• Title/Summary/Keyword: Heat treatment process

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Effect of Carburizing Heat Treatment Process on Microstructure and Residual Stress Changes in AISI 9310 Steel. (AISI 9310강의 침탄열처리 경로가 조직 및 잔류응력 변화에 미치는 영향)

  • Youngchul Jeong;Joohyeon Bae;Jaeman Park;Seungjun OH;Janghyun Sung;Yongsig Rho
    • Journal of the Korean Society for Heat Treatment
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    • v.37 no.3
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    • pp.128-137
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    • 2024
  • In this study, the carburizing heat treatment process used in aircraft gear manufacturing was compared with the general carburizing heat treatment process using AISI 9310 steel. The process of carburizing followed by slow cooling, and then quenching after austenitizing(Process A) showed less compressive residual stress and less retained austenite in the surface layer compared to the process of quenching directly after carburizing(Process B). In prpcess B, there was a large amount of retained austenite when quenched immediately after carburization, and when treated with subzero, martensite rapidly increased and the compressive residual stress increased significantly, but at the same time, there is a risk of cracking due to severe expansion in volume. Therefore, in the case of aviation parts, it is believed that a step-by-step heat treatment cycle was adopted to ensure stability against heat treatment cracks. As a result of the final tempering after sub-zero treatment, the A process specimen showed a deeper effective case depth and HV700 depth and a higher hardness value above HV700 than the B process specimen.

Heat source control intelligent system for heat treatment process

  • Lee, JeongHoon;Cho, InHee
    • International journal of advanced smart convergence
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    • v.11 no.4
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    • pp.28-40
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    • 2022
  • Although precise temperature control in the heat treatment process is a key factor in process reliability, there are many cases where there is no separate heat source control optimization system in the field. To solve this problem, the program monitors the temperature data according to the heat source change through sensor communication in a recursive method based on multiple variables that affect the process, and the target heat source value and the actual heat treatment heat source to match the internal air temperature and material temperature. A control optimization system was constructed. Through this study, the error rate between the target temperature and the atmosphere (material surface) temperature of around 10.7% with the existing heat source control method was improved to an improved result of around 0.1% using a process optimization algorithm and system.

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 Cyclic Heat Treatment Process for Fine Microstructure of TiAl Cast Alloy (주조용 TiAl 합금의 조직 미세화를 위한 반복열처리 공정 조건에 관한 연구)

  • Kong, Man-Sik;Yang, Hyunseok
    • Journal of the Korean Society for Heat Treatment
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    • v.32 no.5
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    • pp.195-200
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    • 2019
  • For expanding the applications and workability of TiAl alloy, elongation is very important property. Fine microstructure is needed for elongation and physical properties of TiAl alloys. In this study, The effects of cyclic heat treatment process for fine microstructure of Ti-46Al-Nb-W-Cr-Si-C alloy, which was made by VAR (vacuum arc remelting) and VIM(vacuum induction melting) centrifugal casting process, was investigated. Cycle heat treatment process was very effective for recrystallization of this TiAl system, which has microstructure size of $50{\sim}100{\mu}m$ through pre-heat treatment, cyclic heat treatment in ${\alpha}+{\gamma}$ phase region and solution heat treatment respectively. Refined grain size was finally confirmed by photos of optical microscope and scanning electron microscope.

A Study on SCr420HB Helical Gear Deformative Simulation by Heat Treatment Quenching Method (열처리 냉각방식 변화에 따른 SCr420HB 헬리컬 기어 시뮬레이션 적용에 관한 연구)

  • Byun, J.H.;Byun, S.D.;Yi, C.H.
    • Journal of the Korean Society for Heat Treatment
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    • v.28 no.1
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    • pp.24-31
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    • 2015
  • In this study, a simulation was used to derive an optimal process of heat treatment with carburizing, and compared the derived result with SCr420HB helical gear in heat treatment with carburized quenching process about a change of the quenching method. The optimal carburizing process time is derived by the simulation with the theoretical time. The process has been performed by oil quenching and salt quenching method. Through the comparison of the results from the simulation(Hardness, effective case depth hardened by carburizing treatment and deformation) and the actual process, analyzed the error value of each quenching. And it verified the applicability of the simulation.

Development of the Diode Laser Heat Treatment Robot System Based on OLP Simulator (OLP 시뮬레이터 기반의 다이오드 레이저 열처리 로봇시스템 개발)

  • Park, Kee-Jin;Yoon, Sung-Ho
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.14 no.5
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    • pp.8-14
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    • 2015
  • Heat treatment for car body molds is mainly a manual process performed by a worker. The performance of this process is affected by workers' skill level, and has limitation in maintaining uniform product quality. In this study, we developed a diode laser heat treatment robot system that implements an OLP type simulator to overcome the limitation of manual process, and to improve and stabilize the quality level. In addition, we verified the efficiency of the robot system and mechanism stability from the early stage through design verification and simulated analysis in the development stage. In addition, we carried out a field test to study the way to establish optimized D/B for diode laser heat treatment criteria for car body molds, such as heat treatment speed, interval, etc. via site experiment.

