Effect Of Thermal Deformation Research Articles

Evolution of Fe-bearing phases during the fabrication and its effect on the mechanical properties of AA8014 aluminum alloy

The morphology of Fe-bearing phase particles has significant influences on the mechanical properties of AA8014 aluminum alloy sheets. This study aims to investigate the evolution of the morphology, size, and distribution of Fe-bearing phases during casting, homogenization, and rolling. In the paper, the effects of thermal treatment and deformation on the evolution of the Fe-bearing phases, and the mechanical properties of AA8014 aluminum alloy annealing sheet have been studied quantitatively. The main phase components in the ingot are α-Al matrix, Al6(Fe,Mn), and a small amount of Al3(Fe,Mn) and α-Al(Fe,Mn)Si. Homogenization at 630℃ for 12 h leads to the transformation of the metastable Al6(Fe,Mn) particles into stable α-Al(Fe,Mn)Si with “pore structures”. Subsequent hot rolling (75.0 mm to 7.0 mm, deformation rate of 91%) results in a significant increase in the area number density of Fe-bearing particles, accompanied by a notable decrease in average length and aspect ratio, leading to a more uniform distribution of Fe-bearing phases. Cold rolling (7.0 mm to 0.7 mm, deformation rate of 90%) or further annealing causes slight changes in the area number density and size of Fe-bearing phases. Notably, the content of α-Al(Fe,Mn)Si is minimal in the non-homogenized ingot. After hot rolling and cold rolling, the coarse Fe-bearing particles are observed in the non-homogenized sheets with 7.0 mm and 0.7 mm thickness, with a non-uniform distribution of the Fe-bearing phases. A comparative study was conducted on the mechanical properties and microstructure in final sheets with 0.7 mm thickness fabricated from homogenization and non-homogenization. The yield strength, ultimate tensile strength, elongation, and work hardening exponent in sheet with homogenization are higher due to smaller grain and Fe-bearing phase particles.

Microstructure, mechanical properties and wear behaviors of TiN/Ti composite coating on laser surface textured Ti6Al4V alloy fabricated by MHz picosecond laser surface alloying

Ceramic-reinforced metal matrix composites (MMCs) coating fabricated by laser surface melting effectively improves the surface mechanical and wear properties of titanium alloys. However, power of several hundred watts is generally used in traditional laser processing, which introduces excessive heat input and leads to thermal deformation and thermal effects, resulting in cracks and reducing mechanical properties and service life of coatings. In order to improve the microhardness and anti-wear properties of Ti6Al4V alloy and extend the service life, a picosecond laser (ps-laser) with a power of 23 W and repetition rate of 19 MHz was utilized to fabricate the uniform and crack-free MMCs coating (TiN/Ti) by melting TiN powders on the textured Ti6Al4V surface. Three different textures with different texture densities and depths were used to evaluate their effects on coatings. Results showed that the reinforced TiN phase was in the form of fine dendrites with an average secondary dendrite arm spacing of 0.84 µm. The microhardness and the anti-wear properties were both inversely proportional to the texture densities because of controlling the volume fraction of TiN in the coating. The microhardness of the sample with greatest microhardness increase was significantly improved from 355 HV0.5 (base material) to 1000 HV0.5 due to the addition of the TiN phase. The sample with a texture density of 5% showed the best anti-wear properties (about 22 times that of the substrate) due to the effective suppression of three-body abrasive wear.

The effect of thermal-elastic deformation on the sealing performance of supercritical CO2 dry gas seal

PurposeThe purpose of this study is to investigate the sealing performance of S-CO2 dry gas seals (DGSs) by considering the effects of pressure-induced deformation, thermal deformation and coupling deformation.Design/methodology/approachA hydrodynamic lubrication flow model of S-CO2 DGS was established, and the model was solved using the finite difference and finite element methods. The pressure-induced deformation and thermal deformation of the sealing ring, as well as the sealing performance under the effects of pressure-induced deformation, thermal deformation and coupling deformation, were obtained.FindingsThe deformation of the sealing ring is mainly thermal deformation. The influence of pressure-induced deformation on leakage and gas film stiffness is greater than that of thermal deformation and coupling deformation. However, thermal deformation has a greater impact on friction torque and minimum film thickness than pressure-induced deformation and coupling deformation. The influence of deformations on sealing performance is important.Originality/valueThe sealing performance of S-CO2 DGSs was analyzed considering the effect of pressure-induced deformation, thermal deformation and coupling deformation, which can provide a theoretical basis for S-CO2 DGS optimization design.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2023-0120/

