• Title/Summary/Keyword: ${\varepsilon}$ martensite

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Dependence of Damping Capacity on Volume Fractions of Thermal and Deformation-induced ${\varepsilon}$ Martensites in an Fe-Mn Alloy (Fe-Mn 합금에서 열적 ${\varepsilon}$ 마르텐사이트와 변형유기 ${\varepsilon}$ 마르텐사이트 부피분율에 대한 진동감쇠능의 의존성)

  • Jun, Joong-Hwan;Hong, Kwon-Pyo;Choi, Chong-Sool
    • Journal of the Korean Society for Heat Treatment
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    • v.15 no.6
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    • pp.272-278
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    • 2002
  • The changes in damping capacity with volume fractions of thermal and deformation-induced ${\varepsilon}$ martensites were compared and analyzed in an Fe-23%-Mn alloy. The volume fraction of thermal ${\varepsilon}$ martensite increased with decreasing cooling temperature, whereas that of deformation-induced ${\varepsilon}$ martensite increased steeply up to 10%- of cold rolling and nearly saturated in further cold rolling. In the case of thermal ${\varepsilon}$ martensite, the damping capacity increased linearly with the increase in ${\varepsilon}$ martensite content. For the deformation-induced ${\varepsilon}$ martensite, however, the damping capacity increased continuously up to 70%- of ${\varepsilon}$ martensite, over which it decreased suddenly. TEM microstructures showed that the deterioration of damping capacity above 70%- of deformation-induced ${\varepsilon}$ martensite is ascribed to the introduction of perfect dislocations, which play a important role in inhibiting the movement of damping sources such as stacking fault boundaries inside ${\varepsilon}$ martensite, ${\varepsilon}$ martensite variant boundaries and ${\gamma}/{\varepsilon}$ interfaces.

Measurement of Volume Fraction of ${\varepsilon}$ Martensite using Specific Volume Difference in Fe-Mn Based Alloys (Fe-Mn 계 합금에서 비부피 차를 이용한 ${\varepsilon}$ 마르텐사이트의 부피분율 측정)

  • Jee, K.K.;Han, J.H.;Jang, W.Y.
    • Journal of the Korean Society for Heat Treatment
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    • v.16 no.4
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    • pp.211-215
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    • 2003
  • In this work, a new way of measuring the volume fraction of e martensite in Fe-based alloys has been proposed. Since the specific volume of ${\varepsilon}$ martensite, depending on alloy composition, is smaller than that of austenite i.e ${\gamma}$ phase, volume expansion takes place during ${\varepsilon}{\rightarrow}{\gamma}$ reverse transformation. As the amount of the volume expansion is proportional to the product of specific volume difference times the volume fraction of ${\varepsilon}$ martensite, the volume fraction of ${\varepsilon}$ martensite can be calculated by measuring the volume expansion and the specific volume difference. Such a relationship was confirmed in Fe-21Mn and Fe-32Mn-6Si alloys which undergo ${\gamma}{\rightarrow}{\varepsilon}$ martensitic transformation on cooling and by cold rolling, respectively. It was also found that the former has isotropic ${\varepsilon}$ martensite while the latter has anisotropic ${\varepsilon}$ martensite.

Effect of Thermo-Mechanical Treatment on the Damping Capacity of Alloy with Deformation Induced Martensite Transformation (가공유기 마르텐사이트 변태를 갖는 합금의 감쇠능에 미치는 가공열처리의 영향)

  • Han, Hyun-Sung;Kang, Chang-Yong
    • Korean Journal of Materials Research
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    • v.29 no.3
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    • pp.160-166
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    • 2019
  • This study investigates the effect of thermo-mechanical treatment on the damping capacity of the Fe-20Mn-12Cr-3Ni-3Si alloy with deformation induced martensite transformation. Dislocation, ${\alpha}^{\prime}$ and ${\varepsilon}-martensite$ are formed, and the grain size is refined by deformation and thermo-mechanical treatment. With an increasing number cycles in the thermo-mechanical treatment, the volume fraction of ${\varepsilon}-martensite$ increases and then decreases, whereas dislocation and ${\alpha}^{\prime}-martensite$ increases, and the grain size is refined. In thermo-mechanical treated specimens with five cycles, more than 10 % of the volume fraction of ${\varepsilon}-martensite$ and less than 3 % of the volume fraction of ${\alpha}^{\prime}-martensite$ are attained. Damping capacity decreases by thermo-mechanical treatment and with an increasing number of cycles of thermo-mechanical treatment, and this result shows an opposite tendency for general metal with deformation induced martensite transformation. The damping capacity of the thermo-mechanical treated damping alloy with deformation induced martensite transformation greatly affect the formation of dislocation, grain refining and ${\alpha}^{\prime}-martensite$ and then ${\varepsilon}-martensite$ formation by thermo-mechanical treatment.

