Inclusion Variations of Hot Working Die Steel H13 in Refining Process

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• 作者：Jian-hua LIU^a ; ^{liujianhua@163.com}Author Vitae ; Guo-xuan WANG^b ; Yan-ping BAO^a ; Yan YANG^a ; Wei YAO^b ; Xiao-ning GUI^b
• 关键词：hot working die steel ; ESR ; cleanness ; refining slag ; modification
• 刊名：Journal of Iron and Steel Research, International
• 出版年：2012
• 出版时间：November, 2012
• 年：2012
• 卷：19
• 期：11
• 页码：1-7
• 全文大小：770 K

文摘

Inclusion variations of die steel H13, including changes of species, morphologies, compositions, amounts and sizes, in the production of EAF¡úLF¡úVD¡úingot casting¡úelectro-slag refining (ESR) procedure, were investigated by systematic sampling, and analyzed with scanning electron microscope (SEM), energy dispersive spectrum (EDS), and metallographic microscope. The variation mechanism was studied by comprehensive analysis of total oxygen, nitrogen, and acid soluble aluminum as well as chemical test of refining slag. Based on the investigations, technical measures for cleanness improvement were discussed. The results show that oxide inclusions in H13 steel change from irregular Al₂O₃¡únear globular CaO-MgO-Al₂O₃ and CaO-Al₂O₃-SiO₂ complex inclusions¡úfiner CaO-Al₂O₃-SiO₂ inclusions with higher CaO content¡úCaO-Al₂O₃-SiO₂ inclusions with higher Al₂O₃ content and irregular MgO-Al₂O₃ inclusions¡úfine irregular MgO-Al₂O₃-CaS inclusions in various steps of the production; the variations are related with changes of acid soluble aluminum content, reactions between slag and steel, re-oxidation of liquid steel during casting, and refining of ESR. It is also found that A1₂O₃ inclusions are modified by refining slag in LF and VD refining; and ESR plays a good role in inclusion removal, especially in controlling the large linear VC-CrC-MoC inclusions distributed in grain boundaries. It is suggested that casting protection should be improved, and the basicity of refining slag and acid soluble aluminum content in steel should be raised.