Integrated Computational Materials Engineering of Fire-Resistant Steels

• We investigate over 5,000 compositional space of low-carbon fire-resistant steels using the high-throughput CALPHAD modeling. • The Cr and Mo are the most influential elements that enhance solid-solution and precipitate strengthening. • The new alloys represent yield strength of 520–770 MPa at 600 °C, more than twice of the strength of the commercial steel. • The improvement of the tensile strength is due to the formation of nano-sized vanadium carbide at high temperature of 600 °C. We explore a wide compositional space of low-carbon steel, containing 11 alloying elements, assess its feasibility for fire-resistant applications via modeling yield strength at elevated temperatures. We employ the high-throughput CALPHAD-based modeling to calculate the contributions of solid solution, precipitation, and dislocation strengthening for specific compositions. Over 30,000 yield strength predictions are made at two elevated temperatures (600 °C and 700 °C) across about 5,000 unique compositions, each with three different heat treatment conditions. We analyze the big data base and optimize using the machine-learning techniques to understand the significance of different parameters on strength. Experimental validation include thermomechanical treatments, high-temperature tensile tests, and microstructural characterizations. The newly developed alloys demonstrate a yield strength of 520–770 MPa at 600 °C, more than twice the strength of the commercial S355 steel. This approach facilitates the rapid discovery of novel fire-resistant steel compositions and has a high potential for other alloy systems.