Heat-treated Samples Research Articles

Effect of Strain Hardening on Wear Resistance Property of 316 Austenitic Stainless Steel

The main purpose of this investigation was to study the effect of strain hardening on wear properties of 316 austenitic stainless steel (ASS). Cold deformation was performed by using a universal tensile machine for 20% CW and 40% CW followed by heat treatment to relieve internal stresses. A secondary cold working process was performed for the heat-treated samples followed by a secondary heat treatment. Wear test measurements and microscopic examinations were preformed for all samples. It was observed that by increasing the strain hardening percentage the hard brittle martensite phase increases. Also, by increasing both the SiC grit of the emery papers (which was used in the wear test) and the time of the wear test, the weight lost per unit area was decreased. The wear resistance was increased by using single and double 20% strain hardening but by exceeding the cold working to more than 40% the wear resistance decreased.

Influence of Equal Channel Angular Pressing Processing on the Microstructure, Hardness and Corrosion Resistance of Al-Si Alloy

In this study, the impact of heat treatment and Equal Channel Angular Pressing (ECAP) processing routes on refining the microstructure, hardness, and corrosion resistance of Al-7.5% S alloy in a 3.5% NaCl solution was examined. The alloy underwent T5 and T6 heat treatments, followed by ECAP processing via routes A and Bc in a mold with a channel angle of 120° at room temperature. The results indicate that dendritic α-Al grains transformed to globular and fiber shapes after processing routes Bc and A, respectively. Both processing routes fragmented coarse and brittle Si particles into smaller sizes in the eutectic phase. The use of a combination of heat treatment and the Equal Channel Angular Pressing (ECAP) process significantly improved the hardness and corrosion resistance of the samples. The hardness of the heat-treated samples increased considerably from 68 to 116 and 129 HV after three and four passes, respectively. Reducing the area ratio between the noble silicon particles and the less noble eutectic aluminum phase greatly enhances the resistance of alloy to pitting corrosion.

Dissimilar impact spot welding of high-thickness aluminum-steel sheets using vaporizing foil actuators

The automotive industry’s shift towards multi-material structures necessitates efficient joining of aluminum and steel, yet techniques for high-thickness (>2 mm) dissimilar AA6XXX-HSLA steel pairs, remain underexplored. This study explores vaporizing foil actuator welding for spot welding 2.5 mm AA6111-HSLA 340 steel pairs, demonstrating successful joint formation via lap-shear testing and microscopy. Post-weld heat treatment influences joint strength and fracture behavior, with intermetallic compound (IMC) formation at the weld interface affecting mechanical properties. IMC cracking is observed in heat-treated samples. Fracture analysis reveals material transfer and secondary brazing action outside the weld zone. VFAW lap-shear failure loads outperform other joining techniques.

High-temperature oxidation behavior of a novel γ′-strengthened superalloy manufactured by laser-beam powder bed fusion: Effect of post-heat treatment

This study systematically researched the high-temperature oxidation behavior of a γ′-strengthened alloy based on Haynes 230 prepared by laser-beam powder bed fusion (PBF-LB). The results indicate that the experimental alloy showed a higher oxidation resistance than Haynes 230 at 1000 °C. The oxidation products mainly consisted of the outmost MnCr2O4-TiO2 layer, intermediate Cr2O3 layer and inner TiO2 layer. Branched Al2O3 oxides were formed in the interior oxidation zone. Post-heat treatment can increase oxidation resistance by reducing the oxidation rates from 0.0152 mg2cm−4h−1 to 0.0126 mg2cm−4h−1. The decrease in dislocation density and the precipitation of ordered γ' phases can slow down the short-circuit diffusion and lattice diffusion rate of oxygen, and are the main reasons for this improvement. Furthermore, the γ' phase precipitation and dislocation density reduction can provide more sites for Cr2O3 nucleation and reduce the Cr supply required for grain growth. As a result, the Cr2O3 grains on the heat-treated sample surface were smaller.

