• Title/Summary/Keyword: Cold rolled Steel

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자동차용 강판의 물성 데이터베이스 (Database of Steel Sheet for Automotive body)

  • 박현철;이상곤;신철수
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2004년도 추계학술대회 논문집
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    • pp.1483-1486
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    • 2004
  • Purpose of this paper is to accummulate database of automotive steel sheet from mild steel to high strength steel in cold rolled steel sheets. Physical properties, mainly mechanical properties, of steel sheet are tested and all data are arranged to one sheet. Methods of test are composed of FLD, tensile strength test, chemical composition, surface roughness and product conditions. Finally this database will be helpful to automotive body designers and die designers to design automotive body parts and tools in a material point of view.

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강판의 두께 깊이와 소성변형비 변화 (The Variation of Plastic Strain Ratio Through Thickness in Sheet Steel)

  • 김인수;박노진;김성진;서완영;이민구
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1997년도 춘계학술대회논문집
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    • pp.117-120
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    • 1997
  • Microstructure and pole figure through thickness in cold rolled sheet steel were investigated. The calculated plastic strain ratio in surface is greatly different with that in center layer and measured value in tensile test.

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고주파열처리에 의한 자동차용 고강도 강판의 기계적 성질변화 (Mechanical Properties of High Stength Sheet Steels for Auto-Body by Induction Heat Treatment)

  • 이두환;윤치상;임종대
    • 열처리공학회지
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    • 제17권2호
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    • pp.73-77
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    • 2004
  • The efforts which increase the strength of the auto-body structure and decrease its weight lead to develop a new concept of part production systems, such as Post-Form Strengthening by induction heat treatment. In this study, several cold and hot-rolled sheet steels were used to find out optimum induction heat treatment conditions. After induction heat treatment, strength of heat-treated sheet steels was increased significantly compared with that of as-rolled steels. From these results, auto-body structure which has more light and safe has been made by using this induction hardening method.

X선 잔류응력을 이용한 냉간압연강의 피로손상 모델링에 관한 연구 (A Study on Fatigue Damage Modelling in Cold Rolled Steel using X-ray Residual Stress)

  • 조석수;주원식
    • 한국해양공학회지
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    • 제13권4호통권35호
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    • pp.55-62
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    • 1999
  • Cold rolled steel has much plastic strain in the material surface produced by manufacturing process. The strain causes the variation of surface residual stress, in which influences the fatigue behavior under repeated loading. As experimental results, it was confirmed that the behavior of residual stress ${\sigma}_r$, with cycle N consisted of three stages except stress amplitude near fatigue limit in SPCC steel. On the first stage compressive residual stress decreased rapidly, on the second stage gradually, and on the last stage slightly. The relation between ${\sigma}_r$, and log N appeared linear behavior except the early part of cycle ratio $N/N_f$. The average gradient of ${\sigma}_r$, with respect to log N seemed to take a constant value without initial cycle ratio. On the other hand, the $N_f$ line was regressed by the first-order polynomial equation on ${\sigma}_r-log\;N_f$ diagram. Therefore, this study showed that both the gradient of ${\sigma}_r$, with respect to log N and the $N_f$ line was useful in predicting the cycle ratio $N/N_f$.

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P 첨가 0.15C-1.5Mn-1.5Al TRIP형 냉연강판의 미세조직과 기계적 성질 (Microstructure and Mechanical Properties of P Added 0.15C-1.5Mn-1.5Al TRIP Aided Cold Rolled Steel)

  • 안만욱;조경목;서동우;오창석;김성준
    • 소성∙가공
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    • 제14권8호통권80호
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    • pp.712-717
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    • 2005
  • Microstructure and mechanical properties are investigated for 0.15C-1.5Mn-1.5Al TRIP aided cold rolled steels containing $0.05wt\%P$ and $0.1wt\%P$. Despite of the complete replacement of Si by Al, the TRIP steel shows tensile strength of 700MPa and total elongation of $35\%$ by addition of $0.1wt\%$ P. Tensile strength of P added TRIP steels is not only affected by the solid solution hardening but also the volume fraction of retained austenite. As P content increases from $0.05wt\%$ to $0.1wt\%$, tensile strength and volume fraction of retained austenite are increased, but elongation is decreased. The lower stability of austenite in $0.1wt\%$ P added steel is responsible for the decrease of the elongation.

