Post-processing and heat treatment techniques effectively reduce residual stress in metal parts produced through additive manufacturing (AM), thereby enhancing mechanical properties and extending their service life. The present study investigates the impact of aging, double aging, and solutioning the heat treatments on surface characteristics, residual stresses, and tensile behaviour of laser powder bed fusion (LPBF) maraging steel, which has critical applications in aerospace and defence. Surface analysis of the steel parts scans the tracks in the as-built samples, with aging that causes deformations. Aging treatment proves to be more effective than double aging and solutioning treatments. Aged treatment (AT) samples have a higher surface roughness of 4.65 µm and shows greater tensile strength of 1510 MPa and lower residual stress of -188 MPa compared to other heat-treated (HT) and as-built samples. It forms the precipitates that prevent dislocation movements, and the conversion of tensile into compressive residual stresses. The LPBF process plays a critical role due to its rapid cooling capability, which results in elevated residual stresses. Controlled thermal and mechanical processes reduce internal stresses, and stabilize the components. This research explores the influence of heat treatment on LPBF maraging steel. Optimized heat treatments can be developed to improve the mechanical properties and surface characteristics of the components.

The study focuses on the enhancement of microstructural and microhardness characteristics of Laser-Based Powder Bed Fusion (LPBF) maraging steel 1.2709 with the effect of different heat treatment (HT) conditions including aging (AT), double aging (DAT), and solutioning (ST) and compared with the as-built (AB) condition. The samples were fabricated with the LPBF process parameters, utilizing 120 W of laser power, 500 mm s-1 of scanning speed, maintaining 20 mu m layer thicknesses, with the laser spot width and hatch spacing of 0.0550 mm and 100 mu m respectively in the argon environment with the 45 degrees rotating raster scanning pattern. Further the as-built and heat treated samples were evaluated utilizing electron backscatter diffraction (EBSD), Field Emission Scanning Electron Microscope (FESEM), microhardness, x-ray diffraction (XRD) and relative density. The FESEM analysis indicated that the DAT samples exhibit a more refined and uniform interdendritic grain growth of precipitates Ni3 (Al, Ti) compared to the as-built sample, which exhibited porosity and lack of fusion. Aging reduces the presence of interlayer defects, while the solution-heat-treated sample reveals the formation of lath martensite. The microhardness exhibited an increase following three distinct heat treatment conditions: AB, AT, DAT, and ST, measuring 450 HV, 650 HV, 760 HV, and 520 HV, respectively. The ferrite content was recorded at 99.6%, 87.4%, 99%, and 99.4%, while the austenite content was 0.4%, 12.6%, 1%, and 0.6%. The grain size in the ferrite phase was 8.72 mu m, 6.087 mu m, 6.86 mu m, and 0.32 mu m, and in the austenite phase the grain size was 0.26 mu m, 0.86 mu m, 2.51 mu m, and 6.89 mu m.

This study examines the machining characteristics of sintered aluminium composites, including Al+6% SiC and Al+4% SiC+2% B4C, utilising electrical discharge machining (EDM) by changing the input machining factors like current (C) in amperes, Pulse-OFF and Pulse-ON time in mu s, at three distinct levels. The L9 Orthogonal array was employed to examine the influence of process factors on output variables, including Surface Roughness (SR), Material Removal Rate (MRR), and Hole Circularity (HC). An Analysis of Variance (ANOVA) was conducted to determine the percentage contribution of the input factors to the output variables. Observation implies that the GRG ANOVA for Al+6%SiC composite has achieved the most significant contribution to the total GRG, with the current contributing 86.66%, followed by the Pulse-ON at 8.52% and the Pulse-OFF at 3.63%. In contrast, the Al+4%SiC+2%B4C composite shows the current contributing 74.07%, followed by the Pulse-ON at 15.25% and the Pulse-OFF at 9.82%. The ideal input levels for Al+6%SiC and Al+4%SiC+2%B4C composites were found to be A3B3C1 and A3B3C3, correspondingly.

