DOI QR코드

DOI QR Code

Effect of Heat Treatments on the Microstructures and Mechanical Properties of OCTG

유정용 강관의 미세조직 및 기계적 성질에 미치는 열처리의 영향

  • Received : 2017.01.23
  • Accepted : 2017.05.12
  • Published : 2017.05.31

Abstract

This study examined the effect of heat treatment on the microstructure and mechanical properties of J55 line pipe steel. The experiments were carried out at under the following various conditions: austenization temperature($880^{\circ}C$, $910^{\circ}C$, $940^{\circ}C$), cooling methods(water quenching, oil quenching) and tempering temperature(none, $550^{\circ}C$, $650^{\circ}C$). The phase diagram and CCT curve were simulated based on the chemical composition of J55 steel to predict the microstructures. In the results, A1, A3 temperature decreased. As the austenization temperature increased, existing austenite grains grew exponentially which seriously degraded their mechanical properties. Various microstructures, including martensite, bainite, ferrite, and pearlite, developed in accordance with the heat treatments and were closely correlated with hardness, tensile strength and toughness. Martensite was formed after water quenching, but bainite and ferrite appeared after oil quenching. FeC precipitation formed and coarsened during tempering, which improved their toughness.

Keywords

Heat treatment;Mechanical property;Microstructure;OCTG;Quenching

References

  1. L. Helin, H. Lihong, Z. Wenli, "Demand for and Development of Hi-performance OCTG", Steel Pipe, vol. 1, p. 3, 2009.
  2. J. Yu, H. Jung, K. Noh, S. Cheon, K. Kang, "Technological Development Trend of API steel", Trends in metals & Materials Engineering, vol. 25, no. 6, pp. 4-11, 2012.
  3. Y. Zhang, L. Zhiwei, "Current Development Situation and Prospects of Offshore Oil Pipes". Steel Pipe. vol. 5, p. 3, 2009.
  4. L. Yang, S. Song, X. Han, K. Lin, "Review on the technologies of casing and its development trend", Oil Field Equipment, vol. 3, p. 5, 2005.
  5. H. Kang, "Technological Development Trend of OCTG", Trends in metals & Materials Engineering, vol. 25, no. 6, pp. 57-64, 2012.
  6. Y. Zhang, Z. Mingliang, "Forecast of OCTG Prospects (Part II)", Steel Pipe, vol. 3, 2007.
  7. C. Zhang, "Development of Coiled Tubing Technology", Baosteel Technology, vol. 2, no. 2, pp. 26-29, 2007
  8. Helin Li, "Development Trend of OCTG and Related Topics of General Interest", Steel Pipe, vol. 6, p. 1, 2005
  9. R. Chunming, Cui. Runjiong, "Development and Application of Non-quenched and Tempered Steels for Oil-well Tube", Iron and Steel, vol. 1, pp. 015, 2002
  10. R. L. Klueh, P. J. Maziasz, E. H Lee "Manganese as an austenite stabilizer in Fe-Cr-Mn-C steels", Materials Science and Engineering: A, vol. 102, no. 1, pp. 115-124, 1988. DOI: https://doi.org/10.1016/0025-5416(88)90539-3 https://doi.org/10.1016/0025-5416(88)90539-3
  11. S. J. Kim, C. G Lee, T. H Lee, C. S. Oh "Effect of Cu, Cr and Ni on mechanical properties of 0.15 wt.% C TRIP-aided cold rolled steels." Scripta Materialia, vol. 48, no. 5, pp. 539-544, 2003. DOI: https://doi.org/10.1016/S1359-6462(02)00477-3 https://doi.org/10.1016/S1359-6462(02)00477-3
  12. H Zhao, B. P. Wynne, E. J. Palmiere, "Effect of austenite grain size on the bainitic ferrite morphology and grain refinement of a pipeline steel after continuous cooling", Materials Characterization, vol. 123, pp. 128-136, 2017. DOI: https://doi.org/10.1016/j.matchar.2016.11.025 https://doi.org/10.1016/j.matchar.2016.11.025