• Title/Summary/Keyword: heat treatment processing

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Prediction of Hardness for Cold Forging Manufacturing through Machine Learning (기계학습을 활용한 냉간단조 부품 제조 경도 예측 연구)

  • K. Kim;J-.G. Park;U. R. Heo;Y. H. Lee;D. H. Chang;H. W. Yang
    • Transactions of Materials Processing
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    • v.32 no.6
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    • pp.329-334
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    • 2023
  • The process of heat treatment in cold forging is an essential role in enhancing mechanical properties. However, it relies heavily on the experience and skill of individuals. The aim of this study is to predict hardness using machine learning to optimize production efficiency in cold forging manufacturing. Random Forest (RF), Gradient Boosting Regressor (GBR), Extra Trees (ET), and ADAboosting (ADA) models were utilized. In the result, the RF, GBR, and ET models show the excellent performance. However, it was observed that GBR and ET models leaned significantly towards the influence of temperature, unlike the RF model. We suggest that RF model demonstrates greater reliability in predicting hardness due to its ability to consider various variables that occur during the cold forging process.

Effects of Thermomechanical Processing on Changes of Microstructure and Mechanical Properties in Ti-10Ta-10Nb Alloy (가공 열처리에 따른 Ti-10Ta-10Nb합금의 미세조직 및 기계적 특성 변화)

  • Lee, Doh-Jae;Hwang, Ju-Young;Lee, Kyung-Ku;Yoon, Kye-Lim;Jun, Choong-Geug
    • Journal of the Korean Society for Heat Treatment
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    • v.18 no.2
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    • pp.91-98
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    • 2005
  • Both commercially pure titanium and Ti-6Al-4V alloy have been widely used as biomaterials because of their excellent biocompatibility, corrosion resistance and mechanical properties. However, in recent years, vanadium has been found to cause cytotoxic effects and adverse tissue reactions, while aluminium has been associated with potential neurological disorders. A newly designed ${\alpha}+{\beta}$ type Ti alloy, Ti-10Ta-10Nb alloy showed superior properties to CP Ti and Ti-6Al-4V alloy in the point of biomaterial, and elucidated the future uses as a biomaterial. Microstructural changes of Ti-10Ta-10Nb alloy after hot-rolling, warm-rolling, solution and aging treatment were investigated. According to TEM results, the microstructures after solution treatment were composed of mostly ${\alpha}$ phase with a trace of ${\beta}$ phase due to adding ${\beta}$-phase stabilizer tantalum and niobium. The microstructures after warm-rolling is coarse and elongated ${\alpha}$ phase and hot rolling resulted in very fine ${\alpha}$ widmanst$\ddot{a}$tten. The highest value of hardness was obtained by aging treatment at $400^{\circ}C$ for 20hr in which microstructure consisted of very fine ${\alpha}$ phase in ${\beta}$ matrix.

Finite Element Analysis of Induction Heating Process for Development of Rapid Mold Heating System (급속 금형가열 시스템 개발을 위한 고주파 유도가열 과정의 유한요소해석)

  • Hwang, J.J.;Kwon, O.K.;Yun, J.H.;Park, K.
    • Transactions of Materials Processing
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    • v.16 no.2 s.92
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    • pp.113-119
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    • 2007
  • Rapid mold heating has been recent issue to enable the injection molding of thin-walled parts or micro/nano structures. Induction heating is an efficient way to heat material by means of an electric current that is caused to flow through the material or its container by electromagnetic induction. It has various applications such as heat treatment, brazing, welding, melting, and mold heating. The present study covers a finite element analysis of the induction heating process which can rapidly raise mold temperature. To simulate the induction heating process, the electromagnetic field analysis and transient heat transfer analysis are required collectively. In this study, a coupled analysis connecting electromagnetic analysis with heat transfer simulation is carried out. The estimated temperature changes are compared with experimental measurements for various heating conditions.

