Hot Isostatic Pressing Temperature Research Articles

Generation and propagation mechanism of cracks in welded joints of thin-walled capsules during hot isostatic pressing

The quality of the capsule has an important effect on the quality of hot isostatic pressing (HIP) products. The reliability of the capsule is a key factor in determining the success or failure of HIP. The capsule is mainly formed through a sheet welding process. In order to ensure the reliability of the weld in HIP, stainless steel with better high-temperature and high-pressure performance than Q235 steel needs to be used. In this case, the fusion line becomes a dissimilar-material interface, which is more prone to fusion-line failure. This paper focuses on examining and studying the formation mechanism of fusion line cracks in welded joints during HIP. The results show that, first, the increase of the HIP temperature weakens the strength near the fusion line significantly. Second, the higher the HIP temperature, the more severe the grain coarsening, and the grain size along the radial direction of the capsule exhibits a monotonic change. Third, since the HIP process changes the micro-zone grain orientation of mild steel, the distribution characteristics of ferrite and pearlite change as well. when the temperature and pressure are higher, the texture still exhibits a strong and complex distribution.

Revealing the impact of Hot Isostatic Pressing temperature on the microstructure and mechanical characteristics of Selective Laser Melted CuAlNiMn shape memory alloy

The present research examines the impact of temperature during Hot Isostatic Pressing (HIP) on the mechanical, microstructure, and density characteristics of Cu-based shape memory alloys (SMAs) made by Selective Laser Melting (SLM). HIP improved the density of the built components by 11.5 %, with a reduction in density with an increase in HIP temperature. Pore aspect ratio analysis revealed non-spherical pores at higher temperatures, while spherical and small pores were observed at 950 °C. SEM analysis demonstrated the disappearance of shrinkage porosity and an increase in grain size with higher HIP temperatures. XRD analysis confirmed phase transformation and variation in crystallite size with an increase in HIP temperature. After HIP treatment, microhardness and tensile strength significantly improved, with the 950 °C sample showing the highest values.

Postprocessing of tungsten carbide‐nickel preforms fabricated via binder jetting of sintered‐agglomerated powder

AbstractThis study binder jets a tungsten carbide‐nickel (WC‐Ni) sintered‐agglomerated composite powder, and postprocesses the preforms using an initial sintering step followed by a hot isostatic pressing (HIP) step. The effects of sintering temperatures, sintering durations, and HIP temperatures on notable properties (e.g., porosity, microstructure, hardness, and oxidation behavior) are quantified. The highest average relative density produced in this study was 96.8%, and volumetric shrinkage of these coupons was about 64%. Microstructural characterization shows that the WC grains are homogenously distributed throughout the nickel matrix and grow to an average diameter of 1.6 (a 60% increase) during processing. X‐ray diffraction patterns indicate that no unwanted products were formed. Processed coupons achieved a maximum hardness of 54 Rockwell C, limited by their internal porosity. Oxidation tests result in the production of WO3 and NiWO4 at temperatures above 600°C. Methodologies and results from this study can be leveraged to additively manufacture highly dense, geometrically complex WC‐Ni parts with small carbide grains, low nickel content, desirable microstructure, and suitable functional properties.

Evolution Behavior of Rapidly Solidified Microstructure of a Ti-48Al-3Nb-1.5Ta Alloy Powder during Hot Isostatic Pressing

In this study, Ti-48Al-3Nb-1.5Ta powders were manufactured from cast bars by the supreme-speed plasma rotating electrode process (SS-PREP) and used to prepare hot isostatically pressed (HIPed) material at 1050–1260 °C with 150 MPa for 4 h. The phase, microstructure and mechanical performance were analyzed by XRD, SEM, electrical universal material testing machine and other methods. The results revealed that the phase constitution changed from γ phase to α2 phase and then to γ phase with the material changing from as-cast to powders and then to as-HIPed. Compared with the as-cast material, the grain size and element segregation were significantly reduced for both powders and as-HIPed. When the hot isostatic pressing (HIP) temperature was low, the genetic characteristics of the powder microstructure were evident. With the HIP temperature increasing, the homogeneity of the composition and microstructure increased, and the prior particle boundaries (PPBs) gradually disappeared. The elastic moduli of powder and as-HIPed were superior to those of as-cast, which increased with the HIP temperature increasing. The hardness of as-HIPed was lower than that of the powder. The compressive strength, compressive strain, bending strength, and tensile strength of as-HIPed were higher than those of as-cast. With an increase in the HIP temperature, the compressive strength decreased gradually, and the compressive strain first decreased and then increased.

