Increase Of Solid Solution Temperature Research Articles

Improving the comprehensive mechanical property of the AlSi10Mg alloy via parameter adaptation of selective laser melting and heat treatment

In this work, the AlSi10Mg alloys with distinct molten pool structures, namely fish-scale and lamellar, were fabricated by using selective laser melting (SLM) technology. The effects of solid solution temperature on the microstructural evolution and mechanical properties of the two types of alloys were systematically investigated. The relationship among initial structure, heat treatment and mechanical properties was revealed. The experimental results showed that for the alloy with fish-scale structure, Si diffused more easily after solid solution treatment due to the finer eutectic network, resulting in a larger Si particle size. At 510 °C, the nano Si particles in the fish-scale sample basically disappeared, but a small amount of nano Si particles still existed in the lamellar sample, leading to a bimodal distribution in the Si particle size. Different sizes and distributions of Si particles present different strengthening mechanisms and affect the nucleation and growth of recrystallized grains in the α-Al matrix, leading to significant differences in mechanical properties. The strength of the lamellar sample decreased with increasing the temperature, and the abnormally growth of grains could be found after being treated at 510 °C, resulting in a poor mechanical property. The strength of fish-scale sample first decreased and then increased with the increase of solid solution temperature. When the alloy with fish-scale structure was solid solution treated at 510 °C, Si particles could promote the nucleation of recrystallized grains but hinder their growth, and the ultimate tensile strength decreased from 478.8 MPa of SLMed state to 393.4 MPa, a reduction of 17.8%, while the elongation increased from 7% to 21%, an increase of 300%, showing an excellent overall mechanical property. Therefore, the present study demonstrates that adjusting the SLMed molten pool structure and heat treatment parameters is necessary to obtain a good combination of microstructure and mechanical property.

The beneficial effect of yttrium microalloying in the solid solution treatment of AISI 321 stainless steel：Grain refinement and inclusions modification

Solid solution treatment is an important means of regulating the microstructure and mechanical properties of austenitic stainless steel, and a suitable solid solution process window is critical for austenitic stainless-steel service. In this paper, the effect of (RE) yttrium and solid solution temperatures on the microstructure and mechanical properties of austenitic stainless steel was investigated by adding trace amounts of RE yttrium to AISI 321 stainless steel with different solid solution temperature treatments. The results show that the austenite grains gradually coarsen with the increase of solid solution temperature, and the addition of RE yttrium effectively inhibits the coarsening of grains and keeps an excellent the comprehensive mechanical properties of AISI 321 stainless steel at 1150 °C for 30 min, this indicates that the addition of RE yttrium broad solid solution process window for AISI 321 stainless steel. In addition, the RE yttrium microalloying has a positive modification effect on the carbonitrides with refinement and spherization, which has a good contribution to the strength and plasticity retention of the material. This research is expected to provide more options for the heat treatment of austenitic stainless steels.

Study on the solid solution temperature of achieving ultra-high strength in wire-arc additive manufactured Al-Zn-Mg-Cu aluminum alloy

Al-Zn-Mg-Cu aluminum alloys are typically heat-treatable aluminum alloys. The heat treatment has a significant effect on the microstructure and mechanical properties of Al-Zn-Mg-Cu alloy. In this study, the solid solution temperature of achieving ultra-high strength in wire-arc additive manufactured 7B55 aluminum alloy was systematically investigated. The results showed that the microstructure of the as-deposited 7B55 aluminum alloy was composed of equiaxed grains with an average grain size of 4.2 ± 0.5 μm. A large number of the second phases were continuously distributed along grain boundaries. The precipitated phases within grains were mainly composed of the larger η phases and the smaller η′ phases, and the amount of precipitated phases was fewer. The second phases distributed along grain boundaries gradually dissolved into α-Al matrix with the increase of solid solution temperature, resulting in a higher supersaturation of the α-Al matrix and more homogeneous distribution of alloy elements. Combined with the results of DSC analysis, the optimal solid solution temperature of the 7B55 aluminum alloy was determined to be 480 °C. After solid solution of 480 °C，the microstructure was still composed of equiaxed grains with an average grain size of 4.8 ± 0.4 μm. The size of the grain did not grow significantly. A larger number of nanoscale fine GP zones, η′ phases and secondary Al3(Sc,Zr) particles were precipitated within the grains during subsequently artificial aging process, resulting in a significant increase in tensile properties. The ultimate tensile strength (UTS), yield strength (YS) and elongation (EL) reached 621 MPa, 555 MPa and 5.73%, respectively, which was significantly higher than the strength level of WAAM aluminum alloy reported among all the existing literature.