Analysis of liquid–solid interface bonding behaviour of 7075 aluminium alloy/SiCp reinforced aluminium base alloy

The introduction of heterogeneous elements and the presence of the oxide layer on the surface of aluminum alloy usually play a negative role in the interfacial bonding of Al/Al bimetallic composites. To solve these two key problems of interfacial bonding of bimetallic composites. This work proposes to composite SiCp/7075(solid)-7075 alloy(liquid). The main alloying element Zn of 7075 alloy is selected to perform hot dip treatment on SiCp/7075(solid) to reduce the influence of the oxide layer on the surface of the aluminum alloy and the introduction of heterogeneous elements. Al/Al bimetallic composites were prepared by using a hot-dip/non-hot-dip zinc + liquid–solid composite casting process. The bimetallic composite interfacial bonding of SiCp/7075–7075 matrix alloy was studied. The results revealed that an oxide layer existed at the interface of the bimetallic composite upon preheating at 400–475 °C and hot dipping at 400–425 °C. With an increase in the hot-dip temperature, the interface oxide layer disappeared because of the combined effect of thermal expansion deformation, lower solidus temperature of the zinc-rich layer, and volume expansion of the solid–liquid phase transition. Metallurgically bonded interfaces were obtained at the hot-dip temperatures of 450 and 475 °C. The fracture location was on the SiCp/7075 Al matrix composite side, showing that this composite's interfacial bond strength was higher than that of the SiCp/7075 Al matrix composites. The results of this study provide a new idea for the preparation of lightweight wear-resistant Al/Al bimetallic composites by liquid-solid composite casting.

Effects of Thermal Deformation and Heat Treatment on Microstructure and Texture of Hot Isostatic Pressured Ti-6Al-4 V Alloy

Effects of Thermal Deformation and Heat Treatment on Microstructure and Texture of Hot Isostatic Pressured Ti-6Al-4 V Alloy

Nonlinear dynamics analysis of gear transmission system considering tooth surface friction and thermal deformation

To make the gear better adapt to the high temperature environment, the effects of tooth surface friction and thermal deformation on the dynamic characteristics of the gear were studied. First, based on the basic theory of gear nonlinear dynamics, the backlash model is established considering the effects of thermal deformation. Then, an improved multi-degree-of-freedom nonlinear dynamic model of gears is established taking into account the effects of thermal deformation and friction. The effect of tooth surface friction and thermal deformation on the system motion state is analyzed. Finally, to better analyze the relationship between impact vibration and transmission efficiency, the percussion vibration index is introduced. Compared with the existing research, a gear multi-degree-of-freedom dynamic model is established by considering the influence of tooth surface friction and thermal deformation. The percussion vibration index is introduced as an indicator of gear running health. The research result can provide reference for the optimization and cooling of the gear transmission system.

Study on the effect of thermal deformation on the liquid seal of high-temperature molten salt pump in molten salt reactor

Study on the effect of thermal deformation on the liquid seal of high-temperature molten salt pump in molten salt reactor

Swirl Flow and Heat Transfer in a Rotor-Stator Cavity with Consideration of the Inlet Seal Thermal Deformation Effect

In the typical structure of a turboshaft aero-engine, the mass flow of the cooling air in the rotor-stator cavity is controlled by the inlet seal labyrinth. This study focused on the swirl flow and heat transfer characteristics in a rotor-stator cavity with considerations of the inlet seal thermal deformation effect. A numerical framework was established by integrating conjugate heat transfer (CHT) analysis and structural finite element method (FEM) analysis to clarify the two-way aero-thermo-elasto coupling interaction among elastic deformation, leakage flow, and heat transfer. Simulation results showed that the actual hot-running clearance was non-uniform along the axial direction due to the temperature gradient and inconsistent structural stiffness. Compared with the cold-built clearance (CC), the minimum tip clearance of the actual non-uniform hot-running clearance (ANHC) was reduced by 37–40%, which caused an increase of swirl ratio at the labyrinth outlet by 5.3–6.9%, a reduction of the Nusselt number by up to 69%. The nominal uniform hot-running clearance (NUHC) was defined as the average labyrinth tip clearance. The Nusselt number of the rotating disk under the ANHC was up to 81% smaller than that under the NUHC. Finally, a clearance compensation method was proposed to increase the coolant flow and decrease the metal temperature.