Simultaneously improved the strength and ductility of laser powder bed fused Al-Cr-Fe-Ni-V high-entropy alloy by hot isostatic pressing: Microcrack closure and precipitation strengthening

Hot isostatic pressing (HIP) is usually applied to reduce the defects including cracks and pores in the materials prepared by laser powder bed fusion (LPBF). In the present research, in order to improve the relative density and mechanical property, HIP was employed on the LPBF-processed Al-Cr-Fe-Ni-V high-entropy alloy (HEA) with microcracks and pores. The microstructure evolution and property improvement induced by HIP were investigated. In the LPBF-processed HEA, the microcracks were caused by residual stress and element segregation, and these microcracks as well as the pores reduced significantly after HIP treatments. Remarkably, HIP temperature has a more critical effect on the microcrack closure than the holding time, thus, microcracks and pores still existed after HIP-1 treatment (1273 K, 8 h), while HIP-2 treatment (1473 K, 4 h) could close the microcracks significantly. The crack closure was attributed to the interfacial diffusion of the alloying element under high temperature accompanied by high pressure, and the degree of element diffusion at both interfaces of the cracks determined the bonding strength after crack closure. Higher temperatures at high pressure induced more adequate element diffusion and higher bonding strength. The above high temperature and high pressure also induced the growth of the L12 phase and the precipitation of the B2 phase in HEA. Consequently, the tensile strength and elongation of the LPBF-processed HEA after HIP-2 treatment were simultaneously enhanced (80.7% and 222.5% higher than that of LPBF-processed HEA, respectively). This could be attributed to the combined effect of microcrack/pore closure and precipitation strengthening. The strengthening effect of the B2 phase and L12 phase accounted for 53% (dislocation by-pass mechanism) and 47% (dislocation shearing mechanism) of the total precipitation strengthening, respectively.

Effects of HIP Process Parameters on Microstructure and Mechanical Properties of Ti-6Al-4V Fabricated by SLM

Ti-6Al-4V titanium alloy products formed by selective laser melting (SLM) are characterized by high strength and low plasticity. In addition, there may be pores inside the material, which may become a fracture sprouting point and accelerate the failure of the parts. Using an optical microscope (OM), scanning electron microscope (SEM), and electronic universal testing machine, the effects of hot isostatic pressing (HIP) parameters on the microstructure and tensile property of SLM-formed Ti-6Al-4V titanium alloy were investigated. The results show that HIP performed below the β-phase transition temperature, and the structure of the Ti-6Al-4V titanium alloy is composed of an α phase and β phase. With the increase in the HIP temperature, the α lath coarsens into a short rod, the content of the β phase increases and coarsens, and the tensile strength and yield strength of Ti-6Al-4V show a decreasing trend. With an HIP process performed at a temperature of 910 °C and pressure of 130 MPa for 2 h, the Ti-6Al-4V titanium alloy obtains the best matching of strength and plasticity.

Hybrid laser powder bed fusion and hot isostatic pressing of Ti-6Al-4V parts without degassing for process efficiency

Despite gaining widespread adoption, the slow production speed of Laser Powder Bed Fusion (LPBF) remains a challenge. To address this issue, some studies have proposed a hybrid approach where the outer region (“shell”) of a part is processed by LPBF and powder-filled internal region (“cavity”) is consolidated via hot isostatic pressing (HIP). Typically, the cavity is designed to be externally accessible to degas trapped Ar gas. This, however, restricts design freedom and adds an additional processing step. Therefore, this study investigates the viability of using HIP to consolidate non-accessible powder-filled cavities in an LPBF Ti-6Al-4V part through microstructures analysis and tensile behavior. For comparison, samples were also fabricated via conventional HIP using the same powder. When HIP was performed at 850 °C or 930 °C, globularisation of the α phase occurred in the powder particles resulting in an equiaxed microstructure as opposed to the lamellar microstructure found in the shell. At 1010 °C, however, rapid grain growth in the β phase field resulted in a similar coarsened microstructure across the entire material upon cooling. Despite trapped Ar in the cavities, only ~0.5 % porosity remained regardless of the HIP temperature. Tensile failure always occurred within the cavity region which highlights the excellent bond across the shell/cavity interface. Strengths were similar between the hybrid and the conventional HIP samples, though the former had poorer total elongation (~10 %) due to remnant porosity. Higher HIP temperatures resulted in poorer strength while HIP at 930 °C, displayed the best elongation.