The effect of solid solution temperature on the precipitation phase and properties of plasma arc welded joints of Inconel625 high temperature alloy

The effect of solid solution temperature on microstructure and mechanical properties of plasma welded nickel-based high temperature alloy Incone l625 was investigated by solid solution treatment (The solid solution temperature range is 950 °C to 1150 °C and the intergroup interval is 50 °C). The results show that after solid solution treatment at 950 °C, chain carbides are precipitated at the austenite grain boundary of the base material. With solid solution temperature increasing, carbon chains dissolve gradually at the grain boundary. When solution temperature is higher than 1050 °C, carbides at the grain boundary completely melt back into the matrix. At the weld, dendritic crystal and Laves phase dissolve with the increase of solid solution temperature. When the solid solution temperature is 1100 °C, the dendritic crystal and Laves phase at the weld completely melt into the matrix and transform into cellular crystals. When the solid solution temperature is increased to 1150 °C, the cellular crystal grows further at the weld. When the solid solution temperature is 1100 °C, the comprehensive mechanical properties of the joint are the best.

Microstructure evolution and strengthening mechanism analysis of novel Mg-RE-Ag alloy during heat treatment

Precipitation strengthening is crucial for Mg-RE alloys to achieve excellent mechanical properties. Herein, the high-strength Mg-6Gd-2Y-1.5Ag-1Nd-0.4Zn-0.5Zr alloy was designed and developed by building multi-orientated nano-precipitates. The corresponding microstructure and strengthening mechanism were comprehensively investigated utilizing XRD, OM, SEM, TEM, Brinell hardness and tensile tests under various heat treatment conditions. The results indicated that the as-cast alloy consisted of the primary α-Mg matrix and Mg5(Gd,Y,Nd,Ag,Zn)-type eutectic phase at the grain boundaries. With the increase of solid solution temperature and time, the grain size of the alloy gradually increased. After solution treatment at 510 °C for 10 h, solute atoms from the eutectic phase fully diffused into the matrix, and the supersaturated solid solution was obtained. The solution-treated alloy was subsequently aged, and multiple types of nanoscale precipitates formed in the matrix. The precipitation evolution can be divided into three distinct stages. At the early aging stage, the fine solute clusters were the primary precipitates. And then a mass of basal γ'' and prismatic β′ phases occurred uniformly in the matrix at the peak-aged stage. After reaching the over-aged stage, the primary precipitates further transformed into coarse γ and β phases. The alloy achieved outstanding mechanical properties at both room and high temperatures after the peak-aged treatment, which was mainly related to the synergistic strengthening of the multi-orientated β′ and γ'' nano-precipitates. The peak-aged alloy's ultimate tensile strength, yield strength, and elongation were 370 MPa, 335 MPa, 2.8% at room temperature, and 258 MPa, 215 MPa, 11.8% at 300 °C, respectively.

Effect of Solution Treatment on Microstructure and Mechanical Properties of TC16 Titanium Alloy Wire

Abstract TC16 titanium alloy wire was treated by solution treatment, and then the optical microscope, tensile property and impact property tests were used to analyze the microstructure and mechanical properties of TC16 titanium alloy wire after solution treatment. The results show that there are a lot of primary α phase, metastable β phase and α” phase after solution treatment. With the increase of solution temperature, the content of primary α phase decreases to completely disappear and more α” phase is formed. Under the condition of solid solution, the tensile strength decreases with the increase of temperature, while the plasticity changes little with the increase of temperature. The maximum tensile strength is 969 MPa, the maximum yield strength is 572 MPa, the maximum elongation after fracture is 26 %, and the maximum section shrinkage is 59 %. The impact toughness and impact absorption energy increase with the increase of solid solution temperature, and the maximum impact toughness is 90 J/cm2, and the maximum impact absorption energy is 37 J.

Effects of solid-solution temperature on microstructure and mechanical properties of a novel 2000 MPa grade ultra-high-strength steel

A novel 2000 MPa grade ultra-high-strength steel AIR0509 with high fracture toughness and low cost has recently been developed. The effects of solid-solution temperature on the microstructure and mechanical properties of this steel were investigated. The increase in solid-solution temperature first increased and then decreased the values of ultimate strength (UTS) and Charpy U-notch (CUN) energy. The increase in the UTS and CUN values was caused by the dissolution of the primary carbides M6C and MC, while the decrease in both strength and toughness was due to the increase in the prior austenite grain size. Samples that were solid-solution treated at 1000 °C exhibited an optimal combination of strength and toughness with a UTS of 2020 MPa, yield strength of 1780 MPa, and CUN energy of 68 J, as well as a correlative fracture toughness KIC value of about 105 MPa m1/2.