A Study on Slide Way Deformation from High Frequency Heat Treatment by Finite Element Method (유한요소법을 이용한 고주파 열처리시 안내면 변형에 관한 연구)

  • 홍성오;조규재
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.11 no.3
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    • pp.57-64
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    • 2002
  • Finite element program(ANSYS) estimated thermal deformation quantity in high frequency heat treatment process of a machine tool fred drive system slideway and apply deformation quantity in roughing process. Having processed the heat treatment minimizing methods of the quantity of deformation heat treatment process. Having done heat treatment with high frequency after taper processing with considering the existed heat treatment generating the quantity of deformation, existed quantity of deformation can be reduced down to 80%, consequently productivity and material saving can be achieved. When high frequency heat treatment finite element method estimated deformation quantity at difference temperature and time, it is progress at cost don and saved time.

Net Shape Forming Process for Ball Stud Using High Strength Micro-Alloyed Cold Forging Steel (냉간 비조질강을 이용한 볼 스터드의 정형가공 공정연구)

  • Yoon, D.J.;Choi, H.J.;Lee, H.W.;Lee, G.A.;Jang, B.L.;Seo, S.L.;Choi, S.
    • Transactions of Materials Processing
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    • v.15 no.8 s.89
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    • pp.562-567
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    • 2006
  • Micro-alloyed steel or heat-treatment-free used in clean technology have been replacing for conventional quenched-and-tempered structural steels since the micro-alloyed forging steel was developed in early 1970s in Germany for saving money of heat treatment, simplified process, short delivery and good productivity. In this paper, ball stud assembled in steering system for automobile was selected to compare conventional process making heat treatment with new process using high strength micro-alloyed steel without heat treatment. The conventional process for ball stud was composed of a total of 6 steps including upsetting, forward extrusion, machining, burnishing and tread rolling with heat treatment and shot blasting. As opposed to conventional process, newly proposed process for ball stud using the clean technology without heat treatment is simplified such as forward extrusion, heading, upsetting, forming having a flange shape and tread rolling. Also net shape forming process to achieve specified process not to include machined step fur manufacturing the ball stud was applied to newly simplified process since micro-alloyed steel is difficult to be formed.

Effects of Heat Treatment on Surface Properties of Aluminum 6061 Alloy After Anodization (알루미늄 6061 합금 양극산화 후 열처리에 따른 표면 특성 관찰)

  • Seungmin, Lee;Chanyoung, Jeong
    • Corrosion Science and Technology
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    • v.21 no.6
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    • pp.495-502
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    • 2022
  • Anodization is a representative electrochemical surface treatment method that can improve both heat resistance and corrosion resistance by forming an anodization film on the surface of the aluminum. However, these properties can be changed after an additional heat treatment process. In this study, Al 6061 was subjected to an anodization process at 60 V for 1 hour, 5 hours, or 9 hours. An additional heat treatment process was performed at 500 ℃ for 30 minutes. Field emission scanning electron microscopy (FE-SEM) analysis revealed that the thickness of the anodized film was increased in proportion to the anodization time. Both pore size and pore diameter of the anodized film was also increased after anodization. After an additional heat treatment process, there were no significant changes in the thickness, pore size, or pore diameter of the anodized film. Heat resistance was confirmed through thermal analysis and chemical resistance was evaluated with a potentiodynamic polarization test.

EFFECTS OF LOW-TEMPERATURE HEAT TREATMENT ON ELASTIC MEMORY PROCESS OF COLD WORKED STAINLESS STEEL WIRE (열처리가 냉간가공한 stainless steel wire의 복원양상에 미치는 영향)

  • Oh, Jeung-Sei;Park, Soo-Byung;Son, Woo-Sung
    • The korean journal of orthodontics
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    • v.22 no.3 s.38
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    • pp.647-656
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    • 1992
  • The purpose of this study was to evaluate the elastic memory process in cold worked stainless steel wire and the effect of heat treatment on it. 0.018 inch round and $0.019\times0.025$ inch rectangular wire (ORMCO stainless wire) were used in this study. Each wire type had 4 groups: non-heat treatment group, furnace heat treatment group, electric current heat treatment group, and bending after heat treatment group. Each group was consisted of 10 specimens. With the Jig, each wire was bent into v-shape uniformly, and width of two free ends of each v-shaped wire was measured by caliper (to the point of 0.1 mm correctly) at time interval of offjig, after heat treatment, 1, 2, 3, 4 hours, 1, 2, 3, 4, 5, 6 days, 1, 2, 3, 4 weeks after. The results were as follows: 1. In non-heat treatment group and bending after heat treatment group, elastic memory process was occured $60\%$ within 1 hour, and more than $90\%$ within 1 week. 2. In furnace and electric current heat treatment group, almost all elastic memory process was occured during teat treatment, and then specimen was stabilized dimensionally. 3. Magnitude of deformation by elastic memory was greater in heat treatment group than non heat treatment group and bending after heat treatment group. 4. There was no remarkable difference in deformation pattern between 0.018 inch round wire and $0.019\times0.025$ inch rectangular wire.

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