Effect of Cold Working on the Tensile Strength of Fe-26Mn-4Co-2Al Damping Alloy (Fe-26Mn-4Co-2Al 제진합금의 인장강도에 미치는 냉간가공의 영향)

  • Kang, Chang-Yong;Kim, Seong-Hwi;Jeong, Gyu-Seong
    • Journal of Power System Engineering
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    • v.20 no.6
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    • pp.46-50
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    • 2016
  • This study was carried out to investigate the effect of cold working on the tensile strength of Fe-26Mn-4Co-2Al damping alloy. ${\alpha}^{\prime}$ and ${\varepsilon}$-martensite were formed by cold working, and martensite was formed with the specific direction and surface relief. With the increasing degree of cold rolling, volume fraction of ${\alpha}^{\prime}$-martensite was increased, whereas the volume fraction of ${\varepsilon}$-martensite was decreased after rising to maximum value at specific lever of cold rolling. Tensile strength was linearly increased with an increasing of degree of cold rolling. Tensile strength was strongly affected to the volume fraction of ${\varepsilon}$-martensite formed by cold working, but the effect of volume fraction of ${\varepsilon}$-martensite on the tensile strength was not observed.

The Effect of grain size on the damping capacity of Fe-26Mn-2Al alloy (Fe-26Mn-2Al 합금의 진동 감쇠능에 미치는 결정립 크기의 영향)

  • Kang, C.Y.;Eom, J.H.;Kim, H.J.;Sung, J.H.
    • Journal of Power System Engineering
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    • v.11 no.1
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    • pp.115-120
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    • 2007
  • The effect of grain size on the damping capacity of Fe-26Mn-2Al alloy studied in this paper has been investigated after changing the microstructure by cold rolling and changing grain size. Micro structures in Fe-26Mn-2Al at room temperature consist of a large quantity of austenite and a small quantity of ${\varepsilon}\;and\;{\alpha}'$ martensite. And ${\varepsilon}\;and\;{\alpha}'$ martensite was increased by increasing the degree of cold rolling. The content of deformation induced martensite was increased with increasing the degree of cold rolling. Damping capacity was linearly increased with increasing ${\varepsilon}$ martensite content, which suggests that stacking faults and ${\varepsilon}$ martensite variant boundaries are the principle damping sources. With increasing the grain size in Fe-26Mn-2Al alloy, the damping capacity was increased due to increasing the volume fraction of ${\varepsilon}$ martensite by decrement in stability of austenite phase. With decreasing the grain size, the content of deformation induced martensite was decreased and the damping capacity was decreased.

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Effect of Heat Treatment Temperature on Amount of Stress-Induced ${\varepsilon}$ Martensite in an Fe-Mn Baesd Alloy (Fe-Mn계 합금에서 응력유기 ${\varepsilon}$ 마르텐사이트의 양에 미치는 열처리 온도의 영향)

  • Jee, K.K.;Han, J.H.;Jang, W.Y.
    • Journal of the Korean Society for Heat Treatment
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    • v.17 no.6
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    • pp.342-345
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    • 2004
  • In this work, a new method of measuring volume fraction of deformation-induced ${\varepsilon}$ martensite is proposed using endothermic heat on reverse transformation. As grain size increases, the amount of ${\varepsilon}$ martensite forming on cooling increases. However, with a decrease in grain size, more ${\varepsilon}$ is induced by deformation, improving shape memory effect.

Effect of ε Martensite Content and Strain Amplitude on Damping Capacity of Fe-17%Mn Alloy (Fe-17%Mn 합금의 진동감쇠능에 미치는 ε 마르텐사이트 함량과 진폭변형율의 영향)

  • Jun, Joong-Hwan;Lee, Young-Kook;Choi, Chong-Sool
    • Journal of the Korean Society for Heat Treatment
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    • v.9 no.2
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    • pp.112-120
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    • 1996
  • The effects of ${\varepsilon}$ martensite content and strain amplitude on damping capacity of an Fe-17%Mn alloy have been studied to establish damping mechanism of Fe-Mn system corresponding to the magnitude of strain amplitude. In a range of $1{\times}10^{-4}{\sim}3{\times}10^{-4}$ strain amplitude, the damping capacity is linearly proportional to the ${\varepsilon}$ martensite content, which suggests that stacking faults and ${\varepsilon}$ martensite variant boundaries are the principal damping sources. In the range of $4{\times}10^{-4}{\sim}6{\times}10^{-4}$ strain amplitude, however, a maximum damping capacity is observed around 68 vol.% ${\varepsilon}$. This behavior is very similar to dependence of relative area of ${\gamma}/{\varepsilon}$ interface on ${\varepsilon}$ martensite content. This means that in this strain range, ${\gamma}/{\varepsilon}$ interface acts as damping source in addition to the stacking faults and variant boundaries in Fe-17%Mn alloy.