The effect of solid-solution temperature on phase composition, tensile characteristics and fracture mechanism of V-containing CrMn-steels with high interstitial content C+N>1 mass. %

New high-interstitial austenitic Fe–19Cr–22Mn–1.6V–0.4C–0.8N (mass. %) and Fe–22Cr–26Mn–1.3V–0.7C–1.2N steels were designed. A combination of high interstitial content (C + N = 1.2 mass. % and C + N = 1.9 mass. %, C/N = 0.5–0.6) and V-alloying of these steels provides a complex hardening mechanism (a solid-solution hardening, a particle strengthening and a grain boundary hardening). Increase in solid-solution temperature in the interval 1100–1230 °C forces solid-solution hardening, causes grain growth and changes a distribution and volume fraction of the precipitates in austenite. The relation of these factors governs the value of a yield strength, an ultimate tensile strength and an elongation in the high-interstitial steels. The variation in particle strengthening with solid-solution temperature has minor effect on the yield strength of the steels, but the distribution of precipitates strongly influences a tensile fracture micromechanism of the steels. The effect of solid-solution temperature on fracture peculiarities is described based on microstructural analysis of the steels.

Effect of solution and aging system on microstructure and mechanical properties of 7000 series aluminum alloy produced by powder metallurgy

Different solid solution treatments (G1, G2, G3) and aging treatment were performed on the 7000 series aluminum alloy prepared by powder metallurgy (PM). The phase analysis and microstructure observation of the alloy material were carried out using metallographic microscope (MM), x-ray diffraction (XRD) analyzer and scan electron microscope (SEM). Hardness, electrical conductivity and the compressive mechanical properties of the alloy were measured. The results show that the size and quantity of the undissolved phase in the 7000 series aluminum alloy gradually decrease with the increase of the highest temperature of solid solution and the total solid solution time. When the highest temperature of solution rises to 470 °C (G2), the amount of undissolved phase in the alloy decreases slowly; As the solid solution temperature increases, the hardness of the alloy gradually increases under the aging treatment at 121 °C. The alloy under G3 solid solution has the highest hardness after 15 h aging, and the peak value is 227.5HV. With the increase of solution temperature, the electrical conductivity of aluminum alloy decreases gradually after aging. With the increase of solid solution temperature and solid solution time, the compressive strength value of the alloy after the aging increases first and then decreases. The compressive strength of alloy under G2 solid solution process reaches a maximum of 675.15 MPa, and its fracture strain is 7.73%.

Effect of multi-stage solution and aging process on microstructure and properties of Al-11.2Zn-3.0Mg-1.3Cu-0.2Zr aluminum alloy extrusion

The aluminum alloy extrusion materials were treated by multi-stage solution aging, and the microstructure and mechanical properties were characterized and tested. The results show that with the increase in solid solution temperature and time, the strength shows a trend of increasing first and then decreasing, and reaches a maximum value in G3. Under the conditions of 450 °C × 2 h + 460 °C × 2 h + 470 °C × 2 h in solid solution process and 121 °C × 5 h + 133 °C × 16 h in the aging process, the aluminum alloy has excellent comprehensive properties, with a strength of 828.0 MPa and elongation of 8.1%.

Microstructural evolution and phase transformation of Inconel 718 alloys fabricated by selective laser melting under different heat treatment

The microstructure, hardness and phase transformation of Inconel 718 Ni-based alloys fabricated by selective laser melting (SLM) before and after different heat treatment including the direct double ageing (720 °C, 3 h/furnace cooling plus 620 °C, 3 h/air cooling), 950 °C solid solution plus double ageing and 1050 °C solid solution plus double ageing are studied. Results show that the obvious weld beads structure can be observed on the X-Y surface in as-received alloys, and the alloys show seriously inhomogeneous with distributing columnar crystals and fine dendrites. After direct double ageing, the columnar and small dendritic crystals transformed into bulk crystals and the weld beads structure disappeared instantly with the X-Y surface hardness of alloys is about 490–540 HV. With the increase of solid solution temperature, the X-Y surface of alloys shows an obvious refining characterization. The hardness value on the surface is gradually reduced as well. The typical columnar crystals, dendrites, intermetallic compounds and precipitated hardening phase (such as Cr-Fe-Mo-Ni, FeNi and Ni8Nb) are also reduced or could not be found. Under the 950 °C solid solution plus double ageing, the fine homogeneous δ phase in the grain and γ, phase near the grain boundary have an important effect for improving the X–Y surface hardness of alloys.

