Temperature Aging Treatment Research Articles

Research on fatigue performance of “sandwich metal-structured ” composite materials in ultra-low temperature environments

The aim is to investigate the influence of aluminum content in the FeCoCrNiAlx series high-entropy alloys, different aluminum alloy damping layers, and the thickness of damping layers on the fatigue performance of sandwich structure composite material plates after room temperature and low-temperature aging treatment. By using abaqus/fe-safe simulation, as well as liquid nitrogen low-temperature aging treatment and fatigue tensile testing, the differences in fatigue performance between composite materials treated with low-temperature aging and those untreated at room temperature were observed. The increase in aluminum content significantly improves the lifespan of the composite materials, and after low-temperature aging treatment, the change in strength is even more pronounced. Keeping the thickness and material of the upper and lower layers constant, the tensile life of the material, both untreated and treated at low temperatures, shows a significant increasing trend as the thickness of the middle damping layer increases. Other conditions being equal, the iMPact of different damping layer aluminum alloys on fatigue performance is also very evident. In terms of tensile cycles, the ranking is as follows: 7075 > 2A12 > 6061. After low-temperature treatment, the fatigue tension cycles of the 2A12, 6061, and 7075 damping layers under a force of 100 N are respectively 8.66, 7.43, and 2.01 times those of the untreated composite materials.

Accelerated improvement in tensile superelasticity of electron beam directed energy deposition manufactured NiTi alloys by artificial thermal cycling combined with low temperature aging treatment

ABSTRACT The low-temperature aging treatment at 250°C can significantly improve the tensile superelasticity of NiTi alloys fabricated by electron beam directed energy deposition (EB-DED). However, it requires a very long aging duration (up to 200 h) to achieve excellent tensile superelasticity due to inherent coarse grain size. To accelerate the aging process, the high-density dislocations are introduced by artificial thermal cycling treatment prior to the aging treatment (the original dislocation content in EB-DED processed NiTi alloys is very low), which will promote the subsequent uniform precipitation of nanoscale Ni4Ti3 particles during low-temperature aging treatment. The phase transformation behaviour always maintains a stable two-stage martensitic phase transformation. Under a cyclic tensile test at 6% strain, 24 h aged sample with thermal cycling maintains a recovery rate exceeding 90% even after 10 cycles, comparable to the performance of the sample aged for 200 h without thermal cycling, indicating a substantial improvement in aging efficiency.

Understanding the Room Temperature Recovery Behavior in a Ti–24Nb–4Zr–8Sn Superelastic Alloy

Metastable β Ti–Nb‐based superelastic alloys have potential uses in the biomedical and aerospace industries due to an attractive combination of properties. However, their mechanical response can be seen to vary with cycling, limiting their uptake. Furthermore, recent studies have also highlighted changes in properties under no applied stress at room temperature, with the reasons for these changes poorly understood. To investigate potential mechanisms for these changes, the superelastic behavior of Ti–2448 is studied during mechanical cycling both pre‐ and post‐room temperature (RT) aging treatments. On cycling, there is a reduction in both σSIM and hysteresis area, consistent with behavior commonly seen in the literature. However, during RT aging, there is a rapid, time‐dependent process leading to a partial recovery. In situ diffraction data indicated that this recovery is coincident with a reduction in internal stresses, the potential mechanisms for which are discussed.

Effect of aging treatment on the microstructure and properties of cold rolled Ti-10V-2Fe-3Al alloy

As a typical metastable titanium alloy with high strength and toughness, Ti-10V-2Fe-3Al titanium alloy has found wide applications in aerospace industry to replace forging steel components for light weight, long service life and high reliability. In the present study the microstructure evolution and mechanical properties of cold rolled Ti-10V-2Fe-3Al alloy undergoing aging treatment were characterized by optical microscopy, X-ray diffraction, transmission electron microscopy and mechanical testing, in attempt to understand the relationship between the microstructural evolution and aging treatment temperature and time. It is revealed that the secondary α phase had a very short propagation time to nucleate, and holding 5 min could give rise to the transformation from β phase to secondary α phase when cold rolled alloy suffered from aging at 550°C. This could be attributed to the large amounts of dislocations and grain boundaries by cold deformation, which provide nucleation sites for α phase. Increasing aging time could accelerate the transformation from β phase to secondary α phase. With aging at 550°C for 30 min, a large amount of fine secondary α phase formed, offering a good combination of strength and ductility. With increasing aging time the coarsening secondary α phase led to a decrement of strength of the alloy.

