Key Engineering Materials Vol. 1036

Abstract: This study presents an atomistic analysis of the stress-strain characteristics in the laser powder bed fusion (LPBF) process for the AlSi10Mg alloy. The stress-strain response of printed components is investigated by introducing defects through molecular dynamics simulation. The simulation box dimensions for tensile tests and crack propagation are 152.416 Å, 201.228 Å, and 42.49 Å along the X, Y, and Z directions. Periodic boundary conditions are applied along all sides. A constant strain rate of 10⁹ s⁻¹ is applied along the Y-direction at a temperature of 300 K. The simulation results reveal that the maximum stress occurs at the initial time step, followed by a gradual decline as stress decreases and strain increases, indicating plastic deformation through dislocation slip. Dislocation Analysis (DXA) shows that dislocations increase with increasing strain. These findings enhance the understanding of the material's deformation behaviour and provide insights for optimizing its properties through laser processing parameters.

Abstract: Nickel-based coatings are a vital technology in industrial applications, offering protection to metallic objects against high temperatures, wear, corrosion, and erosion. The current research work examines the deposition of NiCrBSi powder in Stainless steel (AISI SS 304) using the high-velocity oxy-fuel (HVOF) thermal spray coating technique. The effects of HVOF-deposited NiCrBSi coatings on the microstructure, morphology, and mechanical and physical properties of the coated stainless steel. Microstructural and morphological analyses were performed using scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD) to characterize the coating. The coatings were systematically assessed for surface roughness, deposition efficiency, coating thickness, and porosity. Adhesion strength was measured using a pull-off adhesion tester to ensure robust bonding. The results demonstrate that HVOF-sprayed NiCrBSi coatings possess low porosity (2-3%), strong adhesion (45–55 MPa), and increased hardness, making them highly suitable for high-temperature, anti-wear applications, with improved durability and performance under harsh operating conditions.

Abstract: Mg-Al-Zn alloy, an Mg alloy having Al and Zn as the major constituents, is exceptionally lightweight and has potential to become an essential component of modern engineering applications and healthcare systems. This paper presents valuable insights to the friction stir processing (FSP) applied to Mg-Al-Zn alloy in dry conditions. FSP induced extreme plastic deformation in the metal alloy which causes substantial microstructural alterations. These changes were investigated using optical microscope. Microstructural evaluation of FSP-processed zone indicated that average grain diameter of the FSP-processed zone increased in proportion to tool rotating speed. This is attributed to the frictional zone's degree of plastic deformation. In alignment with results obtained from optical microscopy, morphological study conducted using scanning electron microscope (SEM) also demonstrated the synthesis of refined grains. In addition, the study includes evaluation of the FSP-processed alloy's micro-hardness and tensile characteristics in contrast to the base (unprocessed) alloy.

Abstract: This study investigates plantain peduncle extract as a green corrosion inhibitor for AA6063 aluminium alloy in 1M NaCl using electrochemical techniques (OCP, LSV, Tafel analysis). Extract concentrations were tested at 30–50°C. Results showed concentration-dependent inhibition, with (0.3 ml) achieving maximum efficiency: 85.48% (30°C), 88.00% (40°C), and 89.92% (50°C). Tafel data confirmed reduced corrosion rates (0.18–0.13 mm/yr vs. control: 1.24–1.29 mm/yr) and increased polarization resistance (1.71–2.34 kΩ·cm² vs. control: 0.247 kΩ·cm²). OCP/LSV curves demonstrated cathodic potential shifts and suppressed current densities, indicating mixed-type inhibition. Langmuir isotherm analysis (R² > 0.994) confirmed monolayer adsorption, with ΔG_ads values (−64.32 kJ/mol at 30°C) suggesting chemisorption dominance. Optical micrographs revealed reduced corrosion with inhibitor concentration, though isolated pitting persisted. Empirical optimization (ANOVA) identified 0.144 ml at 30.1°C as optimal for minimal corrosion rate (0.21 mm/yr).

Abstract: A FeCoNiCu high-entropy alloy was synthesized via mechanical alloying using elemental powders. The structural evolution during milling and the effects of subsequent sintering were investigated. X-ray diffraction confirmed the formation of a single-phase FCC solid solution with nanocrystalline structure. SEM and EDS analyses showed homogeneous element distribution without segregation. Microhardness testing revealed an average value of 105.47 HV1, indicating sufficient mechanical performance. The results demonstrate the potential of FeCoNiCu HEAs for structural applications.

