• 제목/요약/키워드: Treatment Phase

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용융 접합한 주철 - Al 합금의 금속간화합물 층 형성 거동에 미치는 열처리의 영향 (Effect of Heat Treatment on the Formation Behavior of Intermetallic Compound Layer in Fusion Bonding of Cast Iron and Al Alloy)

  • 강성민;한광식;강용주;김광원;임예라;문지선;손광석;김동규
    • 한국주조공학회지
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    • 제32권1호
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    • pp.50-56
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    • 2012
  • Fusion bonding of cast iron and Al alloy is an effective way to improve the properties such as low inertia, high efficiency and corrosion resistance in machinery parts. In case of fusion bonding, intermetallic compound layers are formed at the interface between cast iron and Al alloy interface. It is important to control the intermetallic compound layers for improving bonding strength. The formation behavior of intermetallic compound layer by heat treatment has been investigated. Heat treatment was performed at temperature from $600^{\circ}C$ to $800^{\circ}C$ with $100^{\circ}C$ interval for an hour to investigate the phase transformation during heat treatment. Heat treated specimens were analyzed by using FE-SEM, EPMA and EDS. The EPMA/WDS results revealed that various phases were formed at the interface, which exhibited 4 distinct intermetallic compound layers such as ${\tau}_6-Al_{4.5}FeSi$, ${\tau}_2-Al_3FeSi$, ${\tau}_{11}-Al_5Fe_2Si $and ${\eta}-Al_5Fe_2$. Also, fine precipitation of ${\tau}_1-Al_2Fe_3Si_3$ phase was formed between ${\tau}_{11}$ and ${\eta}$ layer. The phase fraction in intermetallic compound layer was changed by heat treatment temperature. At $600^{\circ}C$, intermetallic compound layer of ${\tau}_6$ phase was mainly formed with increasing heat treatment time. With increasing heat treatment temperature to $800^{\circ}C$, however, ${\tau}_2$ phase was mainly distributed in intermetallic compound layer. ${\tau}_1$ phase was remarkably decreased with increasing heat treatment time and temperature.

SAF 2205 듀플렉스 스테인레스강의 미세조직 및 기계적 특성에 미치는 냉각속도의 영향 (Effect of Cooling Rate on Microstructural and Mechanical Properties of SAF 2205 Duplex Stainless Steel)

  • 오영주;양원존;이종훈;김두현;유위도;이재현
    • 열처리공학회지
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    • 제26권1호
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    • pp.14-20
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    • 2013
  • Duplex stainless steel, which is a kind of stainless steel with a mixed microstructure of about equal proportions of austenite and ferrite, is generally known as a unique material with excellent corrosion resistance and high strength. However, toughness, strength, and corrosion resistance of the steel could be reduced due to precipitation of topologically closed packed phases such as sigma phase during cooling. In case of large forged products, they have strong possibility that ${\sigma}$-phase precipitates due to difference of cooling rate between surface and inner of the products. Investigation on sigma phase precipitation behavior of duplex stainless steel with change of cooling rate was carried out in this study. Forged SAF 2205 duplex stainless steel was used as specimens to examine the cooling rate effect. Dissolution behavior of sigma phase was also discussed through resolution test of duplex stainless steel containing lots of sigma phase. Experimental results revealed that impact energy was very sensitive to precipitation of small amount sigma phase. However, sigma phase could be removed by short term resolution treatment and impact resistance of the duplex stainless steel was restored.

수퍼 마르텐사이트계 스테인리스강의 질소침투 열처리 (A Study on Nitrogen Permeation Heat Treatment of Super Martensitic Stainless Steel)

  • 유대경;성장현
    • 열처리공학회지
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    • 제19권1호
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    • pp.3-9
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    • 2006
  • The phase changes, nitride precipitation and hardness variations of 14%Cr-6.7Ni-0.65Mo-0.26Nb-0.05V-0.03C super martensitic stainless steel were investigated after nitrogen permeation heat treatment at a temperature range between $1050^{\circ}C$ and $1150^{\circ}C$. The nitrogen-permeated surface layer was transformed into austenite. The rectangular type NbN, NbCrN precipitates and fine round type precipitate were coexisted in the surface austenite layer, while the interior region that was free from nitrogen permeation kept the martensitic phase. The hardness of surface austenite showed 280 Hv, while the interior region of martensite phase represented 340 Hv. When tempering the nitrogen-permeated steel at $450^{\circ}C$, a maximum hardness of 433 Hv was appeared, probably this is attributed to the secondary hardening effect of the precipitates. The nitrogen concentration decreased gradually with increasing depth below the surface after showing a maximum of 0.3% at the outmost surface. The strong affinity between nitrogen and Cr enabled the substitutional element Cr to move from interiors to the surface when nitrogen diffuse form surface to the interior. Corrosion resistance of nitrogen permeated steel was superior to that of solution-anneaed steel in the solution of 1N $H_2SO_4$.

