Effect Of Post Heat Treatment Research Articles

Effects of Post-Heat Treatment and Carbide Precipitates on Strength-Ductility Balance of GH3536 Superalloy Prepared by Selective Laser Melting

Effects of Post-Heat Treatment and Carbide Precipitates on Strength-Ductility Balance of GH3536 Superalloy Prepared by Selective Laser Melting

Dynamic Response of Ti-6Al-2Zr-1Mo-1V Alloy Manufactured by Laser Powder-Bed Fusion.

Titanium parts fabricated by additive manufacturing, i.e., laser or electron beam-powder bed fusion (L- or EB-PBF), usually exhibit columnar grain structures along the build direction, resulting in both microstructural and mechanical anisotropy. Post-heat treatments are usually used to reduce or eliminate such anisotropy. In this work, Ti-6Al-2Zr-1Mo-1V (TA15) alloy samples were fabricated by L-PBF to investigate the effect of post-heat treatment and load direction on the dynamic response of the samples. Post-heat treatments included single-step annealing at 800 °C (HT) and a hot isotropic press (HIP). The as-built and heat-treated samples were dynamically compressed using a split Hopkinson pressure bar at a strain rate of 3000 s-1 along the horizontal and vertical directions paralleled to the load direction. The microstructural observation revealed that the as-built TA15 sample exhibited columnar grains with fine martensite inside. The HT sample exhibited a fine lamellar structure, whereas the HIP sample exhibited a coarse lamellar structure. The dynamic compression results showed that post-heat treatment at 800 °C led to reduced flow stress but enhanced uniform plastic strain and damage absorption work. However, the HIP samples exhibited both higher stress, uniform plastic strain, and damage absorption work owing to the microstructure coarsening. Additionally, the load direction had a subtle influence on the flow stress, indicating the negligible anisotropy of flow stress in the samples. However, there was more significant anisotropy of the uniform plastic strain and damage absorption. The samples had a higher load-bearing capacity when dynamically compressed perpendicular to the build direction.

Effect of post-heat treatment on the UV transmittance, hydrophobicity, and tensile properties of PVA/Uncaria gambir extract blend films

The physical and mechanical properties of biopolymers can be improved by heating technologies. In this research, we improved the properties of Polyvinyl alcohol (PVA)/Uncaria gambir extract (UGE) blend films by post-heating method. After post-heating, the blend film exhibited higher resistance to UV light and improved contact angle performance, while water vapor permeability and moisture absorption decreased. The tensile strength and toughness of the PVA/UGE blend film with a post-heating duration of 40 min were 68.8 MPa and 57.7 MPa, respectively, an increase of 131 % and 127 %, compared to films without post-heating. This facile and cost-effective fabrication method, with environmentally friendly properties, can be applied to biodegradable PVA/UGE blend films to achieve desired properties for optical devices or food packaging materials.

Self-assembled titanium-based macrostructures with hierarchical (macro-, micro-, and nano) porosities: A fundamental study

This study details the novel self-assembly of sodium titanate converted Ti-based microspheres into hierarchical porous 3D constructs, with macro-, micro-, and nanoporosity, for the first time. Ti6Al4V microspheres were suspended into 5 M NaOH (60 °C/24 h) solutions, with extensive variations in microsphere:solution ratios to modify microsphere interaction and initiate self-assembly through proximity merging of titanate surface dendritic growth. The formed structures, which either produced 1) unbonded, sodium titanate-converted microspheres; 2) flat (non-macroporous) scaffolds; or 3) open, hierarchically porous scaffolds, were then assessed in terms of their formation mechanism, chemical composition, porosity, as well as the effect of post-heat treatments on compressive mechanical properties. It was found that specific microsphere:solution ratios tended to form certain structures (<⅓ powder, 0.5 to 3 porous, >3 flat non-macroporous, >8 powder) due to a combination of microsphere freedom of movement, H2 gas bubble formation, and exposed surface reactivity. This promising discovery highlights the potential for lower temperature, simplistic production of 3D constructs with modifiable chemical properties due to the ion-exchange potential of titanate structures, with clear applications in a wide-range of fields, from medical materials to catalysts.

