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Fe-30at.%A1 합금의 압연성에 미치는 Cr, B, Ti 및 Si 첨가효과
최답천 ( Dap Chun Choi ),이지성 ( Ji Sung Lee ) 한국주조공학회 2003 한국주조공학회지 Vol.23 No.2
N/A Some alloying elements such as Cr, B, Ti and Si were added individually or as a mixture to Fe-30 at.%Al alloys. The alloys were melted using an arc furnace and then heat-treated for homogenization at 1000℃ for 7 days and followed by rolling at 1000℃. The alloying elements on rolling characteristics were investigated by the microstructures and fracture mode before and after rolling. The microstructures before rolling showed that all of the alloys had equiaxed grains. On the other hand, the microstructures of rolling plane as well as its perpendicular plane became elongated after rolling. The alloys such as Fe-30Al, Fe-30Al-3Ti, Fe-30Al-0.5B, Fe-30Al-5Cr and Fe-30Al-3Ti-0.5B revealed better rolling behaviour from the point that intergranular and cleavage fractures were not fundamentally occurred. But the addition of 5Ti or 3Si to Fe-Al alloys had detrimental effects. The Ti-added alloy system such as Fe-30Al-5Ti, Fe-30Al-5Ti-5Cr, Fe-30Al-3Ti-5Cr and Fe-30Al-5Ti-0.5B were cracked through grain and showed cleavage fracture. The Si-added alloy system such as Fe-30Al-5Si, Fe-27Al-3Si and Fe-27Al-5Cr-3Si were cracked along the grain boundary and showed intergranular fracture. DO_3 ↔ B_2 transition temperature of Fe-30at.%Al alloy was 520℃, whereas the addition of 3Ti and 3Ti+0.5B comparably increased the temperature to 797 and 773℃, respectively.
Fe-Cr-Al 3 원계 합금의 미세조직, 기계적 성질 및 파괴거동에 미치는 첨가원소의 영향
최답천,이도재,이광민,주성민,최한철 대한금속재료학회(대한금속학회) 2000 대한금속·재료학회지 Vol.38 No.2
Fe-Cr-Al alloy has been used in automobiles to meet the social needs for clean exhaust gases and reduced weight for better fuel economy. Various other types of high performance Fe-Cr-Al alloy are now being used in the automobile exhaust system. This paper described the changes in the microstructures, mechanical properties and fracture behaviors for automobile exhaust system parts application. As the amount of 0.05 wt.%B or 0.5 wt.%Zr addition was added, the grain size became smaller. The results of XRD were observed α-ferrite(α-Fe) for Fe-(5∼20)wt.%Cr-(5, 6, 8)wt.%Al alloys. However, Fe-(5∼20)wt.%Cr-10 wt.% Al alloys were observed α-ferrite(α-Fe) and α₁(Fe₃Al). Rockwell hardness was increased by increasing Cr and Al amount. Yield strength was decreased by adding 0.5wt.%Zr. Regardless of Cr amount, fracture behaviors in 5 wt.%Al added alloys revealed quasi-cleavage and ductile fracture mode, and 10 wt.%Al added alloys revealed brittle fracture mode with cleavage and river pattern. However the fracture mode in 0.05 wt.%B and 0.5 wt.%Zr added alloy revealed quasi-cleavage and dimple fracture mode due to strengthening of grain boundaries, respectively.