0.2% N을 첨가한 수퍼 2상 스테인리스강의 열처리 조건에 따른 특성 평가 - 제1보: 기계적 특성 및 미세조직 (Characteristic Evaluation Based on the Heat Treatment Conditions of Super Duplex Stainless Steel with 0.2% N as an Additive - Part 1: Mechanical Properties and Microstructure)

  • 안석환;강흥주;남기우
    • 한국해양공학회지
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    • 제22권4호
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    • pp.46-50
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    • 2008
  • Super duplex stainless steel has along life in severe environments because of its strength and corrosion resistance. If 0.2$\sim$0.3% Nitrogen in aninterstitial solid solution is added, the austenite structure is reinforced. This improves the solid solution hardening and the anticorrosionability. In this study, the mechanical properties and structures of the super duplex stainless steel with the 0.2% N additive were investigated to determine the effect of various volume fractions on the austenite phase. The various volume fractions and distributions of the austenite structure in the applied test specimens were obtained by changing the heat treatment temperature and cycle. The characteristics by amounts of the $\sigma$ phase obtained from the precipitation heat treatment were alsoinvestigated. From the results, when the austenite volume fraction increases, the tensile strength decreases and elongation increases. And the $\sigma$ phase was rapidly increased by increasing the heat treatment time. When the volume fraction of the $\sigma$ phase increased, tensile strength increased.

STD11 공구강의 열처리 온도에 따른 탄화물 거동 (Carbide Behavior in STD11 Tool Steel during Heat Treatment)

  • 홍기정;송진화;정인상
    • 열처리공학회지
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    • 제24권5호
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    • pp.262-270
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    • 2011
  • Carbide precipitation and dissolution behavior at various temperatures during heat treatment has been studied in STD11 cold working die steel through confocal scanning laser microscopy; dilatometry; and X-ray diffraction analysis. The equilibrium phase diagram and phase fractions with temperature were calculated using a FactSage program. Confocal laser microscopic observation revealed that ${\alpha}$ to ${\gamma}$ transformation temperature is near $800^{\circ}C$; M7C3 carbides melt at $1245^{\circ}C$; and the melting temperature of STD11 is near $1370^{\circ}C$. XRD results indicated that the M23C6 carbides dissolve in the matrix if austenitized at over $1030^{\circ}C$; while the M7C3 carbides remain up to $1200^{\circ}C$ although their amount decreases. The calculated equilibrium phase diagram showed good agreement with experimental results on carbide dissolution and phase transformation temperatures.

Bi-2223 초전도 선재의 열처리에 따른 초전도 특성 및 상분석 (The effect of heat treatment condition on superconducting property and phase analysis of Bi-2223 tapes)

  • 최정규;하홍수;이동훈;양주생;황선역;하동우;오상수;권영길;이세종
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2003년도 춘계학술대회 논문집 초전도 자성체 연구회
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    • pp.73-76
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    • 2003
  • Phase transformation of Bi-2223 tape during the final heat treatment has been investigated through the various duration time of heat treatment in a specially designed 3-step heat treatment. It was found that the phase assemblage in the sintering was determined by the sintering time and temperature. In this study, sintering time was changed to optimize the Bi-2223 phase assemblage, and acquire high critical current density. High critical current samples with Ic = 85 A and Je = 8.9 kA/$cm^2$ have been measured at 77K and self-field for 55-filament tapes sintered by optimum condition.

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랫드에 있어서 주야 시차가 Bromobenzene 대사에 미치는 영향 (Effect of Circadian Rhythms on the Bromobenzene Metabolism in Rats)

  • 김광진;신중규;윤종국
    • Toxicological Research
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    • 제13권4호
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    • pp.377-383
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    • 1997
  • To investigate the circadian variation in the bromobenzene metabolism, bromobenzene(400 mg/kg body weight) was intraperitoneally administered to the rats every other day for 6 days both in the night; 24:00 and the day; 12:00. Each group of animals was sacrificed at 8hr after last injection of bromobenzene. The contents of hepatic CYP were more increased in control rats of night phase than those of day phase but in case of bromobenzene treatment there were no differences in hepatic CYP between rats of the night phase and those of day phase and the injection of prednisolon inhibited the hepatic CYP content in rats. Furthermore, the decreasing rate of hepatic glutathione contents to the control was higher in rats of day phase than those of night phase by the bromobenzene treatment. And the hepatic glutathione S-transferase activities were increased both in control and bromobenzene treated rats of the night phase than those of day phase. On the other hand, liver weight per body weight(%), hepatic lipid peroxide content, serum levels of alanine aminotransferase were more increased both in bromobenzene-treated and control rats of the night phase than those in the day phase. These results indicate that the rats of night phase may induce more accelerated formation of bromobenzene 3,4-oxide from bromobezene than those of day phase in rats.

