• 제목/요약/키워드: paint baking

검색결과 7건 처리시간 0.019초

고강도 강판 저항 점용접부 강도 및 파단에 미치는 Paint Baking의 영향 (The Effect of Paint Baking on the Strength and Failure of Spot Welds for Advanced High Strength Steels)

  • 최철영;이동윤;김인배;김양도;박영도
    • 대한금속재료학회지
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    • 제49권12호
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    • pp.967-976
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    • 2011
  • Conventional fracture tests of resistance spot welds have been performed without consideration of the paint baking process in the automobile manufacturing line. The aim of this paper is to investigate the effect of the paint baking process on load carrying capacity and fracture mode for resistance spot welded 590 dual phase (DP), 780DP, 980DP, 590 transformation in duced plasticity (TRIP), 780TRIP and 1180 complex phase (CP) steels. With paint baking after resistance spot welding, the l-shape tensile test (LTT) and nano-indentation test were conducted on the as-welded and paint baked samples. Paint baking increased the load-carrying capacity of the resistance spot welded samples and improved the fracture appearance from partial interfacial fracture (PIF) to button fracture (BF). Improvement in fracture appearance after LTT is observed on weldments of 780 MPa grade TRIP steels, especially in the low welding current range with paint baking conditions. The higher carbon contents (or carbon equivalent) are attributed to the low weldability of the resistance spot welding of high strength steels. Improvement of the fracture mode and load carrying ability has been achieved with ferrite hardening and carbide formation during the paint baking process. The average nano-indentation hardness profile for each weld zone shows hardening of the base metal and softening of the heat affected zone (HAZ) and the weld metal, which proves that microstructural changes occur during low temperature heat treatment.

780 MPa급 TRIP강의 저항 점용접부 강도 및 파단에 미치는 Paint Baking의 영향 (Effect of Paint Baking on the Strength and Failure of Spot Welds for 780 TRIP Steels)

  • 손종우;남대근;김동철;박영도
    • Journal of Welding and Joining
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    • 제28권2호
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    • pp.66-73
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    • 2010
  • Conventional fracture test of resistance spot weld had been performed without consideration of paint baking process in automobile manufacturing line. This study was aim to investigate the effect of paint baking on fracture mode and load carrying capacity in fracture test for resistance spot welded 780TRIP steels. With paint baking cycle after resistance spot welds, peel tests and microhardness were conducted on the as-welded and baked samples. Resistance spot welds in AHSS (Advanced High Strength Steels) are prone to display partial interfacial fractures during fracture test or vehicle crash. Baking cycle increased the load-carrying capacity of the resistance spot welded samples and improved the fracture appearance from partial to full button fracture for the L-type peel tests. Specially, the differences in fracture appearance are apparent when the nugget size of spot welds is small enough to produce the partial interfacial fracture. The comparison of macrohardness and microstructure between as-welded and baked samples showed that there are no large difference in change the fracture mode. However, the results of the instrumented indentation test suggested that fusion zone and HAZ of baked sample have less tensile and yield strength and proves that the tempering effects are applied and enhanced the resistance to fracture on welds with application of baking cycle.

하이브리드 센터필러 제조 시 열처리 이력이 7075 알루미늄 합금 판재의 인장강도에 미치는 영향 (Effect of Heat Treatment History in Fabrication of Hybrid Center Pillar on Tensile Strength of 7075 Aluminum Alloy Sheet)

  • 유동훈;김지훈;박상언;장홍규;김대용
    • 소성∙가공
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    • 제30권2호
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    • pp.61-68
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    • 2021
  • As part of efforts to reduce the weight of automotive body-in-white, a hybrid center pillar with high strength 7075 aluminum alloy (AA7075) sheet and carbon fiber reinforced plastic (CFRP) has been recently studied. In the fabrication of the AA7075-CFRP hybrid center pillar, the AA7075 sheet might go through heating-forming-in-die quenching (HFQ), artificial aging, hybridizing, and then paint baking processes. In this study, we investigate the effects of the heat treatment history associated with each process on the tensile strength of the AA7075 sheet. Typical heat treatment conditions are HFQ for 20 minutes at 480℃ and then cooling down with die, artificial aging of T6 temper for 24 hours at 120℃, hybridizing for 10 minutes at 150℃, and paint baking for 20 minutes at 180℃. The tensile strength of the AA7075 sheet is continuously increased by a series of heat treatments of hybridizing and paint baking and is expected to have yield stress above 500MPa without artificial aging of T6 temper.