Microstructural Evolution and Phase Transformation on the X-Y Surface of Inconel 718 Ni-Based Alloys Fabricated by Selective Laser Melting under Different Heat Treatment

Abstract Microstructure, hardness, precipitates and phase transformation on the X-Y surface of Inconel 718 Ni-based alloys fabricated by selective laser melting (SLM) were studied before and after a suitable heat treatment. The test results show that the obvious weld beads structure was observed on the surface of the as-built alloys, and the microstructure shows seriously inhomogeneous with distributing columnar crystals and fine dendrites. When the 720°C, 3 h/furnace cooling+620°C and 3 h/air cooling was used, the columnar and small dendritic crystals begun to transform into bulk crystals, and the weld beads structure disappeared instantly. The X-Y surface hardness of alloys is about HV490-540, which is higher than the one of other heat treatment processes. With the increase of solid solution temperature, the microstructure on the surface of alloys shows an obvious refining characterization. The hardness value on the surface was also reduced gradually. The typical columnar crystals, dendrites, intermetallic compounds and precipitated hardening phase (Cr-Fe-Mo-Ni, FeNi and Ni8Nb) were also reduced or could not be found. Under the solid solution process of 950°C, the fine homogeneous δ phase and γ′ phase in the grain or near the grain boundary had an important effect on the suitable surface hardness value (HV476-500) of alloys.

Effect of α phase on fatigue crack growth of Ti-6242 alloy

Fatigue crack growth as a function of a phase volume fraction in Ti-6Al-2Sn-4Zr-2Mo (Ti-6242) alloy was investigated using fatigue testing, optical microscopy, scanning electron microscopy, and transmission electron microscopy. The α+β annealing treatments with different solid solution temperatures and cooling rates were conducted in order to tailor microstructure with different a phase features in the Ti-6242 alloy, and fatigue crack growth mechanism was discussed after detailed microstructure characterization. The results showed that fatigue crack growth rate of Ti-6242 alloy decreased with the decrease in volume fraction of the primary α phase (αp). Samples with a large-sized a grain microstructure treated at high solid solution temperature and slow cooling rate have lower fatigue crack growth rate. The appearance of secondary a phase (αs) with the increase of solid solution temperature led to crack deflection. Moreover, a fatigue crack growth transition phenomenon was observed in the Paris regime of Ti-6242 alloy with 29.8% αp (typical bi-modal microstructure) and large-sized a grain microstructure, owing to the change of fatigue crack growth mechanism.

Influence of heat treatment on microstructure and mechanical properties of as-cast Mg–8Li–3Al–2Zn–xY alloy with duplex structure

In this study, the microstructure evolution and mechanical properties of as-cast Mg–8Li–3Al–2Zn–0.5Y alloy during solid solution treatment from 300°C to 450°C were firstly investigated, and then the effect of Y content (from 0.5wt% to 1.5wt%) on the age softening of solid solution treated Mg–8Li–3Al–2Zn alloy was also analyzed. The results show that the as-cast Mg–8Li–3Al–2Zn–0.5Y alloy mainly consists of α-Mg, β-Li, Al2Y and AlLi phases. With the increase of solid solution temperature from 300°C to 450°C for as-cast Mg–8Li–3Al–2Zn–0.5Y alloy, the AlLi phase is decomposed and the atoms of Al and Li dissolve into the matrix gradually. The hardness, yield strength and ultimate tensile strength of the tested alloy are increased dramatically; however, the ductility is relatively decreased. Meanwhile, the room temperature aging treated Mg–8Li–3Al–2Zn–0.5Y has age hardening during initial time, and the addition of Y is helpful to the thermal stability of Mg–8Li–3Al–2Zn alloy. In addition, the fracture behavior and strengthening mechanism of the studied alloys were also investigated systematically.

