Post-processing Heat Treatment Research Articles

Wires using multi-hole SolidStir Extrusion

SolidStir® Extrusion, a newly-innovated manufacturing process, offers tooling design adaptability as a significant advantage over conventional extrusion processes. Aluminum 6061-T6 was extruded using a modular multi-hole three-piece die. Microstructural characterization of as-extruded 3 mm diameter wire revealed refined equiaxed grains of 9.5 ± 4.0 µm average size. Tensile testing showed that as-extruded wires exhibited a tensile yield strength (YS) of 110 MPa, ultimate tensile strength (UTS) of 171 MPa, and elongation of 15.3%. After subjected to post process heat treatment, the extruded wires had a tensile YS of 246 MPa, UTS of 298 MPa, and elongation of 9%.

Elucidating the microstructure evolution and performance response of wire-arc directed energy deposited Al–Zn–Mg–Cu alloy at as-deposited and post-processing heat treatment states

Wire-arc directed energy deposition technology was employed to manufacture ultra-high-strength Al–Zn–Mg–Cu alloy taking advantage of variable polarity cold metal transfer (CMT) process. The grain characteristics and precipitation behavior under as-deposited (AD) and post-processing heat treatment (PHT) states were comparatively analyzed. The relationship between the microstructure evolution and mechanical performances was fully disclosed. The obtained results show that the grain structure of AD sample exhibited a nearly fully-equiaxed feature (average size: ∼45 μm), which was caused by the low heat input and variable polarity of CMT advance mode. The microhardness distribution of AD sample consisted of slight fluctuation and stable areas along the building direction due to the different thermal history and precipitation process. After the PHT process, the average grain size and morphology almost remained unchanged. However, compared with the size and type of precipitation phases under the AD state, high-density nanoscale (∼5 nm) metastable η′ phases were precipitated in the grain interior of the PHT sample, which contributed to the crucial precipitation strengthening effect. The homogeneous microhardness distribution was achieved with a high level (∼180 HV0.2). Meanwhile, tensile properties and elongation significantly increased to 524.68 ± 7.31 MPa and 7.10 ± 2.09 % after the PHT process, respectively.

Effect of Accumulative Roll Bonding Cycles and Postprocessing Heat Treatment Temperature on Shape Memory Properties of Cu–Al–Ag Alloys

Herein, Cu/Al/Ag‐layered composites with two silver powder concentrations (2 wt% and 3 wt%) are fabricated with the aid of accumulative roll bonding (ARB). The ARB‐ed samples are heat treated at different temperatures (750, 850, 950, and 1050 °C), times (30, 45, and 60 min), and cycles (1–9 cycles) to produce Cu–Al–Ag shape memory alloys. The samples are characterized by X‐ray diffraction, scanning electron microscope, and electron backscattering diffraction. Phase transformation temperatures are measured by differential scanning calorimetry. Strain recovery and shape memory behavior are evaluated by bending and tensile tests, respectively. The results indicate that alloys containing 2 wt% Ag, rolled till 9 cycles, heat treated at 950 °C for 60 min, and samples with 3 wt% Ag, fabricated by 9 cycles, annealed at 850 °C for 60 min show maximum β martensite phase amount. The strain recovery ratios of the first and second samples are 71.7% and 71.2%, respectively. Additionally, the tensile test shows that the residual plastic strain and the recovered strain for the first sample with 2 wt% Ag are equal to 0.7% and 3.0%, respectively. These results for the second sample with 3 wt% Ag are 1.2% and 3.4%, respectively.

Influence of Post-processing and Build Direction on the Wear Behaviour of Laser Powder Bed Fused Maraging Steel

Abstract Present study investigates the effect of post processing (heat treatment: solutionising at 850°C for 2 hr with aging at 490°C for 3 hr and cryogenic treatment at -196°C for 24 hr) and the effect of build direction (along the build direction (BD) and perpendicular to the build direction (PBD)) on the wear behavior of maraging steel fabricated by Laser powder bed fusion (LPBF). The results are also compared with conventional hot-forged samples. The pin on disc equipment was used to conduct the wear experiments with an EN31 steel disk as the counter body. Heat treatment decreased the wear rate of LPBF material by 54.78% and 83.84% in BD and PBD, respectively. This is due to the restriction of grain expansion by the Ni-based precipitants in age hardening treatment. The cryogenic treatment further decreased the wear rate of LPBF material by 87.84% and 90.9% in BD and PBD, respectively. This significant reduction can be attributed to the change of phase to martensite, as confirmed through microstructure and X-ray diffraction (XRD) analysis. Moreover, hot forged material also obtained a reduced wear rate after heat and cryogenic treatments. The highest wear resistance was found with the LPBF cryo-treated BD sample due to increased hardness from 388 HV to 640 HV. The worn surface of test samples was examined by using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), 3D profilometer, and XRD analysis. Oxidation wear, adhesive wear, and abrasive wear are the predominant wear mechanisms identified using SEM.

