High Temperature Tensile Strength Research Articles

Effects of tantalum on microstructure and mechanical properties of cast IN617 alloy

Effects of Ta on microstructure and mechanical properties of cast IN617 alloy were investigated. The results showed that the addition of Ta increased size and area fraction of MC carbides, which was in agreement with the prediction of thermodynamic calculation, rather than influencing as-cast microstructure features such as grain size, secondary dendrite arm spacing, and carbide distribution. Ta-doped cast microstructure showed that Ti (C, N) nitride-carbide was substituted by MC carbide and at the same time, M6C and MC tended to form a eutectic structure. The lattice constant of the matrix in a heat treatment condition increased from 3.593 to 3.601nm and the high temperature tensile strength also improved, when Ta content are from 0 to 2.0wt%. It was attributed to the solution of Ta with solid solution strengthening in the matrix. However, when the Ta level exceeded 1.0wt%, the ductility and fracture toughness significantly reduced. It was believed that remained Ta-rich MC carbides in the supersaturated matrix accelerated the initiation and propagation of cracks. Therefore, the optimized Ta content in cast IN617 alloy is suggested to below 1.0wt% for balanced properties.

High Temperature Flexural, Tensile Strength and Oxidation Behavior of Ti3SiC2 Ceramic at 900°C–1300°C in Ambient Air

Abstract High temperature flexural and tensile strength of hot-pressed Ti3SiC2 ceramic were measured and analyzed from 900 to 1300°C in ambient air atmosphere. The high temperature flexural and tensile strength are strong functionals of temperature. With the temperature increasing, the high temperature flexural and tensile strength decrease correspondingly. Moreover, the transition from brittle to plastic deformation was observed for both flexural and tensile testing. The oxidation behavior and oxidation mechanism were investigated.

Nano-scaled Ti5Si3 evolution and Strength Enhancement of titanium matrix composites with two-scale architecture via heat treatment

To further improve the mechanical properties of Ti5Si3 and TiBw reinforced Ti6Al4V ((Ti5Si3 + TiBw)/Ti6Al4V) composites with a two-scale network structure, heat treatments were carried out to adjust nano-scaled Ti5Si3 (n-Ti5Si3) particles and matrix characteristics. The fraction of Ti5Si3 particles in the vicinity of first-scale TiBw reinforcements decreases with increasing quenching temperatures. When the quenching temperature is elevated to 1200°C, the Ti5Si3 particles dissolve and re-solute into the matrix. Both the size and fraction of n-Ti5Si3 particles increase with increasing aging temperatures. The size of n-Ti5Si3 particles in the β phase can be refined from 400–500nm (as-sintered) to 10–60nm after heat treatments. The strength of the heat-treated composites was significantly enhanced through heat treatments, when compared with the composites with one-scale architecture and Ti6Al4V alloy. The room temperature compressive strength and high temperature (600°C) tensile strength can reach 2245MPa and 880MPa, respectively. This can be attributed to the heat treatments adjustment of n-Ti5Si3 particles, supersaturated martensite α' phase and two-scale network structure.

Effect of transition elements on the microstructure and tensile properties of Al–12Si alloy cast under ultrasonic melt treatment

This paper shows that the addition of transition elements significantly influences the microstructure and tensile properties of Al–12Si alloy cast under ultrasonic melt treatment (UST). The alloys contained primary Si, eutectic Si and a variety of intermetallic compounds (IMCs); the addition of Mn and Ni changed the solidification sequence by forming primary α-Al15(Fe,Mn)4Si2 and ε-Al3Ni prior to primary Si formation. The primary Si and primary IMCs competitively consumed the nucleation sites introduced by UST, thereby influencing their refining efficiencies; the efficiency of primary Si refinement by UST increased with increasing the fraction of primary Si formed prior to IMC formation, whereas it deteriorated with increasing primary IMC fraction. The refining efficiency of eutectic Si and eutectic IMCs was not affected by the type and fraction of the primary phase. Using a Ti sonotrode for UST caused Ti contamination, resulting in grain refinement by forming Ti(Al,Si)3 particles and increasing the amount of Ti solutes. Regardless of transition elements content, the application of UST improved the tensile strength at 25 °C and 350 °C. The refinement of IMCs caused by UST allowed the alloy to contain more IMCs without deterioration of room-temperature tensile strength. This enhanced the increment of high-temperature tensile strength by IMCs. Ductility of heavily alloyed systems was also improved by UST.