Physical, mechanical, and thermal properties of heat-treated poplar and beech wood

Air-dried density, weight loss (WL), impact bending strength (IBS), Shore-D hardness, and thermal conductivity values were determined for heat-treated poplar (Populus nigra L.) and beech (Fagus orientalis Lipsky) wood and compared with those for untreated samples. The test samples were heat-treated at 140, 160, 180, and 200 °C for 2 h. The results showed that density decreased and WL increased with increasing temperature for all temperatures. Additionally, during the heat treatment, the IBS increased in beech wood samples at 140 °C, but at higher temperatures, these values gradually decreased in both wood species. The highest decline in IBS values, found at a temperature of 200 °C, was 66.5% for beech and 55.7% for poplar. The Shore-D hardness of both wood species increased after heat treatment and regarding beech wood, the hardness increasing rate at temperature at 140 °C, 160 °C, 180 °C and 200 °C, 8.94%, 14.19%, 8.27% and 11.7%, respectively according to control samples. Regarding poplar wood, hardness increasing rates were 6.20% at 140 °C, 4.41% at 160°C, 5.88% at 180°C and 5.31% at 200°C according to control samples. The thermal conductivity of poplar and beech wood samples decreased after heat treatment, except for samples heat treated at 160 °C.

Effect of heat treatment on microstructure and wear properties on Binder Jetting Additive manufactured M2 High-Speed steel

In this study, the influence of heat treatments (annealing at 1175 °C, sub-zero at −80 °C, and triple tempering at 565 °C) of Binder Jet Additive Manufactured (BJAM) M2 grade HSS on the microstructure and tribological properties are investigated and were compared with that of conventionally manufactured samples. The residual austenite was transformed into martensite phase upon heat treatment. The tribological analysis was performed using a pin-on-disc experiment for 40 N, 50 N, and 60 N loads. It was observed that the heat-treated BJAM samples exhibited 11.5 %, 7.5 %, and 5.5 % higher specific wear resistance compared to the as-sintered samples. The enhancement in the wear resistance is primarily due to the presence of metal carbide precipitates in the heat-treated sample.

Development of an ultra-clean sample heating stage for thermal desorption spectroscopy

Control of surface molecular contamination (SMC) for components used in chemical vapor deposition (CVD), atomic layer deposition (ALD) and EUV photolithography is important to maintaining high yield and optimal tool operation at the latest process nodes in leading edge semiconductor manufacturing. High temperature thermal desorption spectroscopy (TDS) is a versatile tool for analyzing the cleanliness of surfaces, simulating thermal vacuum processes and studying the kinetics of desorption processes. A basic analysis of TD spectra allows for full characterization of volatile outgassing from surfaces, while detailed analysis can provide chemical information about the substrate surface.In fundamental studies, TDS is often carried out from low temperatures to room temperature or for small samples. However, for microelectronics applications, high temperature studies of large (100 mm or greater) samples are of greater interest due to direct applications for cleanliness testing and thermal vacuum simulation. A limitation for TDS sensitivity is the outgassing of sample stage materials, particularly when analyzing gases that may be present in the chamber background such as water, CO and CO2. Typical sample stages are often tested only for total pressure or at room temperature.In this study, we present a simple ultra-high vacuum (UHV) compatible sample heating stage for trace outgassing analysis of 100 mm samples at high temperatures. Simulation results are presented to support the feasibility of the concept. Experimental results verify the cleanliness of the stage via room temperature residual gas analysis (RGA) analysis and X-ray photoelectron spectroscopy (XPS) of stage components. Finally, use of this stage in a TDS analysis of a 100 mm Si witness wafer and comparison to room temperature RGA demonstrates operational capability.The sample heating stage is both shown to be clean at high temperature and capable of analyzing 100 mm wafers to higher sensitivity than room temperature RGA for all m/z at the 1 × 10−9 mbar level. Despite its high performance, the heating stage is also easily produced by any laser machining service, greatly improving the accessibility of UHV science for all researchers.

Microstructure and fatigue crack growth behavior of heat-treated electron beam melted Ti-6Al-4V alloy

The effect of post-deposition heat treatment on microstructure and fatigue crack growth has been analyzed for electron beam melted Ti-6Al-4V plates. Samples have been heat-treated at temperatures of 950 °C and 1050 °C, and subsequently cooled at different cooling rates in the furnace and the water. The as-built sample possesses columnar prior β grains filled with exceptionally fine α+β Widmanstätten patterns and epitaxially grows in the vertical direction. Heat treatment with a slow cooling rate increases the α lath thickness, whereas fast cooling results in multiple needle-shaped α/α′ phases inside the prior β grains. The yield strength and ultimate tensile strength in as-built conditions are greater than the extruded mill annealed sample. The as-built samples show better crack growth resistance during the fatigue crack growth rate test than the heat-treated and mill-annealed samples. The lower plastic deformation of the as-built sample than the mill-annealed sample is attributed to the existence of fine α laths that restrict the motion of dislocation.