Three Hydroxylated Ginsenosides from Heat Treatmented Ginseng (인삼의 열처리 과정 중 생성되는 3종의 수산화진세노사이드에 대한 연구)

  • Lee, Sang Myung
    • Korean Journal of Pharmacognosy
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    • v.51 no.4
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    • pp.255-263
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    • 2020
  • Ginsenosides are considered to be the most important ingredients in ginseng. They are chemically converted by endogenous organic acids contained in ginseng and the heat applied during red ginseng processing. During this procedure, various converted ginsenosides are produced through hydrolysis of substitute sugars of ginsenosides and forming double bonds through dehydration in the dammarane skeleton. In order to study the conversion mechanism of protopanaxadiol-type ginsenosides during the heat treatment process of ginseng, we purified the three final converted ginsenosides by heating fresh ginseng for a long time. The three isolated ginsenosides were identified as 25(OH)-ginsenoside Rg5, 25(OH)-ginsenoside Rz1 and 25(OH)-ginsenoside Rg3 through NMR spectrum analysis. As a result of quantification of ginseng heated at 100 ℃ for 0 to 6 days by HPLC/UV and TLC methods, the content of 25(OH)-ginsenosides tended to increase in proportion to the time exposed to heat. In particular, the content of 25(OH)-ginsenosid Rg5 was confirmed to be noticeably increased.

Shear Strength Property of Wood Treated by Steam Treatment at High Temperature (고온수증기처리 목재의 전단강도 특성)

  • Kim, Jung-Hwan;Lee, Weon-Hee;Kim, Jong-Man
    • Journal of the Korean Wood Science and Technology
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    • v.29 no.4
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    • pp.9-15
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    • 2001
  • This study deals with shear strength test for Pinus densiflora and Pinus radiata treated at above $100^{\circ}C$ by heat steam. Treatment conditions of this experiment were operated at regular intervals of $20^{\circ}C$ at temperatures up to $200^{\circ}C$ for 5, 10, 20 and 30 minutes by using the steam-explosion apparatus. It was examined, at high temperatures, degradation of some compounds from wood composition could lead to reduced the shear strength through heat steaming processes and play a large part in the plastic process of solid wood materials. It could be estimated that the shear strength of woods were gradually reduced by heat steaming time. Remarkable reduction of shear strength of woods was observed with increasing steaming temperatures above 10 minutes steaming time. Furthermore, this phenomenon shows a tendency to increase with higher temperatures. Therefore, it was considered that the softening by steaming treatment at high temperatures is necessary for the improvement on the wood processing ability.

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A Study on Forming of Al-Zn-Mg-Sc Aluminum Alloy Bolts (Al-Zn-Mg-Sc 알루미늄 합금 볼트 성형에 관한 연구)

  • Yoon, D.J.;Hahm, S.Y.;Lee, Y.S.
    • Transactions of Materials Processing
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    • v.21 no.7
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    • pp.447-452
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    • 2012
  • This paper is concerned with forming of Al-Zn-Mg-Sc aluminum alloy bolts, focusing on the effects of heat treatment and age-hardening on the formability and ductile damage evolution. Both experimental and finite element studies were performed. From the experiments, it is observed that the heat treatment or the normalization of Al-Zn-Mg-Sc aluminum alloy increases its formability dramatically resulting in successful bolt forming, while the effects of age-hardening at room temperature on the stress-strain relationship and formability are not very critical. Deformation characteristics such as distribution of effective stress and strain, material flow, and ductile damage evolution during bolt forming are examined using a commercial finite element package, Deform-2D. It should be noted that the extrusion load predicted by the finite element method matches well the experiment results. The finite element predictions on the deformation characteristics support the experimental observations such as fracture of bolt head flange, material flow, and distribution of hardness.

