Solid Solution Treatment Temperature Research Articles

Effect of Solution and Aging Heat Treatment on the Microstructure and Mechanical Properties of Inconel 625 Deposited Metal

Inconel 625 deposited metal was prepared by gas metal arc welding. The solid solution treatment temperature was set at 1140 °C for 4 h using the DSC test method, followed by secondary aging at 750 °C/4 h and 650 °C/24 h. The specimens in the prepared state and after heat treatment were subjected to high temperature tensile at 600 °C, respectively. The fracture morphology, thermal deformation behavior, and strengthening mechanism of the samples in different states were analyzed. The results showed that the stress–strain curves of the deposited metals exhibited obvious work-hardening behavior at 600 °C. The solid solution and aging heat-treated samples have higher tensile and yield strength, but the plasticity is obviously lower than that of the deposited metal. It was also found that the γ″ phase and M23C6 carbides, as well as the continuous stacking faults in the alloy, were the main reasons for the increase in tensile strength of the solution and aging heat-treated sample.

Investigation of the Effect of Heat Treatment on the Microstructures and Mechanical Properties of Al-13Si-5Cu-2Ni Alloy

An experimental investigation was carried out to study the effects of solid solution treatment and aging treatment on the microstructures and mechanical properties of an Al-13Si-5Cu-2Ni alloy. The results show that the size of eutectic silicon decreased with solid solution treatment temperature increasing until 510 °C. Subsequently, the eutectic silicon size continued to increase as the temperature increased to 520 °C. Initially, the acicular eutectic silicon of the as-cast alloy was 10.1 μm in size. After the solid solution treatment at 510 °C, the eutectic silicon size was reduced to 6.5 μm. The θ′ phase is the main strengthening phase in the alloy, therefore, the effect of aging treatment on θ′ phases was explored. As the aging time increased, the diameter, length, and fraction volume of the θ′ phases were found to increase. The main reason for the improved performance of this alloy following heat treatment is the passivation spheroidization of the silicon phase and Orowan strengthening due to the θ′ phases. The optimal tensile strength of an Al-13Si-5Cu-2Ni alloy was obtained after solid solution treatment at 510 °C for 8 h followed by an aging treatment at 165 °C for 8 h. Therefore, this work has great significance for promoting the application of Al alloys at high temperatures.

On Temperature Dependence of Microstructure, Deformation Mechanisms and Tensile Properties in Austenitic Cr-Mn Steel with Ultrahigh Interstitial Content C + N = 1.9 Mass.%

The microstructure, deformation mechanisms, tensile properties and fracture micromechanisms of ultrahigh-interstitial austenitic Fe-22Cr-26Mn-1.3V-0.7C-1.2N (mass.%) steel were investigated in wide temperature interval. After conventional homogenization and solid-solution treatment, the steel possesses complex hardening which includes grain boundary, solid-solution and dispersion strengthening. In the temperature interval of −60 to +60 °C, steel demonstrates striking temperature dependence of a yield strength which could be enhanced by the increase in solid-solution treatment temperature. The variation in test temperature does not change the dominating deformation mechanism of the steel, dislocation slip and insufficiently influences tensile elongation and fracture micromechanisms. The insignificant increase in the fraction of brittle cleavage-like component on the fracture surfaces of the specimens in low-temperature deformation regime is promoted by increase in planarity of dislocation arrangement and the gaining activity of mechanical twinning. In high-temperature range (200–300 °C) of deformation, a negative strain-rate dependence, serrations on the stress-strain diagrams and improved strain-hardening associated with a dynamic strain aging phenomenon have been observed.

The effect of ultrasonic melt treatment on solid solution treatment temperature and/or time for an Al-7Si-2Cu-1Mg alloy

ABSTRACT Ultrasonic melt treatment (UST) is known for refining microstructures including intermetallic compound (IMC)s, and it is expected that the microstructural benefits induced by UST may reduce the time and temperature of solid solution treatment (SST). The effect of UST on SST for an Al-7Si-2Cu-1 Mg alloy was investigated in terms of changes of volume fraction of IMCs in connection with the tensile properties. The results show that UST not only refined the constituent phases but also reduced the volume fraction of IMCs in the as-cast microstructure, which promoted dissolution of Cu and Mg rich IMCs during SST, increasing the yield strength of the alloy. In addition, the SST time to achieve maximum strength was shortened by UST. Without UST, the strength was maximised at 520 °C for 8 hours, while with UST the strength was maximised at 2 ~ 4 hours. The dissolution of the constituent phases upon SST was also discussed.

Fabrication, Structure and Mechanical and Ultrasonic Properties of Medical Ti6Al4V Alloys Part I: Microstructure and Mechanical Properties of Ti6Al4V Alloys Suitable for Ultrasonic Scalpel.