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Cu-Al-Ni-Ti-Mn 합금의 변태특성 및 기계적 성질에 미치는 가공열처리의 영향 (The Effect of Thermomechanical Treatment on the Transformation Characteristics and Mechanical Properties in a Cu-Al-Ni-Ti-Mn Alloy)

  • 김춘동;이영수;양권승;장우양;강조원;백승남;곽사호
    • 열처리공학회지
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    • 제12권2호
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    • pp.145-156
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    • 1999
  • The distribution of the second phase, the change of transformation temperature and mechanical properties with thermomechanical treatment conditions were investigated by metallography, calorimetry, EDS, tensile test and fractography in a Cu-Al-Ni-Ti-Mn alloy. The cast structure revealed Ti-rich precipitates($X_L$ phase) between dendrite arms, which have been identified as $(Cu,Ni)_2TiAl$ intermetallic compounds. By homogenizing above $900^{\circ}C$, the $X_L$ phase was melted in the matrix, while the Xs phase was precipitated in matrix and the volume fraction of it was increased. When hot-rolled specimen was betatized below $750^{\circ}C$, recrystallization could not be observed. However, the specimen betatized above $800^{\circ}C$ was recrystallized and the grain size was about $50{\mu}m$, while Xs phase was precipitated in matrix. With raising betatizing temperature, $M_s$ and $A_s$ temperatures were fallen and transformation hysteresis became larger. The strain of the specimen betatized at $800^{\circ}C$ was 8.2% as maximum value. The maximum shape recovery rate could be obtained in the specimen betatized at $800^{\circ}C$ but it was decreased due to the presence of Xs phase with increasing betatizing temperature.

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조류의 Methylglyoxal과 인 Stress 연구 (Study of Methylglyoxal and Phosphorus Stress on Algae)

  • 이기태
    • Environmental Analysis Health and Toxicology
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    • 제13권3_4호
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    • pp.133-142
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    • 1998
  • Effects of phosphorous (P) and methylglyoxal (MG) on the cell number, dry weight, chlorophyll content, photosynthetic and respiratory rate, phosphate uptake and protein content of green algae (Scenedesrnus obliquus) were studied. The algal cell number from the medium treated with 0.5-1.0 mM of MG at 1/2 P or 1/4 P concentration was significantly lower than those of algae treated :with full strength of phosphrous in medium. The inhibitory effect of MG on algal cell division was enhenced at low concentration of phosphorous in medium. At the beginning of logrithmic phase of algal growth, the mean dry weight of algae from the medium without MG-treatment in 1/2 P media was significantly higher than that of algae treated with MG. After logrithmic phase of growth cycle, the mean dry weight of algae from the medium with 1.0 mM of MG-treatment in 1/4 P media was significantly lower than that of algae treated with or without MG. At logrithmic phase of algal growth, there were significant differences in the chlorophyll content among all groups of tested algae with various concentrations of P and MG. At 15 days after inoculation, the mean chlorophyll content per algal cell from the media without MG-treatment in 1/2P was significantly higher than that of other cells from MG-treated media. The adverse effect of MG at concentration of 0.5-1.0mM in 1/2 and 1/4 P media on photosynthetic rate was observed. The mean photosynthetic rate of algal cell without P and MG treatment at 15 days after inoculation was significantly higher than that of MGtreated algae. After logarithmic phase, the algal cell treated with 0.5mM of MG with full strength of phosphorous showed significantly high respiratory rate than that of other cell groups. There were significant differences in mean phosphate uptake rate among all groups of Scenedesmus obliquus at logarithmic phase. At 12 days after inoculation, phosphate uptake rate per each algal cell from the basic media without MG and P treatment was rapidly reduced which shows early introduction to stationary phase.

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미량 Sn을 함유한 AZ91 마그네슘 합금의 미세조직 및 기계적 특성 (Microstructure and Mechanical Properties of AZ91 Magnesium Alloy Containing a Small Amount of Sn)

  • 전중환
    • 열처리공학회지
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    • 제27권3호
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    • pp.115-120
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    • 2014
  • Microstructural features were comparatively investigated in AZ91 (Mg-9%Al-1%Zn) and AZ91-0.5%Sn alloys, in order to clarify the reason for the enhancement in room temperature tensile properties by the addition of small amount of Sn in Mg-Al-based alloy. In as-cast state, the Sn-containing alloy showed increased YS, UTS and elongation than the Sn-free alloy. The microstructural examination revealed that various factors including finer cell size, reduction of lamellar (${\alpha}+{\beta}$) phase and morphological change of bulky ${\beta}$ phase from partially divorced shape to fully divorced shape, are likely to be responsible for the improvement in tensile properties for the Sn-containing alloy. It is noted that two alloys showed similar tensile properties after solution treatment. This implies that microstructural evolution related to the ${\beta}$ phase plays a key role in better tensile properties in the Sn-containing alloy.