Structural Adjustment of In-Situ Surface-Modified Silica Matting Agent and Its Effect on Coating Performance

  • Xu, Qingna;Ji, Tongchao;Tian, Qingfeng;Su, Yuhang;Niu, Liyong;Li, Xiaohong;Zhang, Zhijun
    • Nano
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    • 제13권12호
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    • pp.1850137.1-1850137.9
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    • 2018
  • A series of silica surface-capped with hexamethyldisilazane (denoted as $H-SiO_2$) were prepared by liquid-phase in-situ surface-modification method. The as-obtained $H-SiO_2$ was incorporated into acrylic amino (AA) baking paint to obtain AA/$H-SiO_2$ composite extinction paints and/or coatings. $N_2$ adsorption-desorption tests were conducted to determine the specific surface area as well as pore size and pore volume of $H-SiO_2$. Moreover, the effects of $H-SiO_2$ matting agents on the physical properties of AA paint as well as the gloss and transmittance of AA-based composite extinction coatings were investigated. Results show that $H-SiO_2$ matting agents possess a large specific surface area and pore volume than previously reported silica obtained by liquid-phase method. Besides, they have better dispersibility in AA baking paint than the unmodified silica. Particularly, $H-SiO_2$ with a silica particle size of $6.7{\mu}m$ and the dosage of 4% (mass fraction) provides an extinction rate of 95.2% and a transmittance of 79.3% for the AA-based composite extinction coating, showing advantages over OK520, a conventional silica matting agent. Along with the increase in the silica particle size, $H-SiO_2$ matting agents cause a certain degree of increase in the viscosity of AA paint as well as a noticeable decrease in the gloss of the AA-based composite extinction coating, but they have insignificant effects on the hardness and adhesion to substrate of the AA-based composite coatings. This means that $H-SiO_2$ matting agents could be well applicable to preparing low-viscosity and low-gloss AA-based matte coatings.

Al-Mg-Si계 알루미늄 합금 판재 마찰교반접합부의 결정 방위 분포에 대한 용접후열처리의 영향 (Effect of Post Weld Heat Treatment for Crystal Orientation Distribution on Friction Stir Welds of Al-Mg-Si Series Aluminum Alloy Sheets)

  • 이광진
    • Journal of Welding and Joining
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    • 제27권6호
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    • pp.62-67
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    • 2009
  • Friction stir welding (FSW) was carried out for Al-Mg-Si series aluminum alloys which are being used for automotive body structure. Consequently, Post weld heat treatment (PWHT) was applied to the friction stir welds to evaluate the effect of the paint baking process which is one of the automotive fabrication process on friction stir welded zone (FSWZ) in 443K for 1.2Ks. Grain structure and its crystal orientation distribution was measured about both the as welded specimens and the post weld heat treated specimens. An optical microscope (OM) and an field emission scanning electron microscope (FE-SEM) was used for observing the grain structure and measuring its crystal orientation distribution, respectively. Changes on the grain structure and its crystal orientation distribution were not detected. From the present results, it was confirmed that the paint baking process after FSW do not affect on the grain structure and its crystal orientation distribution of FSWZ. The comprehensive investigations will be performed for various automotive aluminum alloys manufactured by different processes, in the future.

P.V.D.F 페인트 도장강판의 연속공정하의 열처리 조건에 따른 물성 변화 연구 (Study on Physical Properties of Polyvinylidene fluoride Paint Coated Steel by Thermal Treatment Condition under Continuous Mass Production)

  • 정민영;김용희;이보룡;문만빈
    • 한국표면공학회:학술대회논문집
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    • 한국표면공학회 2015년도 춘계학술대회 논문집
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    • pp.187-187
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    • 2015
  • Polyvinylidene fluoride (PVDF) 코팅은 뛰어난 내후성으로 인해 Pre-painted metal에 많이 응용되며 주로 고가의 건축물 외장재에 적용되고 있는데, 수지의 열가소성 특성으로 인해 도막경화시 Baking 온도 및 냉각속도가 도막의 결정화도에 영향을 주어 가공특성이 상이하게 변함을 확인 하였다.

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0.27% C-1.5% Mn-1.0% Cr 강의 미세조직과 기계적성질에 미치는 Si의 영향 (Effect of Si on Mechanical Properties and Microstructure in 0.27% C-1.5% Mn-1.0% Cr Steel)

  • 정우창
    • 열처리공학회지
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    • 제30권3호
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    • pp.117-126
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    • 2017
  • The variation in microstructure and mechanical properties during heat treatment was examined in a series of 0.27% C-1.5% Mn-1.0% Cr steels with silicon contents in the range of 0 to 1.0 wt%. It was found that addition of 0.5%~1.0% silicon increased both tensile strength and impact toughness through solid solution strengthening and microstructural refinement. 0.27% C-1.0% Si-1.5% Mn-1.0% Cr steel showed tensile strength of 1,700 MPa in the as-quenched condition and the steel revealed a full martensitic structure even after air cooling from $900^{\circ}C$ to room temperature, showing air hardening characteristics. Tempering at $150^{\circ}C$ which corresponds to the typical paint-baking temperature after painting of body in white, slightly decreased the tensile strength and increased elongation, but substantially increased the impact toughness compared to the as-quenched steel.