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Thermal stress

Thermal stress refers to the mechanical stress generated within a material due to temperature-induced expansion or contraction, particularly when such deformation is restricted by external constraints or material inhomogeneities.^[1] This phenomenon occurs because most materials exhibit a positive coefficient of thermal expansion, meaning they elongate when heated and shorten when cooled, leading to internal forces if free movement is prevented.^[2] The magnitude of thermal stress is fundamentally described by the formula \sigma = [E](/page/E!) [\alpha](/page/Delta) \Delta T, where \sigma is the stress, [E](/page/E!) is the modulus of elasticity, \alpha is the coefficient of linear thermal expansion, and \Delta T is the temperature change; for instance, in steel with \alpha \approx 12 \times 10^{-6}/\mathrm{K} and [E](/page/E!) \approx 200 \, \mathrm{GPa}, a \Delta T of 100 K can produce stresses exceeding 240 MPa.^[3]^[2] In engineering contexts, thermal stresses arise from nonuniform heating or cooling in uniform materials, or uniform temperature changes in nonuniform ones, often manifesting as tensile stresses during cooling (which can cause cracking) or compressive stresses during heating (which may lead to buckling).^[1] These stresses are critical in applications such as nuclear reactor vessels, where rapid temperature fluctuations combined with pressure changes—known as pressurized thermal shock—can exacerbate material embrittlement and fatigue failure over time.^[1] For example, in thick-walled components like pipelines or bridges, unmitigated thermal gradients can result in structural deformation or catastrophic failure if the induced stresses surpass the material's yield strength.^[2] To manage thermal stress, engineers employ strategies such as allowing controlled expansion through joints or slots, selecting materials with matched thermal expansion coefficients in composite structures, and using finite element analysis to predict and mitigate stress concentrations during design.^[1] Historical analyses, such as those in the U.S. Department of Energy's fundamentals handbooks from the early 1990s, underscore the importance of these considerations in high-stakes environments like nuclear facilities, where thermal stress contributes to long-term aging mechanisms.^[1] Overall, understanding and accounting for thermal stress ensures the durability and safety of thermal systems across mechanical, civil, and aerospace engineering disciplines.

Fundamentals of Thermal Stress

Definition and Basic Principles

Thermal stress refers to the mechanical stress induced in a material by temperature changes that cause constrained thermal expansion or contraction, in the absence of external mechanical loads. This phenomenon arises when a material's natural tendency to change dimensions due to heating or cooling is restricted by its surroundings or internal constraints, leading to internal forces that can be tensile or compressive. The field of thermal stresses, part of thermoelasticity, originated in the 19th century amid advancements in thermodynamics and mechanics, with foundational contributions from Jean-Marie Constant Duhamel's 1837 paper on the coupling of heat and elasticity. At the atomic level, temperature influences thermal stress by altering the vibrational energy of atoms within the material's lattice structure. As temperature rises, atoms vibrate more intensely around their equilibrium positions, increasing the average interatomic distance and causing the material to expand. Conversely, cooling reduces these vibrations, allowing atoms to settle closer together and inducing contraction. If such dimensional changes are prevented—such as in a rigidly fixed component—this mismatch between desired and actual deformation generates stress to maintain the constraint.^[4] The primary factors governing thermal stress magnitude are the material's coefficient of thermal expansion (α), its Young's modulus (E), and the temperature change (ΔT). The thermal strain, which quantifies the fractional length change due to temperature alone, is given by ε_thermal = α ΔT. In a fully constrained scenario, this strain is counteracted by an equal and opposite mechanical strain, leading to stress via Hooke's law, which relates stress (σ) to elastic strain (ε) as σ = E ε. Substituting the thermal strain yields the fundamental equation for thermal stress:

\sigma = E \alpha \Delta T

^[1] This derivation assumes linear elasticity and isotropic behavior, where the mechanical strain exactly opposes the thermal strain to achieve zero net deformation. Here, stress σ is measured in Pascals (Pa), the coefficient of thermal expansion α in inverse Kelvin (K⁻¹), Young's modulus E in Pascals (Pa), and the temperature change ΔT in Kelvin (K). These units ensure dimensional consistency, with σ representing force per unit area resulting from the interplay of material stiffness, expansion tendency, and thermal variation.^[1]

