• 제목/요약/키워드: High-temperature deformation

검색결과 836건 처리시간 0.032초

12%Cr-15%Mn 오스테나이트강의 고온변형거동중의 전위와 질화물의 상호작용 (Interaction between dislocation and nitride precipitates during high temperature deformation behaviors of 12%Cr-15%Mn austenitic steels)

  • 배동수
    • 한국해양공학회:학술대회논문집
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    • 한국해양공학회 2001년도 춘계학술대회 논문집
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    • pp.332-337
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    • 2001
  • The objective of research is to clarify the interaction between dislocations and precipitates during high temperature creep deformation behaviors of high Mn austenitic steels. After measuring the internal stress in minimum creep rate at 873K, a transmission electron microscope (TEM) observation was performed to investigate the interaction between dislocations and precipitates during high temperature creep deformation. The band width of effective stress and internal stress increased when the nitride precipitates distribute more densely. Fine nitrides disturbed the dislocation movement with pinning the dislocations and perfect dislocations were separated into Shockley partial dislocations by fine nitrides. Coarse nitrides disturbed the dislocation movement with climb mechanism.

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Al 6061 합금의 고온 소성변형 조건에 관한 연구 (High Temperature Plastic Deformation Condition of Al 6061 Alloy)

  • 김성일;정태성;유연철;오수익
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1998년도 춘계학술대회논문집
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    • pp.76-79
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    • 1998
  • High temperature plastic deformation behavior of Al 6061 alloy was characterized by hot torsion test. The Al 6061 alloy deformed continuously in the temperature range of 400∼550$^{\circ}C$, and strain rate range of 0.05∼5/sec. The softening mechanism of Al 6061 alloy was dynamic recrystallization and identified by hyperbolic sine law and zener-Hollmon parameter. The evolution of grain size and deformation resistance were calculated by the relationships of deformation variables.

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비탄성 변형 이론을 바탕으로 한 Mg-Al 합금의 슬립기구 천이 현상 해석 (Effect of slip system transition on the deformation behavior of Mg-Al alloy: internal variable based approach)

  • 이현석;방원규;장영원
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2004년도 춘계학술대회 논문집
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    • pp.186-189
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    • 2004
  • Although magnesium has high potential for structural material due to the lightweight and high specific strength, the structural application has been limited by the low ductility at room temperature. The reason of the poor ductility is few activated slip systems of magnesium (HCP structure) during deformation. As temperature increases, however, additional non-basal slip systems are incorporated to exhibit higher ductility comparable to aluminum. In the present study, a series of tensile tests of Mg-Al alloy has been carried out to study deformation behavior with temperature variation. Analysis of load relaxation test results based on internal variable approach gave information about relationship between the micromechanical character and corresponding deformation behavior of magnesium. Especially, the material parameter, p representing dislocation permeability through barriers was altered from 0.1 to 0.15 as the non-basal slip systems were activated at high temperature.

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비탄성 변형 이론을 바탕으로 한 Mg-Al 합금의 슬립기구 천이 현상 해석 (Effect of Slip System Transition on the Deformation Behavior of Mg-Al Alloy: Internal Variable Based Approach)

  • 이현석;장영원;방원규
    • 소성∙가공
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    • 제13권6호
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    • pp.535-539
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    • 2004
  • Although magnesium has high potential for structural material due to the lightweight and high specific strength, the structural application has been limited by the low ductility at room temperature. The reason of the poor ductility is few activated slip systems of magnesium (HCP structure) during deformation. As temperature increases, however, additional non-basal slip systems are incorporated to exhibit higher ductility comparable to aluminum. In the present study, a series of tensile tests of Mg-Al alloy has been carried out to study deformation behavior with temperature variation. Analysis of load relaxation test results based on internal variable approach gave information about relationship between the micromechanical character and corresponding deformation behavior of magnesium. Especially, the material parameter, p representing dislocation permeability through barriers was altered from 0.1 to 0.15 as the non-basal slip systems were activated at high temperature.

변형가공도를 이용한 AI 5083 합금의 고온변형거동 (High Temperature Deformation Behavior of Al 5083 Alloy Using Deformation Processing Maps)

  • 고병철;김종현;유연철
    • 소성∙가공
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    • 제7권5호
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    • pp.450-458
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    • 1998
  • The high temperature deformation behavior of Al 5083 alloy has been studied in the temperature range of 350 to 520 ${\circ}C$ and strain rate range of 0.2 to 3.0/sec by torsion test. The strain rate sensitivity(m) of the material was evaluated and used for estabilishing power dissipation maps following the dynamic material model. These maps show the variation of efficiency of power dissipation(${\eta}$=2m/(2m+1)) with temperature and strain rate. Hot restoration of dynamic recrystallization (DRX) was analyzed from the flow curve, deformed microstructure, and processing maps during hot deformation. Also, the effect of deformation strain on the efficiency of power dissipation of the alloy was analysed using the processing maps. Moreover relationship between the hot-ductility and efficiency of power dissipation of the alloy depending on thmperature and strain rate was studied using the Zener-Hollomon parameter(Z=${\varepsilon}$exp(Q/RT) It is found that the maximum efficiency of power dissipation for DRX in Al 5083 alloy is about 74.6 pct at the strain of 0.2. The strain rate and temperature at which the efficiency peak occurred in the DRX domain is found to be ∼0.1/sec and ∼450${\circ}C$ respectively.

