• 제목/요약/키워드: 고장력 강판

검색결과 88건 처리시간 0.026초

선체구조 Ballast Tank 고장력 TMCP강판의 과방식중 부식피로균열 전파거동 (Corrosion Fatigue Crack Propagation Behaviour of TMCP Steel Plate at Ballast Tank of Ship Structure under the Condition of Cathodic Overprotection)

  • 김원범
    • 한국산학기술학회논문지
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    • 제13권6호
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    • pp.2465-2471
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    • 2012
  • 선박이나 심해저 해양플랜트와 같이 가혹한 해양환경에서 사용되는 강구조물에서 부식피로는 설계수명과 관련하여 해결을 요하는 중요한 문제이다. 본 연구에서는 전기방식중 과도한 전기방식이 부식피로균열 전파거동에 미치는 영향을 고찰하기 위하여 근래 사용이 확대되고 있는 고장력 TMCP에 대하여 합성해수중 -950mV vs. SCE의 과방식 인가전압 환경에서 부식피로균열 전파시험을 실시하고 da/dN-${\Delta}K$ 선도를 구하였다. 이 선도에서 저 ${\Delta}K$ 영역에서는 해수중 전파속도보다 빠른 균열전파속도를 나타내었으나, 고 ${\Delta}K$영역으로 갈수록 해수중 보다 늦은 균열전파속도를 나타내었다. 부식피로균열 전파속도에 영향을 미치는 인자로서 가속요인과 감속요인으로 나누고 각각 수소기체와 석회질생성물의 역할에 대하여 고찰하였다.

차체용 고장력 강판의 동적 인장 특성 평가 (Dynamic Tensile Characteristics of the High Strength Steel Sheet for an Auto-body)

  • 김석봉;허훈;신철수;김효균
    • 한국자동차공학회논문집
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    • 제15권1호
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    • pp.171-176
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    • 2007
  • An important challenging issue in the automotive industry is the light-weight, safe design and enhancement of crash response of an auto-body structures. These objectives lead to increasing adoption of high strength steel sheet for inner and outer auto-body members. This paper evaluates the dynamic tensile characteristics of high strength steel sheets, HS45R, TRIP60, DP60 and DP100, along the rolling direction and transverse direction. Static tensile tests were carried out at the strain rate of 0.003/sec using the static tensile machine (Instron 5583). Dynamic tensile tests were carried out at the range of strain rate from 0.1/sec to 200/sec using a high speed material testing machine developed. The tensile tests acquire stress-strain relation and strain rate sensitivity of each material. The experimental results show two important aspects for high strength steels: the flow stress increases as strain rate increases; the strain hardening decreases as the tensile stress increases. The experiments also produce interesting results that the elongation does not decrease even when the strain rate increases.

자동차용 냉연강판 SPCC와 냉연고장력강판 SPCF590의 유/무기 하이브리드 용액에 의한 내식특성 (Corrosion Resistance by Organic/Inorganic Hybrid Solution for Cold Rolled Steel of SPCC and SPFC590 for Automobile)

  • 이소영;이광호;정희록;남기우
    • 동력기계공학회지
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    • 제19권5호
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    • pp.38-44
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    • 2015
  • The cold-rolled steel sheet for automobile is liable to corrosion, and will be painting in a variety of ways for the anticorrosive. This paper was coated on cold rolled steel (SPCC and SPFC590) for automobiles using five kinds of organic/inorganic hybrid solution. This was evaluated corrosion resistance and so on by the salt spray. Corrosion area was less according to increasing of curing time in 2 types of steel plate with 5 types of the coating solution. No.1 solution was showed the best corrosion resistance regardless of the kinds of the steel sheet. It is judged that the melamin hardner had the role of bridge between $SiO_2$ polysilicate and urethan resin. Other properties were excellent in all solution.