Microstructure and Stress Rupture Properties of K417G Superalloy at Different Hot Isostatic Pressing Temperatures

The effect of hot isostatic pressing (HIP) on the stress rupture property of K417G nickel-based superalloy is studied experimentally. The results show that the stress rupture property of the alloy is improved by the appropriate HIP process. After HIP, the average microporosity of alloy after HIP is 0.04%, which is reduced by nearly 90% compared with the as-cast microstructure. The cubic γ′ precipitates grow up, accompanied by the precipitation of the fine γ′ phase in the matrix. In addition, the area fraction of (γ + γ′) eutectic decreases, dendritic segregation is improved, and the element distribution is homogenized. As the HIP temperature increased from 1175°C to 1195°C, the microporosity and eutectic are further reduced slightly. The stress rupture life at 760°C and 645 MPa of alloys after HIP at 1175°C and 1185°C increased by 90 h and 20 h, respectively, compared with the as-cast alloy, but it is not the case for HIP at 1195°C. In addition, the elongation after HIP is increased by about 60% compared to the as-cast alloy, with an average of 4.7%. The changes in the γ′ phase and the deformation mechanism after HIP are discussed.

Effects of HIP Conditions on the Microstructure and Creep Properties of Ni-base Superalloy Fabricated by Laser Powder Bed Fusion

Ni-base superalloy (IN718) manufactured by laser powder bed fusion (L-PBF) was subjected to hot isostatic pressing (HIP) under various conditions. The effects on microstructure and defects in the builds were investigated, and tensile strength at room and high temperatures and tensile creep properties were evaluated. After HIP at lower temperature, Laves phase in as-built specimen was dissolved and the δ phase was precipitated. However, the δ phase dissolved in the matrix as the HIP temperature increased. When the HIP temperature was less than 1323 K, the tensile strength was almost as high as the forged specimen. The creep rupture strain increased with increasing HIP temperature and was the highest at 1393 K. However, the strain was lower than that of the forged specimen. It was found that there was a factor that reduce the creep rupture strain specific to the HIP specimens.

The optimisation of hot isostatic pressing treatments for enhanced mechanical and corrosion performance of stainless steel 316L produced by laser powder bed fusion

This work compares the mechanical and corrosion properties of 316L steel manufactured by Laser Powder Bed Fusion (LPBF) and post treated by Hot Isostatic Pressing (HIP) to wrought 316L. HIP is often used by default on LPBF components to reduce porosity and obtain the best mechanical properties, however, if the HIP temperatures are too high, there is a risk of reducing mechanical strength and corrosion resistance. The purpose of this work was to investigate the HIP parameters and understand the trade-off in properties. By choosing various HIP temperatures (700 °C, 1125 °C, 1200 °C), pressures (100 MPa, 137 MPa and 200 MPa) and hold times, optimal cycles were investigated based on the most favourable mechanical properties (density, hardness, tensile and low-cycle fatigue), and pitting corrosion resistance. Microstructural features associated with LPBF such as melt pools, melt pool boundaries and sub granular cells were observed. These features were found to disappear with longer and higher temperature treatments, accompanied by increased grain sizes. Low and mid temperature point HIP treatments resulted in higher ultimate tensile strength but lower fracture elongation. The decreasing hardness and tensile strength trends were consistent with decreased grain boundary strengthening and decreased dislocation strengthening (with disappearing sub grain boundary and granular cells). Only one HIP condition, consisting of a low temperature and medium pressure, produced samples that achieved runout under low cycle fatigue testing for both the lower and higher stresses. Despite this, most higher temperature HIP cycles reduced the fatigue resistance. This was again attributed to the coarsening of the microstructure at the higher temperature treatments. The spread of the pitting potentials of HIP treated samples was reduced by 52.46 % compared to the as-built material, although none were better overall compared to the wrought material. Of all the properties, porosity appears to play the most influential role on pitting corrosion, and to this extent, despite having a larger variation in results, some of the treated parts demonstrated improved pitting resistance and some demonstrated improved repassivation potentials compared to wrought 316L.