New modelling capabilities to support the ITER EC H&CD System optimisation and preparation of plasma operation

The ITER Electron Cyclotron Resonance Heating (ECRH) & Current Drive (ECCD) system is planned to be progressively installed and commissioned following the four stage approach of the ITER Research Plan. Starting with an injection of up to 5.8 MW from one Upper Launcher (UL) in the vacuum vessel to assist the plasma breakdown during First Plasma (FP) operation, the system will then be extended to achieve a capability of 20 MW injected power in Pre-Fusion Plasma Operation (PFPO) and Fusion Power Operation (FPO) phases. Development of optical modelling was required to characterize the optical performance of the FP configuration with the so-called First Plasma Protection Components. An optical 3D model using Zemax OpticStudio® has been developed and extended to the UL. Effects of higher order modes, thermal deformations and tolerances on the UL functionality have been characterized and are presented. Finally, in preparation of plasma operation and in the frame of the EC system upgrade layout optimisation, ECRH-ECCD modelling is being undertaken within the ITER Integrated Modelling and Analysis (IMAS) suite.

Thermal characterization and stress analysis of Ho2O3 thin film on 4H–SiC substrate

The performance of a metal oxide semiconductor during operation could be hindered significantly due to thermodynamic instability and mismatch between the gate oxide layer and the substrate. Owing to variation in temperature during thermal applications, the thin film layers and substrates in complementary metal oxide semiconductor (CMOS) structures are subjected to high thermal stresses, which can result in large deformation and failure. In this study, the distribution of heat and thermal stress between the Ho2O3 thin film and the SiC substrate has been simulated numerically with finite element modelling and analysis software (ANSYS). This is necessary to emulate the thermal behaviour of the structure under different thermal loadings, and for each temperature loading, the effects of thermal stress and deformation on the structure were also evaluated. Based on the results of the simulation, an optimum temperature was suggested. The thermal stability and characteristics of the thin film layer/SiC structure were evaluated and validated for better electrical performance.

A study of micro hardness in the machining of Inconel 625 using TiAlSiN coated tools under dry cutting conditions

ABSTRACT Inconel 625, a nickel-based super alloy, has a high tendency to form a work-hardening layer during the milling operation, resulting in further difficulty to process it. However, Inconel 625 is extensively used in the manufacturing of aero-engine exhaust and in many other industries due to its admirable mechanical properties. Further, tighter environmental regulations and higher coolant and disposal costs associated with the nickel-based super alloys are forcing researchers to think about dry machining. PVD TiAlSiN coating is the most suitable in dry machining of difficult-to-cut materials. In this context, this study analysed the micro-hardness of machined surface and sub-surfaces up to 200 µm during the dry milling with coated tool. It was observed from the in-depth analysis of process parameters as well as their interaction effect with TiAlSiN-coated tool in dry conditions that it has a low influence on the micro-hardness gradient in the top layer of machined surface. A blend of the lowest level of cutting speed with the central level of feed per tooth, radial rake angle and depth of cut resulted in minimum micro-hardness due to the balancing of the effects of mechanical and thermal deformation.

Effect of thermal deformation on leakage clearance of claw hydrogen circulating pump for fuel cell system

The leakage clearance have a strong impact on the performance and reliability of hydrogen circulating pump in a fuel cell system, and the thermal deformantion is the most significant factor because of its high working temperature, small size. In this paper, the distribution of leakage clearance with different temperatures and rotors materials is obtained. The radial leakage clearance decreases with the increase of temperature in the working chamber. The axial clearance is increased by about 100 μm at rated working condition. When the material of rotors is aluminum alloy, the minimum radial clearance under rated working condition is about 8.5 μm, and the risk of interference is large. When the material of rotors is structural steel and titanium alloy, the radial clearance is maintained above 30 μm, and the risk of interference is small. The variation of leakage clearance leads to the variation of leakage area. The variation of total leakage clearance first increases and then decreases with the increase of angle. The minimum variation of total leakage area is 6.25 mm2 at 0° and the maximum is 7.578 mm2 at 84°. The total leakage area increased by 7.144 mm2 on average. The results can be used as guidelines for the structural optimization of hydrogen circulating pump.