유/무기하이브리드 용액에 의한 SPCC, SPFC590, SPFC780 강판의 내식성 (일정한 멜라민에서 SiO2 polysilicate 양이 다른 경우) (Corrosion Resistance of SPCC, SPFC590, SPFC780 Steel by Organic/Inorganic Hybrid Solution (Case of different SiO2 polysilicate under a constant melamin))

  • 남기우;정희록;이광호
    • 동력기계공학회지
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    • 제21권2호
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    • pp.5-13
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    • 2017
  • This study has developed an organic/inorganic hybrid solution according to amount of $SiO_2$ polysilicate, and the amount of melamine is constant. The three types of cold rolled steel were evaluated a corrosion resistance properties by using these solutions. $US_3M_3$ and $US_{11}M_3$ solutions were generate a lot of corrosion. $US_7M_3$ solution was excellent in corrosion resistance, regardless of the steel type. The appearance of coating by $US_3M_3$ and $US_{11}M_3$ solutions were bumpy surface, and were a lot of fine defects. $US_7M_3$ solution was made a sophisticated molecular cross-linking structure inside the coating, it was a slick surface. Other characteristics are exhibited the excellent property for all solutions.

고탄소강의 구상화속도에 미치는 초기 미세조직, 냉간압연 및 온도의 영향 (Effect of Initial Microstructure, Cold Rolling and Temperature on the Spheroidization Rate of Cementite in High Carbon Steel)

  • 김준호;하태권
    • 소성∙가공
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    • 제22권3호
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    • pp.158-164
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    • 2013
  • The spheroidization behavior of cementite in a SK85 high carbon steel was investigated in this study. Fine and coarse pearlite microstructures were obtained by appropriate heat treatments according to the TTT diagram of SK85 high carbon steel. Hot rolled plates of SK85 steel were austenitized at $800^{\circ}C$ for 2 hrs and then put directly into a salt bath at either $570^{\circ}C$ or $670^{\circ}C$ to obtain a fine pearlite (FP) structure and a coarse pearlite (CP) structure, respectively. Cold rolling was subsequently conducted on those specimens with reduction ratios from 0.2 to 0.4. Spheroidization heat treatments were conducted at the subcritical temperatures of 600 and $720^{\circ}C$ for 1 to 32 hrs to elucidate the effect of initial microstructures, heat treatment temperature, and cold reduction ratios on the cementite spheroidization rate. Spheroidization proceeded with fragmentation of cementite plates, spheroidization of the cementite platelets, and coarsening consecutively. Mechanical fragmentation of cementite by cold rolling expedited the rate of spheroidization. The spheroidization rate of FP was much more rapid than that of CP and the spheriodization rate increased with increases in the cold reduction ratio.

유/무기 하이브리드 코팅액에 의한 냉간압연강판의 열처리 온도에 따른 내식특성 (Corrosion Resistance of Cold Rolled Steel coated Organic/inorganic Hybrid Coating Solution According to Heat Treatment Temperature)

  • 남기우;김정량;최창민
    • 한국해양공학회지
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    • 제25권6호
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    • pp.56-59
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    • 2011
  • The demand for cold rolled steel (CR) for structural members is gradually increasing. If no surface treatment (coating for corrosion resistance) for CR is conducted, its use is very limited because CR is vulnerable to corrosion. Therefore, we need to develop a coating solution to provide high corrosion resistance for CR. In this study, an organic/inorganic coating solution with Si and Ti (Si polysilicate 7 wt.% + Urethane 13 wt.% + Ti amorphous 0.5 wt.%; LR-0727(1)) was used to evaluate the corrosion resistance of CR under a salt spray test. The specimens with the LR-0727(1) coating were heat treated in a drying oven at $120{\sim}210^{\circ}C$for 5 min. The corrosion resistance was investigated using a salt spray test of 7 h. In addition, an adhesive test was conducted. Rust showed under a heat treatment of $150^{\circ}C$, but no vestiges were found over $160^{\circ}C$. The specimens with heat treatment at $160^{\circ}C$ or more did not experience delamination. From these results, it is considered that the temperature limit for optimum heat treatment is $160^{\circ}C$ considering energy efficiency.