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Effect of Local Softening for Spring-back Reduction of Ultra High Strength Steel on Microstructure and Mechanical Properties (스프링백 저감을 위한 초고강도강의 국부적 연화 열처리에 따른 미세조직과 기계적 특성 변화에 관한 연구)

  • Park, S.E.;Park, B.H.;Oh, M.H.;Kang, B.S.;Ku, T.W.
    • Transactions of Materials Processing
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    • v.30 no.3
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    • pp.134-141
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    • 2021

  • In order to improve excessive spring-back behavior as a result of the roll forming process using ultra high strength steel (UHSS) sheet, local softening in region of a partial area expected to be deformed on an initial blank is considered in this study. With SPFC1470 UHSS sheet with initial blank thickness of 1.20mm, the local softening is performed with the following conditions: temperatures of 500℃, 550℃, 600℃ and 650℃, and holding time of 20s, 40s, 80s and 160s. Mechanical properties, such as yield stress and tensile strength, as well as elongation, are evaluated through uniaxial tensile tests, while the microstructural characteristics as a result of local softening are also investigated using the heat-treated specimens. As a result, it is shown that the spring-back behavior of the roll-formed prototype was reduced about by 78.9%, when the local softening at about 500℃ was performed for 160s considering the practical manufacturing condition.

  • https://doi.org/10.5228/KSTP.2021.30.3.134 인용 PDF KSCI HTML