고강도 강판 성형 공정의 스프링백 제어 (Springback Control in the Forming Processes for High-Strength Steel Sheets)

  • 양우열;이승열;금영탁;황진영;윤치상;신철수;조원석
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2003년도 제4회 박판성형 심포지엄
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    • pp.35-40
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    • 2003
  • In order to develope springback control technology for high-strength steel sheets, some studies have been conducted: dome stretching test, stepped s-rail forming and springback measurement, and optimally shaped initial blank design. First, to find out the formability of TRIP60, dome stretching test was performed. Next the stepped s-rail die, which was designed to form a channel type panel with large twist and wall curl, was manufactured and used to know the effect of controlling forming variables, such as blank holding force and flange amount on the springback. Furthermore, new measurement method of the springback was introduced to define wall curl and twist in geometrically complex panels. Finally, the optimally shaped initial blank was employed to verify one of the best ways to control the springback in channel type, high strength sheet panels.

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다단 이송 성형 공정 해석을 통한 자동차 센터 힌지 성형용 SPFH 590 고강도 강판 블랭크 설계 (Blank Design of SPFH 590 Steel Sheet for Stamping of Center Hinge of Automotive via Analysis of Transfer Forming Process with Multi-Stages)

  • 안동규;송동한;손상식;한길영
    • 한국정밀공학회지
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    • 제27권5호
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    • pp.75-84
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    • 2010
  • The aim of this paper is to design the blank shape of SPFH 590 high strength steel for stamping of the center hinge of automotive via numerical analyses and experiments for multi-stages transfer forming process. Three-dimensional elasto-plastic finite element analyses for the transfer forming process with six stages were performed using a commercial code AUTOFORM V4.2. The influence of the blank shape on the formability and the shape conformity were quantitatively examined through the FE analyses. From the results of the FE analysis, a feasible shape of the blank and the forming load were estimated. Stamping experiments were carried out using the proposed blank shape. The results of experiments were shown that the center hinge parts with the desired shapes can be manufactured successfully as the proposed blank shape is used. Through the comparison of the results of the experiments with those of the analyses, it was shown that the estimation of blank shape using the FE analysis is a proper methodology to create a feasible shape of the blank for the center hinge of automotive.

자동차 내부 보강판 성형 금형 설계 (Design of Stamping Die for Inner Reinforcement Panel of Automotive)

  • 안동규;송동한;노경보;한길영
    • 한국기계가공학회지
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    • 제8권2호
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    • pp.60-68
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    • 2009
  • The objective of this paper is to design stamping die of inner reinforcement panel with DL 950 advanced high strength steel as stamping materials through numerical analyses and experiments. The stamping process was designed as bending dominant process consisting of 1 step of notching and 4 steps of bending processes. In order to obtain a proper design of the stamping die, various three-dimensional elasto-plastic finite element analyses were performed using a commercial code AUTOFORM V4.2. Design parameter of stamping die was chosen as the corner radius of the stamping die for each step. From the results of the FE analysis, feasible corner radii of the stamping die, which can minimize the deviation of corner angle of the stamped part from design data, and forming load for each part were estimated. Stamping experiments were carried out using the manufactured stamping die according to the proposed die design. The results of experiments were shown that the stamping die can successfully manufacture the inner reinforcement panel with DL 950 advanced high strength steel as base stamping material.

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롤 포밍 공정의 롤 갭과 성형속도에 따른 스프링 백 영향 연구 (Study on Spring-Back Effect according to Roll Gap and Forming Velocity of Roll Forming Process)

  • 김동홍;윤대환;설상석;정동원
    • 한국정밀공학회지
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    • 제33권6호
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    • pp.477-483
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    • 2016
  • The spring-back and bow phenomenon in the roll forming process are important factors regarding the accuracy of evaluation of production goods. The purpose of this study was to determine the influence of spring-back and bow phenomenon according to the main variables (forming velocity and roll gap). The material of the forming sheet was high tension steel (SPFH 590), which has been used commonly in recent years. In order to accurately measure the spring-back and bow phenomenon, the forming sheet was formed into a V-shape. The study was applied to OFAT (One Factor at a Time) experimentation, with respect to the experimental variables (the forming speed and the roll gap). In the experimental results, the forming speed had a small influence on the spring-back and bow phenomenon. However, the roll gap had a greater influence on the springback and the bow phenomenon, as opposed to the forming speed.

