22 Jan 2026

Carbon Partitioning Effects on Martensitic Phase Transformation of Type 301 Steel Under Various Thermal Processing Conditions

Abstract: Simultaneous improvement of strength and ductility in steels has been a daunting challenge for materials scientists, as these properties are by nature mutually exclusive. One design approach that has the merit to use traditional steel processing technologies is the thermo-mechanical stabilization of the austenitic phase. Owing to its highly symmetric FCC crystal structure, if austenite can be maintained during processing, and then further preserved under mechanical deformation, the final microstructure can solve the Pareto design problem where the high strength does not compromise the ability of the material to resist strain localization/incompatibility. The thermomechanical stability of austenite is achieved through compositional modification of the phase, thereby making the control of the elemental partitioning mechanism between existing phases during manufacturing as the main design metric. In this work, we have developed a phase field framework to model the partitioning mechanism of one of the cheapest austenite stabilizers, carbon, in a 301 stainless steel grade. The model uses a coupled framework between thermomechanical and latent heat effects to capture carbon partitioning during martensite nucleation, propagation, and growth kinetics as well as austenite stability and distribution during and after various heat treatment routines. Various microstructures were simulated for the quench state only as well as quench-and-temper heat treatment routines. The resulting microstructure and carbon distribution shed light on various evolutionary effects such as carbon segregation, grain boundary effects, stable martensite morphology, austenite distribution, and phase fraction. In particular, the model was able to reproduce the evolution of carbon-depleted martensite zones and carbon-enriched austenite regions as well as carbon distribution similar to experimental observation at austenite–martensite interfaces.

20 Aug 2021

Crevice Corrosion and Environmentally Assisted Cracking of High-Strength Duplex Stainless Steels in Simulated Concrete Pore Solutions

Abstract: This paper presents a study of crevice corrosion and environmentally assisted cracking (EAC) mechanisms in UNS S32205 and S32304 which were cold drawn to tensile strengths of approximately 1300 MPa. The study utilized a combination of electrochemical methods and slow strain rate testing to evaluate EAC susceptibility. UNS S32205 was not susceptible to crevice corrosion in stranded geometries at Cl- concentrations up to 1.0 M in alkaline and carbonated simulated concrete pore solutions. UNS S32304 did exhibit a reduction in corrosion resistance when tested in a stranded geometry. UNS S32205 and S32304 were not susceptible to stress corrosion cracking at Cl- concentrations up to 0.5 M in alkaline and carbonated solutions but were susceptible to hydrogen embrittlement with cathodic overprotection.