Segregation-dependent mechanical stability of reverted austenite and resultant tensile properties of Co-free maraging steel fabricated by wire-arc directed energy deposition

The segregation-dependent mechanical stability of reverted austenite (RA) and resultant tensile properties was investigated on Co-free maraging steel fabricated by wire-arc directed energy deposition (DED). The results showed that the segregation in the interdendritic regions enabled the formation of gradient reverted austenite in Co-free maraging steel fabricated by wire-arc DED when subjected to aging heat treatment. The content and mechanical stability of reverted austenite and resultant tensile properties were strongly dependent on the degree and compositional gradient of segregation in the interdendritic regions as well as the post heat treatment process. The reverted austenite with compositional gradient inherited from the segregation, transformed into martensite successively from the edge to the interior within individual reverted austenite grain at different strain levels. Besides, the variations in the degree and compositional gradient of segregation in the interdendritic regions widened the range the mechanical stability of the reverted austenite and thereby activating martensite transformation over a broad strain regime. Annealing process prior to aging could modify the degree and compositional gradient of segregation in the interdendritic regions and accordingly tune the content and the range of mechanical stabilities of reverted austenite grains, thus attaining a gradual and consistent transformation induced plasticity effect over whole deformation regime and thereby increasing ductility without sacrificing strength of Co-free maraging steel fabricated by wire-arc DED.

Hybrid additive manufacturing of aluminum matrix composites with improved mechanical properties compared to extruded counterparts

Great difficulties existed in fabricating large components of SiC particles reinforced aluminum matrix composites with excellent mechanical properties using existing manufacturing procedures. This study demonstrated that the challenges can be addressed by developing a hybrid solid-state additive manufacturing method. The influence of the deposition procedures and the post-processing heat treatment on the microstructure and mechanical properties of the SiC particles reinforced 2009 aluminum ally matrix composites (SiCp/2009Al composites) was systematically investigated using advanced technologies such as spherical aberration corrected transmission electron microscope, atom probe tomography, etc. The results showed that the SiCp/2009Al composites produced by the hybrid solid-state additive manufacturing exhibited enhanced tensile properties and improved isotropy in mechanical properties compared to the extruded feedstock of SiCp/2009Al composites. This was attributed to the formation of dense metal with uniformly distributed SiC particles, high-density of Cu–Mg co-clusters, refined grains and SiC particles, low deformation texture, tightly bonded SiCp/2009Al interface, and sound interfacial bonding between deposited layers.

Effect of Post-Processing Heat Treatment on Micro-Contact Damage of Zirconia-Reinforced Lithium Silicate Dental Materials.

Zirconia-reinforced lithium silicate (ZLS) is utilized as a material for prosthetic tooth crowns, offering enhanced strength compared to other dental glass-ceramics. In this study, we investigate a commercial ZLS material, provided in a fully crystallized form. We examine the effects of an optional post-processing heat treatment on micro-contact damage using controlled indentation tests simulating the primary modes of contact during chewing: axial and sliding. Our findings indicate that the heat treatment does not affect mechanical properties such as the elastic modulus, hardness and indentation fracture toughness. However, it does enhance the resistance to contact damage by fracture and chipping in both axial and sliding modes, as well as the resistance to crack initiation measured from sliding tests. This improvement is attributed to the refinement of the flaw population achieved through the heat treatment. The results are analysed using principles of contact and fracture mechanics theory, discussing their significance in prosthetic dentistry.