고장력 강판 부분용입 맞대기 용접부의 피로균열진전수명 평가 (Fatigue Crack Propagation Life of Partially Penetrated Butt Welds in High Strength Steel)

  • 한승호;신병천;이웅;최전호
    • Journal of Welding and Joining
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    • 제21권1호
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    • pp.72-79
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    • 2003
  • Fatigue behaviour of partially penetrated butt-welded joints in high strength steel plates, in which crack-like structural defect, i.e. lack of penetration(LOP), is inevitably introduced during welding processes, was investigated. Fatigue lives of two types of welded joints, namely X-grooved and K-grooved joints, were experimentally determined first. Observed fatigue crack propagation behaviours of the partially penetrated butt-welds were interpreted through considering 3-dimensional semi-elliptical crack shape in front of the LOP. Based on such interpretation, a fracture mechanical method to estimate stress intensity factors at the crack tip was proposed. Since the fatigue lift of the partially penetrated butt-welds was strongly influenced by the ratio of size of the LOP to thickness, D/t, the D/t was used as a main parameter to calculate the fatigue lift by using the proposed method. Comparison of the fatigue lift obtained experimentally and analytically agreed well with each other. Hence it is suggested that the method used in this work to predict fatigue lift of the partially penetrated butt-welds can be applied to real cases with improved lift-prediction capability.

고장력 강판의 초음파 피로시험 (Ultrasonic Fatigue Test for a High Strength Steel Plate)

  • 염현호;정용찬;김차영;강기영;이문구;홍민성;전용호
    • 한국생산제조학회지
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    • 제24권6호
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    • pp.589-593
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    • 2015
  • The demand of high cycle fatigue behavior on plate material is increasing because of its various applications. However, the high-cycle fatigue life data of the plate material is very rare compared to the rod material. Thus, in this study, a plate specimen is designed for the ultrasonic fatigue test because it is time efficient as compared to the conventional fatigue test. To apply the ultrasonic fatigue test, the specimen design is required to resonate at 20 kHz. Therefore, the dynamic elastic modulus was determined by measuring the resonance frequency with a piezoelectric element and laser doppler vibrometer (LDV). As a result, the plate specimen is designed and demonstrated using the ultrasonic fatigue testing machine. The ultrasonic fatigue test results were compared with the hydraulic fatigue test results.

고장력 냉연강판에서 미세조직에 대한 연속어닐링조건의 영향 (Effects of Continuous Annealing Parameters on Microstructures in a Cold-Rolled High Strength Steel)

  • 정우창
    • 열처리공학회지
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    • 제17권5호
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    • pp.283-292
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    • 2004
  • The effects of the annealing parameters on microstructures were examined in a cold-rolled high strength steel containing 0.1% C, 0.5% Si, 1.5% Mn, and 0.04% Nb. It was impossible to avoid martensite in the microstructure even though the continuous annealing parameters were controlled. This indicates that the alloying elements such as silicon and manganese contributing to manganese equivalent($Mn_{eq}$) should be reduced to produce the ferrite-pearlite microstructure for the solid solution and precipitation hardened steel. It was found that a decrease in the rapid cooling temperature to $520^{\circ}C$ was effective to change the microstructure from ferrite-martensite to ferrite-pearlite-martensite. Typical dual-phase properties exhibiting a low yield ratio and a continuous yielding behavior were obtained when the rapid cooling temperature was in the range of $680^{\circ}C$ to $600^{\circ}C$. The critical volume fraction of martensite for the typical properties of dual-phase steel was about 11 percent.