Cu-8.6wt%Al 삽입금속을 사용한 페라이트계 스테인리스강의 아크 브레이징 접합부의 미세조직과 인장성질 |
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Microstructures and Tensile Properties in Arc Brazed Joints of Ferritic Stainless Steel using Cu-8.6%Al Insert Metal |
Young-Ho Cho, Chang-Eun Chung, Myoung-Chang Kang, Chung-Yun Kang |
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Abstract |
Microstructures and tensile properties in arc brazed joints of ferritic stainless steel, 429EM using Cu-8.6%Al insert metal was investigated as function of brazing current. The brazing speed was fixed at 800㎜/min and brazing current varied in the range of 80A to 120A. The initial phase of filler metal was Cu single phase. However, the insert metal structures of brazed joints was composed of Cu matrix and intermetallic compound such as γ1(Al₄Cu?), and flower-shape Fe-Cr. The fraction of γ1(Al₄Cu?) phase was similar with 80A and 100A brazing currents while that of brazed with 120A was decreased. On the other hand, the fraction of Fe-Cr phase increased with increasing of the brazing current. A reaction layer at the base metal/insert metal interface was observed and this reaction layer was thickened with increasing of the brazing current. In the brazed joints with the current lower than 100A, crack was grew up along the interface which was perpendicular to the tensile stress, and then, passed through the insert metal in the final stage of fracture. As the brazing current increased to 120A, fracture occurred at the base metal. |
Key Words:
Ferritic stainless steel, Arc brazing, Microstructures, Tensile properties, Second phase |
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