Effects of post heat treatment on the microstructure and mechanical properties of selective laser melted AlSi10Mg alloys

The effects of direct aging (DA), annealing (AN), solid solution (ST), annealing + aging (AA) and solution + aging (SA) on the microstructure and mechanical properties of AlSi10Mg alloys fabricated by selective laser melting were studied. The results showed that direct aging can completely preserve the network Si structure of the as-built (AB) alloy, and the ultimate tensile strength of horizontal and vertical samples were both increased from 486 MPa to 487 MPa–502 MPa and 515 MPa, respectively. Annealing can lead to the disintegration and breaking up of eutectic Si networks, with the coarsening of grains and the deduction in dislocation density, the strength of the alloy was significantly reduced and the plasticity was improved. Annealed + aged alloys had the highest plasticity, with both transverse and longitudinal elongation exceeding 20 %. After solution treatment, the eutectic grid in the alloy completely collapsed and Si particles grew into coarse blocks. The transverse ultimate tensile strength was barely 256 MPa, which increased to 281 MPa after aging. The direct aging process adopted in this study further enhances the strength of the as-built AlSi10Mg alloy, providing a certain reference significance for optimizing the post heat treatment of AlSi10Mg.

Effect of Post-heat Treatment on Microstructure and Mechanical Properties of Laser Cladded High Co-Ni Secondary Hardening Steel Coating

The effect of post-heat treatment on the microstructure and microhardness of laser cladded high Co-Ni secondary hardening steel coating was investigated. The microstructures were analyzed using a SEM equipped with an EDS, and the microhardness was measured with a Vickers indenter. Decomposition of the retained austenite in the coating occurred during the post-heat treatment. As the temperature increased from 200 °C to 600 °C, the quantity of the retained austenite at the boundaries decreased significantly, while that of the needle-shaped M3C cementite and M2C carbides increased. The M2C carbides evidently coarsened when the temperature was higher than 500 °C. The microhardness of high Co-Ni steel coating increased as the temperature of post-heat treatment increased from 200 °C to 400 °C because the fine-scale M2C carbides were coherent with the matrix and increased distinctly in this temperature range. It decreased sharply when the temperature further increased from 500 °C to 600 °C due to both the incoherency of the coarsened M2C carbides and the recovery of dislocations in the carbon-supersaturated matrix.

Post-heat treatment effect on dielectric and optical properties of magnesium-based spinel

Post-heat treatment effect on dielectric and optical properties of magnesium-based spinel

Optimization of Printing Process Variables and the Effect of Post-Heat Treatments on the Mechanical Properties of Extruded Polylactic Acid-Aluminum Composites.

Polymer extrusions are employed in the fabrication of crucial parts for automotive, aerospace, and other mechanical applications. The use of fillers and microfibers is contributing to the advancement of material extrusion polymers. In order to enhance their mechanical characteristics, printed materials undergo a post-heating process utilizing microwaves. Specimens were fabricated using polylactic acid filaments containing 2 wt% aluminum. Two sets of specimens were fabricated and subjected to testing in order to evaluate the features of extruded specimens and specimens that underwent post-heating. In terms of mechanical performance, specimens subjected to post-heating exhibited superior results compared to specimens merely subjected to extrusion. The tensile, flexural, and Shore D hardness properties of the specimens exhibited improvements of 5.07, 6.16, and 1.32%, respectively, after being subjected to heating. Furthermore, the wear rate decreased by 13.58 percent. The results of the regression analysis indicate that the print angle and the air gap exhibit the greatest influence on the observed responses. The validation test outcomes exhibit a high level of concordance with the predicted findings. The mechanical and surface properties of components extruded with filler-added material are enhanced by subsequent heating.

The effect of post heat treatment and TiO2 addition on tribological and electrochemical performances of thermally sprayed alumina

ABSTRACT The heat treatment of alumina ceramics is a fundamental process for controlling the physical, mechanical and thermal properties of these components during industrial operations. The problem statement in this case is about the effects of TiO2 addition and post heat-treatment on the expansion behaviour of alumina coating. For that alumina (Al-99) and alumina-titania coatings 5% wt. TiO2 (AT-5) and 15% wt. TiO2 (AT-15) were formed onto E335 substrate steel via the flame spraying technique. The samples were heat-treated (1000°C for 2 h in Air) and their wear and electrochemical behaviour was compared with the as-sprayed samples. The X-ray diffraction (XRD) patterns reveal a change in the phase composition of the heat-treated coatings compared to the as-sprayed coatings, as alpha alumina matrix but with different ratio. The heat-treated coatings exhibit higher values to as-sprayed coating. At the same time, the addition of TiO2 present hardness twice than pure alumina coating (Al-99). The tribological properties show that the deposits after heat treatment have low wear values compared to the as-sprayed coatings, the lowest specific wear rate was obtained for the heat-treated AT-5 composite coatings. The heat treatment had a positive effect on the corrosion resistance.