Effects of preexisting dislocations on phase transition and deformation of NiTi shape memory alloy: An in situ multi-scale study

Phase transition and deformation in cold-rolled and heat-treated Ni50.6Ti49.4 alloys are explored by in situ multi-scale measurements with simultaneous X-ray diffraction and optical digital image correlation. Macroscale stress−strain curves, mesoscale strain fields and microscale X-ray diffraction peaks are obtained. Electron backscatter diffraction and transmission electron microscopy are also conducted on samples before and after tension as complements. For cold-rolled samples, since martensite nucleation is strongly associated with the widely distributed preexisting dislocations, homogeneous martensite phase transition takes place, in contrast with the localized mode in heat-treated samples. For localized phase transition, the intense growth of martensite results in clear Lüders bands. The beginning and the end of phase transition plateau on the stress−strain curve are associated with the initiation and complete propagation of Lüders bands. For the homogeneous phase transition, broad growth of martensite leads obscure Lüders bands and uniform strain fields, without any phase transition plateau. Given the initial {110}〈110〉 and {111}〈110〉 sheet textures in the heat-treated samples, different martensite variants with different preferred orientations are activated with respect to the loading directions.

The effect of biosecurity heat treatment on soils: implications for soil analytical methods and mineral exploration

Soils are widely used as geochemical sample media. A recent advancement in soil analytical methods for exploration developed in Australia, the UltraFine+ ® method, concentrates the clay-sized fraction of <2 µm and then analyses this fraction for over 50 elemental concentrations, pH, electrical conductivity and spectral mineralogy/properties (i.e., visible –near- to shortwave and mid- infrared reflectance spectroscopy). This new approach was initially limited to Australian soils due to strict biosecurity legislation. However, since 2022 samples can be shipped to Australia and heat-treated to 160 °C to be released from quarantine-approved premises prior to analysis. A study was undertaken to determine the influence of the temperature heat treatment on the spectral and geochemical properties of soils. One hundred and three soils were collected from multiple regions of Australia to provide a background set of samples to test the effect of heat treatment on the analytical response using the clay-sized fraction analytical method. These soils comprised multiple clay types and are representative of general soil types and target commodities in mineral exploration settings. Results show that heat treatment did not significantly impact elemental abundance of common pathfinder and target elements in minerals exploration with strong correlation and linear trends between the treatments. Spectral parameters measured in the visible to mid infrared range were also unaffected by heating. Some observed elemental changes were related to inconsistent extraction of resistate elements (Hf, Nb, Zr). Counter to other studies, a pH decrease was observed in heat-treated samples. The study concludes that biosecurity release heat treatment at 160 °C does not hinder analysis of the ultrafine fraction soils with a concentrated aqua regia assay and spectral mineralogy measurements.

Effect of heat treatment on chemical durability and TL dosimetric properties of Na2O-SrO-B2O3 glass system

Na2O-SrO-B2O3 glass system prepared by the known melting-quenching method was applied to a progressive heat treatment (HT) at 600 °C for 4, 6, 8 and 10 h. Glass (G) and its corresponding heat treated (HT) samples were characterized by density, molar volume and XRD technique that revealed the complete amorphous structure of the glassy matrix and the coexistence of two crystalline phases in the corresponding glass ceramics; monoclinic phase of NaSrBO3 and the triclinic phase of sodium strontium pentaborate Na3SrB5O10. Testing chemical durability of G and HT samples at 95 °C for 24 h, revealed higher chemical stability in aqueous (H2O) and acidic (H2SO4) solutions, while the highest leachability was detected in the alkaline medium (NaOH). pH of leaching solution was found to control the leaching process and displayed rising behavior with time of immersion. The progressive rising of leaching solution temperature; 25, 40, 60 and 95 °C, revealed a quiet leachable enhancement as well. SEM photographs represented rough and heterogeneous surface morphology with continual leaching and the formation of colloidal layers at the later stages of corrosion.The TL-dosimetric properties indicated extremely higher thermoluminescence properties of HT samples than the untreated glass. The analysis of the exhibited TL signals revealed the composition of the glow curves of the treated and untreated samples of eight TL components. The obtained results recommend the acceptable chemical durability of the heat treated samples especially in the neutral medium that displayed no more than 8.5% leachability rate yearly, besides their promising TL-dosimetric features, accordingly their possible application in the field of radiation dosimetry.

