 10-6 in GCr15 bearing steel liquid,mag-nesium aluminum spinel and solid calcium aluminate inclusions can be generated respectively.The research results provide theoretical guidance and reference to the production of bearing steel.

bearing steelinclusionevolution lawaluminum oxidemagnesium oxide

刘洪波、刘颖、谢荣圆、张彩东、车晓锐、李民、高鹏、田志强、张杰

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河钢材料院,河北石家庄 050023

河钢数字技术股份有限公司,河北石家庄 050100

河钢集团石钢公司,河北石家庄 050199

北京科技大学冶金与生态工程学院,北京 100083

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轴承钢 夹杂物 演变规律 氧化铝 氧化镁

河北省自然科学基金资助项目中央引导地方科技发展资金项目

E2021318004216Z1009G

2024

中国冶金
中国金属学会

中国冶金

CSTPCD北大核心
影响因子:0.907
ISSN:1006-9356
年,卷(期):2024.34(2)
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