Microstructure and mechanical properties of the laser-welded Mg-3Nd-0.2Zn-0.4Zr (NZ30K) magnesium alloy

This study aimed to investigate the microstructure and mechanical properties of the laser-welded Mg-3Nd-0.2Zn-0.4Zr (NZ30K) magnesium alloy. A fiber optic laser was used to weld 4-mm-thick Mg-3Nd-0.2Zn-0.4Zr (NZ30K) and AZ31 magnesium alloy plates. The microstructures of NZ30K and AZ31 joints were compared, and the distribution of Nd in NZ30K was emphatically investigated. Besides, microhardness distributions and tensile properties of NZ30K and AZ31 joints at room temperature and high temperature (200°C) were tested, and fracture features were observed and analyzed. The results indicated that the NZ30K rare-earth magnesium alloy showed better properties especially at a high temperature (200°C), benefiting from the strengthening phase, compared with the AZ31 joint, such as high-temperature tensile strength, creep resistance at high temperature, and corrosion resistance. The microhardness in the fusion zone of NZ30K changed a little compared with that in base metal, while the microhardness in the fusion zone of AZ31 decreased significantly. The grain of NZ30K in the fusion zone was significantly refined with strengthening-phase distribution on the grain boundary. The tensile strength of NZ30K laser beam–welded joints at a high temperature (200°C) decreased by 29% compared with that at room temperature, while the tensile strength of AZ31 joint at a high temperature (200°C) decreased by 53% compared with that at room temperature, which was mainly because of the stable existence of the strengthening-phase Mg12Nd in the NZ30K rare-earth magnesium alloy while the strengthening-phase Mg17Al12 in AZ31 would soften and coarsen with the rise in temperature.

Effects of first-scale TiBw on secondary-scale Ti5Si3 characteristics and mechanical properties of in-situ (Ti5Si3+TiBw)/Ti6Al4V composites

Abstract In order to further improve mechanical properties, Ti6Al4V matrix composites reinforced with secondary-scale Ti 5 Si 3 particles and first-scale TiB whiskers were designed and prepared by reaction hot pressing. The effects of first-scale TiBw fractions on secondary-scale Ti 5 Si 3 microstructure characteristics and mechanical properties of two-scale network structured composites were investigated. With increasing TiBw fractions, the size of Ti 5 Si 3 particles in β phase increased, the quantity of Ti 5 Si 3 particles near TiBw reinforcement increased and the morphology changed from isolated particles to interconnected particles. These changes resulted in that the room and high temperature tensile strength of the composites increased, moreover, the creep resistance of the composites improved. Compared with the Ti6Al4V alloy, the room and high temperature tensile yield strength of the composites with 3.4 vol%TiBw increased by 36.5% and 70%, and the elongation remained at 5.0% and 11.5%, respectively. The composites possess approximately one order of magnitude lower steady-state creep rate and about eight times higher time-to-rupture at 873 K/200 MPa. The superior tensile and creep properties can be attributed to adjustment of secondary-scale Ti 5 Si 3 characteristics and two-scale network structure.

Transient Thermal Tensile Behaviour of Novel Pitch-Based Ultra-High Modulus CFRP Tendons.

A novel ultra-high modulus carbon fibre reinforced polymer (CFRP) prestressing tendon made from coal tar pitch-based carbon fibres was characterized in terms of high temperature tensile strength (up to 570 °C) with a series of transient thermal and steady state temperature tensile tests. Digital image correlation was used to capture the high temperature strain development during thermal and mechanical loading. Complementary thermogravimetric (TGA) and dynamic mechanical thermal (DMTA) experiments were performed on the tendons to elucidate their high temperature thermal and mechanical behaviour. The novel CFRP tendons investigated in the present study showed an ambient temperature design tensile strength of 1400 MPa. Their failure temperature at a sustained prestress level of 50% of the design tensile strength was 409 °C, which is higher than the failure temperature of most fibre reinforced polymer rebars used in civil engineering applications at similar utilisation levels. This high-temperature tensile strength shows that there is potential to use the novel high modulus CFRP tendons in CFRP pretensioned concrete elements for building applications that fulfill the fire resistance criteria typically applied within the construction industry.

