EFFECTS OF MODIFICATION OF THE CARBIDE CHARACTERISTICS THROUGH GRAIN BOUNDARY SERRATION ON CREEP-FATIGUE LIFE IN AUSTENITIC STAINLESS STEELS
来源期刊：Acta Metallurgica Sinica2004年第5期
论文作者：S.W.Nam H.U.Hong K.J.Kim K.S.Min
Key words：cavity nucleation factor; grain boundary serration; carbide morphology; austenitic stainless steel; grain boundary cavitation;
Abstract: Modification of the carbide characteristics through the grain boundary serration is investigated, using an AISI 316 and 304 stainless steels. In both steels, triangular carbides were observed at straight grain boundaries while planar carbides vere observed at the serrated grain boundaries. The serrated grain boundary energy is observed to be much lower than that of the straight one. Therefore, the carbide morphology is found to be changed from triangular to planar along the serrated boundary to reduce the interfacial energy between the carbide and the matrix. The creep-fatigue properties of these steels at 873K have been investigated. The creep-fatigue life of the sample vith planar carbide at the serrated grain boundary was found to be much longer than that with triangular carbide at the straight one. These results imply that the planar carbides with lower interfacial energy have higher cavitation resistance, resulting in the retardation of cavity nucleation and growth to increase creep-fatigue life.
S.W.Nam1，H.U.Hong2，K.J.Kim1，K.S.Min3
(1.Dept. of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Deajeon 305-701, Korea;
2.Posco Technical Research Laboratory, #1 Koedong-dong, Nam-gu, Pohang, 790-300, Korea;
3.Process Solution Development Team 1, LCD R&D Center, AMLCD Division, Device Solution Network,Samsung Electronics Co., LTD.San 24 Nongseo-ri, Giheung-eup, Yongin, Gyeonggi-do, 449-771, Korea)
Abstract:Modification of the carbide characteristics through the grain boundary serration is investigated, using an AISI 316 and 304 stainless steels. In both steels, triangular carbides were observed at straight grain boundaries while planar carbides vere observed at the serrated grain boundaries. The serrated grain boundary energy is observed to be much lower than that of the straight one. Therefore, the carbide morphology is found to be changed from triangular to planar along the serrated boundary to reduce the interfacial energy between the carbide and the matrix. The creep-fatigue properties of these steels at 873K have been investigated. The creep-fatigue life of the sample vith planar carbide at the serrated grain boundary was found to be much longer than that with triangular carbide at the straight one. These results imply that the planar carbides with lower interfacial energy have higher cavitation resistance, resulting in the retardation of cavity nucleation and growth to increase creep-fatigue life.
Key words:cavity nucleation factor; grain boundary serration; carbide morphology; austenitic stainless steel; grain boundary cavitation;
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