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The Effects of Microstructure in Austenitic 316L Stainless Steels on the Strength and Damping Capacity (오스테나이트계 316L 스테인리스강의 강도 및 감쇠능에 미치는 미세조직의 영향)

  • SON DONG-WOOK;LEE JONG-MOON;KIM HYO-JONG;NAM KI-WOO;PARK KYU-SEOP;KANG CHANG-YONG
    • Journal of Ocean Engineering and Technology
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    • v.20 no.1 s.68
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    • pp.1-6
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    • 2006
  • The effects of microstructure on the damping capacity and tensile properties of 316L stainless steel were investigated. Increasing the degree of cold working, the volume fraction of $\varepsilon-martensite$ decreased after rising to maximum value at specific level of cold working, the volume fraction of d-martensite slowly increased and then dramatically increased from the point of decreasing $\varepsilon-martensite$ volume fraction. Increasing the degree of cold working, the behnvior of damping capacity is similar to that of the $\varepsilon-martensite$. After the damping capacity showing the maximum value at about $20\%$ of cold rolling, damping capacity was decreased with the volume fraction of $\varepsilon-martensite$. Tensile strength was proportional to the volume fraction of d-martensite, and elongation steeply decreased in the range low volume fraction of a'-martensite, then slowly decreased in range the above $10\%$ volume fraction of d-martensite. The damping capacity and elongation is strongly controlled by the volume fraction of $\varepsilon$ martensite with liner relationship. However, the effect of the volume fraction of d-martensite and austenite phase on the damping capacity was not observed. Tensile strength was governed by the volume fraction of d-martensite.

Development of Alloy with High Strength and Damping Capacity for High-Performance of Precision Devices by Vibration Control (진동제어에 의한 정밀기기의 고성능화를 위한 고강도 및 고감쇠능 합금개발)

  • Kana, Chang-Yong;Kim, Ik-Su
    • Journal of Ocean Engineering and Technology
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    • v.22 no.6
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    • pp.46-51
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    • 2008
  • The effect of the addition of Co and N and subzero treatment on tensile strength and damping capacity was investigated in Fe-Cr-Mn alloy. Austenite was transformed into martensite by cold rollins increasing the degree of cold rollins led to an increase in the volume fraction of martensite. The damping capacity linearly increased with increasing volume fraction of ${\varepsilon}$ martensite in cold rolled specimens and subzero treated specimens after cold rolling. The volume fraction of ${\varepsilon}$ martensite, tensile strength and damping capacity was also increased by the addition of Co, while this treatment decreased the elongation. However, the volume fraction of ${\varepsilon}$ martensite, elongation and damping capacity were reduced by the addition of N, although the tensile strength increased. Tensile strength and damping capacity werealso increased by subzero treatment, while elongation decreased.

Effect of Deformation Induced Martensite on the Damping Capacity of Fe-26Mn-4Co-2Al Alloy (Fe-26Mn-4Co-2Al 합금의 감쇠능에 미치는 가공 유기 마르텐사이트의 영향)

  • Jeong, Kyu-Seong;Kang, Chang-Yong
    • Korean Journal of Materials Research
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    • v.26 no.9
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    • pp.493-497
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    • 2016
  • This study was carried out to investigate the effect of deformation induced martensite on the damping capacity of Fe-26Mn-4Co-2Al damping alloy. ${\alpha}^{\prime}$ and ${\varepsilon}$-martensite were formed by cold working, and; deformation induced martensite was formed with according to the specific direction and the surface relief. With an increasing degree of cold rolling, the volume fraction of ${\alpha}^{\prime}$-martensite increased rapidly, while the volume fraction of ${\varepsilon}$-martensite decreased after rising to a maximum value at a specific level of cold rolling. Damping capacity was increased, and then decreased with an increasing of the degree of cold rolling. Damping capacity was influenced greatly by the volume fraction of ${\varepsilon}$-martensite formed by cold working, but the effect of the volume fraction of ${\alpha}^{\prime}$-martensite have a actually on effect on the damping capacity.