Solid Solution Heat Treatment Research Articles

Effect of heat treatment before fast multiple rotation rolling on friction surfaced Al–Si–Cu alloy

In this study the effect of combination of heat treatment of consumable rod and solid solution heat treatment before fast multiple rotation rolling (FMRR) processing on microstructure, mechanical property and wear resistance of Al–Si–Cu alloy friction surfaced on commercial pure aluminum alloy were investigated. Results show that after the FMRR process, there is a significant reduction (99% reduction) in the friction surfaced coating surface roughness. The surface roughness after FMRR processing in the coatings created by homogenized and solid solution treated consumable rod is 0.74 ± 0.12, and 0.56 ± 0.08 μm, respectively. In the coating created by homogenized rod the minimum grain size (1.7 ± 0.2 μm) formed in the FMRR processed layer. Using homogenized consumable rod and FMRR processing by rotational speed of 3000 rpm and traverse speed of 140 mm/min, the maximum hardness (9.8 ± 0.3 GPa) and minimum wear rate (4.6 ± 0.1 μg/m) created at processed layer. FMRR processing by rotational speed of 3000 rpm and traverse speed of 140 mm/min, result in 27 and 24 % increasing in hardness at friction surfaced coating created by homogenized and solid solution treated consumable rods, respectively.

Enhancing performance: Pre-processing heat treatment's influence on fast multiple rotation rolling of friction-surfaced Al-16Si-4Cu alloy

This study investigated the influence of pre-processing heat treatment on the fast-multiple rotation rolling (FMRR) of Al-16Si-4Cu alloy friction-surfaced onto the AA1050 aluminum substrate. Results showed that applying solid solution treatment before both the friction surfacing and FMRR processes yielded the thinnest coating thickness (1.4 ± 0.2 mm). Moreover, using a solid solution-treated Al-16Si-4Cu alloy rod resulted in the smallest average size of Si particles (4.2 ± 0.1 μm) in the FMRR-treated layer. Additionally, the most uniform distribution and smallest size of Al2Cu precipitates in the FMRR-treated layer were achieved by subjecting the alloy to solid solution treatment prior to both FMRR and friction surfacing. Notably, solid solution treatment preceding both FMRR and friction surfacing processes produced maximum nano-hardness (10.42 ± 0.54 GPa), shear strength (174.32 ± 9.21 MPa), and elastic modulus (221.03 ± 0.54 GPa) in the clad layer. Furthermore, pre-processing with solid solution heat treatment led to the lowest wear rate of the clad layer, exhibiting a reduction of 74.47 % compared to the AA1050 substrate.

Effects of residual Laves phase on microstructural evolution and mechanical properties of wire arc additive manufactured GH4169 Ni-based superalloy

The GH4169 Ni-based superalloy is prepared by wire arc additive manufacturing and the sizes and morphologies of Laves phases under different heat treatment strategies are obtained to further investigate the influence of residual Laves phases on the tensile properties of the superalloy. After the solution treated at a higher 1150 °C and followed by aging, the Laves phase is completely dissolved, with limited δ phase with varying sizes distributed at the grain boundaries. While for lower 1020 °C solid solution heat treatment temperature, the Laves phase in the sample changes from chain-like to particle-like shapes by partially dissolving, and the needle-like δ phase exists around the particle-like Laves phase. Such residual "Laves + δ" impede high-temperature tensile crack propagation, significantly enhancing plasticity. This mechanism makes the lower temperature solid solution treated sample exhibit similar tensile stress but ∼2 times of elongation when compared to the sample treated by higher solid solution.

Transition in Tensile Deformation Behavior of Fe-Cr-C/Low-Carbon Steel Wire Arc Additive Manufactured Joint Before and After Solid Solution Heat Treatment

Transition in Tensile Deformation Behavior of Fe-Cr-C/Low-Carbon Steel Wire Arc Additive Manufactured Joint Before and After Solid Solution Heat Treatment

Effect of solid solution heat treatment duration on microstructure evolution and the high temperature and low stress creep properties of a low-cost fourth-generation single crystal superalloy

