Effects of carbon, nickel, and molybdenum on the high temperature strength of Fe-Cr-Ni alloys

In order to design a new kind of high-temperature Fe-Cr-Ni alloy with good weldability which could be used as structural material of Iron-ore sintering furnaces and Magnesium-smelting tanks, effects of additions of carbon, nickel, and molybdenum to Fe-Cr-Ni alloy on strength at 1250°C have been studied. The rupture strength at high-temperature of the alloy is mainly determined by grain-boundaries. Addition of carbon to the alloy can affect the morphology of the precipitates at grain-boundaries apparently. With increasing carbon content, the rupture strength increases significantly at first, and then begins to decrease acutely when carbon content exceeds about 0.43%. The addition of nickel increases the alloy strength until its content reach about 10%, further addition of nickel will slightly decrease the alloy strength. The effect of molybdenum on the strength is similar to that of nickel, the maximum value of the strength is obtained by the addition of 0.30% molybdenum. However, neither nickel nor molybdenum could obviously affect the microstructure of the alloy.