Thermal Expansion and Material Properties

Thermal expansion refers to the tendency of materials to change their dimensions in response to temperature variations, a fundamental phenomenon that gives rise to thermal stresses when expansion is constrained. This expansion occurs in three primary forms: linear, areal, and volumetric. Linear thermal expansion describes the change in length of a one-dimensional object and is quantified by the coefficient of linear thermal expansion, α, through the relation \Delta L / L = \alpha \Delta T, where \Delta L is the change in length, L is the original length, and \Delta T is the temperature change.^[5] For two-dimensional surfaces, areal expansion accounts for changes in area, approximated as \Delta A / A = 2\alpha \Delta T for small expansions in isotropic materials, where \Delta A is the change in area and A is the original area.^[6] Volumetric expansion, relevant for three-dimensional objects, follows \Delta V / V = 3\alpha \Delta T in isotropic solids, with \Delta V as the volume change and V as the original volume; this relation holds because volume expansion combines three orthogonal linear expansions.^[7] The magnitude of thermal expansion is governed by the material's coefficient of linear thermal expansion, α, which varies significantly across material classes and reflects their atomic and molecular structures. Metals typically exhibit moderate α values, such as steel with α ≈ 12 × 10^{-6} K^{-1}, due to their metallic bonding allowing relatively free atomic vibration.^[8] Ceramics, characterized by strong ionic or covalent bonds, display lower coefficients, exemplified by glass at α ≈ 9 × 10^{-6} K^{-1}, making them suitable for applications requiring dimensional stability.^[8] Polymers, with weaker van der Waals forces and chain-like structures, show high expansion, ranging from 50 to 200 × 10^{-6} K^{-1} for common plastics, leading to greater susceptibility to thermal stresses.^[8] Composites, engineered combinations like fiber-reinforced polymers, can have tailored α values, often anisotropic with low expansion (e.g., < 5 × 10^{-6} K^{-1}) along the fiber direction in carbon-fiber composites due to the reinforcing phase's stiffness.^[9] Anisotropy is prominent in natural materials such as wood, where α is higher perpendicular to the grain (≈ 30–50 × 10^{-6} K^{-1}) than parallel (≈ 5 × 10^{-6} K^{-1}), and in crystals, where directional differences arise from lattice symmetry, potentially varying by factors of 2–10 along principal axes.^[9] The coefficient α is not constant but depends on temperature, influencing expansion behavior over wide ranges. In metals, α generally increases with rising temperature above ambient levels, as enhanced thermal vibrations amplify interatomic distances; for instance, aluminum's α rises from about 23 × 10^{-6} K^{-1} at 20°C to 25 × 10^{-6} K^{-1} at 100°C.^[10] This variation must be accounted for in precise engineering calculations, often using mean coefficients or temperature-dependent models derived from empirical data. In assemblies of dissimilar materials, differential thermal expansion induces internal stresses at interfaces, as seen in bimetallic strips composed of two bonded layers with differing α values. The resulting stress at the interface can be approximated as \sigma = \frac{E_1 E_2 d (\alpha_2 - \alpha_1) \Delta T}{E_1 t_1 + E_2 t_2}, where E_1 and E_2 are the Young's moduli, t_1 and t_2 are the thicknesses, and d is the distance between centroids of the layers; this formula highlights how mismatch in α drives bending and stress under temperature change.^[11] Such effects are exploited in thermostats but can cause failure in welded joints or coatings if not designed for. Experimental determination of α relies on techniques like dilatometry, which measures dimensional changes in a sample as it is heated or cooled in a controlled furnace. In push-rod dilatometry, a specimen's length variation is detected via a contacting probe or extensometer, enabling precise calculation of linear expansion over temperatures up to 2000°C for metals, ceramics, and polymers; optical dilatometry uses non-contact laser interferometry for high accuracy in anisotropic or fragile materials.^[12] These methods provide essential data for material selection in thermal stress-prone applications.