Low-cost Ni-based single crystal superalloy with high performance attracted much attention to the researchers in recent years. A Ru-free low-cost fourth-generation single crystal superalloy was designed in this study, which was rarely reported previously. This study mainly focused on the effect of solid solution heat treatment duration on the microstructure evolution and high temperature and low stress creep properties on the experimental superalloy. By the metallographic method, it was revealed that the dendritic segregation was gradually eliminated with the increasing solid solution heat treatment duration. Segregation of Al and Ta were well homogenized as well as W. Segregation of Re could still be observed after 32 h solid solution heat treatment. Quantity and fraction of pores increased, which has a significant influence on the creep properties. Compositional variation between dendritic and inter-dendritic region was the main factor that caused the qualitative difference in the size and volume fraction of the γ' phase. Gap of the γ' size and volume fraction between dendritic cores and inter-dendritic region after solid solution heat treatment became minor. Homogeneous dislocation networks formed during the creep test and the ruptured dislocation networks of the specimen subjected to 32 h solid solution heat treatment were found. In the tertiary stage of the creep test, the primary creep deformation mechanism is the super-dislocations with Burgers vector of a 〈010〉 shearing the rafted γ' phases. The specimen subjected to 16 h solid solution heat treatment has the optimal creep performance, followed by those subjected to 32 h and 8 h, respectively.

Effect of aging on the structure and mechanical properties of austenite stainless steel N50 alloyed with nitrogen, niobium and vanadium

In this study, the austenitic, corrosion-resistant N50 steel alloyed with different nitrogen, niobium and vanadium content was investigated. This steel is used in the production of high-strength, cryogenic pipes. The production process for these pipes involves aging at 650 °C–665 °C for 50–100 h. Therefore, steels were examined in their as-delivered state, after aging at 650 °C, 100 h and after solid solution heat treatment. The structure of the steel was analyzed using optical and scanning microscopy, tensile and impact strength tests were conducted at room temperature and at −196 °C. It was found that the total volume fraction of the precipitated phase after aging is more dependent on the total concentration of nitride-forming elements—Nb and V, than on nitrogen. Aging does not affect the basic operational properties at room temperature, but it can significantly affect toughness at −196 °C.

Effect of solutionizing heat treatment on the structure and mechanical properties of silicon bronze (Cu-10wt%Si-2wt%Ni)

The effect of solutionizing temperature, soaking time, and quenching media on the structure and mechanical properties of silicon bronze (Cu-10wt%Si-2wt%Ni) has been examined. The samples were produced using the sand casting technique, machined to the required dimensions, and solutionized at temperatures of 700 oC, 800 oC, and 900 oC for 0.5, 1.5, 2.5, and 3.5 hrs and quenched in brine and oil respectively. The prepared as-cast and solution heat-treated samples were subjected to mechanical tests (hardness, and impact strength tests) as well as microstructural analysis. The results of the microstructural analysis revealed the presence of coarse grains and coarse sparse distribution of Ni2Si precipitate in the as-cast sample while the surface morphology of the heat-treated samples consisted of fine grains of intermetallic compounds evenly dispersed in the copper matrix. It was also observed that the microstructures of samples solutionized at lower temperatures (700 oC) revealed finer grains with better grain distributions compared with samples solutionized at higher temperatures (800 oC and 900 oC). These microstructural changes led to the improvement of the hardness and impact strength of the alloy. The hardness value of the as-cast sample 48.5 HRB, increased to 53.7 HRB and 57.8 HRB after solid solution heat treatment at 700 oC for 3.5 h and cooled in brine and oil, respectively. It was also observed that the hardness of the brine-cooled samples increased further to 72.45 HRB after 3.5 h at 900 oC. The results obtained also showed that the solid solution heat-treated samples gave an optimum impact strength value of 214 J/m3 and 183 J/m3 from the samples solutionized at 900 oC and 800 oC for 3.5 h and 1.5 h and cooled in brine and oil respectively. This was concluded to be a result of solid solution alpha and beta phases formed which improve energy absorption in the alloy.

Investigation on effect of high-efficiency solid solution and hot stamping process on microstructure evolution and mechanical properties of high-strength aluminum alloy

Aluminum alloy has become an important lightweight material in the automotive industry due to its excellent performance. The development of hot stamping technology has effectively promoted the application of high-strength aluminum alloys in auto parts. However, aluminum alloy hot stamping requires a long time for solid solution and aging heat treatment, which hinders its mass production application in the existing mature hot stamping production line. Therefore, this paper studies the effect of a high-efficiency solid solution and hot stamping process on the microstructure and mechanical property strengthening mechanism of high-strength aluminum alloy. The contact heating and hot stamping experiment device was designed. It was found that the temperature rise rate of the sheet during the contact heating process could reach 44.51 °C/s. The experiment results show that contact heating treatment with a solution temperature of 480 °C and a solution time of 20s can achieve the high-efficient solution treatment of the sheet metal. The high-temperature deformation behavior of 7075-T6 at different temperatures (300-450 °C) and different strain rates (0.01∼1/s) under the condition of high-efficiency solid solution rapid heating was studied.