Ti6Al4V alloy has been considered as a key component used in ultrasonic scalpels. In this series of papers, the fabrication, structure, and mechanical and ultrasonic properties of medical Ti6Al4V alloys suitable for ultrasonic scalpel are studied systemically. These alloys with low elastic modulus and present a typical bimodal microstructure with relatively high β phase content (~40%) and lamellar α thickness of ≤ 0.9 µm. In the first paper, the relationship between the microstructure and mechanical properties of hot-rolled Ti6Al4V alloys treated by heating treatment is discussed. In the second paper, the dependence of the ultrasonic properties on the microstructure of the heat-treated Ti6Al4V alloys is reported. With increasing solid solution temperature, the content and size of the primary α phase decrease. In contrast, the content and size of the lamellar α phase increase. Additionally, the β phase content first increases and then decreases. The microstructure of Ti6Al4V alloys could be slightly changed by aging treatment. When the solid solution treatment temperature increases to 980 °C from 960 °C, the average size of the lamellar α phase in the alloys increases by 1.1 µm. This results in a decrease in the average yield strength (93 MPa). The elastic modulus of alloys is mainly controlled by the β phase content. The microstructure of alloys by solution-treatment at 960 °C shows the highest β phase content and lowest average elastic modulus of 99.69 GPa, resulting in the minimum resonant frequency (55.06 kHz) and the highest average amplitude (21.48 µm) of the alloys at the length of 41.25 mm.

Fabrication of a Novel TRIP‐Aided Ni‐Free Lean Duplex Stainless Steel with Good Corrosion Resistance by Twin‐Roll Strip Casting and Its Deformation Mechanisms

The thin strip of novel TRIP‐aided Ni‐free lean duplex stainless steel with good corrosion resistance is fabricated by twin‐roll strip casting. The microstructure, corrosion resistance, and mechanical properties of the present Ni‐free steel (DSS‐2) are investigated in detail in this study. Meanwhile, comparison with duplex stainless steel containing about 2% Ni (DSS‐1) is also conducted to discuss the effect of alloying Ni on corrosion resistance and mechanical properties. The DSS‐2 has the more excellent mechanical properties than the comparison steel DSS‐1 due to the strain induced martensitic transformation during plastic deformation, which the ultimate tensile strength and total elongation are measured to be about 960 MPa and 55%, respectively. The strain induced martensitic transformation in DSS‐2 will be suppressed with the increase of solid solution treatment temperature and strain rate. The austenitic stability is more dependent on element partitioning in austenite phase than on grain size of austenite for the present TRIP‐aided Ni‐free lean duplex stainless steel. The novel Ni‐free steel has the better corrosion resistance and mechanical properties than the austenitic stainless steel SUS304, which may potentially be applied to substitute SUS304 in some fields as anti‐corrosive structural material.

Pitting corrosion behavior in novel Mn–N alloyed lean duplex stainless steel containing Cu

The novel Mn–N alloyed lean duplex stainless steels with different addition of Cu were fabricated and studied in this paper. The effects of Cu addition, solid solution treatments and second phase precipitation on resistance to pitting corrosion were discussed in detail. The addition of 0.5% Cu can significantly improve the resistance to pitting corrosion due to that Cu can increase the activity of alloying Cr and facilitate the diffusion of Cr into ferrite phase, leading to the concentration of alloying Cr in ferrite phase. The corrosion resistance of present steels was decreased with the increase in solid solution treatment temperature from 1000 to 1150 °C due to the increasing difference of pitting corrosion resistivity between ferrite and austenite. The second phase precipitation of Cr2N can consume the beneficial elements of Cr and N in ferrite, leading to a dramatic decrease in corrosion resistance. The pitting potential of the present steel was sensitive to the aging treatments, and it was continuously decreased with the increase in aging time.

Comparative Study on the Properties of CuCoBe Alloy and CuNiCoBe Alloy

CuNiCoBe alloy and CuCoBe alloy were cast by the vacuum inductive melting technique, and were heat treated under certain parameters. By using optical microscope, sclerometer and conductivity meter, the properties of two alloys were investigated after heat treatment. Experimental results show that the process of 980 °C for solid solution and three hours of aging at 450 °C is the best heat treatment for CuCoBe alloy, while 960 °C is the best solid solution treatment temperature for CuNiCoBe alloy with the same aging measures. Ni is beneficial to improve the hardness and conductivity of alloys, and CuNiCoBe alloy has better strength, hardness and conductivity than CuCoBe alloy at different temperatures, and two alloys all have a conductivity mutation increase near 450 °C. CuNiCoBe alloy and CuCoBe alloy soften respectively at 464 °C and 471 °C.

Effect of Solid Solution Treatment on the Microstructure and Mechanical Properties of IN738LC Superalloy

Cast IN738LC alloy mainly consists of primary gamma matrix, gamma prime precipitates, and carbides. SEM-EDS analysis results suggested that most of the carbides are MC type ones that possess high Ti or Ta contents. MC carbides were partly dissolved into the matrix during the solid solution treatment, and the morphology and size of carbides were influenced by the solid solution treatment temperature. Characteristics of gamma prime precipitates were also significantly affected by the solid solution treatment conditions. Single or duplex size distributions of gamma prime precipitates were obtained depending on the solid solution treatment condition. Higher tensile strength was obtained in the case of finer precipitation size and in the case of single size distribution as compared with that of duplex size distribution.

