Q&P와 AM강의 잔류오스테나이트 분율과 안정도에 따른 인장특성 거동

변상호; 오창석; 남대근; 김영석; 강남현; 조경목; Sang-Ho Byun; Chang-Suk Oh; Dae-Geun Nam; Young-Seok Kim; Namhyun Kang; Kyung-Mox Cho

Korean Journal of Materials Research, Vol.19, No.6, 305-312, June, 2009

DOI10.3740/MRSK.2009.19.6.305 Export Citation

Q&P와 AM강의 잔류오스테나이트 분율과 안정도에 따른 인장특성 거동

Effects of Stability and Volume Fraction of Retained Austenite on the Tensile Properties for Q&P and AM Steels

변상호, 오창석¹, 남대근², 김영석², 강남현 ^†, 조경목

부산대학교 재료공학과
¹한국기계연구원 부설 재료연구소 구조재료연구본부
²한국생산기술연구원 동남권 기술지원본부

Sang-Ho Byun, Chang-Suk Oh¹, Dae-Geun Nam², Young-Seok Kim², Namhyun Kang^†, and Kyung-Mox Cho

Department of Materials Science and Engineering, Pusan National University, Busan 609-735, Korea
¹Department of Structural Materials, Korea Institute of Materials Science, Korea
²Division for Dongnam Area Technology Service, Korea Institute of Industrial Technology, Korea

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The effects of Quenching and Partitioning (Q&P) and Annealed Martensite (AM) heat treatment on the microstructure and tensile properties were investigated for 0.24C-0.5Si-1.5Mn-1Al steels. The Q&P steels were annealed at a single phase (γ) or a dual phase (γ + α), followed by quenching to a temperature between Ms and Mf. Then, enriching carbon was conducted to stabilize the austenite through the partitioning, followed by water quenching. The AM steels were intercritically annealed at a dual phase (γ +α) temperature and austempered at Ms and Ms ± 50 oC, followed by cooling in oil quenching. The dual phase Q&P steels showed lower tensile strength and yieldyield strength than those of the single phase Q&P steels, . and tThe elongation for the dual phase Q&P steel was partitioning 100s higher than that of that for the single phase Q&P steels as the partitioning time was less than 100s up to partitioning 100s. For AM steels, the tensile/yield strength decreased and the total elongation increased as the austempering temperature increased. The stability of the retained austenite controlled the elongation for Q&P steels and the volume fraction of the retained austenitecontrolled the elongation for AM steels.

Keywords:retained austenite;stability;annealed martensite;bainite;tensile property

[References]

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Sugimoto K, Kobayashi M, Nagasaka A, Hashimoto S, ISIJ Int., 35, 1407 (1995)
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[Related Articles]

[1] Song S, Sugimoto K, Kobayashi M, Matsubara H, Kashima T, ISIJ Int., 86, 563 (2000)

[2] Sugimoto K, Kobayashi M, Nagasaka A, Hashimoto S, ISIJ Int., 35, 1407 (1995)

[3] Hiwatashi S, Takahashi M, Katayama T, Usuda M, J. Jpn. Soc. Technol. Plast., 35, 1109 (1994)

[4] Matsumura O, Sakuma Y, Ishii Y, Zhao J, ISIJ Int., 32, 1110 (1992)

[5] Hirose Y, Nakai S, Furuyama H, Sudoh S, Ueno K, J. Jpn. Soc. Technol. Plast, 35, 1071 (1994)

[6] Nagasaka A, Sugimoto K, Kobayashi M, Hashimoto S, ISIJ Int., 83, 335 (1997)

[7] De Cooman BK, Solid State Mater. Sci., 8, 285 (2004)

[8] Streicher AM, Speer JG, Matlock DK, DE Cooman BC, AHSS proceedings, 51 (2004). (2004)

[9] Sugimoto KI, Bingzhe YU, MUKAI YI, Shushi I, ISIJ Int., 45, 1191 (2005)

[10] Sugimoto KI, Kanda A, Kikuchi R, Hashimoto SI, Kashima T, Ikeda S, ISIJ Int., 42, 910 (2002)

[11] Miller RL, Trans. ASM, 57, 892 (1964)

[12] Miller RL, Trans. ASM, 61, 572 (1968)

[13] Cullity BD, Elements of X-Ray Diffraction, p.113, 2nd ed. Addison-Wesley Publishing Co., Inc., (1978). (1978)

[14] Speer JG, Matlock DK, De Cooman BC, Schroth JG, Acta Mater., 51, 2611 (2003)

[15] Matlock DK, Brautigam VE, Speer JG, Mater. Sci. Forum, 426, 1089 (2003)

[16] Hong SC, Ahn JC, Nam SY, Kim SJ, Yang HC, Speer JG, Matlock DK, Materials Int., 13, 439 (2007)

[17] Kim SJ, Speer JG, Kim HS, De Cooman BC, Advanced Steel Processing and Products Research Centre, Colorado School of Mines, Golden, Colorado, USA 80401.

[18] Matsumura O, Sakuma Y, Takechi H, ISIJ, 27, 570 (1987)

[19] Speer JG, Edmonds DV, Rizzo FC, Matlock DK, Curr. opin. Solid State Mat. Sci., 8, 219 (2004)