Browse > Article
http://dx.doi.org/10.5228/KSPP.2006.15.2.118

The Influence of Microstructure on the Bauschinger Effect in X80 Grade API Steel  

Park, J.S. (포항공과대학교 신소재공학과)
Kim, D.W. (포항공과대학교 신소재공학과)
Chang, Y.W. (포항공과대학교 신소재공학과)
Publication Information
Transactions of Materials Processing / v.15, no.2, 2006 , pp. 118-125 More about this Journal
Abstract
API steel is used for line-pipe to transport the oil and natural gas. As the recent trends in the development of API steel are towards the use of larger diameter and thicker plate, many researches have been studied to achieve higher strength, higher toughness and lower yield ratio in API steel. However, the strength of API steel after pipe forming is changed depending on the competition of the Bauschinger effect and work hardening which are affected by the strain history during pipe forming process. So, the purpose of this study is to investigate the influence of microstructure on the Bauschinger effect for API steel. To change the microstructure of API steel we have changed the hot rolling condition and the amounts of V and Cu addition. The compression-tensile test and the microstructure observation by OM and TEM were conducted to investigate the yield strength drop and the correlation between the Bauschinger effect and microstructure of API steel. The experimental results show that the increase of polygonal ferrites volume fraction increases the Baushcinger effect due to the back stress which comes from the increase of mobile dislocation density at polygonal ferrite interior during the compressive deformation. The hot rolling condition was more effective on the Bauschinger effect in API steel than the small amount of V and Cu addition.
Keywords
Bauschinger Effect; API Steel; Polygonal Ferrite; Low Temperature Transformation Phases; Back Stress; Pre-Strain;
Citations & Related Records
연도 인용수 순위
  • Reference
1 Kwangjun Euh, Yong Chan Kim, Keesam Shin, Sunghak Lee, Nack J. Kim, 2003, Effect of Tempering on Hardness Improvement in a VC/steel Surface-Alloyed Material Fabricated by High-Energy Electron-Beam Irradiation, mater. sci. eng. A, Vol.346, p. 228   DOI   ScienceOn
2 D. J. Lloyd, 1977, The Bauschinger Effect in Polycrystalline Aluminum Containing Coarse Particles, Acta, Met., Vol.25, p. 459   DOI   ScienceOn
3 S. P. Gupta, S. P. Kodali, 1976, The Effect of Pre-Strain on the Bauschinger Effect, Scripta Met., Vol. 10, p. 111   DOI   ScienceOn
4 G. Tither, M. Lavite, 1975, Beneficial Stress-Strain Behavior of Moly-Columbium Steel Line Pipe, JOM, p. 15
5 J. Bauschinger, 1886, Mit. Mech.-Tech., Lab. Munchen, Heft 13, 1
6 E. Orowan, 1959, Causes and Effects of Internal Stresses, Internal stresses and Fatigue in Metals, Symposium, Detroit
7 D. V. Wilson, 1965, Reversible work hardening in Alloys of Cubic metals, Acta. Met., Vol. 13, p. 807   DOI   ScienceOn
8 H. Asahi et. al., 2003, Pipe Production Technology and Properties of X120 Linepipe, Proceedings of The Thirteenth International Offshore and Polar Engineering Conference, Honolulu, Hawaii, USA