Functionally Graded Materials (FGMs) enable gradual transitions of properties between dissimilar materials, making them attractive for advanced engineering applications. Directed Energy Deposition (DED) provides a pathway to fabricate such multi-material structures through controlled compositional gradients. In this study, SS316L-IN718 single track deposits were produced via DED to evaluate the effects of energy density and composition on melt pool geometry, microstructure and defect formation. A constant scanning speed of 11 mm/s was used with laser powers of 1500, 1800 and 2100 W, corresponding to energy densities of 54.54, 65.45 and 76.36 J/mm². Thermal simulations in ABAQUS showed strong agreement with experimental measurements, with errors below 2

Powder Bed Fusion–Laser Beam (PBF-LB) is a widely used additive manufacturing technique that enables the fabrication of geometrically complex components, yet it remains susceptible to internal defects, particularly porosity, which can compromise mechanical performance. This study presents a physics-based thermal simulation algorithm developed to predict porosity in Ti6Al4V parts fabricated via PBF-LB without relying on extensive training datasets. The algorithm numerically solves the transient three-dimensional heat conduction problem using the finite volume method, incorporating temperature-dependent material properties, a Gaussian-distributed laser heat source, and relevant thermal loss mechanisms. To validate the predictive capability of the model, six Ti6Al4V specimens were fabricated under varying process parameters using a PBF-LB system, and porosity levels were experimentally evaluated through Archimedes density measurements and high-resolution X-ray micro-Computed Tomography (µ-CT). Additional characterization by Scanning Electron Microscopy (SEM), optical microscopy, and Energy-Dispersive X-ray Spectroscopy (EDS) was performed on cross-sectioned subsurface regions to assess pore morphology and elemental homogeneity. The porosity values predicted by the simulation algorithm exhibited strong agreement with experimental findings in terms of trend and ranking, with predicted porosity ranging from 4.78

Functionally graded materials (FGMs) fabricated by laser-based directed energy deposition (LDED) offer a promising route for integrating dissimilar alloys; however, achieving low-defect multilayer structures remains challenging due to composition dependent thermal behavior, which directly affects defect formation and microstructural stability. This study systematically investigates the role of composition-dependent energy density (ED) control in governing defect formation, microstructural evolution and mechanical response in multilayer SS316L-IN718 FGMs. Three ED strategies were systematically compared: a composition-mismatched under-optimized strategy (FGM 1), a high-input (delayed-reduction) strategy (FGM 2) and a composition-adaptive gradient strategy (FGM 3). Optical and electron microscopy revealed that insufficient energy density resulted in incomplete melting, lack of fusion defects and the highest porosity (2.47

Additive manufacturing (AM) technologies are prone to microstructural and mechanical anisotropy, driven primarily by directional solidification and the non-uniform thermal history associated with their layer-by-layer fabrication. This problem is more pronounced in Wire Arc Additive Manufacturing (WAAM), where elevated heat input and large molten pools increase thermal gradients and favor columnar grain development accompanied by δ-ferrite segregation in stainless steels. To address these issues, post-processing strategies such as inter-pass rolling, hammer peening, and heat treatment are frequently implemented. Nevertheless, regardless of being partially effective, these methods will add more processing steps that will result in an increase of time and costs. In this context, the present study seeks solutions to commonly reported limitations in the WAAM fabrication of AISI 316LSi stainless steel, which is widely used in industrial applications, by varying the wire feed speed (WFS) to regulate heat input with the aim of improving microstructural characteristics and mechanical performance. Accordingly 3 different heat input was attained by changing WFS in the system of CMT based WAAM method. Based on this approach, subsequent microstructural analysis revealed changes in δ-ferrite morphology from skeletal δ-ferrite to more refined lathy and globular forms across the investigated conditions. Within the examined processing parameters, samples corresponding to higher heat input levels, associated with increased wire feed speed (WFS), showed reduced anisotropy in grain orientation. Furthermore, samples produced under these conditions exhibited yield strength values of approximately 390 MPa, ultimate tensile strength values of approximately 620 MPa, and enhanced impact toughness, accompanied by a reduction in anisotropy. Overall, the findings indicate that adjustment of heat input during WAAM provides a viable process-engineering route for microstructural refinement and anisotropy reduction in AISI 316LSi stainless steel.

