Effect of Carbon and Nitrogen on <i>Md</i>₃₀ in Metastable Austenitic Stainless Steel

• Masumura Takuro

  Research Center for Steel, Kyushu University International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University

• Fujino Kohei

  Graduate School of Engineering, Kyushu University

• Tsuchiyama Toshihiro

  Research Center for Steel, Kyushu University International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University Department of Materials Science and Engineering, Kyushu University

• Takaki Setsuo

  Research Center for Steel, Kyushu University

• Kimura Ken

  Titanium & Stainless Steel Research Lab., Steel Research Laboratories, NIPPON STEEL CORPORATION

抄録

Md₃₀ is defined as the temperature at which 50 vol.% of α’-martensite is formed at a true tensile strain of 0.3 in metastable austenitic steels. The effect of C concentration on Md₃₀ is known to be identical to that of N, as shown by Nohara’s equation. However, we found that Md₃₀ of C-added steel is lower than that of N-added steel, which indicates that the effect of C concentration on the mechanical stability of austenite is more significant than that of N. In addition, the relationship between Md₃₀ and C and N concentration is not linear. The effect of C and N concentration on Md₃₀ is higher at lower C and N concentration (<0.1%). As this effect was not considered in the previous study, the austenite-stabilizing effects of these elements were underestimated. Therefore, in this study, new equations were proposed to accurately estimate Md₃₀ of an Fe–Cr–Ni alloy system. The modified Md₃₀ equation is shown below:<br><img align="middle" src="./Graphics/abst-61_546_eq_a.jpg"><br>C_eq (C equivalent) is a function of C and N concentrations and temperature.<br><img align="middle" src="./Graphics/abst-61_546_eq_b.jpg"><br><img align="middle" src="./Graphics/abst-61_546_eq_c.jpg"><br>These equations show that the difference in austenite-stabilizing effects of C and N increases with increasing temperature due to the difference in stacking fault energy between C- and N-added steels.

収録刊行物

• ＩＳＩＪ　Ｉｎｔｅｒｎａｔｉｏｎａｌ

  ＩＳＩＪ　Ｉｎｔｅｒｎａｔｉｏｎａｌ 61 (2), 546-555, 2021-02-15

  一般社団法人 日本鉄鋼協会

キーワード

• mechanical stability
• metastable austenitic steel
• <i>Md</i>₃₀
• deformation-induced <i>α</i>’-martensite
• stainless steel
• carbon
• nitrogen

詳細情報

• CRID: 1390005667261475328
• NII論文ID: 130007987393
• DOI: 10.2355/isijinternational.isijint-2020-719
• ISSN: 13475460
• ISSN: 09151559
• Web Site: https://www.jstage.jst.go.jp/article/isijinternational/61/2/61_ISIJINT-2020-719/_pdf
• 本文言語コード: en
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