Effect of thermal deformation and Nb element action on the organization and performance of steel

The influences of Nb element and hot deformation on the strength of steels were systematically investigated. The microstructures and mechanical properties of the steels are determined through optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and tensile tests. The nanometer sized carbide particles precipitated in the grain boundary are attributed mainly to severe deformation at high temperature. Of the two steels with different content of Nb element and deformation, the strength of 2#steel is more lager due to more content of Nb can form more precipitates to limit grains growth. Furthermore, the results also shown that adding Nb can refine the microstructure of the steel and effectively improve the mechanical properties, but only thermal deformation has no obvious effect on the improvement of the properties of the steel.

Effect of Nb content and thermal deformation on the microstructure and mechanical properties of high-strength anti-seismic rebar

Rebar is the most important material in large-scale engineering structures, and its fine structure determines the strength and seismic resistance of rebar. The objective of this study is to investigate the effect of Nb content on the microstructure and mechanical properties of high-strength anti-seismic rebar under the condition of thermal deformation. The Gleeble-3800 thermal simulator was used to simulate the continuous rolling process, which analyzed that effect of precipitation behavior of Nb on the microstructure and mechanical properties of rebar. Scanning electron microscope (SEM), transmission electron microscope (TEM) and universal tensile testing machine were used to characterize the microstructure, precipitation and mechanical properties of high-strength anti-seismic rebar. Under the condition of process I or process II, when the Nb content changed from 0.012 wt% to 0.020 wt%, the microstructure of the experimental steel was mainly composed of ferrite and pearlite, resulting in relatively low the tensile strength and good the plasticity, and the tensile fracture belonged to ductile fracture. Under the condition of process I or process II, when the Nb content changed from 0.035 wt% to 0.060 wt%, the microstructure of the experimental steel was mainly composed of ferrite, pearlite and bainite, resulting in relatively high the tensile strength, which reached 995.30±5 MPa and low the plasticity, and the tensile fracture belonged to shear fracture. Whether under the condition of process I or process II, when the Nb content changed from 0.012 wt% to 0.060 wt%, TEM confirmed that the main precipitates of the experimental steels were mainly (Ti, Nb) C, (Ti, Nb, V) C, (Nb, Ti, V) C, respectively. These carbides were mainly distributed on the ferrite grains or grain boundaries, and the shapes were elliptical, square, strip, respectively. The average particle size of these carbides was less than 50 nm, and the crystal structure of these carbides belonged to the cubic structure.

A real-time dressing method for metal lapping pads based on the thermal deformation effect

Surface shape and accuracy of the metal lapping pad have a significant impact on the performance of the lapping process for flat optical components, which are usually improved by the dressing process. A real-time dressing system for metal lapping pad surface shape (RDLS system) based on the bimetal thermal deformation effect is proposed. Unlike traditional dressing methods (e.g., turning dressing with a diamond tool), the real-time dressing based on the RDLS system is a material-loss-free and in-process dressing method. A full-aperture lapping turntable based on the RDLS system was designed, in which the working heat was analyzed. The displacement models of the lapping pad surface were established by regression analysis. Finally, several experiments were conducted to verify the functionality of the RDLS system. During turning dressing (turntable rotational speed n = 100 rpm), the displacement error was compensated by the RDLS system, which was caused by the working heat of the turntable shaft system. During the lapping processing for optical elements (n ≤ 20 rpm), the correction displacement was controlled by the RDLS system, which realized the real-time dressing of the lapping pad surface. The process performance of the plane optical component was optimized with the RDLS system (process parameter: the coolant temperature t). The effectiveness and practicality of the RDLS system were demonstrated experimentally.

