• Title, Summary, Keyword: heat treatment

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Growth of Intermetallic Compounds by Heat Treatment at Interface of Friction Welded Al-Cu System (Cu-Al 마찰용접 접합부 계면에서 열처리에 따른 금속간화합물 성장)

  • Kim, Ki-Young;Choi, In-Chul;ITO, Kazuhiro;Oh, Myung-Hoon
    • Journal of the Korean Society for Heat Treatment
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    • v.32 no.2
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    • pp.79-85
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    • 2019
  • To investigate the influence of heat treatment on the growth intermetallic compounds (IMCs) at the joint interface of friction-welded Cu-Al, several heat treatments are performed at three different temperature with different times. The experiments reveal three different IMCs layers which are significantly influenced by atomic diffusion of Cu and Al with heat treatment conditions. Since the formation of these IMCs layers can affect mechanical properties of friction-welded Cu-Al interfaces, the relationship between the microstructure of IMCs layers and the tensile strength is analyzed according to heat treatment temperature and times.

A Study on Heat-Treatment Process Scheduling for Heavy Forged Products using MIP (열처리 공정의 생산스케줄 수립과 적용에 관한 연구)

  • Choi, Min-Cheol
    • Korean Management Science Review
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    • v.29 no.2
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    • pp.143-155
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    • 2012
  • The purpose of this study is to formulate and solve the scheduling problem to heat-treatment process in forging process and apply it to industries. Heat-treatment is a common process in manufacturing heavy forged products in ship engines and wind power generators. Total complete time of the schedule depends on how to group parts and assign them into heat furnace. Efficient operation of heat-treatment process increases the productivity of whole production system while scheduling the parts into heat-treatment furnace is a combinatorial problem which is known as an NP-hard problem. So the scheduling, on manufacturing site, relies on engineers' experience. To improve heat-treatment process schedule, this study formulated it into an MIP mathematical model which minimizes total complete time. Three methods were applied to example problems and the results were compared to each other. In case of small problems, optimal solutions were easily found. In case of big problems, feasible solutions were found and that feasible solutions were very close to lower bound of the solutions. ILOG OPL Studio 5.5 was used in this study.

The Effects of Solution Heat Treatment and Aging Treatment on the Electrical Conductivity and Hardness of Cu-Cr Alloys (크롬동합금의 도전율과 경도에 미치는 용체화처리와 시효처리의 영향)

  • Kim, Shin Woo
    • Journal of the Korean Society for Heat Treatment
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    • v.15 no.1
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    • pp.21-24
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    • 2002
  • The electrode materials for welding machine in automobile industry such as Cu-Cr, Cu-Zr and Cu-$Al_2O_3$ require the high electrical conductivity and the proper hardness. Therefore the effects of solution heat treatment and aging treatment on the electrical conductivity and hardness of Cu-0.8wt%Cr and Cu-1.2wt%Cr alloys have been investigated. Cu-0.8wt%Cr alloy showed the higher electrical conductivity and hardness than Cu-1.2wt%Cr alloy and both alloys showed the better electrical conductivity at $930^{\circ}C$ among 930, 980 and $1030^{\circ}C$ solution heat treatment temperatures. The electrical conductivity and hardness in both alloys were not affected by aging treatment but remarkably affected by solution heat treatment temperature. The final drawing process reduced electrical conductivity and increased hardness more in Cu-1.2wt%Cr alloy.

Hygroscopicity and Surface Hardness of Domestic Wood Heat-Treated at $220^{\circ}C$

  • Kang, Ho-Yang
    • Journal of the Korea Furniture Society
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    • v.19 no.4
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    • pp.229-234
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    • 2008
  • In a previous study, it was revealed that three major softwoods, Japanese pine, Korean pine and Japanese larch, heat-treated at $220^{\circ}C$, could produce high quality dark-colored boards. It is known that heat treatment decreases the hygroscopicity of wood. The hygroscopicity of major domestic softwoods and hardwoods heat-treated at $220^{\circ}C$ was investigated by a saturated salt solution method and compared with that of black and white charcoals. Equilibrium moisture contents of wood decreased with the increase of heat treatment time. Isotherm shapes of wood species were different from those of charcoals. Heat treatment decreases the equilibrium moisture contents of black locust more than those of Korean pine and Japanese larch. It was found that surface hardness of wood is improved by heat treatment to a certain extent, but a longer heat treatment causes thermal degradation, resulting in the decrease of the surface hardness.