Effect of Aging Treatment Temperature on Microstructure and Properties of Al-Si-Mg Cast Aluminum Alloy

Effect of Aging Treatment Temperature on Microstructure and Properties of Al-Si-Mg Cast Aluminum Alloy

X-ray absorption spectroscopy study of the local atomic structure in a ductile Cu-Al-Mn shape memory alloy

The martensitic transformation temperature and low-temperature aging treatment of Cu-Al-Mn (CAM) shape memory alloys play crucial roles in thermal- and stress-induced martensitic transformations. The local structural changes in Cu induced by low-temperature aging were investigated using X-ray absorption spectroscopy. The average local structure of Cu in the as-quenched CAM alloys is mainly composed of a D03-like structure, which is relatively close to the preparation composition. Furthermore, X-ray absorption near-edge structure spectral analysis of the CAM alloy showed no martensite phase (lattice angle change) was found after the low-temperature aging treatments at less than 150 °C. Instead, we found that the arrangement of Mn atoms changes in two stages during aging treatment.

Achieving high strength-ductility properties of wire-arc additive manufactured Al-Mg-Sc aluminum alloy via friction stir processing post-treatment and high temperature aging treatment

In this study, the high strength-ductility properties of wire-arc additive manufactured (WAAM) Al-Mg-Sc aluminum alloy were achieved by friction stir processing post-treatment (FSPPT) and high temperature aging treatment (HTAT). The FSPPT significantly refined the microstructure and eliminated porosity defects, which the average grain size was about 2.4 ± 0.2 μm in stirring zone (SZ). There was no obvious growth in grain size after HTAT and the average grain size was about 2.7 ± 0.4 μm in SZ. Many fine secondary Al3(Sc,Zr) phases were precipitated. Compared to WAAM sample, the average ultimate tensile strength (UTS), yield strength (YS) and elongation (EL) of FSPPT + HTAT sample increased by 57.9%, 54.7% and 205.9%, respectively.

Microstructural evolution and mechanical properties of (FeCoNi)85·84Al7·07Ti7.09 high-entropy alloy by selective laser melting with aging treatment

Faced-centred cubic nanoparticles-strengthened FeCoNiAlTi system high-entropy alloy (HEA) has demonstrated unique mechanical performance advantages with recently developed HEA alloy compositions. One of the key factors determining the performance of an alloy is the efficient manipulation of precipitation. However, the traditional aging method used to achieve this can be problematic. It is time-consuming and difficult to accurately control the distribution of the precipitated phase, which restricts the development of new, high-performance structural materials. Consequently, researchers have been exploring alternative methods to more precisely and effectively manipulate precipitation in alloys. Here, we have utilized both high-efficiency additive manufacturing processes and a short-term aging process to produce (FeCoNi)85·84Al7·07Ti7.09 high-entropy alloys that exhibit outstanding mechanical properties with an ultimate tensile strength of 1625 MPa, yield strength of 1214 MPa and an elongation to failure of 11.6%. Our findings reveal the formation of L12 and L21 nanoparticles phases after aging treatment, and their contents gradually decrease with increasing aging treatment temperature. And, we introduce two strengthening mechanisms of dislocation strengthening and precipitation strengthening into the alloys, and realized the coexistence of high-density dislocations and precipitated phases, thereby exhibiting excellent comprehensive mechanical properties. This approach represents a promising new direction in the development of high-performance alloys, offering a more efficient and effective means of producing materials with improved properties.

Influence on seed quality parameters under different temperature and artificial ageing treatment in cumin (Cuminum cyminum)

The experiment was conducted in the Department of Seed Science and Technology, B A College of Agriculture, Anand Agricultural University, Anand to know the influence on seed quality parameters under different temperature and artificial ageing treatment in cumin (Cuminum cyminum L.). Two varieties were tested for seed quality, viz. Gujarat Cumin 1 (GC 1) and Gujarat Cumin 4 (GC 4). The laboratory experiment was laid out in completely randomized design (factorial concept) with four temperature treatments (10oC, 15oC, 20oC and 25oC) and three repetitions. The artificial ageing experiment consisted of three ageing treatments (0 day, 3 days and 5 days) with four repetitions. The experiment results revealed that, the different temperature regimes showed significant effect on seed germination and other quality parameters in cumin genotypes. The GC-1 interacting with 20oC was higher for different quality parameters like first count (45.66%), final count (94%), seedling length (9.33 cm), seedling fresh weight (219.66 mg), seedling dry weight (10.76 mg), seedling vigour index I (877) and seedling vigour index II (93). In seed ageing experiment, the different days of artificial ageing also showed significant effect on the seed viability and longevity. GC-1 recorded higher germination (55.50%), seedling length (3.45 cm), seedling dry weight (27.57 mg), vigour index –I (192) and vigour index –II (1539) as compared to GC-4 at the end of five days ageing period.