Synergistic enhancement of strength and ductility in novel solid-stir continuous extrusion: Influence of heterogeneous microstructure and alloy chemistry

Friction stir-derived solid-state processes leverage the synergistic effect of frictional heating and intense shear deformation to achieve localized microstructural modification for the improvement of mechanical properties. In the present work, a novel processing route called solid-stir extrusion (SSE) has been explored for continuous, high-rate extrusion of a high strength non-age-hardenable-AlMgSc alloy. In the current study, loss of strength associated with frictional heating during the process is mitigated as elevated strength is observed in as-extruded condition, thereby eliminating the need for post process heat treatment. The effect of process attributes on mechanical property and microstructure evolution was investigated. The SSE process caused extensive grain refinement and fragmentation of thermally stable Al3Sc intermetallic periodically at shear bands, which contributes to the elevated mechanical strength. The spatial variation in mechanical properties and microstructural heterogeneity was characterized using nanoindentation and microstructural correlation. The current findings indicate the significance of the process-specific alloy design approach to increase performance of material in as-processed condition.

Effect of solution treatment on the microstructure, phase transformation behavior and functional properties of NiTiNb ternary shape memory alloys fabricated via laser powder bed fusion in-situ alloying

Post-heat treatment is commonly employed to improve the microstructural homogeneity and enhance the mechanical performances of the additively manufactured metallic materials. In this work, a ternary (NiTi)91Nb9 (at.%) shape memory alloy was produced by laser powder bed fusion (L-PBF) using pre-alloyed NiTi and elemental Nb powders. The effect of solution treatment on the microstructure, phase transformation behavior and mechanical/functional performances was investigated. The in-situ alloyed (NiTi)91Nb9 alloy exhibits a submicron cellular-dendritic structure surrounding the supersaturated B2-NiTi matrix. Upon high-temperature (1273 K) solution treatment, Nb-rich precipitates were precipitated from the supersaturated matrix. The fragmentation and spheroidization of the NiTi/Nb eutectics occurred during solution treatment, leading to a morphological transition from mesh-like into rod-like and sphere-like. Coarsening of the β-Nb phases occurred with increasing holding time. The martensite transformation temperature increases after solution treatment, mainly attributed to: (i) reduced lattice distortion due to the Nb expulsion from the supersaturated B2-NiTi, and (ii) the Ti expulsion from the β-Nb phases that lowers the ratio Ni/Ti in the B2-NiTi matrix, which resulted from the microstructure changes from non-equilibrium to equilibrium state. The thermal hysteresis of the solutionized alloys is around 145 K after 20% pre-deformation, which is comparable to the conventional NiTiNb alloys. A short-term solution treatment (i.e. at 1 273 K for 30 min) enhances the ductility and strength of the as-printed specimen, with the increase of fracture stress from (613 ± 19) MPa to (781 ± 20) MPa and the increase of fracture strain from (7.6 ± 0.1)% to (9.5 ± 0.4)%. Both the as-printed and solutionized samples exhibit good tensile shape memory effects with recovery rates >90%. This work suggests that post-process heat treatment is essential to optimize the microstructure and improve the mechanical performances of the L-PBF in-situ alloyed parts.

Microstructure and texture control of Ni-Mn-Ga magnetic shape memory alloys manufactured by laser powder bed fusion

The Laser Powder Bed Fusion (LPBF) process was used to manufacture Ni-Mn-Ga polycrystalline samples. The initial powders with a fine particle size of about 20 µm were firstly prepared by a ball milling from melt-spun ribbons. The microstructure and texture evolution of Ni-Mn-Ga alloy manufactured by LPBF were investigated employing SEM, TEM, and synchrotron radiation diffraction. Using two different scanning strategies, optimization of laser parameters and post-processing heat treatment, a homogeneous microstructure with a strong crystallographic texture was obtained. The localized heating/cooling conditions allow obtaining a layered structure with preferred <100> fiber orientations along the growth direction. The crystal structure and crystallographic texture drastically change when the laser oscillation mode is chosen. The strong crystalline anisotropy and layered-type microstructure have a significant impact on twining flow behavior giving rise to an anisotropic mechanical response. The variant reorientation during mechanical training is realized by the so-called orthogonal shearing. It is also shown that the resulting crystal structure and characteristic transformation temperatures are strongly dependent on chemical composition related to Mn losses and internal stresses along with chemical order creating metastable phases due to the extremely high cooling rate upon the 3D printing. Therefore, all the above parameters are thoroughly monitored during the three-stage fabrication process.