Effect of post-heat treatment on the microstructure, mechanical, and corrosion properties of laser powder bed fused Al–Zn–Mg–Cu–Si–Zr–Er alloys

Three different post-heat treatments, including direct aging (DA), solution heat treatment + precipitate hardening (T6), and retrogression and re-ageing (RRA), were carried out on a Si–Zr–Er modified Al–Zn–Mg–Cu alloy, which is manufactured by laser powder bed fusion (LPBF). The results show that direct aging maintains the cellular structure of the as-printed (AP) alloy, while T6 and RRA promoted the damage and decomposition of the cellular structure. The size of the primary Al3(Er,Zr) phase increased after heat treatment, and secondary Al3(Er,Zr) phases were uniformly distributed in the matrix with a size of 5–20 nm. The Mg2Si phase in the DA alloy was a long strip pattern, but uniformly distributed in the T6 and RRA alloy. The ultimate tensile strength of the AP, DA, T6, and RRA alloys reached 468, 474, 389, and 354 MPa, respectively. The size, shape, and distribution of the Al3(Er,Zr) and Mg2Si phases have a significant impact on their corrosion resistance, with the latter having a stronger effect. To sum up, the strength of the DA alloy is increased, but its corrosion performance is decreased with heat treatment. On the other hand, the strength of the T6 and RRA alloys is somewhat sacrificed, but their plasticity and corrosion resistance are significantly enhanced.

Post-heat treatment of laser powder bed fusion fabricated Al–La–Mg–Mn alloy: On intermetallic morphology control and strength-ductility balance

In this study, a newly developed Al–La–Mg–Mn alloy was subjected to solution heat treatment for the first time. During the solution heat treatment at 500 ℃, the continuous network Al11La3 intermetallics were transformed into a discontinuous granular form. Ultrafine intermetallics (∼0.20 µm) were achieved via multi-point spheroidization with the aid of endogenous nanoprecipitates. Of note, the intragranular intermetallics were inert to coarsening, while the intergranular intermetallics grew gradually to ∼0.58 µm within 6 h. Compared to the as-printed alloy (UTS ∼588 MPa, Elongation ∼6.4%), the solution-treated alloy at 500 ℃ for 1 h (UTS ∼477 MPa, Elongation ∼14.3%) demonstrated a remarkable improvement in ductility, with a 123% increase, despite a modest decrease of 19% in strength, thereby balancing the strength-ductility. The limited decline in strength is primarily attributed to the high-content solute Mg atoms and thermally stable intragranular intermetallics. Interestingly, the mechanical properties were independent of the holding times at 500 ℃, despite the coarsening of intergranular intermetallics. This is mainly due to the optimization of intermetallics’ scale distribution, which tailors and equalizes the stress distribution between the grain boundary and interior, as well as between the melt pool boundary and interior during deformation. These findings provide the first insight into the effect of post-heat treatment on the intermetallic evolution and mechanical properties of LPBF Al–(La, Ce) alloys.

Friction deposition additive manufacturing of alloy 718: Effect of post-heat treatment on microstructures and mechanical properties

Friction deposition additive manufacturing of alloy 718: Effect of post-heat treatment on microstructures and mechanical properties

Effect of post-heat treatment with super β transus temperature on the damping behaviour of LPBF-processed Ti6Al4V thin rotor blade

This article investigates the damping behaviour of laser powder bed fusion-processed Ti6Al4V thin plate samples and thin rotor blades. The effect of microstructural changes owing to the post heat treatments (PHTs – 850 °C, 950 °C and 1050 °C) on damping behaviour was assessed. The microstructural characterisation was performed using optical microscopy, X-ray diffraction and scanning electron microscope techniques. The impact hammer test was performed on thin plate samples and rotor blades to characterise damping behaviour. The microstructure of the thin plate samples subjected to PHT conditions varied in grain structure and morphology compared to the as-printed ones. Further, PHT at a higher temperature (i.e. 1050 °C) induces a higher amount of β phase than the other PHT temperatures. The PHT performed at 1050 °C exhibited α- Widmanstätten microstructure consisting of elongated β and a small amount of α. Moreover, the frequency response function plots revealed broader peaks for thin plate samples and the rotor blade than others. The PHT was favourable in enhancing the α lath thickness and β volume fraction, increasing the damping ratio. The results showed that PHT performed at 1050 °C improves the overall damping of ∼348% and ∼140% of rotor blade and thin plate samples, respectively. The amplitude decay for the rotor blade subjected to PHT at 1050 °C was ∼66% shorter than the as-printed one due to high β phase content relieving the energy resulting in a high damping ratio.