The development of orthopedic implants requires bone cements that combine bioactivity with mechanical stability. In this study, 25% Akermanite/PMMA/25% Zirconia composites were fabricated using a bio plotter additive manufacturing process in three structural configurations, solid, 5-channel, and 6-channel-mimicking the lotus root's porous structure. Structural and biological characterizations were conducted using SEM, micro-CT, mechanical testing, antibacterial assays, and hemocompatibility and cytocompatibility analyses. SEM confirmed uniform phase dispersion and strong interfacial bonding, while micro-CT revealed porosities of 53 +/- 1 % (5channel) and 67 +/- 3 % (6-channel). The 6-channel design exhibited superior antibacterial activity against E. coli (16 mm) and S. aureus (21 mm), higher cell viability, and the lowest hemolytic effect. Compressive strengths were 145.6 MPa (solid), 132.8 MPa (5-channel), and 120.5 MPa (6-channel), demonstrating a balance between porosity and strength. Overall, the 6-channel structure achieved an optimal trade-off between mechanical performance and biological functionality, suggesting its potential for next-generation orthopedic applications.

The present research work attempts to narrow down the suitable sized flux for enhancing the weld pentation depth and acceptable weld bead morphology, with reliable coating consistency for welding thicker sections. Nano- and micro-sized TiO2 flux were used in the study to examine the adherence of the flux particles to determine the ease of coating and their thermal decomposition for melting point depression. Nano-TiO2 showed a high degree of decomposition, aiding in early melting pointing depression. No significant differences in microstructural features and hardness were observed. However, the nano-TiO2 weldment exhibited a penetration depth of 5.734 ± 0.2888 mm, 22

The current study looks at the mechanical, corrosion, and tribological aspects of tungsten carbide milling inserts coated with Aluminum Chromium Nitride (AlCrN) and Diamond-Like Carbone (DLC) in a dry cutting environment. Using the Desirability Analysis, the cutting force (N) and surface roughness (Ra) are considered as output responses, and three different cutting speeds (500, 710, and 1000 rpm), three different feeds (40, 60, 100 mm/min), and depth of cut (0.5, 0.75 and 1 mm). According to ANOVA results, the most effective parameters in multi-objective optimization were feed rate (60.06

The development of advanced bone cements is critical for enhancing the performance and longevity of orthopaedic implants. This study introduces a combination synthesis method for producing akermanite (AKT-Ca2MgSi2O7) ceramics and commercial zirconia (ZrO2) bioceramics. This study aims to improve the material's mechanical strength, bioactivity, and biocompatibility by the incorporation of bioceramics into the polymethyl methacrylate (PMMA) matrix. The PMMA matrix ensures appropriate handling characteristics and setting times suitable for clinical applications. Characterization studies reveal that the composite achieves an optimal balance between bioactivity and mechanical performance. The results indicated that the AKT/PMMA/ZrO2 composite bone cements that were produced exhibited a substantially lower polymerization temperature than pure PMMA. Additionally, they maintained high compressive strength (similar to 105 MPa) and optimal setting times (9-14 minutes). The bioactivity assessment, through simulated body fluid immersion tests, indicates a layer of hydroxyapatite is formed on the composite surface within 7 days, confirming its osteointegration potential. Furthermore, the composite exhibits excellent biocompatibility, with in vitro assays showing over 90% cell viability after 24 hours of culture. Scanning electron microscopy and X-ray diffraction analyses confirm the homogeneous distribution of akermanite and zirconia throughout the PMMA matrix, contributing to ensuring the uniform mechanical characteristics and bioactivity of the composite material. [GRAPHICS] .

This study aimed to enhance the depth of penetration (DoP) of AISI 304L weldments through the application of oxide fluxes. Various flux application methods, such as flux-bound TIG (FB-TIG) and flux-zoned TIG (FZ-TIG), were compared to A-TIG and conventional TIG (C-TIG). Reverse Marangoni convection and arc constriction effects were found to be the primary factors contributing to higher DoP and minimal bead width (BW) in all flux-assisted welds. FZ-TIG (centre: TiO2; side: SiO2) and FB-TIG (TiO2—1 mm gap) demonstrated 131.26

