• Title/Summary/Keyword: Tempered steel

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A Study on the Machining Charcterisitics of Milling of cylinderical Rod Materials for Passenger Car (승용차용 CYLINDER ROD 소재의 밀링 적삭 특성 연구)

  • 채왕석
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1996.03a
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    • pp.143-148
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    • 1996
  • In this paper, we have studied internal quality including chemical compositions, microscopic structure and nonmetalic inclusion of test materials. We have analyzed dynamic characteristics of cutting force of milling including tensile strength value hardness etcs. Test materials are used the tempered carbon steel and the non-tempered carbon steel. The obtained results are as follows: 1.In analyzing internal quality, the tempered carbon steel have typical martensite structure and the non-tempered carbon steel have ferrite+pearlite structure. 2.Yield strength, tensile strength and hardness value are in the non-tempered carbon steel but elongation is maximum value in the tempered carbon steel. 3.Cutting force is smaller non-tempered carbon steel than tempered carbon steel when feed speed and depth of cut is constant. 4.Cutting force is smaller to the tempered carbon steel and smaller non-tempered carbon steel than tempered carbon steel when cutting conditions

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A Study on the Metrial Charcterisitics of Material Quality and Milling of Axle Materials for a Automobile (자동차 차축 소재의 금속적 특징 및 밀링 절삭 특성 연구)

  • 채왕석
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.6 no.1
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    • pp.77-83
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    • 1997
  • In this paper, we have studied internal quality including chemical compositions, microscopic structure and nonmetalic inclusion of test materials. We have analyzed dynamic characteristics of cutting force of milling including tensile strength value, hardness etc. Test materials are used in the tempered carbon steel and the non-tempered carbon steel. The obtained results are as follows: 1. In analyzing internal quality, the tempered carbon steel have typical martensite structure and the non-tempered carbon steel have ferrite + pearlite structure. 2. Yield strength, tensile strength and hardness value are in the non-tempered carbon steel but elongation is maximum value in the tempered carbon steel. 3. Cutting force is smaller non-tempered carbon steel than tempered carbon steel when feed speed and depth on cut is constant. 4. Cutting force is smaller non-tempered carbon steel than tempered carbon steel when cutting speed and depth of cut is constant.

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A Study on the Machining Characteristics of Engine Cap Meterials for a Automobile (자동차 엔진 캡 소재의 절삭 특성에 관한 연구)

  • 채왕석;김동현
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1995.10a
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    • pp.185-188
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    • 1995
  • In this paper, We have analyzed dynamic characteristics of cutting force. Test materials are used in the tempered carbon steek and non-tempered carbon steel. The obtained results ase as follows: 1. Cutting force is smaller non-tempered carbon steel than tempered carbon steel when feed speed make a change. 2. Specific cutting force is smaller non-tempered carbon steel than tempered caron steel when cutting depth make a change

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Effects of Hardness on Sliding Wear Behavior of Tempered Bearing Steel (베어링강의 미끄럼 마모거동에 미치는 Tempering 경도의 영향)

  • Lee, Han-Young
    • Tribology and Lubricants
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    • v.29 no.6
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    • pp.360-365
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    • 2013
  • In this study, sliding wear tests were conducted to investigate the effects of tempered hardness on the sliding wear behavior of bearing steel. At a sliding speed of 0.3 m/s, the wear resistance of bearing steel with a tempered hardness of HRC 54 was superior to that with HRC 62. It was found that bearing steel with HRC 54 showed a strong tendency for the occurrence of oxidation wear at that speed, compared to that with HRC 62. This would be due to the troostitic structure of bearing steel with HRC 54, which is highly susceptible to corrosion. In this context, it is considered that sliding wear behavior could be affected by the corrosion resistance of the material.