Effects of post-heat treatment on anisotropic mechanical properties of laser additively manufactured IN718

In this presented work, the effects of different heat treatments on the anisotropic mechanical properties of Inconel 718 (IN718) fabricated by laser powder bed fusion (LPBF) and laser directed energy deposition (LDED) were comparatively investigated. Samples prepared in build direction (BD) and transverse direction (TD) for tensile and creep tests were heat-treated with Solution + double aging (SA) and Homogenization + solution + double aging (HSA) procedures, separately. Experimental results indicate that both SA-treated LPBF-IN718 and LDED-IN718 show strong anisotropy in tensile and creep properties. TD samples have higher tensile strength and relatively better creep performance. After HSA treatment, LPBF-IN718 samples still show strong anisotropic tensile and creep properties. In contrast, anisotropy in mechanical properties of LDED-IN718 samples is mitigated significantly. The columnar grains in as-built LDED-IN718 recrystallized after HSA treatment, resulting in similar tensile and creep properties in both directions. The difference in residual stresses of LPBF-IN718 and LDED-IN718 is the main reason that causes the totally different conditions after HSA treatment. This work can provide a deeper understanding of the difference in anisotropic mechanical properties of LPBF-IN718 and LDED-IN718, which may guide the design of proper heat treatment of laser additively manufactured nickel-based superalloy potentially.

Effect of post-heat treatment on Ti2AlNb-based alloy fabricated by twin-wire alternating dual-electron beam additive manufacturing technology

Thanks to its excellent high-temperature performance and moderate density, Ti2AlNb-based alloy is considered to be a new generation of high-temperature structural material in the aerospace field. However, its application is restricted currently due to the limitations of traditional processing methods. Recently, our group first successfully prepared this alloy with an unconventional approach named wire-based in-situ additive manufacturing (AM) technology, and great mechanical performance has been obtained. The unbalanced thermal process of AM easily causes inconsistent or undesired microstructures, as well as mechanical properties. Therefore, in this study, we further carried out post-heat treatment research on the as-printed sample so as to optimize its mechanical performance. Results show that the α2-phase will precipitate from the as-deposited samples (B2/β+O) after solution treatment(ST), while all precipitates were dissolved to the B2/β-matrix when the solution temperature was 1100 °C. The aging treatment(AT) promoted a great number of O-phases precipitated and led to an increase in its proportion. With the increase in aging temperature, the tensile strength decreased (995 to 821 MPa) gradually coupling the increase of fracture strain (1.65% to 2.12%), while the aging duration time did not show an obvious effect on its performance. In addition, after proper heat treatment, the high temperature (650 °C) tensile strength of the samples was as high as 818 and 792 MPa. This research not only promotes the development of Ti2AlNb-based alloy fabricated through in-situ AM, but also facilitates its further application in the aerospace field.

Effect of post-heat treatments on the microstructure, martensitic transformation and functional performance of EBF3-fabricated NiTi shape memory alloy

In the present work, a single solution treatment as well as solution/aging treatments were employed to regulate the precipitation behavior, martensitic transformation, mechanical and functional properties of EBF3-fabricated NiTi shape memory alloys. Under the optimized post-process heat treatment conditions, i.e., solution treatment at 1000 oC for 10 h followed by subsequent aging treatment at 500 oC for 4 h, the previously existing elongated Ti4Ni2Ox oxides were partially dissolved and interrupted into granular form and relatively uniformly distributed in the NiTi matrix. Meanwhile, the preexisting nanoscale Ni4Ti3 precipitates gradually transformed from clustered or segregated granular to a lenticular shape with the increase of the aging time. The martensite transformation routes also underwent an accompanying alteration, which changed from a one-step (B2-A ↔ B19’-M) to two-step (B2-A → R → B19’-M) transformation. Moreover, Ni4Ti3 precipitated with a coherent relationship of {123} <111>B2-A //{11–20} <0001>Ni4Ti3 which increase the material strength by hindering dislocation movement and improve plasticity by providing a transition domain for accommodating deformation at the interface. The superelastic stability and narrow response hysteresis promoted by the presence of the R-phase are affected by residual (100) compound twins martensite in the NiTi matrix and the permanent plastic deformation activated in (011) [001] slip system of the B2-A phase. This deteriorates the superelastic recovery ratio from 83.6 to 57.4%, as observed after 10 loading-unloading cycles. The post-heat treatment regime presented in the current investigation can be used to modulate the material precipitation, phase transformation, as well as the mechanical and functional properties of EBF3-fabricated NiTi alloys. These results allow to extrapolate the potential for carefully selected post-heat treatment scheduled for additively manufacturing NiTi shape memory alloys.