Causes of Thermal Stress

Uniform Temperature Changes

Thermal stress arises in a material or structure when it undergoes a uniform temperature change but is prevented from expanding or contracting freely, leading to internal forces that develop to maintain dimensional constraints. In such scenarios, heating induces compressive stresses as the material attempts to expand against restraints, while cooling generates tensile stresses during attempted contraction. This phenomenon is particularly relevant in fully constrained bodies, where no deformation is permitted in any direction, resulting in a uniform stress state throughout the volume. For a fully restrained isotropic material subjected to a uniform temperature change ΔT, the thermal stress σ is calculated using the formula \sigma = \frac{E \alpha \Delta T}{1 - 2\nu}, where E is the Young's modulus, \alpha is the coefficient of linear thermal expansion, \nu is Poisson's ratio, and the sign of ΔT determines whether the stress is compressive (positive ΔT) or tensile (negative ΔT). This hydrostatic stress is equal in all directions and derives from the principle that the restrained thermal strain \epsilon_\mathrm{thermal} = \alpha \Delta T is counteracted by mechanical strains, leading to zero net strain under full constraint. In cases of partial restraint, such as biaxial conditions where deformation is prevented in two directions but allowed in the third (plane stress), the in-plane stresses adjust to \sigma_x = \sigma_y = \frac{E \alpha \Delta T}{1 - \nu}. These formulations assume linear elasticity and small deformations, applicable to most engineering materials at moderate temperature changes.^[13] A practical example occurs in railroad tracks, which are often fixed at intervals and experience uniform heating from sunlight, potentially causing buckling if the induced compressive stress exceeds the material's yield strength. For steel tracks with E \approx 200 \, \mathrm{GPa}, \alpha \approx 12 \times 10^{-6} /^\circ\mathrm{C}, and yield stress \sigma_\mathrm{yield} \approx 250 \, \mathrm{MPa}, the critical temperature change for yielding is \Delta T_\mathrm{max} = \sigma_\mathrm{yield} / (E \alpha) \approx 104 ^\circ\mathrm{C}, highlighting the risk of failure during extreme weather fluctuations. Engineers mitigate this by incorporating expansion joints to reduce constraint. In free bodies without external constraints, a uniform temperature change in a homogeneous material produces no thermal stresses, as the body undergoes uniform expansion or contraction without differential strains or internal forces. However, residual stresses may persist if the temperature change follows a non-uniform history or if material inhomogeneities exist. Practical limits are reached when \sigma = E \alpha \Delta T approaches the yield stress \sigma_\mathrm{yield} in uniaxial cases, beyond which plastic deformation occurs, as seen in constrained components like turbine blades during steady-state heating.

Temperature Gradients

Temperature gradients arise in materials when heat conduction occurs unevenly, such as from localized heating on one surface, leading to non-uniform temperature distributions that cause differential thermal expansion and internal stresses. The temperature profile T(x) in one dimension follows the heat conduction equation derived from Fourier's law, given by \partial T/\partial t = \kappa \partial^2 T/\partial x^2, where \kappa is the thermal diffusivity, defined as \kappa = k / (\rho c_p) with k as thermal conductivity, \rho as density, and c_p as specific heat capacity.^[14] This equation describes how heat diffuses through the material, creating a gradient that drives thermal stresses when expansion is constrained.^[14] In stress analysis for simple geometries like beams or plates under a linear temperature gradient through the thickness, the resulting stresses manifest as bending stresses due to the differential expansion between hotter and cooler layers. For a restrained plate with a linear temperature variation \Delta T across its thickness h, the maximum surface stress is \sigma = (E \alpha \Delta T)/2, where E is the Young's modulus and \alpha is the coefficient of thermal expansion; this arises from the thermal moment inducing curvature that is resisted, producing compressive stress on the hot side and tensile on the cold side.^[15] This formulation assumes plane stress conditions and neglects higher-order effects, providing a baseline for understanding gradient-induced bending.^[15] For more complex two-dimensional (2D) or three-dimensional (3D) temperature gradients, thermoelasticity theory is employed, coupling thermal and mechanical fields through the constitutive relations and equilibrium conditions. The stress tensor \sigma satisfies the equilibrium equation \nabla \cdot \sigma = 0 in the absence of body forces, while the constitutive relation for an isotropic material is \sigma = 2\mu \varepsilon + \lambda \mathrm{tr}(\varepsilon) \mathbf{I} - (3\lambda + 2\mu) \alpha \Delta T \mathbf{I}, where \mu and \lambda are the Lamé constants, \varepsilon is the strain tensor, \mathrm{tr}(\varepsilon) is its trace, \mathbf{I} is the identity tensor, and \Delta T is the temperature change from a stress-free reference state.^[16]^[17] In 1D simplifications, this reduces to forms used in beam analysis, but full 2D/3D solutions require solving the coupled system with boundary conditions on traction and heat flux.^[16] Practical examples illustrate the impact of temperature gradients in engineering components. In welded joints, uneven cooling after fusion creates steep thermal gradients, leading to residual tensile stresses near the weld toe that can promote cracking; for instance, simulations show peak stresses exceeding yield strength in steel joints without controlled cooling.^[18] Similarly, turbine blades in gas engines experience severe gradients from hot combustion gases on the leading edge versus cooler internal cooling channels, inducing thermal stresses up to hundreds of MPa that limit blade life through creep and fatigue.^[19] Numerical methods, particularly finite element analysis (FEA), are essential for predicting stresses from arbitrary temperature gradients in complex geometries. FEA discretizes the domain into elements, solving the coupled heat transfer and thermoelastic equations iteratively; for example, axisymmetric shell elements have been developed to compute through-thickness stress variations under quadratic temperature profiles, validating against analytical solutions with errors below 1%.^[20] In additive manufacturing contexts, FEA models optimize scanning parameters to minimize gradient-induced distortions, incorporating temperature-dependent properties for accuracy.^[21]