Achieve high plasticity and strength in 6016 alloy by high-pressure torsion combined with post-aging treatments

High-pressure torsion (HPT) processing currently receives much attention mainly because it can significantly improve the strength of alloys compare to other sever plastic deformation. However, a common problem for these HPT processed alloys is that they suffer from low plasticity. Here we proposed an optimized post-aging treatment that achieves HPT processed 6016 alloy with tensile elongation as large as ∼36% and ultimate tensile strength over 500 MPa. Through systematically comparing the effects of high and low temperature aging treatments on the microstructure and properties of alloys, it was found that low-temperature long-time aging treatment can make HPT processed 6016 alloy exhibit higher plasticity while maintaining higher strength. The higher strength mainly originates from finer grains and higher strengthening effect of L precipitates, while the higher plasticity is attributed to the formation of nanoscale Si particles with smaller size and distributed in the grain interior after low-temperature long-time aging treatment. In addition, thermo-kinetic calculation demonstrates that the low-temperature long-time aging treatment provides higher thermodynamic driving force, higher kinetic activation energy and higher generalized stability for L phase precipitation, which is conducive to achieve a good strength–plasticity combination of HPT processed alloys.

Formation and morphology of grain boundary proeutectoid pearlite in 100Mn13 steel during low temperature aging treatment

The different morphologies of grain boundary proeutectoid pearlite formed in 100Mn13 steel, which was conducted by solution treatment at 1050 ℃ and followed by aging treatment respectively at 475 ℃ and 500 ℃, were studied by transmission electron microscope. The results show that the proeutectoid phase formed at austenite grain boundary is the pearlite composed of carbide and ferrite after low temperature aging treatment, rather than one phase of carbide or ferrite which currently is widely considered. And there are two kinds of growth mechanisms for the grain boundary proeutectoid pearlite as follows: (1) The grain boundary proeutectoid pearlite consists of one layer of carbides and one layer of ferrite jointly arranged continuously along grain boundary, the carbides are M 3 C+M 7 C 3 mixed carbides, which is the leading phase of pearlite precipitation. (2) The grain boundary proeutectoid pearlite makes up short rod-like carbides and short rod-like ferrites arranged alternately along grain boundary, the carbide is M 3 C carbide.

Precipitation behavior of spray-formed aluminum alloy 7055 during high temperature aging

The precipitation behavior of spray-formed aluminum alloy 7055 during high temperature aging at 360–440 °C was studied by using scanning electron microscopy and transmission electron microscopy, together with hardness and electrical conductivity measurements. The nucleation, growth and dissolution mechanism of η phase were analyzed based on precipitation thermodynamics. The results show that the main precipitates of the alloy during high temperature aging is η phase. At the initial rapid heating-up stage, the nucleation is dominant to influence the size and number density of η phase; during the subsequent isothermal aging, the growth rate has a dominant effect on η phase. The existence of η phase is related to its critical size at a given temperature. For the spray-formed aluminum alloy 7055, a most suitable high temperature aging treatment is 400 °C for 2 min. In this condition, the alloy forms more η phases in finer sizes, and its precipitation free zone around grain boundaries becomes narrower. Such microstructure is benefited from the balance of nucleation and growth of η phase, which in turn improves the hardness and conductivity of this alloy. • The precipitation behavior of spray-formed aluminum alloy 7055 were studied. • Nucleation and growth rate of η phase during aging at 360–440 °C were calculated. • Nucleation or growth dominated differently during aging process. • The most suitable aging treatment at high temperatures was 400 °C for 2 min.

Chromizing of Additively Manufactured Maraging Steel; Microstructural Evolution and Corrosion Performance

Abstract While maraging steels are excellent candidates for additive manufacturing of high-strength materials, most of them provide little to no corrosion resistance. In this study, the surface of additively manufactured maraging steel is augmented with diffusion-based chromizing. The diffusion of chromium into the surface results in the formation of α-Cr, σ-phase and austenite depending on the chromium content at the respective distance from the surface. The bulk consists of a ductile bcc martensite hardened by precipitation of intermetallics during a low temperature ageing treatment. The σ-case provides a very high hardness, while the austenite phase is rather soft and unaffected by the ageing treatment. The chromizing treatment significantly reduced the corrosion rate of the maraging steel up to a factor of 14. Decomposition of the σ-case into a uniform case of austenite (austenitic stainless steel) further improved the corrosion resistance almost 24 times. This showed the strong potential of the chromizing treatment on a highstrength material to obtain a combination of their beneficial properties.