Microstructure optimization of cold sprayed Ti-6Al-4V using post-process heat treatment for improved mechanical properties

Cold spray is a solid state additive process involving layer-by-layer deposition onto a substrate at supersonic speed. In contrast with conventional additive manufacturing routes, particles remain at temperatures below the melting point. This feature would be beneficial for titanium alloys through limiting oxidation and epitaxial growth of β grains during manufacturing. However, low strength and ductility were reported for as-deposited materials. In this study, pathways were explored to improve the tensile properties of cold sprayed Ti-6Al-4V. Heat treatments of deposits were carried out using different temperatures and cooling rates. In addition, some samples were manufactured using in situ shot peening to reduce porosity. The resulting microstructures and mechanical properties were thoroughly characterized using different techniques. This approach allowed to reach comparable, or even higher, tensile strength and ductility than its conventionally processed counterparts in spite of residual porosity. Microstructural features were analyzed to clarify this behavior and the relationships between microstructure and tensile properties of cold sprayed Ti-6Al-4V deposits. The outcome of this study leads to promising insights into the use of cold spray as an alternative additive manufacturing route for Ti alloys.

Residual Stress Mapping in Heat-Assisted Additive Manufacturing of IN 718: An X-Ray Diffraction Study

Laser powder bed fusion (LPBF) is a type of additive manufacturing (AM) technique characterized by multiple localized thermal processes that result in rapid heating and cooling. The thermal variations observed in the LPBF process can generate residual stress (RS) inside the fabricated part, impacting the surface integrity and geometric tolerances of the manufactured components. To reduce thermal variation during manufacturing, heat-assisted AM was employed, thereby minimizing RS and any thermal distortion that could occur during the fabrication of materials. The present research utilizes non-destructive x-ray diffraction to analyze the influence of an in-situ heated building plate and processing parameters on the RS distribution in Inconel 718 (IN718) fabricated by LPBF. This study examines the impact of two scanning procedures and three laser power levels and offers critical insights into both measurement techniques and RS characterization. By understanding the effect of the processing parameters on RS, we aim to enhance the quality of manufactured parts through process optimization. Post-processing heat treatment consistently reduced RS in all samples, regardless of laser power levels or scanning strategies. Combining a chess scanning strategy with 270 W laser power resulted in the most significant RS reduction in IN718.

Fabrication of large-scale steel-aluminum components with homogenously distributed amorphous interfacial layer and enhanced bonding strength using modified friction stir additive manufacturing

Large-scale components of steel and aluminum alloys (Fe-Al) with high bonding strength are highly needed from space exploration to the fabrication of transportation systems. The formation of detrimental intermetallic compounds at the Al-Fe interface has limited the application range of the Fe-Al components. The modified friction stir additive manufacturing was developed for fabricating large-scale Fe-Al components with homogenously distributed interfacial amorphous layers rather than detrimental intermetallic compounds. The interfacial amorphous layers comprised an Mg-O rich amorphous layer < 20 nm in thickness and an Al-Fe-Si amorphous layer < 120 nm in thickness. The interfacial amorphous layers exhibited high thermal stability and did not change even after the post-processing heat treatment of heating at 500 °C for 20 min and aging at 170 °C for 7 h. The tensile strengths of the Fe-Al tensile specimens were increased from 160 to 250 MPa after the application of the post-processing heat treatment. The fracture occurred in the aluminum alloys instead of at the dissimilar metal interface, demonstrating that high bonding strength at the Al-Fe interface was enabled by the formation of homogenously distributed interfacial amorphous layers.

Tailoring friction stir welding and postheat treatment of high-carbon steels to obtain nanostructured bainite

Conventional welding processes destroy the unique microstructural characteristics in nanobainitic steels. A novel method, i.e. tailored friction stir welding (FSW) and postheat treatment, was employed to overcome this problem. The postprocessing austempering was carried out on friction stir welded high-carbon steel to obtain nanobainite, and obtained microstructural characteristics were compared to that achieved by simple isothermal bainite transformation. Bainitic sheaves and austenite microblocks could be achieved in both production procedures. However, bainitic ferrites and austenite films within the bainitic sheaves were thinner, and austenite microblocks were finer when implementing the post-processing heat treatment after FSW. FSW enhanced the hardness of the primary steel from 385 HV to above 800 HV, which was maintained at about 520 HV even after post-heat treatment, higher than that of after implementing the isothermal bainite transformation (490 HV). This achievement can be related to FSW that reduced the mean diameter of austenite blocks, the thickness of bainitic ferrite, and the thickness of austenite films from 3820, 138, and 122 nm to 2200, 92, and 78 nm, respectively. Moreover, the microstructure and hardness of various microstructural zones of friction stir welded sample before and after heat-treatment were analyzed and discussed in detail. The outcome of this study can be applied in academic and industrial areas to propose a cost-effective method to weld nanobainitic steels.