High Temperature Tensile Strength Evaluation with Non-contact Measuring Method for Small Diameter Solders Specimen

High Temperature Tensile Strength Evaluation with Non-contact Measuring Method for Small Diameter Solders Specimen

Combined effects of ultrasonic melt treatment, Si addition and solution treatment on the microstructure and tensile properties of multicomponent Al[sbnd]Si alloys

The effects of ultrasonic melt treatment (UST) on the microstructure and tensile properties of three multicomponent AlSi alloys with different Si contents (12, 15, and 18 wt%Si) and solution treatments were systematically investigated at room and elevated (350 °C) temperatures. The microstructures of these alloys consisted of primary Si, eutectic Si, Mg2Si, and various types of aluminides, but the average size and area fraction of the primary Si increased with Si content. The application of UST caused a transformation from dendritic to equiaxed cells and a reduction in grain size, with a significant reduction in the size of all secondary phases (i.e., Si, Mg2Si and aluminides). Both the strength and ductility at room and elevated temperatures were greatly improved by UST, mainly due to microstructure refinement. Improvements in the high-temperature tensile strength as a result of UST increased with increasing Si contents, due to the enhanced refinement of primary Si by UST with increasing Si contents. The spherodization of rigid phases induced by solution treatment can improve the strength and ductility at room temperature, but can also cause a loss of strength at elevated temperatures due to the relaxation of the interconnected network structure of rigid phases caused by their spherodization.

The Different Roles of Entropy and Solubility in High Entropy Alloy Stability

Multiprincipal element high entropy alloys stabilized as a single alloy phase represent a new material system with promising properties, such as high corrosion and creep resistance, sluggish diffusion, and high temperature tensile strength. However, the mechanism of stabilization to form single phase alloys is controversial. Early studies hypothesized that a large entropy of mixing was responsible for stabilizing the single phase; more recent work has proposed that the single-phase solid solution is the result of mutual solubility of the principal elements. Here, we demonstrate the first self-consistent study of the relative importance of these two proposed mechanisms. In situ high-throughput synchrotron diffraction studies were used to monitor the stability of the single phase alloy in thin-film (Al1-x-yCuxMoy)FeNiTiVZr composition spread samples. Our results indicate that a metastable solid solution can be captured via the rapid quenching typical of physical vapor deposition processes, but upon annealing the solid-solution phase stability is primarily governed by mutual miscibility.

EFFECT OF ELASTOMER NANOPARTICLES ON IMPROVING THE WET SKID RESISTANCE OF SBR/NR COMPOSITES

ABSTRACT How to improve the wet skid resistance of rubber composites for tire tread while decreasing the rolling resistance is very important for both rubber researchers and industry. The irradiation-vulcanized elastomer particles, ultrafine fully-vulcanized powder nitrile butadiene rubber (UFPNBR), having the diameter of about 80 nm, were studied on modifying the dynamic mechanical properties of styrene butadiene rubber/natural rubber (SBR/NR) composites for tire tread. It is notable that the UFPNBR particles can improve the tanδ values of SBR/NR composites in a temperature range from −10 to 20 °C and decrease the tanδ values in the temperature range from 50 to 70 °C simultaneously, which indicates that the UFPNBR particles not only can improve the wet skid resistance but also can reduce the rolling resistance of the SBR/NR composites. On the other hand, the UFPNBR-modified SBR/NR composites also have good dynamic properties for safety operation of tires at high temperature and good tensile strength, tear strength, and fatigue properties in the range of 8 phr UFPNBR loadings.