Effects of cryorolling, room temperature rolling and aging treatment on mechanical and corrosion properties of 7050 aluminum alloy

In this study, effects of cryorolling (CR), room temperature rolling (RTR) and subsequent aging treatment on mechanical and corrosion properties of 7050 aluminum alloy (AA7050) were investigated. After the severe rolling deformation, the ultrafine-grained structure and high-density dislocations are produced in CR and RTR AA7050 alloys. CR AA7050 exhibits higher volume fraction of UFGs and dislocation density compared to RTR AA7050. Both CR and RTR AA7050 alloys follow the precipitation procedure of nucleation, growth and coarsening, while the DSC test shows that CR AA7050 has stronger response to aging treatment and age-hardening effect. CR AA7050 presents higher micro-hardness (253 HV), yield strength (650 MPa) and ultimate tensile strength (685 MPa), while the elongation (2.2%) is less than RTR AA7050 (245 HV, 573 MPa, 613 MPa, 3.5%). The aging treatment can improve the elongation of rolled samples, while the other mechanical properties are gradually decreased with the increasing in aging time. CR and RTR AA7050 sheets show a low corrosion resistance, while CR are beneficial to improving the corrosion resistance of the aged samples.

Effects of Heat Treatment on the Microstructure Evolution and Mechanical Properties of Selective Laser Melted TC4 Titanium Alloy

The effects of heat treatments on microstructure and basic mechanical properties of selective laser melted (SLM) TC4 titanium alloy were investigated in detail. The results demonstrated that a lot of acicular α/α′ and β phases exist in the SLM TC4 titanium alloy. With the increase in the aging treatment temperature, the metastable α′ phase of SLM TC4 was decomposed into α + β laths. Moreover, the α/α′ phase and β phase grew coarser, leading to a gradual decrease in strength, that is, plasticity and hardness increased and decreased, respectively. In terms of solid-solution aging treatment, the β phase was transformed into the α′ martensite phase in the solid-solution treatment, and the aging treatment induced the decomposition of the metastable α′ phase into α + β laths. The strength and hardness of SLM TC4 alloy increased as the temperature increased. The optimal mechanical properties could be obtained by water quenching after holding at 960 ℃ for 1 h and then air cooling after holding at 600 °C for 8 h.

Adsorption properties and influencing factors of Cu(II) on polystyrene and polyethylene terephthalate microplastics in seawater

As an emerging contamination in the ocean, microplastics can act as effective vectors of pollutants, the ecological risks caused by the combined pollution of microplastics and other pollutants have attracted growing attention. In this work, Copper (Cu(II)) was chosen as the classic pollutant, polystyrene (PS) and polyethylene terephthalate (PET) pellets were used as the typical marine microplastics, the adsorption performance of Cu(II) on PS and PET beads was investigated by adsorption kinetics and isotherm experiments, and other influencing conditions, such as pH, salinity, coexisting heavy metals ions and aging treatment, were evaluated. The results indicated that the adsorption behavior of Cu(II) on PS and PET was spontaneous and endothermic in the simulated seawater environment, and the batch experimental data can be effectively described by pseudo-second-order model and Freundlich isothermal model. Besides, the adsorption capacity of microplastics for Cu(II) was the best at pH 7, the change of salinity had no obvious effect on the adsorption in the natural marine environment. Moreover, co-existence of lead (Pb(II)) exhibited evident impacts on Cu(II) sorption onto PS and PET, which confirmed the adsorption competition effect between them. Additionally, high temperature aging treatment of microplastics in different environments for different duration time could obviously affect the properties of microplastics. It was found that the microplastics after being exposed to high temperature environment in the air for 168 h showed relatively stronger adsorption amount for Cu(II). In summary, these findings suggested that electrostatic interaction and distributed diffusion mechanisms may be the main mechanisms of adsorption, while no new functional groups were generated after the adsorption, indicating that physisorption may dominate the adsorption performance of PS and PET pellets for Cu(II). This study provides supplementary insights into the role of microplastics as carriers of heavy metals in the marine environment.

