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Vol.41, No.12, 855 ~ 863, 2003
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| Title |
| Discussion on the Effects of Grain Size on the Cleavage Fracture Toughness of Bainitic Low Alloy Steels in the Transition Temperature Region |
| 양원존 Yang Won Jon , 이봉상 Lee Bong Sang , 김민철 Kim Min Cheol , 홍준화 Hong Jun Hwa , 허무영 Heo Mu Yeong |
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| Abstract |
| The effects of the prior austenite grain size on the cleavage fracture toughness were investigated in the transition region of bainitic low alloy steels. Cleavage fracture toughness was evaluated by the ASTM standard E 1921. Yield strengths satisfied the Hall-Petch relationship, but fracture toughness in the transition region did not show significant dependence on the austenite grain size. Fracture surfaces showed that the facet size was related to the austenite grain size, but cleavage initiation distance(CID) from the original crack tip showed no direct relationship to the grain and facet sizes. Therefore, the austenite grain size may have little effects on the fracture toughness of bainitic low alloy steels in the transition region. In the viewpoint of the weakest link theory, particle distribution in front of the crack tip is probably more important than the grain size in the transition temperature range where fracture was controlled by cleavage crack initiation. The experimental results in this study supported the weakest-link-theory. |
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| Key Words |
| Low alloy steel, Transition region, Cleavage fracture, Cleavage Initiation Distance, CID, Fracture toughness, Weakest link theory, Characteristic distance |
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