Effects of Tempering on Tensile Properties of Medium-Carbon Low-Alloy Steels (중탄소 저합금강의 인장성질에 미치는 템퍼링의 영향)

  • Lee, Young-Kook;Krauss, George
    • Journal of the Korean Society for Heat Treatment
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    • v.12 no.4
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    • pp.327-337
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    • 1999
  • A series of Ni-Cr-Mo alloy steels were austenitized, quenched to martensite, and tempered at various temperature and time conditions. Tensile testing was conducted at room temperature with cylindrical specimens, and hardness was measured using Rockwell hardness tester. In the tempering stage I, high strain hardening and yield strength accounted for the high ultimate strength and hardness. In the tempering stage II, strengths and hardness linearly decreased with increasing tempering temperature. Specimens tempered in the temperin stage III showed incipient discontinuous yielding and tensile strengths only slightly higher than yield strengths. Ductilities decreased slightly in specimens tempered in the tempered martensite embrittlement range, and severely decreased in specimens tempered for 10 hours at $500^{\circ}C$ in the temper embrittlement range. Specimens tempered at $600^{\circ}C$ for 10 hours showed recrystallized microstructures, a number of fine dimples, and increased strain hardening, probably due to the precipitation of alloy carbides. The simple formulae for the mechanical properties of these steels were suggested as a function of carbon content and Hollomon-Jaffe tempering parameter.

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Effect of Cr and Mo Contents on Hydrogen Embrittlement of Tempered Martensitic Steels (템퍼드 마르텐사이트강의 수소취성에 미치는 Cr 및 Mo 함량의 영향)

  • Sang-Gyu, Kim;Jae-Yun, Kim;Hee-Chang, Sin;Byoungchul, Hwang
    • Korean Journal of Materials Research
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    • v.32 no.11
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    • pp.466-473
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    • 2022
  • The effect of Cr and Mo contents on the hydrogen embrittlement of tempered martensitic steels was investigated in this study. After the steels with different Cr and Mo contents were austenitized at 820 ℃ for 90 min, they were tempered at 630 ℃ for 120 min. The steels were composed of fully tempered martensite with a lath-type microstructure, but the characteristics of the carbides were dependent on the Cr and Mo contents. As the Cr and Mo contents increased, the volume fraction of film-like cementite and prior austenite grain size decreased. After hydrogen was introduced into tensile specimens by electrochemical charging, a slow strain-rate test (SSRT) was conducted to investigate hydrogen embrittlement behavior. The SSRT results revealed that the steel with lower Cr or lower Mo content showed relatively poor hydrogen embrittlement resistance. The hydrogen embrittlement resistance of the tempered martensitic steels increased with increasing Mo content, because the reduction in the film-like cementite and prior austenite grain size plays an important role in improving hydrogen embrittlement resistance. The results indicate that controlling the Cr and Mo contents is essential to achieving a tempered martensitic steel with a combination of high strength and excellent hydrogen embrittlement resistance.

The Effect of Cementite Morphology and Matrix-ferrite Microstructure on the Sliding Wear Behavior in Spheroidized High Carbon Steel (구상화 열처리된 고탄소강의 미끄럼 마멸 거동에 미치는 시멘타이트 형상과 페라이트 기지조직의 영향)

  • Hur, H.L.;Gwon, H.;Gu, B.;Kim, Y.-S.
    • Transactions of Materials Processing
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    • v.25 no.2
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    • pp.96-101
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    • 2016
  • The current study was conducted to elucidate the effect of cementite morphology and matrix-ferrite microstructure on sliding wear behavior in spheroidized high carbon (1wt. % C) steel. The high carbon steel was initially heat treated to obtain a full pearlite or a martensite microstructure before the spheroidization. The spheroidizing heat treatment was performed on the full pearlitic steel for 100 hours at 700℃ and tempering was performed on the martensitic steel for 3 hours at 650℃. A spheroidized cementite phase in a ferrite matrix was obtained for both the full pearlite and the martensite microstructures. Sliding wear tests were conducted using a pin-on-disk wear tester with the heat treated steel as the disk specimen. An alumina(Al2O3) ball was used as the pin counterpart during the test. After the spheroidizing heat treatment and the tempering, both pearlite and martensite exhibited similar microstructures of spheroidized cementite in a ferrite matrix. The spheroidized pearlite specimens had lower hardness than the tempered martensite; however, the wear resistance of the spheroidized pearlite was superior to that of the tempered martensite.