Influence of High Temperature Annealing on Microstructure Evolution of Ni-24Fe-14Cr-8Mo Superalloy

The effect of high temperature annealing on microstructure evolution of Ni-24Fe-14Cr-8Mo alloy was investigated through Optical Microscopy (OM), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Rockwell Hardness Testing Machine. Three kinds of grain growth patterns were found at different annealing temperatures due to carbides precipitation and dissolution. After a combination of high temperature annealing and aging treatment, the hardness versus time curves performed a parabolic pattern. The highest hardness was achieved under 1070°C/60 minutes treatment, and the desirable annealing time should be 60 minutes to 90 minutes.

Effect of rejuvenation heat treatment on re-service aging stability of γ′phase in directionally solidified superalloy

High temperature aging treatment was first conducted on the rejuvenated directionally solidified superalloy to simulate the re-service aging damage of turbine blades and the virgin directionally solidified superalloy respectively. Then re-service aging stability of γ′ phase in the virgin and rejuvenated directionally solidified superalloy was compared and analyzed, and the effect of different rejuvenation parameters on γ′ phase microstructure of the rejuvenated directionally solidified superalloy after the same re-service aging time was studied. The results show that although rejuvenation heat treatment can effectively restore creep microstructure to a nearly ‘‘as-new’’ condition, the re-service aging stability of γ′ phase in the rejuvenated directionally solidified superalloy is worse than that of the virgin directionally solidified superalloy, which is attributed to the decomposition of MC carbide. The rejuvenation heat treatment parameters have a great influence on re-service aging stability of the rejuvenated directionally solidified superalloy. The re-service aging rate of γ′ phase in the rejuvenated directionally solidified superalloy becomes higher, the higher the solution temperature, the shorter the holding time and the greater the cooling rate after solution higher. However, the increased primary aging temperature and holding time cause the decrease of the re-service aging rate of γ′ phase in the rejuvenated directionally solidified superalloy. The second aging condition has no obvious effect on the re-service aging stability of γ′ phase.

Effect of Aging Treatment on Microstructure and Wear Properties of CoCrFeNiTiNbB1.25 High Entropy Alloys Coatings by Laser Cladding

ABSTRACTLaser cladding CoCrFeNiTiNbB1.25 high entropy alloys (HEAs) coatings on H13 steel was fabricated. The effect of aging treatment temperature on microstructure and wear resistance of the HEAS coatings was investigated. Results showed the phases of the HEAs coatings were not changed as the aging treatment increased, the volume fraction of TiB phase was firstly increased, then reduced. The diffraction peak of fcc phase was firstly shifted to the right, and then shifted to the left. The HEAs coatings consisted of typical dendrite, interdendritic eutectic and dispersed intermetallic compound after aging treatment, and the dendrite obviously was coarsened after aging treatment at 850 °C. Compared with HEAs coatings before aging treatment, the microhardness of the HEAs coatings was firstly increased as the aging treatment temperature increased, then decreased, and the mass loss was opposite. The microhardness and mass loss was decreased by 4.3% and 11.9%, respectively for the aging treatment at 750 °C. The wear mechanism of the HEAs coatings before aging treatment was the abrasive wear, and was the abrasive wear and adhesive wear after aging treatment.

Effect of Aging Treatment on Precipitates and Intrinsic Mechanical Behavior of Austenitic Matrix in Ti–V–Nb‐Alloyed High‐Manganese Steel

The collaboration of precipitated particles and austenitic matrix plays a significant role in the overall wear performance of high‐manganese (high‐Mn) austenitic steels. The austenitic matrix cannot support micrometer‐sized precipitates because of its poor Young's modulus and hardness before work hardening, and the relative sliding of abrasive particles over the matrix may result in the precipitates detaching from the matrix and deteriorating the overall wear performance of the steels. Herein, a solid‐solution temperature of 1100 °C is applied to balance the size of the austenite grains and precipitates. Different volume fractions of submicrometer V2C are precipitated in the austenitic matrix by aging at different temperatures, and the volume fraction of submicrometer V2C precipitates increases with aging treatment temperature. When the aging temperatures are higher than 450 °C, Young's modulus and nanohardness of the austenitic matrix are significantly enhanced, and the overall Brinell hardness and strength of the specimens are also improved. The improvement in the mechanical properties of the matrix is mostly related to the precipitation strengthening of nanoscale precipitates, and the enhancement in the overall hardness of the steels is mainly related to a sufficient amount of precipitated submicrometer V2C particles in the austenitic matrix.