Electrochemical deposition of hydrothermally pretreated TiO2 on aluminium substrate through the formation of peroxotitanium complex and their application towards visible light assisted photocurrent generation

Herein, we report a novel method for the electrochemical deposition of TiO2 on Al substrate through the formation of peroxotitanium complex without any post heat treatment process. The alkaline treated titanium precursors were used as an electrolyte and TiO2 was deposited onto aluminium substrate by both cathodic reduction and electrophoretic deposition through the formation of peroxotitanium complex. The electrodeposition process was optimized by varying the pH, concentration of the electrolyte, deposition voltage, time and area of the electrode respectively. The optimized condition to obtain a maximum yield is as follows: voltage (4.5 V), time (2.5 h), pH (5) and area of the electrode 3 × 3 cm2. The deposits were then characterized using various material characterization techniques such as high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and Raman spectroscopy respectively. The morphological analysis showed the deposition of nanocrystalline TiO2 with irregular morphology on Al substrate. The AFM revealed a non-uniform deposition of TiO2 with high surface roughness (average roughness: 44.60 nm). The XRD pattern and Raman spectrum confirmed the presence of anatase phase of TiO2. The obtained TiO2 were then subjected to photoelectrochemical studies by coating over an ITO electrode. The nanocrystalline TiO2 showed excellent photocurrent response which could be due to the short hole retrieval and fast electron transport across the electrode-electrolyte interface. The proposed method can be promising towards the industrial application for the extraction and recovery of TiO2 from the mineral ore residues and spent mining waste.

Direct artificial aging of the PBF-LB AlSi10Mg alloy designed to enhance the trade-off between strength and residual stress relief

The AlSi10Mg alloy is one of the most studied alloys processed by the Powder Bed Fusion-Laser Beam (PBF-LB). Many already published works focus on post-process heat treatments to reduce residual stress or improve mechanical strength. Instead, the present study aims to identify direct artificial aging (AA) heat treatment able to optimize both aspects, thus enhancing the trade-off between strengthening and residual stress relief for the PBF-LB AlSi10Mg alloy produced using a no-heated platform. Higher temperatures (190–240 °C) than those typically used in AA heat treatment were selected based on thermal analysis to benefit both residual stress relief and precipitation of reinforcing phases from the supersaturated solid solution of the metastable as-built alloy. The effects of AA heat treatment on mechanical properties (i.e. hardness) and residual stress were evaluated by plotting aging curves and by XRD and Raman analyses and demonstrated that different trade-offs between strengthening and stress relief can be achieved by tuning heat treatment parameters (temperature and time). In particular, the exposure at the lowest temperature (190 °C) induced a partial decrease in residual stress and a slight increase in hardness. By increasing heat treatment temperature and soaking time, the relief was more significant, whilst the decrease in hardness was rather limited. The results are supported by the microstructural changes observed on the samples due to the different heat treatment conditions applied and show the feasibility of designing an AA heat treatment for the PBF-LB AlSi10Mg alloy capable of satisfying the mechanical response required by the final application.

Tailoring heat treatment for AlSi7Mg0.6 parts with as-built surface generated by laser powder bed fusion to reduce surface roughness sensitivity

The most important advantage of additive manufacturing by laser powder bed fusion (PBF-LB) technique is the ability to produce geometrically complex parts, but the problem is their rough surfaces, often difficult or inaccessible to finish by machining. Therefore, research to improve the reproducibility of the mechanical behavior of parts manufactured from aluminum alloy powders with as-built surfaces is of vital importance for the aerospace and automotive industries. Since local notches occurring on rough surfaces after the PBF-LB process are unavoidable, the way to solve this problem is to obtain as-built surfaces of the highest possible quality and to adapt a post-process heat treatment that increases the ductility and fracture toughness of the material. To this end, the present work focused on the study of the mechanical performance of AlSi7Mg0.6 samples with a rough as-built surface in the as-built state and after several variants of post-process heat treatment, combined with a detailed analysis of the microstructures corresponding to these states. Tensile samples built on a platform preheated to 100 °C, achieved a relative density of 99.85%, satisfactory surface quality, a relatively low level of residual stress and moderate crystallographic texture. Despite the rough surface, the samples under the as-built condition and after different variants of heat treatment (direct aging (DA), stress relieving (SR), and solution annealing followed by artificial aging (T6)), achieved tensile properties comparable to those reported in the literature for PBF-LB samples with machined surfaces. The resulting combinations of tensile properties of PBF-LB samples after different heat treatment variants were evaluated using the quality index (QI) commonly used to assess the quality of heat-treated Al-Si-Mg castings. It was found that the proposed T6 treatment provides the best combination of strength properties and ductility, compared to those obtained after both DA and SR, as well as after T6 treatment of high-quality castings, from the point of view of reducing the sensitivity of AlSi7Mg0.6 alloy to surface roughness.