The shot peening procedure enhances the mechanical characteristics with the transformation of compressive residual stresses which helps in the increment of operational lifespan of the product. The study comprehensively analyzed the effect of consecutive shot peening procedures up to four peening passes with the coverage increases 100% on each peening pass up to 400% on the laser powder bed fused austenitic stainless steel and compared with the as-built condition focusing on surface characteristics, mechanical characteristics, and corrosion potential. Surface damage of the peened samples was found very minimal with the absence of visible scan tracks and unmelted powder particles due to the controlled peening parameters. The inducement of compressive residual stresses (-625 MPa) was observed to be higher at the fourth consecutive peening passes without strain-induced martensite, with an increment of hardness proportion of 29.12% with a depth of 1 mm, and increment of corrosion resistance across each peening pass.

In the current investigation, powder metallurgy was used for effective production of a hybrid aluminum matrix that was reinforced with SiC and B4C particles. The effects of reinforcements (SiC and B4C) on the microstructure of the composites, wettability and tribological behavior were examined. Aluminum (Al) matrix with reinforcements of silicon carbide (SiC) at weight percentages of 2, 3, 4, 5 and 6 was produced through powder metallurgy (PM) method, and also hybrid Al composites reinforced by SiC at different weight percentages of 2, 3, 4, 5 and 6 with constant addition of boron carbide (B4C) with 2 wt.

The present study examines the vibration characteristics of GFRP sandwich beams incorporated with cellular co-continuous architected periodic gyroidal bio-inspired cores. Using the higher-order shear deformation theory (HSDT), free vibration analysis was performed analytically on the designed sandwich beam. Four distinct configurations of bio-inspired cores are considered and 3D printed using Poly-lactic Acid (PLA) material. Subsequently, alternative dynamic approach (ADA) and ASTM E1876 is used to determine the properties of core and laminate. Amongst various bio-inspired beam configurations, GM02 yield better stiffness and prominent shear modulus for its structural weight proportions and parametric studies were performed for all the core models.

In recent years, super duplex stainless steel (SDSS) has gained a lot of importance due to its strength and excellent resistance to corrosion cracking for applications in marine and chemical processing industries, etc. In spite of various progress in the field, the drilling of SDSS leads to the formation of chips that are very strong and abrasive, which makes it challenging to have proper drilling. To overcome this issue by utilizing suitable parameters such as drill bit coating, environmental conditions and parameters for drilling. The SDSS machining output results were compared for both dry and minimum quantity lubrication (MQL) conditions using coated and uncoated drill bits. A scalable pulse power plasma (S3P) technique was utilized to deposit the titanium silicon nitride (TiSiN) and aluminum titanium nitride (AlTiN) coatings on solid carbide drill bits. In the experiments, three levels of drilling parameters have been chosen, including spindle speed (550, 700, 850 rpm), feed rate (0.035, 0.045, 0.060 m/min), and drill bit types. The experiment was designed using Taguchi's orthogonal L9 array. The influence of machining parameters such as cutting force, surface roughness, and circularity error were examined using variance analysis (ANOVA) and signal-to-noise (S/N) ratios. To enhance the drilling process parameters through a single comprehensive output measure, the obtained results were taken as an input to the fuzzy logic networks using multi-factor analysis. At the L7 trial, the least cutting force was observed at 525.7 N for dry conditions and 227.6 N for MQL conditions and gave cone-spiral and continuous chips. In order to analyze the signal-to-noise ratio effectively, high value correspond to better-quality characteristics. In accordance with ANOVA results pertaining to cutting force, a percentage contribution variance of 48.92% was obtained for the feed rate, which contributed to cutting force to a greater extent, followed by 36.82% for spindle speed and 14.19% for the type of drill bit.

The laser powder bed fusion LPBF method in additive manufacturing for metals have proven to produce a final product with higher relative density, when compare to other metal additive manufacturing processes like WAAM, DED and it takes less time even for complex designs. Despite the use of many metal-based raw materials in the LPBF method for production of products. Maraging steel (martensitic steel) is used in aeronautical and aircraft applications in view of its advantages including low weight, high strength, long-term corrosion resistance, low cost, availability, and recyclability. A research gap concerns the selection of design, dimension, accuracy, process parameters according to different grades, and unawareness of various maraging steels other than specific maraging steels. In this comprehensive review, the research paper provides information about on LPBF maraging steel grades, their process parameters and defects, microstructure characteristics, heat treatments, and the resulting mechanical characteristics changes. In addition, detailed information about the aging properties, fatigue, residual and future scope of different maraging steel grades in LPBF for various applications are discussed.