Effects of Mg content on the mechanical properties and corrosion resistance of Al–Cu–Mg–Ag alloy

The effects of Mg content on the mechanical properties, corrosion resistance and the microstructure of Al–Cu–Mg–Ag alloys were investigated by hardness tests, tensile tests, intergranular corrosion tests, electrochemical analysis, optical microscopy (OM) and transmission electron microscopy (TEM). With the increase of Mg content, the aging hardening process of Al–Cu–Mg–Ag alloy was accelerated, and the peak hardness and the tensile strength at room temperature both increased and then decreased slightly, due to the smaller dimension and larger fraction volume of Ω phases, whereas the high temperature tensile strength increased gradually. In addition, the increase of Mg content led to a larger corrosion current density and thus a higher corrosion rate of Al–Cu–Mg–Ag alloy. The poorest corrosion resistance of Al–Cu–Mg–Ag alloy with the highest Mg content (1.2%) may be due to the largest potential difference between the PFZ and the matrix in this alloy. The alloy with higher Mg content consumed more Cu solution atoms to form the precipitations on the grain boundaries, which results in lower potential of the PFZ correspondingly.

Effect of Zr, Mo and TiC on microstructure and high-temperature tensile strength of cast titanium matrix composites

In this paper, five types of TiC particle reinforced titanium matrix composites (TiC-PTMCs) were fabricated by casting route in order to investigate the influence of Zr, Mo and TiC on microstructures and tensile strengths of TiC-PTMCs. The increase of Zr content promoted the precipitation of eutectic TiC and refined primary TiC, while increasing Mo content led to the refinement of α lath. The composites with high Zr and Mo contents and low TiC content showed superiority in ultimate tensile strength (UTS) below 650°C, whereas above 700°C, high UTS was obtained in the composites with high TiC content and low Mo content. Below 650°C, solid solution strengthening and fine grain strengthening of matrix make the largest contribution to the improvement of UTS. However, above 700°C, solid-solution strengthening of Zr and the load bearing effect of TiC play a dominant role in the enhancement of UTS. Accordingly, effective routes for improving UTSs of TiC-PTMCs in different temperature ranges are different.

Studies on Microstructure and Properties by Mass Smelting for Directionally Solidified Superalloy

Large quantities of VIDP400 vacuum furnace smelting DZ417G oriented superalloys smelting process has been researched, analysis of the main factors affecting the organizational uniformity and stability, as well as the impact of high temperature tensile and lasting properties has been studied. The results showed that: At pulling rate of 4.5~8.5mm•min-1, after 1220°C solid solution treatment and 980°C aging system, the DZ417G superalloy had uniform chemical constitution with oxygen and nitrogen content of the alloy in sharply reduced to 13ppm. It can be got available treatment uniform structure with proper γ'phase size, with high-temperature tensile strength up to 750MPa, elongation of 17% reduction of area 22%. The lasting high temperature performance can reach to more than 100 hours.

Effect of electric pulse modification on mircostructure and properties of Ni-rich Al-Si piston alloy

In order to improve the properties of Ni-rich (2.5wt.%) Al-Si piston alloy, electric pulse modification was applied in fabricating the Ni-rich Al-Si piston alloy in this study. The effect of electric pulse modification on the mechanical properties of the Ni-rich Al-Si piston alloy was studied using optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), microhardness measurement and tensile strength testing. The results showed that the microstructures of Ni-rich Al-Si piston alloy treated by electric pulse modification were refined, the solid solubility of Cu, Ni, Si, etc. in cr-AI matrix was improved, and furthermore, the microhardness and high-temperature tensile strength were increased by 9.41% and 17.5%, respectively. The distribution of second phases was also more uniform compared with that of a non-modified sample.

High-Temperature Aluminum Alloys for Automotive Powertrains

Abstract This article describes research aimed at developing cast aluminum alloys with the necessary high-temperature tensile and fatigue strengths to withstand the modern automotive engine environment. Micro-additions of Ti, V, and Zr were added to an Al-7Si-1Cu-0.5Mg cast alloy, leading to the formation of phases that increase stability at high temperatures, positively affecting alloy strength.

Characterization of Microstructure and Mechanical Properties of 9.2Cr0.45V0.7C Heat-Resistant Steel

Microstructure and mechanical properties of 9.2Cr0.45V0.7C steel have been evaluated in this work. Differential scanning calorimetry study indicating the various phase changes during heating and cooling is consistent with high-temperature XRD analysis. Carbide precipitates are observed during tempering in the temperature range of 750–800 °C. Two types of precipitates are identified, MC-type precipitates with an average size of 50 ± 15 nm and M23C6-type precipitates with an average size of 150 ± 50 nm. The tensile properties of the steel are dependent on tempering and processing conditions. Room-temperature tensile properties increase with tempering temperature. The hot rolling is more effective than hot forging to improve tensile properties of the steel at room temperature. High-temperature tensile strength decreases, whereas elongation increases with increasing temperature. Conventional creep curve shows three stages of behavior for this steel at 60 MPa and 600 °C.