Bonding Strength of 12Cr-0.4C/Low Carbon Steel (LCS) Weld Joint After Solid Solution Heat Treatment

Bonding Strength of 12Cr-0.4C/Low Carbon Steel (LCS) Weld Joint After Solid Solution Heat Treatment

CALPHAD simulation and experimental study on heat treatment process of Al-Cu-Mn-Mg-Sc cast alloys

Because different heat treatment parameters have different effects on the microstructure and mechanical properties, it is necessary to optimize the heat treatment parameters to obtain alloys with better properties. In this study, the heat treatment parameters of Al-Cu-Mn-Mg-Sc cast alloys were optimized by using thermal simulation and experimental methods. The results show that the phase transformation temperature of the low melting point eutectic phase Al2Cu is 542.9 ℃, and the time for element homogenization distribution of the alloy during solid solution at 525 ℃, 535 ℃ and 550 ℃ is 8 h, 7 h and 4.5 h, respectively. With the rise of solid solution temperature, the microhardness increase at first and then decrease, and the microhardness reaches to 96.4 HV at 535 ℃. When solid solution heat treatment is carried out at 535 ℃ for different times, the microhardness increase at first and then decrease with time, and the microhardness reaches to 118.4 HV at 5 h. It is known that the number of metastable phase decreases gradually with the increase of aging heat treatment temperature by using the calculation of thermodynamic software. The optimal aging heat treatment process parameter for the alloy is 170 ℃ for 10 h, and the microhardness at this time reaches to 142.3 HV.

Interface characteristics and tensile fracture behavior of CoCrFeNi/6061Al matrix composites fabricated via spark plasma sintering and heat treatment

In this study, 3vol%CoCrFeNi high-entropy alloy (HEA) reinforced 6061Al matrix composites were prepared using spark plasma sintering (SPS), and a new strategy to regulate the interfacial structure of the diffusion layer by solid solution heat treatment was proposed. Based on the thermodynamics and kinetics of solid-state diffusion, the mechanism of the formation and growth of the diffusion layer and its influence on the mechanical properties of the composites were analyzed. At a solid solution temperature of 535 °C, a uniform diffusion layer forms between HEA and Al matrix, and the thickness of the diffusion layer increases with the extension of solid solution time. The diffusion layer is determined as a two-layer structure, with a columnar solid solution grain near HEA and an equiaxed crystal along with Al9Co2 solid solution layer near Al matrix. Optimal tensile strength and elongation of 211.5 MPa and 21.4% respectively are obtained at solid solution time of 60 min, with 12.8 μm in thickness. Superior interface bonding resulting from diffusion layer prevents the crack from expanding into the matrix, contributing to an enhanced ductility with the extension of solid solution time. This study provides valuable insights and theoretical guidance for developing HEA/Al composites with superior strength-ductility synergy.

Creep strength and toughness synergistic strengthening mechanism investigation of the Inconel625/ BNi-2 brazed joint

Creep strength and toughness synergistic strengthening mechanism of Inconel625/BNi-2 brazed joint is investigated based on the post-brazing solid solution heat treatment (PSSHT). The heat treatment temperature of 1150 °C is adopted. The results show that borides in brazed joint are eliminated and broken gradually with the increasing of PSSHT time, and the elements are more uniformly distributed. The brazed joint with PSSHT time of 3 h has the longest creep life and the highest toughness, followed by those with PSSHT time of 6 h and 0 h, respectively. Elements homogenization can promote the creep strength and toughness of the brazed joint. While more PSSHT time will increase the grain size of brazed joint, and thus it degenerates the creep strength and toughness of the brazed joint. Although the borides can increase the risk of joint crack failure, the proper amount of punctate borides distribute along the grain boundary or in the interior of the grain can serve as the pinning points to slow down the dislocation movement of grain boundary, so as to improve the creep strength of brazed joint. Therefore, creep strength and toughness strengthening of the brazed joint caused by PSSHT is the synergistic action of element homogenization, borides distribution and grain size. The solid solution heat treatment time of 3 h at 1150 °C is a recommended heat treatment procedure.

