The influence of primary cooling and rebound temperature at C–Mn slab corner surfaces during continuous casting on ferrite film transformation and AlN precipitation was investigated. Laboratory simulations included primary cooling to minimum temperature, T_min, rebounding to various maximum temperatures, T_max, followed by secondary cooling. The negative effect of a low T_min on hot ductility could not be readily reversed, even at relatively high temperatures. Quantitative metallography was employed to study the evolution of the microstructure during rebounding and secondary cooling. Following primary cooling to temperatures just above the Ar₃, thin films of allotriomorphic ferrite formed on the austenite grain boundaries. These films did not completely transform to austenite during the rebound at 3 °C/s up to temperatures as high as 1130 °C and persisted during slow secondary cooling up to the simulated straightening operation. Whilst dilatometry did not indicate the presence of ferrite after high rebound temperatures, metallography provided clear evidence of its existence, albeit in very small quantities. Coincident with the ferrite at these high temperatures was the predicted (TC-PRISMA) grain boundary precipitation of AlN in bcc iron during the rebound from a T_min of 730 °C. Importantly no thin ferrite films were observed, and AlN precipitation was not predicted to occur when T_min was restricted to 830 °C. Cooling below this temperature promotes austenite grain boundary ferrite films and AlN precipitation, which both increase the risk of corner cracking in C–Mn steels.

AISI 301LN metastable austenitic stainless steels (MASSs) are known to exhibit high work‐hardening rates attributed to martensite evolution during straining which results in the second‐phase strengthening mechanism. This enhances surface hardness and potentially reduces wear and rolling contact fatigue (RCF). The aim of this study is therefore to evaluate the work hardening, wear, and RCF performance of AISI 301LN metastable austenitic stainless steel as a possible alternative material for rolling and sliding applications by varying the contact conditions such as slip ratio against the standard R350HT rail steel using a twin‐disc simulator. The results show that 301LN MASS has high surface work hardening and increased hardness because of martensitic transformation, while R350HT rail steel has only slightly changed. The formation of a hard martensitic phase is also confirmed by X‐ray diffraction analysis as well as by two other techniques, indicating a secondary hardening effect. Although it shows potential for work hardening, its susceptibility to wear‐related problems may make it less suitable for rolling and sliding applications due to a cracking and spalling mechanism induced by martensite formation. The surface strains required for the observed martensite formation are calculated and found to be very high, approaching 0.4.