Gamma titanium aluminide intermetallic alloys (γ-TiAl) find extensive application in the automotive and aerospace engineering sectors, primarily for achieving weight reduction in various components. The utilization of additive manufacturing (AM) for producing γ-TiAl components has gained significant traction in recent years. AM presents notable advantages such as high design flexibility and reduced material consumption. However, it may also result in parts with poor surface quality. The advancement in laser technology has introduced new approaches, including AM of metals. Laser Polishing (LP) emerges as a viable alternative for improving surface roughness by selectively remelting the top layer of the surface. In the current investigation, concave and convex γ-TiAl samples, fabricated using electron beam melting (EBM), underwent laser polishing facilitated by a robotic manipulator. The outcomes of the LP process were assessed through morphological analyses, microstructural analyses, and microhardness measurements. Morphological analyses revealed a considerable enhancement in the roughness values, demonstrating an improvement of approximately 95–98

Functionally graded materials (FGMs) enable the investigation of oxidation behavior across variable compositions, allowing efficient evaluation of how gradual changes in alloy content influence high-temperature performance. In this study, stainless steel 316 L (SS316L) and Inconel 718 (IN718) were combined to produce both a nine-layer gradient FGM and a bimetallic sample via laser-directed energy deposition (LDED). After prolonged high-temperature exposure to 500 h at 850 degrees C in air, the effects of composition and interface design on oxidation resistance were systematically examined using localized analysis of oxide scale formation and microstructural evolution. A clear improvement in oxidation resistance and oxide adhesion was observed above a threshold of 30 wt.% IN718 in the FGM with gradient composition. At the same time, the abrupt transition in bimetallic print did not result in severe spallation due to interdiffusion at the interface. The results further reveal that an intermediate IN718 region (10-20 wt.%) is prone to solidification cracks that promote internal oxidation, and that, in the IN718-rich areas (70-100 wt.%), microhardness decreases after oxidation due to the dissolution of strengthening phases (gamma'/gamma") and grain coarsening. This combinatorial and composition-sensitive approach, utilizing FGMs, offers valuable new insights for designing oxidation-resistant materials for high-temperature applications.

Laser Direct Energy Deposition (L-DED) is a promising additive manufacturing technique with potential application in joining two dissimilar materials to fabricate bi-metallic components. The quality and functionality of the bonding interfaces are of great significance and rely heavily on the process parameters. In this work, we first deposited IN718 on a wrought SS316L substrate to create a bimetallic interface. Different energy density values, ranging from 71.43 to 127.7 J/mm, were used through various combinations of laser power and scanning speed for deposition. The bimetallic interface quality in terms of interface geometry, morphology, and dilution values was investigated for every energy density. Geometric analyses and dilution measurements revealed that the optimum bimetallic fabrication was achieved with an energy density of 90–100 J/mm. To deposit bimetallic SS316L-IN718 blocks for mechanical testing, the laser power and scan speed were set to 1400 W and 14 mm/s, respectively. Line EDS measurements revealed a transition zone across the bimetallic interface within a 4 mm distance, avoiding abrupt chemical discontinuities. Micro-hardness testing using Vickers revealed a smooth hardness transition between the SS316L (~210 HV) and IN718 (~300 HV) sides without any defect formation, suggesting successful joining. The bimetallic structure exhibited yield strength of 268.88 ± 20 MPa, tensile strength of 462 ± 12 MPa, and elongation of 19.6 ± 0.8%, in good agreement with SS316L. The fracture occurred on the SS316L side with noticeable necking and ductile behavior, demonstrating good interfacial bonding. These findings demonstrate the potential of L-DED in the fabrication of bimetallic structures for structural applications.

Powder Bed Fusion–Laser Beam (PBF-LB) has emerged as a leading additive manufacturing technique for producing complex metallic components; however, its susceptibility to process-induced defects, particularly porosity, continues to limit its widespread application. In this study, a physics-informed computational framework was developed to predict porosity formation in Ti-6Al-4V parts by explicitly resolving transient thermal fields, melt pool dynamics, and layer-wise liquid fractions with temperature-dependent material properties. A dedicated graphical user interface was implemented, providing flexibility in defining the critical processing variables in PBF-LB. Model validation was performed using experimentally reported datasets from the literature. Benchmarking against melt pool geometries demonstrated that the algorithm successfully reproduced the depth and width evolution under different laser powers (100–195 W) and scan speeds (500–750 mm/s). Further comparisons with porosity data revealed strong quantitative consistency: for example, a numerical prediction of 0.19% porosity closely matched Archimedes (0.115%) and µ-CT (0.070%) results, while micrograph-based measurements indicated a higher value (0.204%). Across all investigated specimens, the algorithm reliably reflected experimentally observed porosity trends, including near fully dense conditions (