Microstructural evolution during post heat treatment of the Ti–6Al–4V alloy manufactured by laser powder bed fusion

The purpose of the present study is to investigate the effect of post heat treatment as well as the manufacturing strategy on the microstructure evolution during martensite decomposition of Ti–6Al–4V manufactured by laser powder bed fusion (LPBF). The microstructural evolution was tracked using in situ high-energy synchrotron X-ray diffraction and differential thermal analysis. The phase fraction, the mean lattice parameters, d-spacing and the Full Width at Half Maximum (FWHM) variations were determined by Rietveld refinement from XRD patterns during continuous heating up to the single β phase domain with different heating rates and manufacturing strategies. The complementarity of characterization tools clearly evidences a shift of the α/α’ → β transformation kinetics toward higher temperatures as the heating rate increases. The variations in transformation kinetics are discussed with regard to the predicted values at thermodynamic equilibrium. In addition, the combined analysis of d-spacing and FWHM shows the deviations from linearity at intermediate and high temperatures that are related to the heating and manufacturing strategy. These variations were analyzed in regard of internal stress relaxation or changes of chemical composition. Moreover, the anisotropic elastic distortions in martensite α’ caused by the manufacturing strategy were examined.

Effect of post-heat treatment on microstructure and tribological performance of AISI 410L coatings processed by laser-directed energy deposition (L-DED)

Effect of post-heat treatment on microstructure and tribological performance of AISI 410L coatings processed by laser-directed energy deposition (L-DED)

Characterization of sol-gel derived NiO thin films: Effect of post-heat treatment

Characterization of sol-gel derived NiO thin films: Effect of post-heat treatment

Effects of post heat treatment on microstructure and mechanical properties of Ti5553 parts made by laser powder bed fusion

Rapid heating and solidification rates involved in additive manufacturing result in non-homogenous microstructural features, microsegregation and residual stresses, leading to deteriorated mechanical properties. Although the rather new Ti-5553 (Ti‐5Al‐5Mo‐5V‐3Cr) metastable β-Ti alloy is printable by laser powder-bed fusion (LPBF), it exhibits poor mechanical strength compared to conventionally forged components due to the lack of second phase strengthening in the as-printed state. Therefore, post-processing heat treatment is essential to enhance the mechanical properties of the printed parts. In this research work, LPBF-made Ti-5553 specimens were subjected to varying heat treatment cycles to modify their corresponding microstructure in terms of the morphology and distribution of α particles. Differential Scanning Calorimetry (DSC), X-Ray diffraction (XRD) patterns, and electron backscatter diffraction (EBSD) results suggest that solutionizing at the upper α + β region (800 °C) offers a good combination of finer grain size and satisfactory α dissolution. On aging in the range of 500 – 700 °C for 0.5 – 4 h, growth of α particles with different morphologies was observed. A combination of multiple α morphologies, including Widmanstätten, lenticular, cylindrical and lamellar was identified based on the heat treatment conditions. Consequently, a wide range of microhardness from 300 to 500 HV was observed due to phase transformations in the microstructure, which control the mechanical properties. The subsequent tensile tests validated the improved mechanical properties further as the tensile strength increased from 780 ± 10–1640 ± 6.29 MPa, compared to the as-printed specimens. Examination of the fracture surfaces revealed intergranular failure following aging at 500 °C due to segregation of α particles at grain boundaries. At 600 °C, the fracture was initially intergranular, which slowly transformed to a ductile fracture with time. At 700 °C, the fracture was mainly ductile irrespective of the aging duration.