Numerical and experimental behavior of fiber reinforced polymer type and layer number effect on the flexural properties of heat-treated black pine wood

Heat treatment is one of the environmentally friendly methods applied to improve the structural properties of wooden materials. While heat treatment improves some properties of wood material, it also negatively affects its mechanical properties depending on the heat treatment conditions applied. The decrease in mechanical properties due to heat treatment limits the use of wood material in various applications requiring mechanical strength. For this purpose, various fiber-reinforced polymers have been used in recent years. In this study, it was aimed to experimentally and numerically examine the flexural properties of unheat-treated and heat-treated black pine (Pinus nigra Arnold.) wood reinforced 1, 2 and 3 times with carbon, glass and aramid. Following the experimental flexural tests, the samples were modeled and analyzed in the finite element software program. The average flexural strength of the heat-treated sample is 11.72% lower, and the elasticity modulus is 1.23% lower than the unheat-treated sample.It has been determined that carbon-based polymer fabrics, among fiber-reinforced polymer fabrics, have the best reinforcement effect. The flexural strength of the UHT-C-3 sample is 6.1% and the elasticity modulus is 3.52% higher than the UHT-C-1 coded sample. Compared to the sample without reinforcement, flexural strength increased by 30% and elasticity modulus increased by 7%. It is seen that as the number of fiber reinforced polymer layers increases, the flexural properties also increase. When the experimental and numerical analysis results were examined, the flexural strength and modulus of elasticity values gave similar results at the R2: 0.88–0.99 level. In addition to technologies using kinds of reinforcement evaluated in conservation applications, it may be utilized for numerical analysis in the field of repairing or reinforcing different grades, patterns, and types of reinforcement in already-existing wooden structures.

Microstructural stability and mechanical properties of the as-cast and heat-treated newly developed TiNbCrTa refractory complex concentrated alloy

In this study, a TiNbCrTa refractory complex concentrated alloy (RCCA) was prepared using vacuum arc remelting. The microstructural evolution and mechanical properties of both as-cast and heat-treated RCCA samples were analyzed. Heat treatment (HT) was performed at 800–1200 °C for 1 h in a vacuum-sealed environment. These samples exhibited a formation of Cr2Nb and Cr2Ti Laves phases. A variation in elemental distribution was observed, with interdendritic (ID) regions showing higher fractions of Ti and Cr, while the dendritic regions had a greater concentration of Ta and Nb. Micro-segregation at the IDs was confirmed through energy dispersive x-ray spectroscopy mapping, which inferred the formation of Cr- and Ti-rich phases during HT at 800–1200 °C. High-temperature HT at 1200 °C for 1 h led to the evolution of the hcp omega phase. Prolonged HT at 1200 °C for 96 h resulted in the evolution of a Cr-rich Laves phase (Cr2Ta), which was homogeneously distributed within the microstructure, indicating an unstable microstructure. Furthermore, despite prolonged HT, a variation in the elemental distribution persisted due to the presence of dendritic and ID regions. Electron backscattered diffraction analysis revealed the presence of bcc and hcp phases in the dendritic and ID regions, respectively, of the as-cast and HTed samples. The as-cast samples demonstrated a high compressive strength of approximately 2 GPa. Micro-hardness values increased with the HT temperature up to 1000 °C. Further increases under HT conditions did not significantly reduce the microhardness value, whereas prolonged HT at 1200 °C led to an increase in the microhardness value. Overall, the newly developed TiNbCrTa RCCA exhibited high-strength behavior even after the phase transformation.