Influence of the LPBF Process Parameters on the Porosity of the AlSi10Mg Alloy

Abstract: Laser powder bed fusion (LPBF) process has a great ability to produce complex AlSi10Mg 3D components with uncommon degrees of freedom for broad span of applications in different industries. Presence of the microstructural imperfections such as porosity, dependent on the parameters of the process can be detrimental to the printed products for different engineering applications. Parameters of the process and different post-processing heat and surface treatments are recognized for decrease of the occurrence of microstructural defects and for the improvement of the mechanical properties. The influence of laser power by applying four different laser speeds at one layer thickness with a constant hatch distance, on the microstructure and microhardness of the AlSi10Mg alloy was examined in this paper. The goal of the research was to determine whether increasing the laser speed will have a significant impact on the change in microstructure and the appearance of porosity in the tested samples.

Determining the Effects of Inter-Layer Time Interval in Powder-Fed Laser-Directed Energy Deposition on the Microstructure of Inconel 718 via In Situ Thermal Monitoring.

Cylindrical Inconel 718 specimens were fabricated via a blown-powder, laser-directed energy deposition (DED-L) additive manufacturing (AM) process equipped with a dual thermal monitoring system to learn key process-structure relationships. Thermographic inspection of the heat affected zone (HAZ) and melt pool was performed with different layer-to-layer time intervals of ~0 s, 5 s, and 10 s, using an infrared camera and dual-wavelength pyrometer, respectively. Maximum melt pool temperatures were found to increase with layer number within a substrate affected zone (SAZ), and then asymptotically decrease. As the layer-to-layer time interval increased the HAZ temperature responses became more repetitive, indicating a desirable approach for achieving a more homogeneous microstructure along the height of a part. Microstructural variations in grain size and the coexistence of specific precipitate phases and Laves phases persisted among the investigated samples despite the employed standard heat treatment. This indicates that the effectiveness of any post DED-L heat treatment depends significantly on the initial, as-printed microstructure. Overall, this study demonstrates the importance of part size, part number per build, and time intervals on DED-L process parameter selection and post-process heat treatments for achieving better quality control.

Tailoring microstructure and mechanical properties of 17-4PH steel fabricated by wire-arc directed energy deposition via a combination of intrinsic and post-processing heat treatments

This paper examines the effect of intrinsic heat treatment, i.e., multiple transient heating from subsequent passes, and post-processing heat treatment on the microstructure and mechanical properties of 17–4PH stainless steel fabricated by wire-arc directed energy deposition. By carefully controlling the interpass temperature to remain below the martensite start (Ms) temperature, intrinsic heat treatment effectively triggers the formation of Cu-rich clusters and the reversion of austenite. This approach results in a concurrent enhancement in the ultimate tensile strength, increasing from 1036 MPa to 1128 MPa, and elongation, increasing from 13.2% to 18.5%, for the as-built part. During post-processing heat treatment, the microstructural response to direct aging treatment hinges on the initial microstructure induced by intrinsic heat treatment. Notably, direct aging treatment significantly enhances the hardness and ultimate tensile strength of the as-built part created at an interpass temperature surpassing the Ms temperature. Conversely, its influence on the mechanical properties of the as-built component, fabricated at an interpass temperature lower than the Ms temperature, remains minimal. Additionally, the application of a solution treatment effectively eradicates the inherent microstructural characteristics, regardless of the initial fabrication conditions. Nonetheless, the grain size of the solution-treated specimen is markedly influenced by the as-built microstructure. Ultimately, a judicious amalgamation of intrinsic and post-processing heat treatments yields an exceptional combination of properties, including high hardness (465 HV), ultimate tensile strength (1437 MPa), and elongation (14.5%). These results underscore the significance of a comprehensive consideration of intrinsic and post-processing heat treatments to tailor the microstructure and mechanical properties of 17–4PH steel fabricated by wire-arc directed energy deposition.