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The Effects of Heat Treatment on the Fatigue Life and Welding Residual Stress of Welded Carbon Steel Plates (탄소강 후판용접부의 피로수명 및 잔류응력에 미치는 열처리 영향)

  • An, I.T.;Kim, W.T.;Jo, J.R.;Moon, Y.H.
    • Journal of the Korean Society for Heat Treatment
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    • v.16 no.3
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    • pp.141-147
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    • 2003
  • The effects of heat treatment on the fatigue life and welding residual stress of welded plates were investigated in this study. The plates were welded by flux cored arc welding process, and post weld heat treated at $600^{\circ}C$ for 1 hour. The residual stresses of welded plates before and after post weld heat treatment were measured by hole drilling method. To measure the fatigue life of welded plates, low cycle fatigue tests under strain control and high cycle fatigue tests under load control were performed respectively, by using cylindrical specimens containing weld metal and heat affected zone. The obtained result shows that the post weld heat treatment reduces the residual stress, and resultantly changes the fatigue life of welded plate. Goodman diagrammatic analysis has also been performed to study the effect of post weld heat treatment on the high cycle fatigue life.

Effect of Heat Treatment Environment on the Microstructure and Properties of Kinetic Sprayed Tantalum Coating Layer (Kinetic Spray 공정으로 제조된 탄탈륨 코팅층의 열처리 분위기에 따른 미세조직 및 물성)

  • Lee, Ji-Hye;Kim, Hyung-Jun;Lee, Kee-Ahn
    • Journal of Korean Powder Metallurgy Institute
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    • v.22 no.1
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    • pp.32-38
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    • 2015
  • The effect of heat treatment environment on the microstructure and properties of tantalum coating layer manufactured by kinetic spraying was examined. Heat treatments are conducted for one hour at $800^{\circ}C$, $900^{\circ}C$, and $1000^{\circ}C$ in two different environments of vacuum and Ar gas. Evaluation of microstructure and physical properties are conducted. High density ${\alpha}$-tantalum single phase coating layer with a porosity of 0.04% and hardness of 550 Hv can be obtained. As heat treatment temperature increases, porosity identically decreases regardless of heat treatment environment (vacuum and Ar gas). Hardness of heat treated coating layer especially in Ar gas environment deceases from 550 Hv to 490 Hv with increasing heat treatment temperature. That in vacuum environment deceases from 550 Hv to 530 Hv. The boundary between particles became vague as heat treatment temperature increases. Oxygen distribution of tantalum coating layer is minute after heat treatment in vacuum environment than Ar gas environment.

THE EFFECTS OF HEAT TREATMENT OF ORTHODONTIC WIRES (교정용 강선재의 열처리 효과에 관한 실험적 연구)

  • Lee, Myeung-Suck;Sohn, Byung-Hwa
    • The korean journal of orthodontics
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    • v.22 no.3
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    • pp.591-602
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    • 1992
  • The purpose of this study was to evaluate the effect of heat treatment on physical properties of 0.016' and 0.016' x 0.022' stainless steel wires. Temperature of heat treatment had intervals of $50^{\circ}C$ from $400^{\circ}C$ to $700^{\circ}C$, and time of heat treatment were 3, 6 and 9 minutes. Tensile tests were measured by ultimate tensile strength and yield strength. Bending tests were assessed by maximum bending force, recovery force, and stiffness. Torsion test was evaluated by torsion cycle until wires were fractured. The results were as follows: 1. In round wires, the highest value of ultimate tensile strength and yield strength were recorded of heat treatment at $500^{\circ}C$. In rectangular wires, the highest value of ultimate tensile strength were after 9 minutes at $400^{\circ}C,\;450^{\circ}C$ and 3, 6 minutes of heat treatment at $50^{\circ}C$, yield strength were the highest value after 3, 6 minutes of heat treatment at $500^{\circ}C$. 2. In both round and rectangular wires, maximum bending force and recovery force were the highest values after 6 minutes of heat treatment at $500^{\circ}C$. In round wires, highest value of stiffness were formed after 9 minutes at heat treatment at $500^{\circ}C$. In rectangular wires, the highest value of stiffness were for 6 minutes in $500^{\circ}C$. 3. In rectangular wires, torsion cycle was minimum after 6 minutes of heat treatment at $500^{\circ}C$. 4. In all of tension, bending, and torsion tests, the heat treated wires were softened over at $700^{\circ}C$. 5. In all of tension, bending, and torsion tests, physical properties of the wires were more influenced by the temperatures than the duration of the heat treatment.

