This study aims to evaluate the microstructure evolution and toughness improvement of API X65 steel ERW pipe welds through heat treatments. Heat treatment schedules of one step process (Normalizing) and two step process (QT: quenching and tempering) were tried to control the properties in the ERW welds and were simulated by Gleeble simulator. In as-welded specimen, metal flow and elongated vertical pearlite have been found at the as-welded bond line, and the microstructure consisted of bainite, Widmansta¨tten ferrite and elongated pearlite. The microstructures of the bond line were changed to polygonal ferrite and elongated pearlite after normalizing. Meanwhile, tempered martensite was found at the bond line after QT process and metal flow and elongated pearlite were disappeared. Charpy impact toughness of transverse specimens has shown that toughness of the as-welded bond line decreased with comparing to that of base metal, which is due to the microstructure degradation. While, toughness in the welds was remarkably improved by all heat treatments; in addition, it has been observed that normalizing treatment of them was the most effective to improve toughness in the API X65 steel ERW pipe welds.
- International Petroleum Technology Institute and the Pipeline Division
Improvement of Toughness of API X65 ERW Pipe Welds
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Ham, Y, Kim, S, Lim, J, & Lee, C. "Improvement of Toughness of API X65 ERW Pipe Welds." Proceedings of the 2008 7th International Pipeline Conference. 2008 7th International Pipeline Conference, Volume 3. Calgary, Alberta, Canada. September 29–October 3, 2008. pp. 165-166. ASME. https://doi.org/10.1115/IPC2008-64233
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