[학위논문]TRIP 강의 변형유기 마르텐사이트 변태 및 기계적 특성에 미치는 초기조직의 영향 (The) Effect of prior microstructure on strain-induced martensitic transformation and mechanical properties in TRIP assisted steel원문보기
To improve the mechanical properties of Fe-2.94%Mn-1.25%Si-0.14%C TRIP assisted steel, the effect of prior microstructure of TRIP assisted steel on the microstructure, transformation temperature and tensile properties is studied by metallography, X-ray diffractometry, thermomechanical analysis and t...
To improve the mechanical properties of Fe-2.94%Mn-1.25%Si-0.14%C TRIP assisted steel, the effect of prior microstructure of TRIP assisted steel on the microstructure, transformation temperature and tensile properties is studied by metallography, X-ray diffractometry, thermomechanical analysis and tensile test, The prior microsturcture could be modified by annealing time and temperature. Color metallography is also adapted to reveal the multi phases in TRIP assisted steel, i. e, ferrite, bainite and untransformed austenite. (1) The color of ferrite, bainite and untransformed austenite after heat treatment is blue, brown and white(yellow), respectively. The color change of each phase is attributed to the amount of dophant, S^(+4) ion in etchant. (2) The A_(cl) transformation temperatures with increasing annealing time is increased to 707 ℃, 708 ℃, 710 ℃ and 710 ℃. However, A_(c3) transformation temperatures were almost constant even with increasing annealing temperature. (3) The tensile strength and elongation of annealed specimen at 900 ℃ for 40min was 827 Mpa and 31 %, respectively. Therefore, the maximum tensile strength x elongation of annealed specimen is 25,296. (4) Untransformed austenite after intercritical annealing and isothermal heat treatment exists at ferrite, grain boundary and the phase boundary of ferrite and bainite. The shape of untransformed austenite is classified to granular and film types. (5) The morphology of strain induced martensite after tensile test was lath martensite and strain induced martensite could be observed between bainite and bainite or bepween bainite and ferrite.
To improve the mechanical properties of Fe-2.94%Mn-1.25%Si-0.14%C TRIP assisted steel, the effect of prior microstructure of TRIP assisted steel on the microstructure, transformation temperature and tensile properties is studied by metallography, X-ray diffractometry, thermomechanical analysis and tensile test, The prior microsturcture could be modified by annealing time and temperature. Color metallography is also adapted to reveal the multi phases in TRIP assisted steel, i. e, ferrite, bainite and untransformed austenite. (1) The color of ferrite, bainite and untransformed austenite after heat treatment is blue, brown and white(yellow), respectively. The color change of each phase is attributed to the amount of dophant, S^(+4) ion in etchant. (2) The A_(cl) transformation temperatures with increasing annealing time is increased to 707 ℃, 708 ℃, 710 ℃ and 710 ℃. However, A_(c3) transformation temperatures were almost constant even with increasing annealing temperature. (3) The tensile strength and elongation of annealed specimen at 900 ℃ for 40min was 827 Mpa and 31 %, respectively. Therefore, the maximum tensile strength x elongation of annealed specimen is 25,296. (4) Untransformed austenite after intercritical annealing and isothermal heat treatment exists at ferrite, grain boundary and the phase boundary of ferrite and bainite. The shape of untransformed austenite is classified to granular and film types. (5) The morphology of strain induced martensite after tensile test was lath martensite and strain induced martensite could be observed between bainite and bainite or bepween bainite and ferrite.
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