Effect of Gd content on high temperature mechanical properties of Mg–Gd–Y–Zr alloy

In this study, the compositional dependence of the age hardening response and high temperature tensile properties of the Mg–xGd–3Y–0.5Zr (x=3, 6, 10, and 12wt%) alloys are investigated. The amount of cuboid-shaped phases and β′ precipitates increased significantly with increasing the Gd content. The Mg–10Gd–3Y–0.5Zr alloy exhibited the maximum ultimate tensile strength at room temperature, while at higher temperatures the Mg–12Gd–3Y–0.5Zr alloy exhibited the maximum yield strength and ultimate tensile strength. The yield strength and ultimate tensile strength of the Mg–12Gd–3Y–0.5Zr alloy increased with the test temperature and showed its maximum at 150°C, and then decreased as the temperature increased further. The Mg–12Gd–3Y–0.5Zr alloy maintained a high ultimate tensile strength of more than 300MPa up to 250°C. The superior high temperature tensile strength of the tested alloy is mainly associated with solution strengthening and precipitation hardening of the cuboid-shaped phases and β′ precipitates in Mg matrix. Especially, β′ precipitates can hinder the dislocation movement at high temperature.

Transient liquid phase bonding of IC10 single crystal with GH3039 superalloy using BNi2 interlayer: Microstructure and mechanical properties

Transient liquid bonding (TLP) of IC10 single crystal with GH3039 alloy was carried out using BNi2 interlayer. Microstructure evolution and mechanical properties of the joints bonded at 1050–1200°C for 2h were investigated. The precipitates in the DZ on the GH3039 side gradually decreased and disappeared with the increase of the bonding temperature. The formation mechanism of the TLP joint was proposed and the asymmetry of the bonding was discussed. Tensile strength and microhardness tests were conducted to investigate the mechanical properties of the joints. The layer of borides with high hardness in the joint bonded at 1150°C significantly reduced the room-temperature tensile strength but had little effect on the high-temperature tensile strength of the joint. The layer of borides became the preferential position to crack during both room-temperature and high-temperature tensile tests. The joints with dispersive precipitates had the highest room-temperature tensile strength and the homogenized joints showed the best ductility.

Effect of microstructure morphology on the high temperature tensile properties and deformation in directionally solidified NiAl-Cr(Mo) eutectic alloy

High temperature tensile properties and microstructure morphologies of directionally solidified NiAl-Cr(Mo) alloy under different compositions and withdrawal rates were investigated. Tensile strength of 513.8MPa was obtained in the directionally solidified NiAl-36Cr-6Mo hypereutectic alloy at 1000°C, which is the highest value reported in the NiAl-Cr(Mo) alloy until now. In addition, perfect cellular eutectic alloy solidified at fast withdrawal rate possessed higher tensile strength and elongation than planar eutectic alloy solidified at low withdrawal rate when they had the same composition. This is because bonding strength between eutectic cells in the perfect cellular eutectic alloy was high, which resulted in high crack propagation resistance and harmonious deformations in the intracellular and intercellular regions. The results above may change the locked-in view that only regular eutectic microstructure morphology grown with planar solid/liquid interface could be used in the eutectic in-situ composites. Perfect cellular microstructure morphology grown in a far fast rate could be also used, which would result in high efficiency in the industrial production. Refined microstructure, larger volume fraction of strengthening phase and dispersion strengthening of second phase particles were contribute to the improvement of high temperature tensile strength of the directionally solidified NiAl-Cr(Mo) alloy. However, the bonding strength of interface was obviously different in the alloys with different microstructure morphologies, which had significant effect on the tensile strength. When bonding strength of phase interface was low, the other strengthening factors could not be able to play their due roles, thus leading to relatively low tensile strength.