Understanding on processing temperature-metallographic microstructure-tensile property relationships of third-generation nickel-based superalloy WZ-A3 prepared by hot isostatic pressing

A third-generation powder metallurgy nickel-based superalloy (WZ-A3) was prepared by hot isostatic pressing (HIP) at 1100 °C, 1150 °C, 1200 °C, and 1250 °C, respectively. The characteristics of grains, precipitates, and elemental distribution revealed its microstructural development. The samples prepared at a sub-solvus temperature (1100 °C) consisted of fine recrystallized grains and dendritic structures. However, the microstructure became a completely recrystallized structure when the HIP temperature reached or exceeded 1150 °C. The average grain size increased from 4.0 µm (1100 °C) to 53.1 µm (1250 °C) due to the promoted recrystallization and atom diffusion rate. Prior particle boundaries (PPBs) with continuously distributed precipitates were identified as a mixture of (Nb, Ti)C carbides and Hf0.5Zr0.5O2 oxides. By increasing the HIP temperature from 1100 °C to 1200 °C, the PPBs were reduced but not eliminated. As a result, samples prepared at 1200 °C experienced interparticle debonding with relatively high strengths, and the ultimate tensile strength values were 1388.7 MPa and 1228.3 MPa at room temperature (RT) and 700 °C, respectively. When the HIP temperature was 1250 °C, the presence of coarse grains, large carbides, as well as eutectic structures formed at the junction of grain boundaries caused dramatic drops of tensile strengths and brittle fractures. These results emphasized the importance of parameter optimization for controlling the microstructure and mechanical properties during the HIPing process.

Fabrication, microstructure, and properties of 8 mol% yttria-stabilized zirconia (8YSZ) transparent ceramics

Fine grained 8 mol% yttria-stabilized zirconia (8YSZ) transparent ceramics with high optical and mechanical properties were fabricated by air pre-sintering and hot isostatic pressing (HIP) using commercial 8YSZ powders as the raw material. The pre-sintered ceramics with fine grains and appropriate relative density play a key role to achieve high transparency and suppressed grain size after HIP post-treatment at relatively low temperatures. With the increase of HIP temperature from 1350 to 1550 °C, the in-line transmittance of 8YSZ ceramics at 600 nm increases from 56.9% to 71.5% (2.5 mm in thickness), and the average grain size increases from 2.4 to 16.3 µm. The corresponding bending strength of 8YSZ transparent ceramics decreases from 328±20 to 289±19 MPa, the hardness (H) decreases from 12.9±0.1 to 12.5±0.2 GPa, and the fracture toughness (KIC) decreases from 1.30±0.02 to 1.26±0.03 MPa·m1/2. Systematical investigations were carried out to study the combination of high optical transparency and excellent mechanical properties in 8YSZ ceramics.

Hot isostatic pressing of laser powder-bed-fused 304L stainless steel under different temperatures

Hot isostatic pressing (HIP) is becoming a key strategic technology for post-processing metallic materials fabricated with laser powder bed fusion (LPBF), acting to eliminate the processing-induced pores and improve the mechanical properties. This paper comprehensively investigated material characteristics (porosity, residual stress, microstructures, phase composition, and inclusion), mechanical properties (microhardness, tensile properties, and fatigue properties), and deformation behaviors of LPBF 304L austenitic stainless steel (ASS) subjected to HIP process with different temperatures (965°C, 1165°C, and 1365°C). Experimental results indicated that the grain size, inclusion size, recrystallization fraction, and dimple size increased with increasing HIP temperature, which resulted in homogenized microstructure, reduced yield strength and microhardness, and significantly improved ductility. The fatigue life of HIP-treated samples after surface post-treatment was mainly influenced by porosity, inclusion, residual stress, and dislocation density. The HIP-1165°C samples with low porosity and small-sized inclusions had a higher fatigue life than HIP-965°C and HIP-1365°C samples. In addition, the evolution of crystallographic texture and inclusion composition associated with the HIP temperature were systematically revealed with the aid of orientation distribution function (ODFs) and elemental mappings. This study provides a profound understanding of the rational design of the hybrid process of LPBF and HIP.

The Mechanical Behavior and Microstructure of Additively Manufactured Ti6AI4V for Different Material States and Loading Conditions

AbstractSelective laser melting (SLM) of Ti6Al4V is a very promising method to produce complex geometries for challenging impact applications. Hot isostatic pressing (HIP) is typically used to improve fatigue behavior, ductility and material reliability of parts produced by SLM. However, this treatment leads to an undesired deterioration of strength. The present study addresses that issue by investigating the effect of two different HIP conditions on the mechanical properties under compression and tensile loading for a strain rate range spanning up to 6 order of magnitudes and two different temperatures. We found a significant tensile-compression anisotropy in both flow stress and strain rate sensitivity depending on the HIP temperatures. These findings was correlated with microstructures and damage mechanisms.

