The effect of chromium content in the range of 1 wt.%–4 wt.% on the microstructure and mechanical properties of controlled-rolled and direct-quenched 12 mm thick low-carbon (0.04 wt.%) steel plates containing 0.06 wt.% Nb has been studied. In these microalloyed 700 MPa grade steels, the aim was to achieve a robust bainitic microstructure with a yield strength of 700 MPa combined with good tensile ductility and impact toughness. Continuous cooling transformation diagrams of deformed and non-deformed austenite were recorded to study the effect of Cr and hot deformation on the transformation behavior of the investigated steels. Depending on the cooling rate, the microstructures consist of one or more of the following microstructural constituents: bainitic ferrite, granular bainite, polygonal ferrite, and pearlite. The fraction of bainitic ferrite decreases with decreasing cooling rate, giving an increasing fraction of granular bainite and polygonal ferrite and a reduction in the hardness of the transformation products. Polygonal ferrite formation depends mainly on the Cr content and the cooling rate. In both deformed and non-deformed austenite, increasing the Cr content enhances the hardenability and refines the final microstructure, shifting the ferrite start curve to lower cooling rates. Preceding austenite deformation promotes the formation of polygonal ferrite at lower cooling rates, which leads to a decrease in hardness. In hot-rolled and direct-quenched plates, decreasing the Cr content promotes the formation of polygonal ferrite leading to an increase in the impact toughness and elongation but also a loss of yield strength.

Hydrogen permeation technique is a widely used testing method for the determination of hydrogen diffusion coefficient (D), which is an important parameter considering hydrogen embrittlement. A palladium (Pd) or nickel (Ni) coating is often utilised on the hydrogen detection side of the test specimens. Here, we investigate the effect of Pd and Ni coatings on hydrogen diffusion in a martensitic 500 HBW hardness low-alloy steel in the thickness range of 0.5 – 0.8 mm using a refined successive transient method and compare against an uncoated reference specimen. Both coatings yield similar average D values (6 – 6.6 × 10⁻⁷ cm²/s), but the best repeatability is achieved with Pd coating. With Ni coating, D values decrease with the increasing specimen thickness, which is partly caused by a slower hydrogen diffusion in Ni, and therefore a concentration gradient at the specimen-coating interface. The uncoated specimen has a poor transient fit, and significantly lower D (2.1 × 10⁻⁷ cm²/s) due to surface oxidation. With both coatings, the steepness of the last decay transient was highly affected by specimen thickness, and therefore the density of reversible hydrogen traps is only comparable for similar thicknesses.

This work investigates the effect of anodized aluminum oxide films on the surface characteristics and corrosion behavior of AlSi10Mg alloy fabricated via laser powder bed fusion (PBF-LB). A ∼10 μm thick oxide layer was formed using sulfuric acid anodizing, under both as-built and stress-relieved (300 °C, 2 h) conditions. Surface morphology, microstructure, and corrosion performance were characterized using scanning electron microscopy, EDS, and immersion testing in 3.5% NaCl solution. Anodizing significantly reduced surface roughness (Ra) from ~14 µm to ~6 µm, with further reduction in extreme topographical features observed in heat-treated samples. Cross-sectional analysis confirmed uniform oxide growth, while immersion tests revealed delayed corrosion onset relative to uncoated material. However, localized pitting was still observed, particularly in heat-treated samples, likely due to Si-network fragmentation. These findings demonstrate that anodizing enhances surface finish and corrosion resistance of AM AlSi10Mg, while microstructural features, such as silicon morphology, remain critical to oxide layer integrity.

Advanced high-strength steels (AHSS) can offer an excellent combination of high strength and light weight for applications including cold forming. These steels may be used in press braking and profile and section manufacturing. The aim of this work is to study the mechanical properties and microstructure of steel used in the manufacturing of roll-formed profiles with decreased radii. In this study, ferritic feedstock steel with 450 N/mm² yield strength, coiled at room temperature, and the sections with wall thicknesses of 7.1 mm and 12.5 mm are studied with middle line radii of 7.5 mm and 13 mm, respectively. Mechanical properties and impact toughness, especially considering the corners of cold-formed profiles, without and with aging (250 °C for 1 h), are studied. Cold deformation on corners is influenced by thickness and tensile strength in aged conditions. Impact energies are at a high level at-40 °C and-60 °C, and aging does influence the toughness but not on the hardness.