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Changes in Allergenicity and Digestibility of Egg and Milk by Heat Treatment (가열처리에 따른 우유와 달걀의 Allegenicity의 변화와 소화율에 관한 연구)

    • Journal of the East Asian Society of Dietary Life
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    • v.11 no.2
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    • pp.104-111
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    • 2001
  • The first purpose of this study was to determine the changes in the allergenicity of milk and egg with heat treatment. The allergenicity of milk and egg is known to have a strong antigen. The second purpose of this study was to observe changes of disestibility of milk and egg after heat treatment. For this study, passive cutaneous anaphylaxis(PCA) inhibition experiment by using guinea pig and nonprotein nitrogen(NPN)experiment were attempted. The result were following: 1. The allergenicity of both milk and egg was reduced by heat treatment. 2. The degree of hydrolysis and PCA inhibition increased with longer heating time. 3. The increse in both the degree of hydrolysis and PCA inhibition of milk was higher than that of egg. 4. Egg contained a greater amount of allergen than milk after heat treatment. 5. The digestibility of both milk and egg was reduced by heat treatment. 6. The digestibility was reduced further by increasing heating time. 7. The digestibility of egg was lower than that of milk after the treatment.

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Effects of Heat Treatment Temperature and Cooling Method on Microstructure and Hardness of Cu-22Sn alloy (열처리 온도 및 냉각방법이 Cu-22Sn합금의 미세조직 및 경도변화에 미치는 영향)

  • Jeong, Museob;Shin, Ari;Han, Jun Hyun
    • Journal of the Korean Society for Heat Treatment
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    • v.31 no.3
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    • pp.104-110
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    • 2018
  • The effects of heat treatment time and cooling method on microstructure and mechanical property of Cu-22wt%Sn alloy were discussed. ${\alpha}+{\delta}$ mixed phase structure was obtained in air-cooled specimens after heat treatment at 775, 750, and $700^{\circ}C$ for 1 hour. On the other hand, in water-cooled specimens, ${\alpha}+{\beta}^{\prime}$ martensite mixed phase was obtained. In the case of water-cooled specimens, the hardness value decreased with decreasing heat treatment temperature because the volume fraction of ${\alpha}$ phase with low hardness value increased as the heat treatment temperature decreased. In water-cooled specimen after heat treatment at $600^{\circ}C$, ${\gamma}^{\prime}$ martensite was formed instead of ${\beta}^{\prime}$ martensite. The hardness value of ${\gamma}^{\prime}$ martensite was lower than those of ${\beta}^{\prime}$ and ${\delta}$ phases.

Comparison of Characteristics on Induction and Continuous Nd:YAG Laser Surface hardening of SM45C Steel (SM45C강의 연속파 Nd:YAG레이저표면경화와 고주파표면경화특성 비교)

  • Shin H.J.;Yoo Y.T.;Ahn D.G.;Shin B.H.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.176-183
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    • 2005
  • Laser heat treatment technology is used for improving the feature of fatigue resistance and wear resistance in mobile parts. The purpose of this study is to compare the characteristics of laser heat treatment and high frequency heat treatment, which is commonly used in industrial place. For the preemptive experiment, the distribution, depth and size of hardening and its micro-structural features were compared between surface heat treatment case by defocusing and variables of each process for heat treatment by exclusively manufactured heat treatment optical system. As a result, high frequency heat treatment has wide distribution of hardening depth and width about 3 times larger than laser heat treatment, however, its average hardness showed 621.4Hv which is smaller than the average hardness of laser heat treatment with 691Hv.

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