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Vol.46, No.12, 788 ~ 800, 2008
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| Title |
| Effect of Mo, Cr, and V on Tensile and Charpy Impact Properties of API X80 Linepipe Steels Rolled in Single Phase Region |
| 한승엽 Seung Youb Han , 신상용 Sang Yong Shin , 서창효 Chang Hyo Seo , 이학철 Hak Cheol Lee , 배진호 Jin Ho Bae , 김기수 Ki Soo Kim , 이성학 Sung Hak Lee , 김낙준 Nack J. Kim |
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| Abstract |
| This study is concerned with the effects of Mo, Cr, and V addition on tensile and Charpy impact properties of API X80 linepipe steels. Four kinds of steels were processed by varying Mo, Cr, and V additions, and their microstructures and tensile and Charpy impact properties were investigated. Since the addition of Mo and V promoted to form fine acicular ferrite and granular bainite, while prohibiting the coarsening of granular bainite, it increased the strength and upper shelf energy, and decreased the energy transition temperature. The Cr addition promoted the formation of coarse granular bainite and secondary phases such as martensite-austenite constituents, thereby leading to the increased effective grain size, energy transition temperature, and strength and to the decreased upper shelf energy. The steel containing 0.3wt.% Mo and 0.06wt.% V without Cr had the highest upper shelf energy and the lowest energy transition temperature because its microstructure was composed of fine acicular ferrite and granular bainite, together with a small amount of hard secondary phases, while its tensile properties maintained excellent. |
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| Key Words |
| API X80 Linepipe steel, tensile properties, charpy impact properties, effective grain size |
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