Effect of Ti De-oxidation on Solidification and Post-solidification Microstructure in Low Carbon High Manganese Steel

• Kikuchi Naoki

  Department of Material Science & Engineering, Carnegie Mellon University

• Nabeshima Seiji

  Steelmaking Research Department, Steel Research Lab, JFE Steel Corp.

• Kishimoto Yasuo

  Steelmaking Research Department, Steel Research Lab, JFE Steel Corp.

• Matsushita Taishi

  Department of Materials Science and Engineering, Royal Institute of Technology

• Sridhar Seetharaman

  Department of Material Science & Engineering, Carnegie Mellon University

抄録

This paper investigates the effect of de-oxidation inclusions on micro-structure in low-carbon steels. Low carbon (0.07 wt%), high Mn (0.9 wt%) steel in a Al₂O₃ or MgO crucible was deoxidized by adding either aluminum (0.05 wt%) or titanium (0.05, 0.03 or 0.015 wt%) in a 400 g-scale vacuum furnace, and cast in a Cu mold at cooling rates between 2.0–6.0 K/s.<br>The oxide inclusions were identified as Al₂O₃ (1–3 μm) in the Al-killed steel and Ti–Al–(Mg)–O (0.3–0.5 μm) in the Ti-killed steel. Oxide inclusion sizes in all the Ti-killed steels were smaller and inclusion densities higher than those in the Al-killed steel.<br>Solidification structure, defined as the density of primary dendrite arms within a defined region was finer with increasing inclusion density and as a result, the solidification structure of the Ti-killed steel was finer than that of the Al-killed steel.<br>A Confocal Scanning Laser Microscope (CSLM) and a Differential Scanning Calorimeter (DSC) were used to study the differences in solid state micro-structural evolution between the Ti-killed, Al-killed and the non de-oxidized samples. The growth of austenite grains were studied under isothermal conditions and it was found that both grain-boundary mobility and final grain size were lower in the Ti-killed sample than for the others. With regards to austenite decomposition, during continuous cooling from a comparable austenite grain structure, the resulting austenite decomposition structure was finer for the Ti-killed sample due to a higher Widmanstätten lath density due to precipitation at particles in addition to grain boundaries.

収録刊行物

• ＩＳＩＪ　Ｉｎｔｅｒｎａｔｉｏｎａｌ

  ＩＳＩＪ　Ｉｎｔｅｒｎａｔｉｏｎａｌ 47 (9), 1255-1264, 2007

  一般社団法人 日本鉄鋼協会

キーワード

• low-carbon steel
• de-oxidation
• aluminum
• titanium
• inclusion
• solidification microstructure
• confocal-laser-scanning-microscopy
• phase transformation
• grain growth

詳細情報

• CRID: 1390282681463964160
• NII論文ID: 10027024674
• NII書誌ID: AA10680712
• DOI: 10.2355/isijinternational.47.1255
• ISSN: 13475460
• ISSN: 09151559
• Web Site: http://www.jstage.jst.go.jp/article/isijinternational/47/9/47_9_1255/_pdf
• 本文言語コード: en
• データソース種別:
  • JaLC
  • Crossref
  • CiNii Articles
• 抄録ライセンスフラグ: 使用不可