An accurate thermoelastic model and thermal output error analysis of a hemispherical resonator gyroscope under varying temperatures

This paper proposes an accurate thermoelastic model of a hemispherical shell resonator (TM-HSR) taking into consideration thermal stress and reveals the effect of its thermal deformation on the hemispherical resonator gyroscope (HRG) output error for the first time. First, a set of thermoelastic dynamic equations of the TM-HSR are derived by leveraging the thermoelastic shell theory, and the relationship between temperature and the equivalent thermal load is determined. Next, an approximate analytical solution of thermal deformation of HSRs is derived using Bubnov-Galerkin method and its accuracy is evaluated by comparing its result with ANSYS simulation results of HSRs with different structures. The approximate analytical solution is found to be very accurate, which is important for temperature testing of HRGs and application to various vibratory sensors with hemispherical shell structures. Subsequently, the effects of thermal deformations under uniform and nonuniform temperature distributions on the HRG output error are revealed by using a thermal output error model. Comparative simulation and experimental results demonstrate the effectiveness and practicability of the proposed model. The proposed model can be used for accurate error analysis and developing a compensation scheme for the thermal output error of HRGs.

Effects of Thermal Deformation and Heat Treatment on Microstructure and Texture of Hot Isostatic Pressured Ti-6al-4v Alloy

Effects of Thermal Deformation and Heat Treatment on Microstructure and Texture of Hot Isostatic Pressured Ti-6al-4v Alloy

Effects of Thermal Deformation and Heat Treatment on Microstructure and Texture of Hot Isostatic Pressured Ti-6al-4v Alloy

Effects of Thermal Deformation and Heat Treatment on Microstructure and Texture of Hot Isostatic Pressured Ti-6al-4v Alloy

Coal Permeability Variation during the Heating Process considering Thermal Expansion and Desorption Shrinkage

In order to explore the influence of coal deformation caused by temperature and desorption on seepage characteristics in the process of heat injection mining of coalbed methane, the permeability test, thermal expansion, and constant temperature adsorption desorption of coal samples under different temperature and stress states were carried out using the high temperature multifunctional triaxial test system, and the influence of thermal expansion and desorption deformation effect on coal permeability in the process of temperature increase is studied. The results show that (1) with the increase of temperature, the sensitivity of coal thermal expansion deformation to temperature decreases gradually. The thermal expansion deformation makes the coal matrix expand, and the seepage channel is squeezed and the permeability decreases. (2) The effect of thermal expansion deformation is related to the porosity of coal. When the porosity of coal is high, the thermal expansion deformation reduces the permeability; on the contrary, the inward expansion of thermal expansion deformation is limited, and the effect on permeability is weakened. (3) The desorption of coal cause matrix shrinkage. The higher the desorption amount, the more obvious the shrinkage and the higher the permeability. Increasing temperature promotes desorption deformation of coal and increases permeability. (4) In the process of increasing temperature, the change of coal permeability is affected by thermal expansion deformation and desorption deformation. With the increase of temperature, when the influence of thermal expansion deformation on coal permeability is dominant, the permeability decreases gradually, and when desorption deformation is dominant on coal permeability, the permeability increases gradually. (5) With the increase of axial pressure, confining pressure, and pore pressure, the decrease of coal porosity is smaller. When the temperature increases, the temperature corresponding to the minimum permeability point is smaller. The research conclusion provides a basis for the technology of heat injection mining coalbed methane.

Multimaterial Lattice Structures With Thermally Programmable Mechanical Behaviors

Traditional lattice structures usually maintain their mechanical properties throughout their lifetime. Designing and manufacturing intelligent materials with environmental adaptability, programmatically sense and respond to external changes (such as light, pressure, solution, temperature, electromagnetic field, electrochemical reaction), and shape transformation, mode conversion and performance regulation with spatial and temporal modulation are still important scientific challenges in the field of artificial materials. In this paper, multimaterial lattice structures with thermally programmable mechanical response were proposed by using polymer materials with disparate glass transition temperatures and temperature dependencies and reasonably designing the spatial distribution of the materials. Combined with theoretical analysis and finite element simulation, the effects of the relative stiffness of constitute materials on Poisson's ratio, deformation mode and structural stability of the multimaterial lattice structures were studied. The elastic constants, crushing response and structural stability of multimaterial lattice structures are regulated by temperature control, which makes the multimaterial lattice structures show giant thermal deformation, hyperelasticity and shape memory effects. This paper opens up new avenues for the design and manufacture of adaptive protection equipment, biomedical devices, aerospace morphing structures, flexible electronic devices, self-assembly structures and reconfigurable soft robots.