Fundamental aspects of functional grading via powder hot isostatic pressing – Development of microstructure and diffusional processes

Functional grading of a ferritic steel (SA508 grade 3) and austenitic stainless steel (316L) powder via hot isostatic pressing (HIP) consolidation is investigated as an alternative to dissimilar welding. Fundamental aspects of this method such as the development of microstructure and diffusional processes during the HIP process of such mixed powder are studied in this work. A change of the post-HIP α to γ ratio with HIP temperature was observed in mixed powder specimens, combined with the formation of a ferritic lath zone which affects the properties of the specimens (throughout this work the term ferritic laths refers to a ferritic phase of unknown structure which is likely to consist of martensite, bainite or a mixture of both). These effects were attributed to extensive diffusion of alloying elements from 316L into SA508 grade 3. Simulation and experimental quantification of diffusion in diffusion couple experiments were applied to derive an empirical model for estimating α-Fe boundary migration and the formation of the ferritic lath zone and phase fractions for various temperatures and dwell times of the HIP process.

The effects of hot isostatic pressing temperature on the structure and properties in GdMnO3 ceramics

In this paper, the effects of hot isostatic pressing (HIP) temperature on the crystal structure, optical, dielectric and magnetic properties of GdMnO 3 ceramics were studied. All samples form a single-phase structure without structural transformation, while HIP temperature induces the changes in lattice parameters. HIP causes the change in Mn ions valence state, oxygen vacancy concentration, Raman vibration modes and microscopic morphology of GdMnO 3 . Vacancy concentration of the samples prepared by HIP at 800 °C increases compared with that of the samples without HIP, then remains unchanged when the HIP temperature is from 800 to 900 °C, and finally decreases with the further increase of HIP temperature. Appropriate HIP temperature can increase the dielectric constant and decrease the dielectric loss. The transition temperature of paramagnetism to antiferromagnetism and magnetization can be significantly affected by HIP temperature. Magnetic transition temperature and magnetization are closely related to Mn 2+ ions concentration and cation vacancy concentration, respectively.

Effect of HIP at 1000–1200 °C on microstructure and properties of extruded Be-Ti composites

Solid titanium beryllide blocks will be used for neutron multiplication in the helium-cooled pebble bed (HCPB) blanket concept of EU DEMO. A combination of hot extrusion of Be-Ti powders and subsequent hot isostatic pressing (HIP) of the obtained Be-Ti composites has been proposed for manufacturing such blocks. This work is devoted to the study of the effect of HIP at 1000–1200 °C on the structure and properties of Be-Ti composites in order to optimize the HIP parameters. The HIP at 1000–1200 °C resulted in an almost single-phase titanium beryllide (TiBe12) with small amounts of Be and other phases, which gradually dissolve with an increase in the HIP temperature. Such a treatment at 1000 and 1100 °C provides a very fine-grained microstructure of TiBe12 with an average grain size of 0.3 and 0.6 μm, respectively. The resulting titanium beryllide is characterized by high microhardness of 1350–1480HV0.1 depending on the HIP temperature. According to the nanoindentation tests of the Be-Ti composite after HIP at 1100 °C, the indentation modulus of TiBe12 can be estimated as 295GPa. The fracture toughness of the TiBe12 was determined as 1.5–1.7 MPa·m1/2. The temperature of 1100 °C was chosen as optimal for the HIP of Be-Ti composites after hot extrusion. The titanium beryllide obtained in this way was used to manufacture a reduced size mockup of Ø20mm × 18 mm. The mockup has no visible surface defects and can be used for further experiments.