Unique Yttria Nanoparticle Strengthening in an Inconel 718 Superalloy Fabricated by Additive Manufacturing

AbstractOxide dispersion strengthened (ODS) nickel (Ni)‐based superalloys are advanced materials known for their outstanding tensile and creep performance at temperatures exceeding 1000 °C. Nevertheless, their conventional synthesis presents a longstanding challenge in cost‐effectively producing intricate components for critical applications. In this work, electrostatic self‐assembly (ESA) of powders with the laser powder bed fusion (LPBF) process are successfully combined to produce yttria ODS Inconel 718 (IN718) alloy for the first time. This approach demonstrates a significant contribution of yttria to the strength of IN718 after the solid solution heat treatment, as evidenced by ≈50% improvement in room temperature yield strength with a 0.5 wt.% yttria addition. The addition of yttria by this process leads to a heterogeneous microstructure. This heterogeneous microstructure comprises two distinct grain areas with varying amounts of yttria nanoparticles and dislocation storage. The results show that the yield strength increase can be predicted by the combination of both Y2O3 dispersion strengthening and dislocation strengthening mechanisms. These findings offer an effective approach to tailor heterogeneous microstructures, unlocking new opportunities for cost‐effectively producing high‐performance ODS Ni‐based superalloy products with excellent mechanical properties.

Binder Based Processing of Magnesium Alloy WE43 towards Biomedical Application Using Metal Injection Molding (MIM)

In this study to the authors knowledge 1st time, Metal Injection Molding (MIM) technique was used to introduce the magnesium alloy WE43 into binder-based powder metallurgical (PM) processing. Towards later adoption to binder-based 3D-printing technologies, Fused Granular Fabrication (FGF) technique, respectively for biomedical application. Metal Injection Moulding (MIM) is a binder based economic near net shape prototyping technique for production of complex shaped parts in high number and high reproducibility, and hence perfect as a “gold standard” for the introduction of new Mg-alloys into binder passed PM processing. In doing so, dogbone shape tensile test specimen were manufactured by MIM, subsequently solvent debound and conventional sintered in argon atmosphere. Next to the as sintered specimens (asS), solid solution heat treatment (T4) and precipitation hardening heat treatment (T6) were performed on additional specimens. Tensile tests pointed out high strength and ductility of as sintered and heat treaded specimens of up to 226 MPa UTS at 7.6% elongation at fracture. The microstructure was investigated using SEM imaging technique equipped with energy disperse x-ray energy analysis (EDX) for secondary phase analysis. Hence, the magnesium alloy WE43 could be identified as a high strength and ductility alloy for binder based PM processing for future additive manufacturing approaches in biomedical applications of patient adapted implants.

Process Optimization Method for Inhibiting TCP Precipitation in A Nickel-Based Single Crystal Superalloy with High Refractory Element Content

In order to study the optimization method of microstructure stability of high generation single crystal superalloys, the influence of manufacturing process on the microstructure stability of a single crystal superalloy containing high content of refractory elements was studied, and the corresponding process optimization method was obtained. The microstructure characteristics of the alloy at different stages were observed and the corresponding element distribution were tested. The microstructure and element distribution of the alloy at different stages of preparation were analyzed with the assistance of kinetic calculation. Results show that the element dendrite segregation is an important reason to reduce microstructural stability. Reducing the dendrite spacing in directional solidification and increasing element diffusion in solid solution heat treatment can reduce the segregation of refractory elements in the dendrite core. As a result, less TCP precipitates in the dendrite core, and thus improve microstructure stability. Based on analyzed results, the manufacturing process were optimized and proved to be effective.

The Role of Boron Addition on Solidification Behavior and Microstructural Evolution of a High Niobium-Containing TiAl Alloy

This work investigates the role of boron addition in the solidification behavior and microstructural evolution during the heat treatment process of Ti-46Al-8Nb-xB (x = 0.1, 0.7, 1.4, 2.5 at.%). The results show that the solid solution boron element prefers to occupy the interstitial vacancies of the α2 phase in the alloy. However, the solid solubility of the boron element in high Nb-containing TiAl alloys is extremely low. Therefore, it does not have a significant effect on the lattice distortion of α2 and γ phases in the alloy. When the boron content is added up to 0.1%, a B27-type TiB precipitated phase is produced in the alloy. The morphology of borides mostly shows short rod-like structures, and a few show long curved shapes. And the addition of boron refines both the alloy colony size and the lamellar structure. Furthermore, it is also found that boron addition weakens the casting texture of the alloy. After a solid solution and different time aging heat treatment process, the microstructure of different boron content alloys have experienced obvious coarsening phenomenon. However, the morphology of the boride is closely related to boron content and heat treatment.

