Study on Fracture Behavior of Mild Steel Under Cryogenic Condition

연강(Mild Steel)의 극저온 파괴 거동에 대한 실험적 연구

Choi, Sung Woong;Lee, Woo IL

  • Received : 2015.08.21
  • Accepted : 2015.12.09
  • Published : 2015.12.31


Considering for plants and structure under extreme conditions is required for the successful design, especially temperature and pressure. The ductile-brittle transition temperature (DBTT) for the materials under extreme condition needs to be considered. In this study, A-grade mild steel for the LNG carrier and offshore plant was examined by performing low-temperature Charpy V-notch (CVN) impact tests to investigate DBTT and the fracture toughness. The absorbed energy decreased gradually with the experimental temperature, which showed an upper-shelf energy region, lower shelf energy region, and transition temperature indicating DBTT. In addition, the fracture surface morphologies of the mild steels indicated ductile fractures at the upper-shelf energy level, with wide and large-sized dimples, whereas a brittle fracture surface, where was observed at the lower-shelf energy level, with both large and small cleavage facets. Based on the experimental results, ductile brittle transition temperature was estimated in about $-60^{\circ}C$.


A-grade mild steel;CVN;DBTT;Ductile fracture;Brittle fracture


  1. Kumar, S., Kwon, H.T., Choi, K.H., Cho, J.H., Lim, W.S. and Moon, I, "Current status and future projections of LNG demand and supplies: A global prospective", Energy Policy, 39-7, 4097-4104, (2011)
  2. Kim, I. P., Heo, Y., Park, Y. S., Yoon, T. Y., "Introduction of Bridge Design Specification, 2008 Interim ", Harmany of the Nature and Civilization / v.56 no.10, pp.59-66, (2008)
  3. Manahan, M., "Determination of Charpy transition temperature of ferritic steels using miniaturized specimens." Journal of Materials Science, 25(8): 3429-3438, (1990)
  4. Tanguy, B., Bensson, J., Piques, R., Pineau, A., "Ductile to Brittle Transition of an A508 Steel Characteristics by Charpy Impact Test Part: I Experimental Result", Engineering Fracture Mechanics, 72(1): 49-72, (2005)
  5. Kumar, A.S., Louden, B.S., Garner, F.A., and Hamilton, M.L., "Small specimen test techniques." ASTM STP 1204, 47, p47, (1993)
  6. Mitra, G., and Boyer, S.E., "Energy balance and deformation mechanisms of duplexes." Journal of Structural Geology 8(3): 291-304. (1986)
  7. Lee, C.H., Shin, S.H., Park, K.T., and Yang, S.H., "Evaluation of the applicability of structural steels to cold regions by the Charpy impact test", Journal of Korean Society of Steel Construction, 23(4): 483-491, (2011)
  8. Kim, J.H., Choi, S.W., Park, D.H,, Lee, J.M., "Cryogenic Charpy Impact Test based on GTAW Method of AISI 304 Stainless Steel for LNG Pipeline", Journal of Welding and Joining, Vol.32, No.3, pp37-42, (2014)
  9. KS B 0810, Method of impact test for metallic materials, Korean Standards, (2003)
  10. Benedetti, M., Heidemann, J., et al., "Influence of sharp microstructural gradients on the fatigue crack growth resistance of ${\alpha}$+${\beta}$ and near ${\alpha}$ titanium alloys." Fatigue & Fracture of Engineering Materials & Structures, 28(10): 909-922, (2005)
  11. Gere, J.M., Goodno, B.J., "Mechanics of Materials." 7th Edition, Cengage Learning, Toronto, (2009)
  12. Commentary and worked examples to EN 1993-1-10 "Material toughness and through thickness properties" and other toughness oriented rules in EN 1993