This paper deals with carbon steel and stainless steel clad-plate properties. Cladding is performed by the submerged-arc welding (SAW) overlay process. Due to element diffusion (Fe, Cr, Ni, and Mn), a 1.5 mm wide diffusion layer is formed between the stainless steel and carbon steel interface of the cladded plate affecting corrosion resistance. Pitting resistance is evaluated by measuring the critical-pitting temperature (CPT), as described in the American Society for Testing and Materials (ASTM) G-48 standard test. Additionally, Huey immersion tests, in accordance with ASTM A262, Type C, are carried out to evaluate the intergranular corrosion resistance. Some hardness peaks are detected in microalloyed steel close to the molten interface line in the coarse-grained heat-affected zone (CGHAZ). Results show that stress-relieving treatments are not sufficient to avoid hardness peaks. The hardness peaks in the CGHAZ of the microalloyed steel disappear after quenching and tempering (Q and T).

An oxide dispersion strengthened (ODS) ferritic steel with nanometric grain size has been produced by low-energy mechanical alloying (MA) of steel powder (Fe-14Cr-1W-0.4Ti) mixed with Y₂O₃ particles (0.3 wt %) and successive hot extrusion (HE). The material exhibits superior mechanical properties with respect to the unreinforced steel up to 400 °C; then such differences tend to progressively decrease and at 700 °C yield stress (YS) and ultimate tensile strength (UTS) values are very close. The microstructure and mechanical behaviour have been compared with those of ODS steels prepared by the most common process, high-energy MA, consolidation through hot isostatic pressing (HIP) or hot extrusion (HE), annealing around 1100 °C for 1–2 h. The main strengthening mechanisms have been examined and discussed to explain the different behaviour. In addition, heat treatments in the range 1050–1150 °C were carried out and a microstructural evolution with a relevant hardness decrease has been observed. TEM observations evidenced defect recovery and partial grain coarsening owing to the not perfectly homogeneous distribution of oxide particles.

Well-defined heat-treatment guidelines are required to achieve the target mechanical properties in high-chromium steels for forgings. Moreover, for this class of materials, the microstructure evolution during heat treatment is not clearly understood. Thus, it is particularly important to assess the steel microstructure evolution during heat treatment, in order to promote the best microstructure. This will ascertain the safe use for long-term service. In this paper, different heat treatments are considered, and their effect on a 7% Cr steel for forging is reported. Results show that, following the high intrinsic steel hardenability, significative differences were not found versus the cooling-step treatment, although prior austenite grain size was significantly different. Moreover, retained austenite (RA) content is lower in double-tempered specimens after heat treatments at higher temperatures.