| Summary: | 碩士 === 國立屏東科技大學 === 機械工程系所 === 97 === The Fe-15Cr-3Ni-1.5Cu alloy has been investigated by using of optical microscope, x-ray diffraction, transmission electron microscope, scanning electron microscope, tensile test and hardness test. Based on the present study, some results are described as followings:
Being solution heat treatment on 1100℃/30 min, the microstructure of the present alloy is a single martensite with high-density dislocations phase belonging to the B.C.C. structure with lattice parameter a=0.287 nm,
During the aging process in the range of the 450-550℃/1-16 hrs, some fine α′-phase precipitates were formed within the matrix. Increasing the aging time, it is found that the twins martensite formed and the rich-Cu phase to be separated in the matrix. When aged at (650-750)℃/128 hrs, it is found that the M23C6 carbides precipitate within the martensite matrix and the some austensite phases been found. In addition, increasing the aging temperature 850℃, the microstructure of the present alloy is a single austensite phase.
Based on the previous heat treated processes, the tensile strength, yield strength, and elongation of the as-quenched specimens, are in the range of the 173-171ksi, 164-150ksi, and 10.3-8.2%, respectively. Being tempering processes, the mechanical properties of the alloy are in the range of the 201-123ksi, 185-118ksi, and 19.4-12.3%. It is noted that the alloy, being SHT+500℃/1hr, posses the mechanical properties such as 201ksi, 185ksi, and 15.3% which been better than the commercial 17-4PH stainless steel.
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