Effect of Heat Treatment on the Microstructural Characteristics of IN738 Turbine Blade

It was observed that both primary and secondary gamma prime precipitates were more significantly influenced by the solid solution treatment temperature as compared to the following cooling rate. Single and duplex size precipitate distribution with different average size could be obtained through the appropriate solid solution and aging treatment. Micro-hardness test result indicated that single size distribution of gamma prime precipitates provides higher hardness than duplex size distribution.

Effects of Solution Temperature on Microstructure and Tensile Properties of Casting Duplex Stainless Steel

In this paper, effects of solid solution treatment temperature on microstructure and tensile properties of casting SAF 2507 super duplex stainless steel were researched by means of optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and tensile test. The results indicate that the amount of γ phase increases according to a linear relationship f(g ) = -0.134T +159.94 during the temperatures from 1100°C to 1250°C. Tensile properties of casting SAF 2507 super duplex stainless steel fluctuate with solution temperature change. Austenitic grain size and morphology are the most important factors on tensile property. The tensile strength is the highest owing to the finest austenitic grain at the solution temperature of 1150°C. The elongation is related to the fracture mode. At 1100 , elongation ration is highest because of the ductile fracture.

The Connection between Micro-Residual Stress and Thermo-Mechanical Treatments in 6061Al-15vol%SiC<sub>w</sub> Composites

In this work it is shown how the microscopic residual stress state in 6061Al-15vol%SiCw composites can be modified by plastic strain and by isothermal annealing (the latter, affecting also the precipitation state). The composites were obtained by a powder metallurgical route, which involves extrusion of Al-SiCw powder blends. Neutron diffraction measurements were carried out to determine the RS state. Several degrees of plastic strain, from 1% up to 15% in compression, have been applied ex-situ to the same specimen on several composite materials. Furthermore, the m-RS was also investigated in one of the composites at several precipitation states as resulting from isothermal annealing at 300°C during different times. Investigations were carried out from a fully hardened state, T6 up to an overannealed condition, OV (obtained after annealing during 100 h). The results show that quenching from solid solution treatment temperature prior to annealing at 146°C to achieve the T6 condition provokes a RS state, which does not relax during this treatment. No decrease of the deviatoric component and partial relaxation of the hydrostatic term of the micro- RS developed in the composite occur when treating from the T6 to the OV condition. Instead, only 1% plastic strain is sufficient to produce total relaxation of the hydrostatic term of the m-RS. Even inversion of the radial component occurs on higher straining. Again, no relaxation of the deviatoric component occurs. This may be explained bearing in mind that the deviatoric component is linked to the geometry of the reinforcing particles (whiskers degree of orientation). The hydrostatic term does not relax totally after heat treatment because is partially re-generated on cooling, while the plastic deformation is ‘locked’ in the microstructure via dislocation activity.

Influence of SSTT, Ageing Regime and Stretching on IGC, Complex of Properties and Precipitation Behavior of 6013 Alloy

The influence of solid solution treatment temperature (SSTT), stretching and two- and three-stage ageing regimes on the tensile properties, IGC, K e (K e0 ) and FCPR of sheets from 6013 alloy in comparison with properties of 6013T6 and 6056T78 alloys sheets has been investigated. The recommended regimes including stretching and two- and three-stage ageing allow to eliminate IGC and to increase strength properties of sheets from 6013 alloy, providing for the higher values of the strength, fracture toughness and the decrease of FCPR in comparison with 6056T78. The precipitates phase composition in body of grains and on the GB is the same - Q'(β')-phases. Their sizes and the width of PFZ are lower than after the standard overageing regime (T78).

Suppression of cryogenic intergranular fracture through heat treatments and roles of boron in high manganese non-magnetic steels.

The effects of cooling rate and reheating conditions after solid solution treatment on mechanical properties, especially low temperature embrittlement, have been investigated by using Fe-32Mn-7Cr-(0.3-0.4)N, Fe-33Mn, Fe-33Mn-0.3C, Fe-44Mn, Fe-44Mn-0.3C, Fe-58Mn, and Fe-32Mn-7Cr-0.3N-(0.002-0.02)P-(0.0002-0.001)B steels melted in vacuum furnaces. It was found that intergranular fracture was suppressed and toughness increased in all these steels through cooling at an intermediate rate from solid solution treatment temperature or through reheating at around 723-773 K. After such toughening heat treatments no change in microstructures was revealed under an electron microscope and the decrease in tensile strength was very small if any. Autoradiography using α particle fission tracks showed that the grain boundary segregation of boron corresponded to the toughening. The reason for the high susceptibility to low temperature intergranular embrittlement of high Mn non-magnetic steels was also discussed together with the mechanism for the toughening resulting from the heat treatments.