Effect of TempCore Processing on Microstructure and Mechanical Properties of 700 MPa-Grade High-Strength Seismic Resistant Reinforced Steel Bars (700 MPa급 고강도 내진 철근의 미세조직과 기계적 특성에 미치는 템프코어 공정의 영향)

  • Shin, S.H.;Kim, S.K.;Lim, H.G.;Hwang, B.
    • Transactions of Materials Processing
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    • v.30 no.2
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    • pp.91-98
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    • 2021
  • The present study deals with the microstructure and mechanical properties of 700 MPa-grade high-strength seismic resistant reinforced steel bars fabricated by various TempCore process conditions. For the steel bars, in the surface region tempered martensite was formed by water cooling and subsequent self-tempering during TempCore process, while in the center region there was ferrite-pearlite or bainite microstructure. The steel bar fabricated by the highest water flow and the lowest equalizing temperature had the highest hardness in all regions due to the relatively fine microstructure of tempered martensite and bainite. In addition, the steel bar having finer microstructures as well as the high fraction of tempered martensite in the surface region showed the highest yield and tensile strengths. The presence of vanadium precipitates and the high fraction of ferrite contributed to the improvement of seismic resistance such as high tensile-to-yield strength ratio and high uniform elongation.

Microstructural Changes on Weld Heat Input in $60kg/mm^2$ Quenched and Tempered High Strength Steel ($60kg/mm^2$급 조질고장력강의 용접입열량에 따른 미세조직변화)

  • 김은석;정인상;박경채
    • Journal of Welding and Joining
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    • v.11 no.4
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    • pp.79-90
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    • 1993
  • Shielded metal arc welding, one-ploe and two-pole submerged arc welding were accomplished to investigate microstructure changes on phase transformation behavior in $60kg/mm^2$ quenched and tempered high strength steel. Microstructures were examined by optical micrograph and TEM. In shielded metal arc welding (oxygen 250ppm), the inclusions were small size (0.3-0.5$\mu\textrm{m}$)and small in number. In submerged arc welding (oxygen 430-529ppm), the inclusions were larger(0.7-2$\mu\textrm{m}$) than that of shielded metal arc welding and large in number. Microstructure mainly depends on number and distribution of inclusions in fusion zone of weld metal. It was noticed that a limited number of inclusions favors the formation of acicular ferrite.

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Effect of Carbides on the Tensile Properties of 0.5C-17Cr-0.5Ni Martensitic Stainless Steel (0.5C-17Cr-0.5Ni 마르텐사이트계 스텐인리스강의 인장성질에 미치는 탄화물의 영향)

  • Kwon, Soon-Doo;Son, Dong-Wook;Kang, Chang-Yong
    • Journal of Power System Engineering
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    • v.20 no.3
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    • pp.11-16
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    • 2016
  • The effect of carbides on the tensile properties in 0.5C-17Cr-0.5Ni martensitic stainless steel was studied. With the increase of austenitizing temperature, the volume fraction of residual carbide was decreased rapidly. In tempered specimens after quenching, the volume fraction of total carbide was decreased with the increase of austenitizing temperature. In tempered specimens after quenching, strength was decrease and elongation was increased with the increase of austenitizing temperature. Tensile strength was increase and elongation was decreased with the increase of volume fraction of residual and total carbides. With the increase of austenitizing temperature, the tensile properties of mod. 0.5C-17Cr-0.5Ni martensitic stainless was affected greatly by residual carbide than tempered carbide.