25Cr-7Ni-2Mo-4W 슈퍼 2상 스테인리스강의 충격인성에 미치는 χ상의 영향
Effect of χ Phase on Impact Toughness of 25Cr-7Ni-2Mo-4W Super Duplex Stainless Steel
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This study was carried out to investigate the precipitation behavior of the χ phase and the impact toughness of 25%Cr-7%Ni-2%Mo-4%W super duplex stainless steel. The χ phase was precipitated in the early stage of aging, and with the increasing aging time. However, after reaching a maximum value, the number decreased as a result of the gradual transformation of the χ phase into the σ‐phase. It was proved that the χ phase was an intermetallic compound, which represented a lower nickel concentration, higher chromium and molybdenum concentrations, and very higher tungsten concentration compared to the matrix phases. It also showed higher molybdenum and tungsten concentrations than the σphase. The decomposition of the ferrite phase into the γ2 and σ phases was retarded by W substitution for Mo. Thus, the number of χ phases increased. The impact value was decreased by the substitution of W for Mo. The impact toughness rapidly decreased with time when the χ phase began to precipitate in the initial stage of aging. The impact toughness was, therefore, greatly influenced for the precipitation of the χ phase.
Abstract
This study was carried out to investigate the precipitation behavior of the χ phase and the impact toughness of 25%Cr-7%Ni-2%Mo-4%W super duplex stainless steel. The χ phase was precipitated in the early stage of aging, and with the increasing aging time. However, after reaching a maximum value, the number decreased as a result of the gradual transformation of the χ phase into the σ‐phase. It was proved that the χ phase was an intermetallic compound, which represented a lower nickel concentration, higher chromium and molybdenum concentrations, and very higher tungsten concentration compared to the matrix phases. It also showed higher molybdenum and tungsten concentrations than the σphase. The decomposition of the ferrite phase into the γ2 and σ phases was retarded by W substitution for Mo. Thus, the number of χ phases increased. The impact value was decreased by the substitution of W for Mo. The impact toughness rapidly decreased with time when the χ phase began to precipitate in the initial stage of aging. The impact toughness was, therefore, greatly influenced for the precipitation of the χ phase.
참고문헌 (8)
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