The analysis of phase transformation and mechanical properties of the Fe-11Cr-8.5Co-8Ni-5Mo-1.25Al alloy

Autor: 徐文光
Rok vydání: 2007
Druh dokumentu: 學位論文 ; thesis
Popis: 95
Student ID: N9432001 Title of Thesis: The Analysis of Phase Transformation and Mechanical Properties of the Fe-11Cr-8.5Co-8Ni-5Mo-1.25Al alloy Total Pages:56 Name of Institute: National Pingtung University of Science and Technology Name of Department: Department of Mechanical Engineering Date of Graduation: June, 2007 Degree Conferred: Master Name of Student: Wen-Kuang Hsu Adviser: Chih-Yeh Chao The Contents of Abstract in this Thesis: The purposes of the present study is investigated the microstructures and mechanical properties of the Fe-11Cr-8.5Co-8Ni-5Mo- 1.25Al alloy by using of the OM, SEM, TEM, XRD, tensile testing machine and micro-hardness. Based on the present studies, some results are describing as following: Being solution heat treatment on 930℃/1H and than subzero treatment in the range of the (-80~-120)℃/8-24H, the microstructure of the present alloy is a fully plate-matensite phase belonging to the B.C.C. structure with the lattice parameter a= 0.288nm. During the aging process in the (450-550)℃/2-8H, some fine B2-phase precipitates and the L12-phase particles were formed within the matrix coherently. When aged at 650℃/2-8 hours, some austenite phase region was found. Based on the previous heat treated processes, the mechanical properties are carried out. The tensile strength, yield strength, elongation and hardness of the specimen, in the subzero treated condition, is the 154.7ksi, 147.1ksi, 11.6 % and HRc32.7, respectively. Being aged at 450~550℃, the mechanical strength are dramatically increasing. In addition, the optimum process is aged the 550℃ for 8 hour. The tensile strength, yield strength, elongation and hardness of these specimen, could reach to the 280.7ksi, 268.4ksi, 9.7 % and HRc54.7, respectively. When the specimen aged at 650℃, the elongation is essentially increased. The tensile strength, yield strength, elongation and hardness of the specimen, is in the ranged of the 173.4~179.8ksi, 120.1~ 129.6ksi, 18.8~22.4% and HRc33.1~35.8, respectively. Keywords：Microstructure, Martensite, Austenite, Lattice parameter, subzero treatment
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