Metal substrate catalyst converter for emission control has several advantages over ceramic substrate one. High chromium, high aluminum FeCrAl alloy foils have been used for catalytic converter substrate for years. For heavy-duty diesel engines, the maximum temperature requirements for catalytic converter is considered to be up to 800 C, lower than 1100 C used for automobile gasoline engines. This has opened an opportunity for lean alloy chemistry in a FeCrAl alloy for ease of manufacturing. This paper describes a new FeCrAl foil substrate alloy by Engineered Materials Solutions for heavy truck diesel catalytic converter applications. The new alloys contains nominal 15.5% wt% Cr and 5.5wt% Al without addition of Y, Hf or rare earth elements. The new alloys were made by roll bonding and diffusion alloying. Al of the outer layers in sandwiched Al/Stainless Steel/Al composite foil was diffused into the stainless steel to form Fe-15Cr-5.5Al alloy in either foil processes or catalytic converter fabrication. The brazing thermal process of catalytic converter is well fitted for in-situ diffusion alloying. Good brazed joints as well as complete diffusion alloying for homogenized microstructure across the foil thickness were achieved. Converter body push-out test showed high strength of the brazed joints. Pre-oxidation for washcoating adhesion was examined. Washcoating test demonstrated that high Al% allowed high washcoating adhesion. Semi-cyclic oxidation testing showed they had excellent oxidation resistance at 800 and 900 C, without any evidence of breakaway up to 1000 hours. Mechanical testing at high temperature showed the material has good tensile strength and proper creep resistance at the service temperature.