Uniformity improvement of microwave heating with switchable frequency selective surface

Microwave heating has attracted interests in many industrial applications, yet heating inhomogeneity remains a critical issue. This study proposes a novel approach to enhance microwave heating uniformity employing a switchable frequency selective surface (FSS). The PIN diodes in each FSS unit cell can be toggled ON or OFF by controlling voltage biases, enabling the FSS to either reflect or transmit incident electromagnetic waves. Placing this switchable FSS in front of a heating cavity wall creates a dynamic reflecting boundary, which, through periodic alterations of the FSS and metallic wall, effectively improves the heating uniformity. To validate this method, we simulated the heating of a potato sample at 2450 MHz using COMSOL Multiphysics and conducted experimental tests. Both simulation and experimental results demonstrate that the proposed method significantly enhances microwave heating uniformity across various materials and sample sizes. This work provides a promising solution for designing microwave heating reactors.

Purification and investigation of tellurium rich Te-As-Se chalcogenide glass for extended far-infrared transmission

In the present study, tellurium-rich (45–55 mol%) As-Se-Te chalcogenide glasses were synthesized and purified further to eliminate the impurities for achieving extended far infrared transmission. The glasses were characterized and studied for physical, thermal, optical, structural and mechanical properties. All the glasses have shown transparency in the wavelength range of ∼1.6–19 µm, with >45 % transmission with impurities. The purification process through vacuum distillation has eliminated the oxide impurities in the glass and the glass displayed ∼52 %T in the wide infrared region. The refractive index for purified glass decreased from 3.487 at 2 µm to 3.362 at 10 µm. The purified glass was heat treated for four hours, and the most dominant crystal phase, As2Te3 was observed in XRD analysis. Presence of sharp Raman peak at ∼120 cm−1 belonging to As2Te3 pyramids in heat-treated sample well agreed with the XRD results.

Effect of heat treatment on microstructure of near-eutectic Al-Ni-Mn alloy, and determination of mechanical and thermoelectrical properties

This study examined the impact of solution heat treatment on the microstructure, mechanical characteristics, thermophysical properties, and electrical resistivity of an Al-Ni-Mn near-eutectic alloy. The investigation focused on varying temperatures and holding periods. The composition of the Al-Ni-Mn near-eutectic alloy system was chosen as Al-5.3%Ni-1.0%Mn (wt). In the non-heat-treated sample, the matrix phase (α-Al) is in equilibrium with the intermetallic Al9(Mn,Ni)2 and Al3Ni phases. The hardness value of the non-heat-treated sample (49.8 kg mm−2) increased to 70.1 kg mm−2 with 2 h of solution heat treatment at 570 °C and then 8 h of artificial aging at 180 °C. The hardness value increased by approximately 41%. TE: 651.81 °C for the non-heat-treated sample and TE:648.79 °C for the heat-treated sample. Fusion enthalpy (ΔH) value was determined as 336.79 (J g−1) for the non-heat-treated sample and 516.36 (J g−1) for the heat-treated sample. Heat Capacity (Cpl) value was found to be 0.364 J g−1.K for the non-heat-treated sample and 0.560 J g−1.K for the heat-treated sample. The electrical resistivity value of the 2 h’ solution heat-treated sample at 600 °C reached its highest value.

Facile synthesis of novel bismuth oxide/bismuth molybdate nanocomposites as advanced anodes for high performance Li‐ion batteries

In this study, a novel nanocomposite material consisting of Bi2O3 and Bi2MoO6, named as Bi2O3@Bi2MoO6, was successfully fabricated by co-precipitation method in ethylene glycol solvent. Morphological analysis of the heat-treated sample at 400 °C for 12 h in Ar atmosphere (Bi2O3@Bi2MoO6 _400 °C) showed that it contained nano-sized particles of Bi2O3 and Bi2MoO6; in addition, an amorphous phase along with a crystalline structure was also observed. When used as an anode for Li-ion batteries (LIBs), Bi2O3@Bi2MoO6 _400 °C anode exhibits excellent electrochemical properties such as high Coulombic efficiency, high specific capacity, excellent capacity retention, and outstanding rate capacity. Specifically, the Bi2O3@Bi2MoO6 _400 °C anode presented a reversible capacity of 786 mAh g−1 at the beginning cycle at 0.1 A g−1 and retained about 90 % of the charging capacity value after 80 cycles. The advanced electrochemical properties of the nanocomposite anode are related to the combination of many aspects such as nanostructure, existence of amorphous phase, and pseudo-behaviour of metal-based components. The structural stability and electrochemical performance of the anode material, therefore, are improved. These results demonstrate Bi2O3@Bi2MoO6 _400 °C as a promising material for establishing high-performance LIB anodes.