WAAM (Wire Arc Additive Manufacturing) is an additive manufacturing method using arc energy as the energy source and welding wire as the raw material. Unlike additive manufacturing, it has excellent advantages, such as significantly reducing raw material utilization rates and increasing production speed in manufacturing large and complex parts. However, WAAM has problems with surface roughness, metallurgical bonding, and residual stress. Due to the nature of additive manufacturing in WAAM, repetitive heating and cooling directly affect the microstructure and phase formation. Understanding the microstructure and phase changes due to repetitive heating and cooling in WAAM with the help of computational methods is very important in the pre-production prediction of the material's microstructure. This study used ER70S-6 (AWS A5.18) steel welding wire in the high-strength low-alloy steel group. CMT-equipped MIG welding type, which can provide a high level of heat input control, was used as a welding method. Three walls with the same number of layers at three different heat inputs were produced by the MIG-CMT method in WAAM. Transverse and longitudinal sections were taken from the produced walls, and microstructure examinations were carried out. Microstructure examinations were carried out along the part in the deposition direction in both sections, and grain orientations were observed. Mechanical characterization was performed using microhardness measurements from the walls. Cooling rates were calculated for the production, followed by a thermal camera. Time, Temperature, and Transformation (TTT) diagrams were created using the Thermo-Calc computational materials engineering program based on the CALPHAD methodology under material-specific conditions. The cooling curves of the production are shown in the TTT diagram. It was observed that the phases obtained by the experiments, the phases obtained by the computational method, the phase ratios calculated in the optical microscope, and the phase ratios calculated in Thermo-Calc were the same. The microhardness values measured along the cross section decreased in the sections where the grain size increased and increased where the grain size decreased. It was observed that the microstructure formation and average grain size because of the manufacturing process with different heat inputs did not show a sharp change, and the average grain size measured by optical microscopy and the phase types identified were consistent with the data obtained by EBSD. As a result, the relationship between process, microstructure, and mechanical properties is explained. Thermo-Calc computational materials engineering program was found to be promising in additive manufacturing with its benefits such as reducing experiment repetition and providing flexibility to research.

The surface condition of additively manufactured (AM) parts strongly influences fatigue performance. Laser shock peening (LSP) is an effective surface enhancement method that improves the quality of AM metals by introducing compressive residual stresses (CRSs). In this study, two different metallic alloys, gamma-TiAl and IN939, were manufactured using powder bed fusion (PBF) techniques. The gamma-TiAl alloy was produced via electron beam melting (PBF-EB), while IN939 was fabricated through laser powder bed fusion (PBF-LB). After fabrication, all specimens were subjected to LSP and then tested under four-point bending fatigue conditions. The results were compared between the as-built and LSP-treated conditions. For the PBF-EB gamma-TiAl alloy, a fatigue limit was determined based on the 2 x 106 cycle run-out criterion, and LSP led to a 50.1% increase in the fatigue limit. For the PBF-LB IN939 alloy, because none of the as-built samples reached the run-out cycle threshold, fatigue life comparisons were made at selected normalized stress levels. The LSP-treated specimens showed fatigue life improvements by factors of 1.87 and 3.72 at stress levels of 0.74 and 0.87, respectively. Scanning electron microscopy (SEM) was used to evaluate the fracture surfaces, and the influence of LSP on fatigue behavior was discussed for both alloys.

Wire arc additive manufacturing (WAAM) is a directed energy metal additive manufacturing technology that features high-speed production of large and dense parts. The process is exposed to thermal shocks due to a high heat input. These thermal shocks may lead to various issues, including distortions, residual stresses, surface morphology defects, and irregular macro- and microstructures. This study proposes adopting infrared heaters in the WAAM process. Thus, it presents a preliminary investigation to promote further studies of the effects of infrared heating on the WAAM process and the quality of the produced parts. An experimental study was carried out to observe the effects of infrared heaters on part quality in WAAM. Two walls were built using ER70S-6 welding wire to compare the conventional WAAM process with the WAAM process that used an infrared heater. The results showed that the wall produced by WAAM with infrared heaters had more regular geometries, refined internal structures, and stable mechanical properties. The optic and SEM images showed that this method reduced the acicular and polygonal ferrite structures. Notably, bainite formation was not observed, and there was a decrease in the formation of defects, such as pores, lack of fusion, and interlayer discontinuities. The specimen subjected to the external infrared heater exhibited approximately 17