Effect of heat treatment on microstructure and mechanical properties of SiCp/2024 aluminum matrix composite

SiCp/2024 aluminum alloy matrix composite was prepared by powder metallurgy method. Effects of heat treatment on the microstructure and mechanical properties of composite were investigated by SEM, EDS, XRD, HREM, tensile and hardness tests. The experimental results showed that SiC particles distributed uniformly in the matrix and were in good combination with matrix. The tensile strength and hardness were improved significantly after heat treatment. With the increase of solid solution temperature, the alloy phases dissolved in the matrix gradually. When the solid solution temperature arrived at 505 °C, the alloy phases dissolved thoroughly, and the composite exhibited the highest tensile strength and hardness (δb=360 MPa, HBS=104). The main strengthening phase was Al2Cu, which was granular and distributed dispersively in the matrix. Effect of T6 was better than that of T4 at the same solid solution temperature.

Effects of Solid Solution Temperature on the Structure and Properties of TC16 Titanium Alloy Bars

The effects of solid solution temperature on the structures and properties of TC16 titanium alloy bars that made solid solution treatment in 780°C, 800°C, 850°C, 900°C, respectively, the processing time for 30min, then cooled in the air were studied. The results show that during solid solution treatment under 800°C, the alloy structures are the primary ɑ phase and the metastable β phase, while solid solution temperature rise to 800°C, the alloy structures begin to appear ɑ" martensite phase. With the increase of solid solution temperature, the alloy grain grow up somewhat, material tensile strength increases gradually, yield strength firstly decreases and then increases, elongation at break firstly increases and then decreases, percentage reduction of area at break decreases gradually. Solid solution state of TC16 titanium alloy bars are not suitable for cold heading forming, strengthening the titanium alloy must be subsequent artificial aging treatment.

Effect of Heat Treatment on the Structure and Properties of EW75 Magnesium Alloy Plate

In this study, Mg-7Gd-5Y-1Nd-0.5Zr alloy (EW75) was produced by melting method and then press-forged into large size plate. The properties of the Mg-7Gd-5Y-1.2Nd-0.5Zr alloy were optimized through T6 heat treatment. The microstructures of alloy were observed by means of optical microscopy (OM), scanning electron microscopy (SEM). Its mechanical properties under different heat treatment conditions were determined by tensile tests. The results indicated that increasing the solid solution temperature and prolonging the solid solution time can both lead to the dissolution of second phase in the alloy back into the matrix. The solid solution temperature affects the dissolution process more than the solid solution time. Grain growth occurred during the solid solution process. The grain size of the matrix enlarges with the increase of solid solution temperature. The tensile test result showed that the tensile strength of the alloy was significantly improved after T6 heat treatment. Its tensile strength in the same direction was nearly 40% up after T6 heat treatment. The analysis shows that T6 heat treatment can effectively eliminate the larger deformed precipitates and beneficial to the formation of hard precipitates, which leads to an improvement in the alloys tensile strength.

The Effect of Heat Treatment on the Properties of LF9 Alloy

The paper experimentally investigated the change of LF9 properties, including strength at room temperature and 350°C, plasticity and impact toughness, under various heat treatment schedules. Results show that the strength of LF9 decreases and plasticity and toughness increase after secondary aging, with the increase of solid solution temperature. Meanwhile, with the increase of aging time, the strength of LF9 increase and plasticity and toughness decrease. The investigation of optical metallography, TEM and phase analysis indicate that the phenomena are mainly caused by the precipitation of η, γ’and γ’’.

Nitrogen partitioning between matrix, grain boundaries and precipitates in high-alloyed austenitic steels

New high-interstitial austenitic Fe–19Cr–22Mn–1.6V–0.4C–0.8N (mass. %) and Fe–22Cr–26Mn–1.3V–0.7C–1.2N steels were designed. A combination of high interstitial content (C + N = 1.2 mass. % and C + N = 1.9 mass. %, C/N = 0.5–0.6) and V-alloying of these steels provides a complex hardening mechanism (a solid-solution hardening, a particle strengthening and a grain boundary hardening). Increase in solid-solution temperature in the interval 1100–1230 °C forces solid-solution hardening, causes grain growth and changes a distribution and volume fraction of the precipitates in austenite. The relation of these factors governs the value of a yield strength, an ultimate tensile strength and an elongation in the high-interstitial steels. The variation in particle strengthening with solid-solution temperature has minor effect on the yield strength of the steels, but the distribution of precipitates strongly influences a tensile fracture micromechanism of the steels. The effect of solid-solution temperature on fracture peculiarities is described based on microstructural analysis of the steels.