Biomedical material advancements have resulted in an increasing demand for innovative and high-performance Akermanite (AKT-Ca2MgSi2O7) ceramics developed for a diverse range of uses. This study conducts a comparative analysis and development of porous AKT structures, employing three distinct synthesis methods: ball milling, sol–gel, and a combining both processes. The objective is to evaluate the microstructural properties, porosity levels, mechanical strength, and bioactivity of the AKT. XRD study confirms the phase purity at 1300 °C, and FT-IR identified the respective functional groups present in the material composition. SEM analysis revealed the porous structure ( 3–6 μm) of AKT samples, which had a uniform distribution. The results suggest that the combination process enhances the structural and functional properties of Akermanite. Biomineralization study reveals that hydroxyapatite formation was attained after 21 days. The achieved compressive strength is 193 ± 5 MPa. The outcome of the antibacterial activity against S. aureus and E. coli test strains suggests that viable material for orthopedic applications.

The utilization of laser shock peening (LSP) in laser powder bed fused (LPBF) stainless steel (SS) 316L components enhances the mechanical characteristics and operational lifespan of the product quality through a significant reduction of residual stress and a noticeable increase in roughness parameters. The key objective of the study is to analyze the influence of consecutive laser shock peening (LSP) without ablative coating and low pulse energy on the surface properties, residual stress distribution, and microhardness of samples produced by LPBF with SS316L material. The surface quality of the sample subjected to consecutive laser shock peening shows a slight deterioration in its condition. This can be attributed to the combined impact of ablative surface and surface damage resulting from the production of high-energy plasma. However, the implementation of successive LSP results in a distinctive enhancement of compressive residual stresses (CRS) that are evenly distributed throughout the central axis and sharp edges. In contrast, the as-built condition exhibits non-uniform stress magnitudes. CRS observed in each LSP iteration exhibits a notable increase, reaching a maximum magnitude of -389 MPa compared to the initial stress level of 165 MPa in the as-built sample. This enhancement can be attributed to the repetitive impact of shock waves on the surface, leading to the formation of plastic deformation. The refinement of surface grains and the presence of favorable residual stresses were proven by the utilization of x-ray diffraction (XRD) studies and the Cos alpha plot. The XRD investigation also indicated the absence of any newly formed phases or secondary phases. A significant enhancement in microhardness was observed, with an increase of 58.3% achieved after the third consecutive peening process. The successive LSP samples displayed a gradual improvement in electrochemical behavior. Though the amplitude parameters increased after LSP, the increase in wear rate was observed.

Metal additive manufacturing (AM) is a revolutionary technological advancement that has made significant inroads in a wide range of sectors, including aerospace, defense, automotive, health care, and engineering applications. It offers unprecedented design freedom, reduced material waste, and enhanced performance, in addition to significant enhancements to fabrication processes. Microstructural defects and internal stresses formed during fabrication directly affect the fabricated product's surface integrity, quality, and service life. Identification, characterization, and prediction of these defects help significant and direct production of defect-free structures with high density. This article provides detailed insights concerning the common defects, mitigation techniques, and challenges reported in both powder bed fusion-based and wire arc AM methods. Defects such as porosity may develop due to the powder sphericity, roughness of the powder, preheating, process parameters, build environment, postprocessing techniques, and environmental factors. Therefore, a critical study of the techniques, alloys, process parameter optimization, and different postprocessing techniques to tone down the defects is made from their formations.