The enhancement in laser technology opened up new methods such as additive manufacturing (AM) of metals. While AM offers high design flexibility and reduced material usage, it can also produce problematic parts due to poor surface quality. A variety of post-processing techniques are available to address the drawbacks associated with the surface properties of AM. Laser Shock Processing (LSP) is one of the unique methods that induces compressive residual stress (CRS) on the surface and subsurface by creating severe plastic deformation. In this study, two critical aerospace alloys (gamma-TiAl and IN939) were manufactured through two different methods called Powder Bed Fusion with Electron Beam (PBF-EB) and Powder Bed Fusion with Laser Beam (PBF-LB). Subsequently, AM samples were investigated to observe single layer LSP effects on the surface. The results of the laser peening process were determined by residual stress, microhardness and surface roughness measurements. The residual stress profiles showed that LSP significantly induces CRS on the surfaces of AM alloys. For the gamma-TiAl and IN939 samples, the maximum values of CRS and depth of CRS were-460 MPa/1000 mu m and-516 MPa/700 mu m, respectively. Similarly, the microhardness of the materials was increased by 44.4 % for gamma-TiAl and 18.2 % for IN939 by laser post-processing. In addition, a comparison of the roughness of the unground and ground AM samples was carried out. Depending on the surface condition of the AM samples, LSP had different outcomes. For example, the extreme roughness of the AM samples was partially reduced by the thermal effects of the high-energy laser shots. When comparing the roughness values in terms of Ra and Rz, there were decreases in the range of 14.7-21.3 % and 3.34-39.3 % for unground IN939 samples. However, for unground gamma-TiAl samples, depending on the direction of measurement, roughness variations were observed as a 0.99 % decrease -5.3 % increase for Ra and a 2.2 % decrease -14.2 % increase for Rz. The roughness values for ground samples of both alloys were drastically increased, varying between 42.1 % and 7x increase. Sa values were recorded on unground AM samples. For IN939 and gamma-TiAl samples these values decreased by 8.41 % and 15.8 % respectively.

Electron beam melting (EBM) process is the most preferable powder bed fusion process for high melting point alloys. γ-TiAl alloys are intermetallic chemical compounds, which are lightweight and resistant to oxidation and heat, and have low ductility as well. EBM is the best manufacturing process for such alloys to produce aerospace parts, but poor surface quality is the main drawback of this process. Thus, surface post-processing is needed after the EBM process. This study presents the surface characteristics of EBM γ-TiAl alloy surfaces post-processed by electrochemical machining (ECM). The surfaces were ECM and the surface roughness values (Sa, Sq and Sz) have been reduced significantly. The mean reduction values of the experiments are 98.6%, 98.5% and 95.3% for Sa, Sq and Sz, respectively. Additionally, it is observed that the surface roughness is inversely proportional to the electrolyte conductivity up to a limit value (115 mS/cm), and after that the roughness increases via the stray current transition. Sq values decrease with the increased feed rate via the increased current density. However, an increase in feed rate negatively affects the Sku values, which statistically describe the sharpness or spread of surface roughness. Also, XRD results showed that Ti2AlN layer is formed on the surface via the HIP operation. This layer inhibits the electrochemical dissolution of γ-TiAl alloy and caused surface defects.

Laser metal deposition (LMD) is of the directed energy deposition (DED) process which is widely used for producing large-scale, dense, and functional parts in the field of additive manufacturing (AM). This research work investigates the microstructure and mechanical properties of PH 13–8 Mo martensitic stainless-steel parts produced via LMD. The workshop trials were conducted using an LMD system collaborated with a robotic arm to deposit single-track thin walls and horizontal blocks. The microstructural characteristics of the additively manufactured parts were analyzed using an optical microscope. The mechanical properties were evaluated through hardness measurements and uniaxial tensile tests. The influence of energy density and powder deposition density on the characteristic geometry of straight walls was also investigated. The microstructural analysis showed that the microstructure consisted of columnar dendrites that grew epitaxially from the substrate, with primary austenite cells containing intercellular ferrite and martensite laths that were roughly parallel with the retained austenite. When the energy density increased from 43 to 86 J/mm 2 (a doubling of energy density), there was an increase in secondary dendritic arm spacing (SDAS) by approximately 250% in the first layer and approximately 90% in the top layer. The difference in SDAS change between the first and top layers can be attributed to the difference in cooling rates experienced by each layer during the additive manufacturing process. Increasing powder deposition density from 0.5 to 1 g/min results in a decrease in porosity from 3% to less than 1% and an increase in strength from 800 to over 1000 MPa. The hardness of the deposits was found to range from 300 to 400 HV. This variation in hardness can be attributed to differences in microstructure resulting from changes in cooling rates at different heights.