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듀플렉스 스테인레스 소재의 고온 변형 안정성 및 어닐링 온도에 따른 특성 분석 (Analysis of High Temperature Deformation Stability and Properties of Duplex Stainless Steels According to Annealing Temperature)

  • 권기현;나영상;유위도;이종훈;박용호
    • 대한금속재료학회지
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    • 제50권7호
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    • pp.495-502
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    • 2012
  • The aim of this study was to analyze high temperature deformation stability and properties of duplex stainless steels(DSS) according to annealing temperature. In order to analyze high temperature deformation stability, a number of compression tests were carried out with a stain rate of $10^{-2}s^{-1}{\sim}10s^{-1}$ up to a compression ratio of 50% in a temperature range of $950^{\circ}C-1300^{\circ}C$. The analysis of high temperature deformation stability of DSS was performed based on the Ziegler model. In order to analyze the high temperature properties of DSS, annealing treatments were conducted by isothermal holding for 1 hr at $950^{\circ}C$ to $1300^{\circ}C$ with $50^{\circ}C$ intervals followed by water cooling. The hardness and tensile tests were performed on specimens with different volume fractions of constituent phases, such as austenite, ferrite and sigma. The hardness and tensile strength of 2507 according to the annealing temperature are better than those of 2205. The strain rate sensitivity and Ziegler parameter are higher in 2205 than in 2507 as a whole, which implies that 2205 is better than 2507 in terms of forgeability at high temperature.

구상 흑연 주철의 고온 변형 거동 (The High Temperature Deformation Behavior of Ductile Cast Iron)

  • 유위도;나영상;이종훈
    • 한국주조공학회지
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    • 제22권1호
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    • pp.11-16
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    • 2002
  • Hot deformation behavior of GCD-50 cast iron has been investigated by employing the compressive test. Phenomenological deformation behaviors, which were modeled based on the dynamic materials model and the kinetic model, have been correlated with the microstructural change taken place during compression. Microstructural investigation revealed that the adiabatic shear band caused by the locallized deformation was taken place in low temperature and high strain rate. On the other hand, the wavy and curved grain boundaries, which repersent the occurrence of dynamic microstructure change such as dynamic recovery and dynamic recrystallization, were observed in high temperature and low strain rate. Deformation model based on hyperbolic sine law has also been suggested.

AZ31 Mg 합금의 가공 조건에 따른 고온 성형성 연구 (Effect of Processing Variables on the High Temperature Formability of AZ31 Mg alloy)

  • 이병호;신광선;이종수
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2004년도 춘계학술대회 논문집
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    • pp.80-83
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    • 2004
  • High temperature deformation behavior of AZ31 Mg alloy was investigated in this study on the basis of a processing map $(\varepsilon\approx0.6)$. To construct a processing map, compression tests were carried out at wide range of temperatures and strain rates $(T=250\~500^{\circ}C,\;\varepsilon=10^{-4}\~100/s)$. Two regions of high deformation efficiency $(\eta)$ were identified as: (1) a dynamic recrystalization (DRX) domain at $250^{\circ}C$ and 1/s and (2) a superplasticity domain at $450^{\circ}C$ and $10^{-4}/s$. Possible deformation mechanisms operating at high temperature were discussed in relation to the activation energy. A two-stage deformation method was found to be effective in enhancing the superplasticity of AZ31 Mg alloy. From the two-stage deformation method, tensile elongation of $1200\%$ was obtained at the superplastic domain.

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고 Mn 오스테나이트계 스테인리스강의 기계적 성질에 미치는 가공온도의 영향 (Effect of Deformation Temperature on Mechanical Properties of High Manganese Austenitic Stainless Steel)

  • 강창룡;허태영;김영화;구차진;한현성;이상희
    • 한국해양공학회지
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    • 제26권3호
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    • pp.55-60
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    • 2012
  • This study was carried out to investigate the effect of the deformation temperature in high manganese austenitic stainless steel. ${\alpha}$'-martensite was formed with a specific direction by deformation. The volume fraction of the deformation induced martensite was increased by increasing the degree of deformation and decreasing the deformation temperature. With the increase in the deformation, the hardness and tensile strength were increased, while the elongation was rapidly decreased at the initial stage of the deformation, and then gradually decreased. The hardness and tensile strength were increased and the elongation was decreased with adecrease in the deformation temperature. The hardness and tensile strength were strongly controlled by the volume fraction of martensite, but the elongation was controlled by the transformation behavior of the deformation induced martensite.

급냉응고된 과공정 Al-Si합금의 고온변형특성에 관한 연구 (High Temperature Deformation Behavior of Rapid-Solidification Processed Al-18Si Alloy)

  • 김성일
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2000년도 춘계학술대회논문집
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    • pp.183-186
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    • 2000
  • The high temperature deformation behavior of spray-formed Al-19wt%Si-1.87wt%Mg-0.085wt.%Fe alloy was studied by torsion testing in the strain rate range of 0.001-1 sec-1 and in the temperature range of 300-500 $^{\circ}C$. The relationship between stress temperature and strain rate is expressed using the Power law. the behavior of dynamic recrystallization is showed in 300-35$0^{\circ}C$, 1-0.1sec-1 and the behavior of dynamic recovery is showed in 450-50$0^{\circ}C$, 0.01-0.001sec-1 The size of Si particles is mall when the temperature is low and the strain rate is high. The strain rate sensitivity(m) and the apparent activation energy(Q) indicate the dependence on strain rate and temperature for flow stress respectively. The hot ductility is high when m is high and Q is low. The maps of strain rate sensitivity and apparent activation energy suggest the optimum processing conditions.

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