Fe–Cr–Al Alloy Development Via Wire-Feed Additive Manufacturing Technology

A new wire-arc additive manufacturing (WAAM) based on Cold Metal Transfer (CMT) welding process is used to fabricate iron-chromium-aluminum (Fe–Cr–Al) alloy by simultaneously feeding two separate wires. A wall of Fe–Cr–Al containing approximately 4.2% Al and 6.5% Cr was deposited over a steel substrate. Chemical composition test performed on the deposited alloy indicated a uniform material distribution of element throughout the deposited wall. It was also found that an increase in Al content or decrease in Cr content improved the hardness of the Fe–Cr–Al alloy. A macro and microstructural characterization revealed that the top region of the wall contained equiaxed grains, whereas columnar grain in the middle region and some acicular precipitates of Fe₃AlC_0.5 phase at the bottom were observed. The phases at different locations within the built wall were very different, especially, in the top section and bottom section. In the top and middle sections Fe₃C carbide were found. The Cr₃C₂ carbides were found in the top section. No (Cr,Fe)_xC_y carbides were found at the bottom of the buildup wall. A comparison of bottom and top sections indicated that the (Fe,Cr)_xC_y carbides have the ability to prevent cracks from occurring.