Fabrication of a Part by Heating and Forming in the Semi-solid State of the SKH51 Material (SKH51의 반응고 상태에서의 가열 및 성형에 의한 부품 제조)

  • Lee, Sang Yong
    • Journal of the Korean Society for Heat Treatment
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    • v.27 no.3
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    • pp.127-132
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    • 2014
  • The semi-solid metal forming process has been applied to realize a near-net shape fabrication of a high speed tool steel. A complicatedly shaped part out of SKH51 was successfully manufactured by introducing pertinent materials, tooling and processing conditions. A SKH51 billet with globular grains was heated at temperatures between 1300 and $1350^{\circ}C$ using high frequency induction heater to get semi-solid microstructure before high rate injection of mushy metal into a die cavity for the forming process. It was necessary to control the preheating of dies between 300 and $400^{\circ}C$ to maintain the homogeneous microstructure during the semi-solid metal forming process. Significant defects such as pores, high fraction of liquid fraction and segregation could be removed from the part by using air vents.

Forging Process with Al6061 Alloy Rheology Material by Electromagnetic Stirring System (전자교반을 응용한 Al6061 레오로지 소재의 단조공정)

  • Kang, S.S.;Oh, S.W.;Kang, C.G.
    • Transactions of Materials Processing
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    • v.16 no.6
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    • pp.443-446
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    • 2007
  • The semi-solid process has been developed near net-shape components for kinds of methods. Thixo-forming with reheating prepared billet and rheo-forming with cooled melt until semi-solid state. Material is applied electromagnetic stirring system to slurry with aluminum 6061 alloy. An experiment has variation factors which are pressure, solid-fraction, stirring current and stirring time. The mechanical properties are compared to forge sample with to apply heat treatment T6. This study is researched function a virtual pressure and fine shape zone. Optimum pressure is found to prevent defect of porosity.

Planarization of Diamond Films Using KrF Excimer Laser Processing (KrF 엑사이머 레이저 법을 이용한 다이아몬드 박막의 평탄화)

  • Lee, Dong-Gu
    • Journal of the Korean Society for Heat Treatment
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    • v.13 no.5
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    • pp.318-323
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    • 2000
  • The planarization of rough polycrystalline diamond films synthesized by DC arc discharge plasma jet CVD (chemical vapor deposition) was attempted using KrF excimer laser pulses. The effects of laser incidence angle and reaction gases (ozone and oxygen) on etching rate of diamond were studied. The temperature change of diamond and graphite with different laser fluences was calculated by computer simulation to explain the etching behavior of diamond films. The threshold energy density from the experiment for etching of pure crystalline diamond was about $1.7J/cm^2$ and fairly matched the simulation value. Preferential etching of a particular crystallographic plane was observed through scanning electron microscopy. The etching rate of diamond with ozone was lower than that with oxygen. When the angle of incidence was $80^{\circ}$ to the diamond surface normal, the peak-to-valley surface roughness was Significantly reduced from $20{\mu}m$ to $0.5{\mu}m$.

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Improvement of Fracture Toughness in 7XXX Series Aluminum Alloy Forings (7XXX계 알루미늄합금 단조재의 파괴인성 개선)

  • Song, K.H.;Lee, O.H.
    • Journal of the Korean Society for Heat Treatment
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    • v.11 no.3
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    • pp.200-206
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    • 1998
  • The aim of this study is to investigate the effect of impurity level and fabrication processes on the strength, impact and fracture toughness of 7075, 7050 and 7175 aluminum alloy forgings. A specially processed 7175S-T74 aluminum forgings was superior to a conventionally processed 7075-T73, 7050-T74 and 7175-T74 aluminum forgings in both strength and toughness. The reduction of impurity level of iron and silicon has significantly diminished the size and volume fraction of second phase particles such as $Al_7Cu_2Fe$ and $Mg_2Si$. A further reduction of the amount of second phase particles has been observed by applying a special fabrication process. This phenomena result from the application of intermediate soaking at higher temperature and more sufficiant hot working temperature than that of a conventional processing.

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