This study was conducted to investigate the synergistic effects of cutting parameters on surface roughness in ball end milling of oxygen-free high conductivity (OFHC) copper and to determine a...

Dual-phase (DP) steels consist of a ferritic matrix dispersed with some percentage of martensite, which gives the material a good combination of strength and ductility, along with the capacity to absorb energy and enhanced corrosion protection properties. The purpose of this work was to study the microstructural and corrosion behavior (mainly pitting and galvanic corrosion) of DP steel compared with that of conventional rebar. To obtain DP steel, low-carbon steels were heat-treated at 950 °C for 1 h and then intercritically annealed at 771 °C for 75 min, followed by quenching in ice-brine water. The corrosion rates of DP steel and standard rebar were then measured in different pore solutions. Macro- and microhardness tests were performed for both steels. It was found that DP steels exhibited a superior corrosion resistance and strength compared to standard rebar. The reported results show that DP steels are a good candidate for concrete reinforcement, especially in aggressive and corrosive environments.

Protective coatings are essential for extending the service life of components exposed to harsh conditions, such as pipes used in industrial systems, where wear and corrosion remain constant challenges. This study explores the development of a nano-sized TiO₂-reinforced electroless nickel-based ternary (Ni-W-P) alloy and composite coating on API X60 steel, a high-strength carbon steel pipe grade widely used in oil and gas pipelines, using an alkaline hypophosphite-reduced bath. The surface morphology, microstructure, elemental composition, structure, phase evolution, adhesion, and roughness of the coatings were analyzed using optical microscopy, FESEM, EDS, XRD, AFM, cross-cut tape test, and 3D profilometry. The tribological performance was evaluated via Vickers microhardness measurements and reciprocating wear tests conducted under dry conditions at a 5 N load. The TiO₂ nanoparticle-reinforced composite coating achieved a consistent thickness of approximately 24 µm and exhibited enhanced microhardness and reduced coefficient of friction (COF), although the addition of nanoparticles increased surface roughness (S_a). Annealing the electroless composites at 400 °C led to a significant improvement in their tribological properties, primarily owing to the grain growth, phase transformation, and Ni₃P crystallization. XRD analysis revealed phase evolution from an amorphous state to crystalline Ni₃P upon annealing. Both the alloy and composite coatings exhibited excellent adhesion performances. The combined effect of TiO₂ nanoparticles, tungsten, and Ni₃P crystallization greatly improved the wear resistance, with abrasive and adhesive wear identified as the dominant mechanisms, making these coatings well suited for high-wear applications.

Electroless composite coatings were deposited on API X60 grade pipeline steel, and the effect of nickel sulfate, sodium hypophosphite, copper sulfate, and TiO ₂ nanoparticle concentration on deposition rate, microhardness, and surface roughness was investigated using a Taguchi L27 experimental design coupled with grey relational analysis (GRA). Analysis of Variance (ANOVA) was used to determine the statistical significance of the process parameters. The optimized coating was subjected to post-deposition annealing at 200°C, 400°C, and 600 °C. Microhardness measurements, surface roughness analysis, field-emission scanning electron microscopy coupled with energy-dispersive spectroscopy, and x-ray diffraction were utilized to evaluate the coating characteristics. Sodium hypophosphite (P) and nickel sulfate (Ni) are identified as the dominant factors affecting microhardness (49.31% (P) and 38.78% (Ni)) and deposition rate (28.95% and 61.11%). In comparison, surface roughness is influenced by sodium hypophosphite (35.10%) and copper sulfate (Cu) (27.57%), as observed in the S/N ratio and ANOVA analysis. GRA optimum bath composition is 20 g l ⁻¹ nickel sulfate, 14 g l ⁻¹ sodium hypophosphite, 0.3 g l ⁻¹ copper sulfate, and 1 g l ⁻¹ TiO ₂ . An experiment conducted under GRA-optimized conditions yielded a microhardness of 599 HV _0.05 , a surface roughness of 0.320 µ m, and a deposition rate of 13.08 mg.cm ⁻² .h ⁻¹ . Microstructural and phase analyses revealed a nodular, amorphous as-deposited coatings, while annealing promoted crystallization through the precipitation of Ni ₃ P phase. The maximum hardness was obtained after heat treatment at 400 °C, whereas further increasing the annealing temperature to 600 °C resulted in a decrease in hardness and an increase in surface roughness, which was associated with microstructural changes and increased surface oxidation.