Al-10%Si 용융도금 보론강 레이저 용접부의 편석과 미세조직 (Segregation and Microstructure in the Fusion zones of Laser joints of Al-10%Si coated Boron Steel)

서지정보

· 발행기관 : 대한금속·재료학회
· 수록지 정보 : 대한금속·재료학회지 / 54권 / 1호 / 40 ~ 48페이지
· 저자명 : 권민석, 강정윤

초록

During laser welding of Al-10 wt%Si coated boron steel, which is used in the automotive industry, Al and Si, which are elements of the coated layer, are diluted in the fusion zone; then, the concentration of Al and Si is distributed randomly. The segregation can be roughly classified into two types. The first forms along the fusion boundary in a long comet shape in the depth direction of the fusion zone. The Al concentration of this comet shape is Fe3(Al, Si)and the material is composed of a single phase. This segregation phase is formed at the same time as the melting of the base metal and the diluting of the coated layer of Fe(Al, Si), without reaction of the molten metal. Then, a static dissolution reaction of the diluted coated layer occurs, scarcely stirring the molten metal; the concentration of Al and Si is reduced to 1/2. The second type of segregation is formed by martensite and bainte in the fusion zone of the segregated zone; the composition of Al is 1.28~0.48 wt%. Considering the results of the analysis of the Fe(Si,C, Mn,Cr)-xwt%Al quasi binary phase diagram, performed using Thermo-Calc, segregated zones are solidified in the form “L→ L+α→γ”. Also, and as a result, it was found that the phase transformation from γ under-cooling results in the solid phase, which undergoes bainite transformation and is transformed to martensite.

영어초록

During laser welding of Al-10 wt%Si coated boron steel, which is used in the automotive industry, Al and Si, which are elements of the coated layer, are diluted in the fusion zone; then, the concentration of Al and Si is distributed randomly. The segregation can be roughly classified into two types. The first forms along the fusion boundary in a long comet shape in the depth direction of the fusion zone. The Al concentration of this comet shape is Fe3(Al, Si)and the material is composed of a single phase. This segregation phase is formed at the same time as the melting of the base metal and the diluting of the coated layer of Fe(Al, Si), without reaction of the molten metal. Then, a static dissolution reaction of the diluted coated layer occurs, scarcely stirring the molten metal; the concentration of Al and Si is reduced to 1/2. The second type of segregation is formed by martensite and bainte in the fusion zone of the segregated zone; the composition of Al is 1.28~0.48 wt%. Considering the results of the analysis of the Fe(Si,C, Mn,Cr)-xwt%Al quasi binary phase diagram, performed using Thermo-Calc, segregated zones are solidified in the form “L→ L+α→γ”. Also, and as a result, it was found that the phase transformation from γ under-cooling results in the solid phase, which undergoes bainite transformation and is transformed to martensite.

참고자료

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