A total of 0.3%C-Cr-Mo-V steel, a high-strength alloy steel widely used in rocket motor housings, suspension systems in high-performance vehicles, etc., is noted due to its high strength-to-weight ratio. However, its high carbon equivalent (CE > 1%) makes it challenging to weld, as it is prone to brittle martensitic formation, which increases the risk of cracking and embrittlement. The present paper focuses on enhancing the microstructure and mechanical properties of 0.3% C-Cr-Mo-V steel by gas tungsten arc welded (GTAW) joints, utilizing post-weld heat treatment and cooling strategies (PWHTCS). A systematic experimental approach was employed to ensure a defect-free weld through dye penetrant testing (DPT) and X-ray radiography techniques. Subsequently, test specimens were extracted from the welded sections and subjected to PWHT protocols, including hardening, tempering, and rapid quenching using air and oil cooling (AC and OC, respectively) mediums. Results show that OC has enhanced tensile strength and hardness while simultaneously maintaining and improving ductility, ensuring a well-balanced combination of strength and toughness. Fractography analysis revealed ductile fracture in AC samples, whereas OC weldments exhibited a mixed ductile–brittle fracture mode. Thus, the findings demonstrate the critical role of PWHTCS, with OC, as an effective method for achieving enhanced mechanical performance and microstructural stability in high-integrity applications.

Selective laser sintering (SLS) enables the fabrication of polymer components with intricate geometries; however, surface roughness remains a concern that affects performance and quality. This study systematically examines the influence of build orientation (X, Y, Z) and part location (inner, middle, outer) on surface roughness of Polyamide 12 (PA12) components. The results show that components built in the Y orientation and placed in the inner chamber exhibited the lowest surface roughness (Sa = 9.88 ± 0.16 µm). In contrast, Z-oriented components at the outer edge showed the highest (Sa = 11.49 ± 0.27 µm), indicating a 10.13% variation. SEM analysis showed smoother morphology and reduced porosity in the inner regions, while DSC confirmed higher crystallinity in samples with improved finish. These findings highlight the role of thermal stability and spatial positioning within the build chamber in controlling surface characteristics, emphasizing the importance of orientation and placement strategies for improving the quality of PA12 components fabricated by SLS.

Decarbonizing industrial energy consumption is critical for global sustainability. This study evaluates renewable energy alternatives to replace fossil-fuel power generation at an oil and gas facility in Khurais, KSA. A comparative thermodynamic and economic assessment was performed between a photovoltaic (PV) array and a parabolic trough collector (PTC) integrated with a Brayton cycle (BC) and a bottoming organic Rankine cycle (RC). The PTC-BC-RC model includes multi-generation capabilities for electricity, process hot water, and hydrogen via a PEM electrolyzer. The baseline PTC-BC-RC system generates up to 118.1 MW with a maximum thermal efficiency of 36.57%. The PEM electrolyzer utilizes 2% of the generated power to produce hydrogen at 0.0152 kg/s. Economically, the recuperated CSP system offsets its higher initial capital costs through diverse revenue streams (power, heat, and hydrogen), achieving a payback period of 5.13 years, significantly outperforming the PV system’s 6.80 years. Both configurations mitigate annual emissions by 747,000 tons of CO₂, 103.4 tons of NO_x, and 3.72 tons of SO₂. Despite regional limitations such as dust and water scarcity, the multi-generation PTC-BC-RC system proves economically and thermodynamically superior to the standalone PV system, offering a highly effective decarbonization strategy for industrial facilities in arid, high-irradiance zones.