Phase Composition and Microstructure of Cast Al-6%Mg-2%Ca-2%Zn Alloy with Fe and Si Additions

Investigating the effect of Fe and Si is essential for any new Al-based composition, as these impurities can be easily found both after primary production and recycling. This study is dedicated to filling the gap in revealing the phase composition of an Al-6%Mg-2%Ca-2%Zn alloy after the combined and separate addition of Fe and Si. This was addressed by permanent mold casting and solid solution heat treatment. The investigation of slowly solidified samples also contributed to understanding potential phase transitions. It was found that the alloy containing 0.5%Fe can have nearly spherical intermetallics after heat treatment, whereas a higher Fe content brought the formation of a needle-shaped Al3Fe intermetallic. We explain this by the formation of a ternary α-Al + Al10CaFe2 + Al4Ca eutectic, which is more compact in as-cast condition compared to divorced binary α-Al + Al4Ca and α-Al + Al3Fe eutectics. Similarly, 0.5%Si readily incurred the formation of a needle-shaped Al2CaSi2 intermetallic, probably also by a binary reaction L → α-Al + Al2CaSi2. In the solidified samples, no Mg2Si phase was found, even in slowly solidified samples. This is contrary to the thermodynamic calculation, which suggests a peritectic reaction L + Al2CaSi2 Mg2Si. Interestingly, the addition of 0.5%Si caused an even coarser microstructure compared to the addition of 1%Fe, which caused the appearance of a primary Al3Fe phase. We conclude that the new alloy is more tolerable to Fe rather than Si. Specifically, the addition of 0.5%Fe can be added while maintaining a fine morphology of the eutectic network. It was suggested that the morphology of eutectic and solid solution hardening governed the mechanical properties. The strength of the alloys containing separate 0.5%Fe (UTS = 215 ± 8 MPa and YS 146 ± 4 = MPa) and the combined 0.5%Fe and 0.5%Si additions (UTS = 195 ± 14 MPa and YS ± 1 = 139 MPa) was not compromised compared to the alloy containing 0.5%Si (UTS 201 ± 24 = MPa and YS = 131 ± 1 MPa).

Mechanism of cryogenic, solid solution and aging compound heat treatment of die-cast Al alloys considering microstructure variation

Mechanism of cryogenic, solid solution and aging compound heat treatment of die-cast Al alloys considering microstructure variation

Fracture Failure Assessment Analysis and Process Improvement of Vessel Bending Test

The high-purity ethylene dichloride (EDC) head tower is an important pressure vessel in the vinyl chloride production process. During the manufacturing process, the bending test of 2 product specimens broke. In this paper, the failure analysis of the bending test fracture of the welding test plate was carried out, and a systematic analysis, including chemical composition, mechanical properties, and microstructure, was carried out. The causes of fracture of welded test plates during the manufacturing process of the head tower were studied. The results show that the incorrect heat treatment process leads to the extension strength, hardness, and impact performance, being lower than the standard requirements. The combined fracture analysis shows that the material is brittle, which makes the welding test board brittle fracture. At the same time, metallographic analysis shows that the steel is tempered. The comprehensive performance of duplex stainless steel in the tempered state is significantly lower than the original solid solution heat treatment performance. Thus, the bending test fracture of the welding test board of the equipment is caused by the improper heat treatment process, resulting in the microstructure and performance of the material not meeting the relevant requirements. According to the cause of the fracture, the heat treatment and welding process are improved. The heat treatment was carried out first, and then the duplex steel was welded to prevent the heat treatment state of the duplex steel supply from changing. Finally, a qualified specimen was obtained.

The Microstructural Degradation of Ni-Based Superalloys with Segregation under the Super-Gravity Condition

The Ni-based superalloy is used as the turbine blade, which is subject to the coupling effect of temperature and super-gravity during service. As the Ni-based superalloys are difficult to become homogenous after using the solid solution heat treatment, a study on morphology and composition distribution of Ni-base superalloys with segregation during microstructural degradation is necessary. This study investigates the microstructure of the ex-service turbine blade and cast samples subjected to the high-temperature centrifugal test. The difference in the size and shape factor of the γ′ phase decreased with the stress caused by the super-gravity condition, indicating a higher magnitude of homogenization degree. The higher stress will also promote the merge of the sub-grain boundaries, leading to a lower density and higher orientational deviation of the sub-grain boundaries.