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Vol.44, No.4, 234 ~ 243, 2006
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| Title |
| Fracture Toughness Analysis in Transition Temperature Region of API X70 Linepipe Steels Rolled in Two Phase Region |
| 신상용 Sang Yong Shin , 김상호 Sang Ho Kim , 이성학 Sung Hak Lee , Guiliang Gong |
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| Abstract |
| The present study aims at analyzing fracture toughness in the transition temperature region of API X70 linepipe steels according to ASTM E1921 standard test method. Three kinds of steels were fabricated by varying finish cooling temperatures after rolling in the two-phase region, and their microstructures, tensile and Charpy impact properties, and fracture toughness were examined. Elastic-plastic cleavage fracture toughness, Kjc was determined by 3-point bend tests, using precracked Charpy V-notch (PCVN) specimens, and then the measured Kjc values were interpreted by the 3-parameter Weibull distribution. Relationship between reference temperature and plane strain fracture toughness in the transition region was discussed on the basis of the cleavage fracture behavior. The steel cooled at 500℃ showed the highest plane strain fracture toughness and the lowest reference temperature because it contained a small amount of bainite instead of martensite and had a small effective grain size. |
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| Key Words |
| API X70 Linepipe steel, ASTM E1921 standard test method, Elastic-plastic cleavage fracture toughness, Weibull distribution |
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