Wire arc additive manufacturing (WAAM) method is a metal additive manufacturing method that allows the production of large and medium complexity parts layer by layer by considering the part-specific CAD model. Process parameters were optimized to achieve minimum heat input, less production time, and higher metal deposition rate and bead geometry. E120C-GH4 metal-cored seamless high-strength wire with a diameter of 1.2 mm and an ER120S-G solid wire of the same diameter were used at different wire feeding speeds with heat input (low, medium, high). Single and double layer 18 beads were deposited with each of these wires. Samples were prepared for macro section examination and macro hardness measurement processes. Samples with similar deposition volumes were compared in terms of bead geometry, microhardness, penetration depth, deposition time, and the metal deposition rate at the equal heat input. With the aid of the Taguchi method and the samples were subjected to multiple regression analyses. So, the analyses and real experiments allowed comparative experimental studies. Considering the economy and time, the result shows that metal-cored wire will be much preferable for the WAAM industry because metal-cored wire has 43% less production time and 74% higher metal deposition rate than solid wire.

Wire Arc Additive Manufacturing method allows producing relatively large metal parts with minimum raw material. However, the high heat input used during production results in heat accumulation and temperature variance. Both of them can cause various problems, such as distortion, overflow, and residual stress. Heat accumulation is the rise in temperature that occurs as a result of the inability to remove heat from the part. On the other hand, temperature variance arises as a result of the deposition path planning, which is usually carried out according to the geometrical shape of the part section. In traditional deposition path planning approaches, temperature variance is not taken into account for two reasons: high computational cost and the need to use more than one tool to implement path planning and thermal analysis. In this study, an algorithm that plans deposition paths by one step via performing thermal analysis to minimize temperature variance on a path basis is presented. The algorithm determines the deposition path by finding the best deposition angle and the sequence of tracks according to the jumping to the coldest deposition area. Thus, the temperature variance is reduced significantly. To evaluate the algorithm performance, a part consisting of a bulk component and a thin-walled component was produced in the workshop using the proposed algorithm and traditional sequential raster strategy. The results showed that the developed strategy reduced surface deformation by 37 % and thin-walled overflow by 21 %.

Additive manufacturing (AM) is a promising method for the manufacturing of complex geometries. Electron beam melting (EBM) is one of the powder bed AM processes which is used for hard metals to produce near and net-shape parts. The most encountered drawback in the EBM process is the surface quality, which plays a critical role on service life of the parts, particularly under variable loads. Electrochemical machining (ECM) is a non-traditional machining method in which the workpiece can be machined regardless of its hardness. This research presents a post-processing method for AM parts and dissolution mechanism of γ-TiAl alloys in order to improve the surface quality. For that purpose, Ti-48Al-2Cr-2Nb alloy is chosen and the sample parts are manufactured by EBM process. EBMed parts are machined using different ECM process parameters such as cathode material, feed rate, and electrolyte conductivity. Measurement results show that better surface roughness (Sa) values are obtained for the brass cathode. Sa values for the copper and brass cathodes are decreased from 63.80 to 1.8 µm and 0.98 µm, which corresponds to improvement rates of approximately 97

Additive manufacturing (AM) offers high design flexibility to produce complex parts, particularly in the powder bed fusion process. However, the use of powder as raw material results in poor surface quality as a major defect. To address this, laser polishing (LP) treatment has gained much industrial interest due to its ability to reduce surface roughness. This research paper investigates the effects of laser parameters on surface morphology, surface integrity, microstructure, and microhardness behavior during the LP process. Specifically, LP was applied onto the surface of Ti-6Al-4V samples produced using the powder bed electron beam melting (EBM) process. After laser polishing, roughness values (Sa, Sq, and Sz) were reduced by 87.5

This general review paper presents a condensed view of recent inventions in the Additive Manufacturing (AM) field. It outlines factors affecting the development and commercialization of inventions via research collaboration and discusses breakthroughs in materials and AM technologies and their integration with emerging technologies. The paper explores the impact of AM across various sectors, including the aerospace, automotive, healthcare, food, and construction industries, since the 1970s. It also addresses challenges and future directions, such as hybrid manufacturing and bio-printing, along with socio-economic and environmental implications. This collaborative study provides a concise understanding of the latest inventions in AM, offering valuable insights for researchers, practitioners, and decision makers in diverse industries and institutions.