Corrosion Science and Technology

  • 제23권4호
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  • Pages.283-288
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  • 2024
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  • 1598-6462(pISSN)
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  • 2288-6524(eISSN)
한국부식방식학회 (The Corrosion Science Society of Korea)
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Effect of Heat Treatment on Corrosion Resistance of Zn-Mg-Al Alloy Coated Steel

  • Il Ryoung Sohn (Automotive Steel Surface Research Group, POSCO Technical Research Lab.) ;
  • Tae Chul Kim (Automotive Steel Surface Research Group, POSCO Technical Research Lab.) ;
  • Sung Ju Kim (Automotive Steel Surface Research Group, POSCO Technical Research Lab.) ;
  • Myung Soo Kim (Automotive Steel Surface Research Group, POSCO Technical Research Lab.) ;
  • Jong Sang Kim (Graduate Institute of Ferrous & Energy Materials Technology) ;
  • Woo Jin Lim (H&A Material Application Technology Team, LG electronics) ;
  • Seong Mo Bae (H&A Material Application Technology Team, LG electronics) ;
  • Su Hee Shin (H&A Material Application Technology Team, LG electronics) ;
  • Doo Jin Paik (Automotive Steel Surface Research Group, POSCO Technical Research Lab.)
  • 투고 : 2024.05.31
  • 심사 : 2024.08.14
  • 발행 : 2024.08.30
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초록

Hot-dip Zn-Mg-Al coatings have a complex microstructure consisting of Zn, Al, and MgZn2 phases. Its crystal structure depends on alloy content and cooling rates. Microstructure and corrosion resistance of these coatings might be affected by heat treatment. To investigate effect of heat treatment on microstructure and corrosion resistance of Zn-Mg-Al coatings, Zn-1.5%Mg-1.5%Al coated steel was heated up to 550 ℃ at a heating rate of 80 ℃/s and cooled down to room temperature. At above 500 ℃, the ternary phase of Zn-MgZn2-Al was melted down. Only Zn and MgZn2 phases remained in the coating. Heat- and non-heat-treated specimens showed similar corrosion resistance in Salt Spray Test (SST). When a Zn-3.0%Mg-2.5%Al coated steel was subjected to heat treatment at 100 ℃ or 300 ℃ for 200 h and compared with GA and GI coated steels, the microstructure of coatings was not significantly changed at 100 ℃. However, at 300 ℃, most Al in the coating reacted with Fe in the substrate, forming a Fe-Al compound layer in the lower part of the coating. MgZn2 was preferentially formed in the upper part of the coating. As a result of SST, Zn-Mg-Al coated steels showed excellent corrosion resistance, better than GA and GI.

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참고문헌

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