High-temperature fretting wear behavior of IN738LC alloy formed by laser powder bed fusion

The fretting wear behavior of IN738LC alloy formed by laser powder bed fusion at 850 ℃ with various load (35 N and 100 N) were systematically studied. The results demonstrate that increases the load, leading the fretting wear mode gradually transitions from the gross slip region (GSR) to the mixed slip region (MSR). Judging with the radar map drawn by experimental data, the high-temperature comprehensive performances of fretting wear for supersolvus heat-treated sample improved significantly. The analysis of fretting wear cross-section microstructure indicates that the thermoplastic deformation of L-PBFed IN738LC alloy occurs under the interaction of different normal loading and force of tangential friction, which results in the accumulation of strong dislocation densities and diverse deformed tissue in damage zone.

High-temperature fracture behavior of an α/β Titanium alloy manufactured using laser powder bed fusion

The room and high temperature (up to 600 °C) mechanical properties, with emphasis on the fracture toughness and fatigue resistance, of an α/β titanium alloy that was additively manufactured using the laser powder bed fusion (LPBF) technique were evaluated in the as-printed (α’ lath martensite with negligible β phase content) and heat-treated (α/β structure with a significant volume fraction of the β phase) states for critically examining the β phase's role in the fracture and fatigue behavior (given the significantly higher diffusion rates of various species in β compared to α). Experimental results reveal that the heat-treated sample exhibits superior ductility and fracture initiation toughness at elevated temperatures, compared to the as-printed sample, due to the presence of β ligaments in the former. They also prevent strain localization along the prior β grain boundaries, and their absence in the as-printed state leads to cracking along those boundaries. While the fatigue crack growth (FCG) rates in both the as-printed and heat-treated samples deteriorated with increasing temperature, the threshold for FCG generally increased, which is attributed to creep-induced crack tip blunting. Moreover, a double Paris exponent phenomenon is observed for the heat-treated sample at 300 °C, attributed to the hydrogen-assisted crack growth, with β phase providing an accelerated diffusion pathway. Overall, the experimental results and their analyses illustrate the intricate relationship between creep, hydrogen diffusion, and the β phase in dictating the fracture behavior of LPBF α/β titanium at elevated temperatures.

Calorimetric and Volumetric Studies of Dislocations During Martensitic Transformations in Shape Memory TiNi Alloy

Based on the use of appropriate approaches, methods and results of the analysis of a number of topical problems of physical materials science, an in-depth analysis has been done of calorimetric and volumetric data for direct, reverse and deformation martensitic transformations in a nanostructured Ti49.3Ni50.7 shape memory alloy obtained by cold rolling with simultaneous action of pulsed high-density current. For the first time, by applying a new technique for processing calorimetric spectra (peaks), the staging and “kinetics” of changes in heat content, as well as thermal effects (enthalpies of individual stages) during direct and reverse martensitic transformations during cooling or heating of samples at a constant rate (3 × K/ min) in the range 170–370 K has been done. It is shown, by processing volumetric data, using theoretical values of the dislocation density and elements of the classical theory of dislocations, that in the Ti49.3Ni50.7 shape memory alloy subjected to cold deformation accompanied by the action of a pulsed current, a deformation martensitic transformation occurs, leading to a positive volume effect (∆V/V) ≈ 3 × 10–3), which can be largely due to dislocations. It is shown, by applying the theoretical values of the dislocation density and elements of the classical theory of dislocations, that the possible contributions of dislocations to the enthalpies of direct and reverse martensitic transformations (in the Ti49.3Ni50.7 alloy) can and should be significantly lower in absolute value, but opposite in sign to the observed enthalpies of direct and reverse martensitic transformation in a given alloy. It is shown that the physics of the processes under consideration is contained to a certain extent in scientific discoveries No. 239 “The phenomenon of thermoelastic equilibrium during phase transformations of the martensitic type – the Kurdyumov effect” and No. 339 “The phenomenon of the formation of non-equilibrium grain boundaries in polycrystals when they absorb lattice dislocations”.