The current investigation involves the fabrication of fifteen samples of austenitic stainless steel 316 L (SS316L) utilizing laser powder bed fusion technology to evaluate the residual stresses through the impact of energy density, which was varied between 30 J/mm3 and 111 J/mm3 by varying process parameters, notably scanning speed and laser power. The energy density range suggested by existing literature has been found to have samples with significant mechanical properties, apart from its impact on residual stress, which can affect the service life of the product. The primary focus of this study is to identify the optimal window for achieving residual stress at various locations within the sample. The study discovered differences in residual stress development at all tested locations. When employing lower laser powers of 140 W and 160 W, residual stress formation remained consistent. Furthermore, when the laser power exceeds 140 W to 160 W, a substantial temperature gradient develops, leading to a considerable rise in tensile stress magnitude. The variation in energy density does not affect residual stress, while there is a variation in two process parameters, laser power and scanning speed, simultaneously. A laser power range of 140 W to 160 W, combined with scanning rates ranging from 500 mm/s to 1100 mm/s, results in a consistent range of minimal residual stress formation across multiple locations. The key outcomes of the study show the crucial role of laser power and scanning speed in residual stress development, which has implications for improving mechanical characteristics and product service life by generating minimal residual stresses.

Additive manufacturing has evolved over the last few decades. Three-dimensional printing is a digital manufacturing technology that provides nearly endless options for the creation of an accessible instrument for all parts of various medical practices, including tissue engineering, through meticulous optimization of material, processing, and geometry for every point in an object. Three-dimensional printing has opened up a new, faster, and safer manufacturing process, despite its incapability to fabricate complex structures and objects. Recently, novel four-dimensional printing techniques have been developed for the transformation of typical stable three-dimensional printed parts into smart objects. The limitations of three-dimensional printing could be remedied with four-dimensional printing, by applying time as the fourth dimension. Self-repairing and speedy printing are two additional benefits of this technology's by using smart materials. By adapting this technology, numerous medical domains could be profited. Four-dimensional printing does not have the ability to produce curved complicated forms. However, five-dimensional printing overcomes the flaws seems in four-dimensional printing. Five-dimensional additive manufacturing relies on the rotation of both the print bed and the extruder head. Five-dimensional printing outlasts in terms of durability than three- and four-dimensional printing. Currently, a combination of the principles of four- and five-dimensional printing into a single process is called six-dimensional printing. In six-dimensional printing, the form changes over time due to the reaction of environmental factors, which is primarily used in biomedical applications. This paper summarizes extensive research on biomaterials in the field of biomedical science and discusses the present implications of three-, four-, five-, and six-dimensional printing techniques.

In the current study, aluminium 7075 were reinforced with different wt% (2 to 6) of silicon carbide (SiC) and aluminium 7075 hybrid composites reinforced with different wt% (2 to 6) of silicon carbide (SiC) with constant 2 wt% of boron carbide (B4C) were fabricated using the Powder Metallurgy method. The microstructural study of sintered samples was performed using FESEM. This mechanical alloying process helped uniform distribution of SiC and B4C particles throughout the aluminium matrix. Electron backscatter diffraction studies demonstrated that Al7075 + 6wt%SiC particles have a finer grain structure. Aluminium 7075 alloy composites analysed using XRD to confirm the peak phases. The higher hardness values were obtained for Al7075 + 6wt% SiC and Al7075 + 3wt%SiC + 2wt%B4C composites as 195 HV and 161 HV respectively. The higher compressive strength values were obtained for Al7075 + 3wt%SiC and Al7075 + 2wt%SiC + 2wt%B4C composites as 220 MPa and 175 MPa respectively. The density of hybrid composites had a considerable impact on the influence of SiC and B4C particles. The surface nature of Al7075 + 2wt%SiC and Al7075 + 4wt%SiC + 2wt%SiC composites have obtained as hydrophilic and hydrophobic respectively. Based on the thermal conductivity measurement, it was found that the Al7075 + 6wt%SiC composite sample has obtained the thermal conductivity of 58.99 W/m.K. Furthermore, the investigation on wear studies showed the wear rate for Al7075 + 4wt%SiC and Al7075 + 6wt%SiC + 2wt%B4C composite as smaller under the load of 10N. The Al7075 + 6wt%SiC and Al7075 + 2wt%SiC + 2wt%B4C hybrid composites have a higher corrosion resistance than in a 3.5% than the other aluminium 7075 composite samples.