| 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. |
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