Simulation of Hot Isostatic Pressing in a Single‐Crystal Ni Base Superalloy with the Theory of Continuously Distributed Dislocations Combined with Vacancy Diffusion

Single‐crystal components made of nickel base superalloys contain pores after casting and homogenization heat treatment. Hot isostatic pressing (HIP), which is carried above the ‐solvus temperature of the alloy, is industrially applied to reduce porosity. A modeling of HIP based on continuously distributed dislocations is developed in a 2D setting. Glide and climb of straight‐edge dislocations, as well as vacancy diffusion, are the deformation mechanisms taken into account. Thereby, dislocation glide is controlled by dragging a cloud of large atoms, and climb is controlled by vacancy diffusion. Relying on previous investigations of the creep behavior at HIP temperatures, it is assumed that new dislocations are nucleated at low‐angle boundaries (LAB) and move through subgrains until they either reach the opposite LABs or react with other dislocations and annihilate. Vacancies are created at the pore surface and diffuse through the alloy until they are either consumed by climbing dislocations or disappear at the LABs. The field equations are solved by finite elements. It is shown that pore shrinking is mostly controlled by vacancy diffusion as the shear stresses at the LABs are too low to nucleate a sufficient amount of dislocations.

Evolution of Microstructure and Elements Distribution of Powder Metallurgy Borated Stainless Steel during Hot Isostatic Pressing

Prepared by powder metallurgy process incorporating atomization and hot isostatic pressing (HIP) sintering at six different temperatures from 600 to 1160 °C, borated stainless steel (BSS) containing boron content of 1.86 wt% was studied. The phase of BSS, relative density of different temperature, microstructure, elemental distribution, and mechanical properties were tested and analyzed. The phases of the alloy were calculated by the Thermo-Calc (2021a, Thermo-Calc Software, Solna, Sweden) and studied by quantitative X-ray diffraction phase analysis. The distributions of boron, chromium, and iron in grains of the alloy were analyzed by scanning electron microscopy and transmission electron microscope. The grain size distributions and average grain sizes were calculated for the boron-containing phases at 900, 1000, 1100, and 1160 °C, as well as the average grain size of the austenite phase at 700 and 1160 °C. After undergoing HIP sintering at 900, 1000, 1100, and 1160 °C, respectively, the tensile strength and ductility of the alloy were tested, and the fracture surfaces were analyzed. It was found that the alloy consisted of two phases (austenite and boron-containing phase) when HIP sintering temperature was higher than 900 °C, and the relative density of the prepared alloys was higher than 99% when HIP temperature was higher than 1000 °C. According to the boron-containing phase grain size distribution and microstructure analysis, the boron-containing phase precipitated both inside the austenite matrix and at the grain boundaries and its growth mechanism was divided into four steps. The tensile strength and elongation of alloy were up to 776 MPa and 19% respectively when the HIP sintering was at 1000 °C.

Effects of hot processes on microstructure evolution and tensile properties of FGH4096 Ni-based superalloy processed by Laser Powder Bed Fusion

Hot Isostatic Pressing (HIP) is one of the most important manufacturing processes to improve the performance of powder metallurgy nickel-based superalloys produced by Laser Powder Bed Fusion (LPBF), which can effectively reduce the pores and cracks in the LPBF alloys. However, there are limited studies on the effects of tuning HIP parameters on the LPBF alloys microstructure and mechanical performance. In this paper, we systematically studied the effects of hot processes on the microstructural evolution and tensile properties of an LPBF prepared typical second generation of powder metallurgy (PM) nickel-based superalloy which was designated as FGH4096. The as-deposited alloy was HIP treated at sub-solvus, solvus, and super-solvus temperature, respectively, followed by an optimized heat treatment (HT). The effects of HIP temperature on the microstructures and mechanical properties of the LPBF alloys were studied by Optical Microscope (OM), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM) and Electron Backscattered Diffraction (EBSD). The results indicated that both HIP and HT processes led to recovery and recrystallization in the as-deposited alloy. During HIP, the increase of HIP temperature gradually eliminated the dendritic and equiaxed structures in the alloy while refined the grains along the long axis simultaneously. However, the columnar crystal morphology in the vertical section, together with straight grain boundaries, was still maintained during HIP. In all the HIPed alloys, the secondary γ′ precipitates were sparsely distributed, and due to the existence of continuous pressure, some grains with large strains remained. After HIP + HT, the dendritic and equiaxed structures basically disappeared. The grains with more curved grain boundaries tended to be equiaxed and irregularly shaped. Compared with other state alloys, the LPBF + HIP (solvus) + HT alloy has a more uniform and dense distribution of secondary γ′ precipitates, together with a chain distribution of block primary γ′ precipitates at the grain boundaries, which contributes mostly to the highest room and high-temperature tensile strengths. Moreover, the LPBF + HIP (solvus) + HT alloy has the lowest internal strain among the treated alloys, leading to the highest elongation.