Abstract: Machining of extremely hard materials with complex shapes are very difficult in traditional processes due to which Electro Discharge Machining (EDM) is being used in many industries mainly aerospace, medical, automotive etc. EDM uses a series of sparks generated between tool-electrode and workpiece-anode to erode materials. These sparks are generated continuously inside the dielectric fluid and produce extreme heat which melt and vaporize the material. Pumping action of the dielectric fluid helps in removing excess material from machined surface. In this experimental work, the impact of input parameters namely current, pulse on time and voltage on two performance features like material removal rate (MRR) and surface roughness (Ra) have been investigated. Incoloy 800HT is used as work-piece and copper as tool material. Incoloy 800HT is an iron-nickel-chromium-based superalloy known for its ability to retain mechanical properties at high temperatures and its exceptional resistance to oxidation, carburization, and corrosion. Taguchi based grey analysis is used the multi-criterion decision-making (MCDM) method for optimization. From the analysis it is revealed that current has the most significant influence on both material removal rate (MRR) and surface roughness (SR), with higher current increasing MRR but deteriorating Ra. Micrograph analysis of machined surface is performed using scanning electron microscope (SEM).

Abstract: This study uses numerical simulation to examine the influence of variations in laser power and transition zone length on the tensile behavior of bimetallic samples designed to be manufactured by selective laser melting (SLM). The materials studied are 316L stainless steel-copper, chosen for their complementary mechanical properties and functional relevance in high-stress applications. The transition between the two materials was modeled by modulating the laser power according to different profiles (linear, concave or convex) and over different lengths (d(x) = 0 mm, 10 mm, 20 mm) in order to evaluate their impact on the simulated mechanical performance. The numerical results show that a gradual transition in laser power, combined with an extended transition zone, significantly improves stress distribution and leads to better mechanical integrity. Simulations performed in ANSYS provide an in-depth analysis of stress fields and highlight the crucial role of manufacturing parameter management. This study thus highlights the importance of precise control of manufacturing parameters in the 3D printing of bimetallic components and demonstrates, through numerical modeling, that optimized transition management can improve the mechanical integrity of parts produced by SLM. Experimental validation of these results will be an essential prospect for future work.

Abstract: Penstock pipelines in hydroelectric power plants are critical components whose structural integrity is paramount for reliable operation. However, they are subjected to severe operational conditions generating complex stresses, favoring low-cycle fatigue crack initiation, particularly at critical weld zones. This is exacerbated by anomalous operational cycles like repetitive emptying and filling. This study presents a comprehensive methodology combining X-ray Diffraction (XRD) with other Non-Destructive Testing (NDT) techniques to assess residual stresses and their impact on pipeline integrity. XRD quantifies net stress under empty pipeline conditions, determining superposition between intrinsic residual stresses (manufacturing, welding, service-induced) and non-hydrostatic loads (self-weight, geomechanical forces). Diffraction pattern analysis yields crucial stress distribution data [1-5], identifying critical concentration zones prone to fatigue [6-10]. Complementary NDT techniques reveal morphological discontinuities influencing material mechanical behavior. Correlating XRD and morphological findings establishes cause-effect relationships between structural state and measured residual stresses. This integrated methodology offers significant predictive maintenance advantages, providing quantitative assessment of current pipeline state and projecting future performance.

Abstract: The early failure of single-lap adhesive joints in carbon fiber reinforced polymer (CFRP) composites is typically induced by stress concentration at the edges of the overlap region. To address this issue, this study proposes a novel local pre-curing process system based on gradient thermal curing regulation. Through multi-physical field modeling of the temperature-curing coupling effect and a gradient curing control strategy, active optimization of the adhesive layer stress distribution is achieved. By optimizing the interface stress distribution, the proposed technique demonstrates the potential to enhance the overall joint performance by 3-6%. This research combines Abaqus finite element simulation and experimental verification. A CFRP single-lap joint model considering the temperature-curing coupling effect was established to analyze the influence of local pre-curing on the stress distribution of the adhesive layer. The results show that: 1. Local pre-curing can reduce the peel stress in the critical edge danger zone by about 3 - 5% while improving the shear strength in the middle region. 2. The preferential curing at the center of the adhesive layer can induce stress redistribution, relieve the stress concentration at the edges, and thus improve the overall load-bearing capacity of the joint. This study provides a low-cost and easily implementable solution for optimizing the performance of CFRP joints, showing potential applications in the field of lightweight aerospace structures. Through the synergistic effect of precise thermal management and regulation of the adhesive's rheological properties, it offers new insights for advanced composite joining technologies.