Effects and Failure Modes

Residual and Internal Stresses

Residual stresses arise in materials subjected to thermal processes involving uneven cooling rates, such as quenching, where temperature gradients induce inhomogeneous plastic deformation. This deformation creates regions of compressive stress on the surface and tensile stress in the interior, which become locked-in as the material returns to equilibrium upon cooling.^[22]^[23] These stresses are categorized into three types based on their spatial scale: Type I (macroscopic) stresses, which achieve equilibrium across the entire body and span multiple grains; Type II (microscopic) stresses, confined to individual grains due to intergranular incompatibilities; and Type III (submicroscopic or intra-granular) stresses, arising within grains from defects like dislocations or inclusions. Thermal processes in manufacturing, such as casting—where differential contraction between the mold and molten metal generates stresses—or heat treatments like annealing and quenching, are primary sources of these residual stresses.^[24]^[25]^[26] Measurement of residual stresses employs several techniques, including X-ray diffraction (XRD), which determines lattice strain ε from peak shifts in diffraction patterns and computes stress using the relation

\sigma = \frac{E \epsilon_{\text{measured}}}{1 + \nu}

where E is the elastic modulus and ν is Poisson's ratio, applicable for uniaxial stress states.^[27] The hole-drilling method involves incrementally drilling a small blind hole and measuring relieved surface strains with strain gauges to back-calculate near-surface stresses, often following ASTM E837 standards.^[28] Neutron diffraction provides bulk measurements by probing lattice spacing changes deep within the material (up to centimeters), enabling three-dimensional stress mapping in large components.^[29] Residual stresses can lead to distortion and warping during subsequent processing or service, as unbalanced tensile zones promote dimensional instability, and they accelerate premature fatigue by superimposing on applied loads to increase mean stress. Conversely, intentionally introduced compressive residual stresses, such as those from shot peening—which plastically deforms the surface to create a compressive layer up to 1 mm deep—enhance fatigue life by retarding crack initiation and propagation, often doubling endurance limits in aerospace components.^[30]^[31] Under mechanical loading, internal residual stresses redistribute to accommodate deformation, potentially relaxing in high-stress regions while intensifying elsewhere; for instance, in welded structures, the initially tensile stress in the weld centerline from rapid cooling can partially relax and shift toward the heat-affected zone during cyclic loading, altering crack growth rates.^[32]^[33]

Thermal Shock and Fracture

Thermal shock refers to the rapid change in temperature that induces transient thermal stresses in a material, often leading to cracking or fracture when these stresses exceed the material's strength. This phenomenon arises from sudden heating or cooling, creating steep temperature gradients that cause differential expansion or contraction across the material's volume. Unlike gradual temperature changes, thermal shock involves high-rate processes where the material cannot accommodate the strain through elastic deformation or creep, resulting in brittle failure modes.^[1]^[34] The mechanics of thermal shock involve the propagation of stress waves due to the abrupt temperature differential (ΔT), generating compressive or tensile stresses on the surface. For a fully constrained material, the maximum transient stress can be approximated as σ_max ≈ E α ΔT_c, where E is the Young's modulus, α is the coefficient of thermal expansion, and ΔT_c is the critical temperature change at which cracking initiates (typically when σ_max reaches the fracture strength σ_f). The severity of the shock is influenced by the Biot number, Bi = h L / k, which compares convective heat transfer at the surface (h: convection coefficient) to internal conduction (L: characteristic thickness, k: thermal conductivity); high Bi (>0.1) indicates significant surface gradients and elevated risk of failure. These stresses propagate as elastic waves, with fracture occurring if the strain energy release rate surpasses the material's toughness.^[1]^[35] Thermal shock resistance is quantified by figures of merit that balance a material's ability to withstand induced stresses without fracture. A key parameter, introduced by Hasselman, is R = σ_f (1 - ν) / (E α), where σ_f is the fracture strength and ν is Poisson's ratio; higher R values indicate greater resistance to crack initiation under thermal loading. Ceramics like yttria-stabilized zirconia exhibit high R due to their elevated fracture toughness and moderate α, making them suitable for high-temperature applications where ΔT exceeds 500°C without failure. This parameter prioritizes materials with low thermal expansion and high strength-to-modulus ratios for optimal performance.^[36] Notable examples illustrate thermal shock's destructive potential. Pyrex borosilicate glass, designed for oven use, can fracture when removed from high heat (e.g., 200°C) and placed in cold water due to surface contraction against the warmer interior, highlighting the need for gradual cooling. In aerospace, rocket nozzles often fail from thermal shock during ignition, as rapid combustion gas exposure (ΔT > 1000°C) causes cracking in graphite or ceramic throats, leading to fragmentation and thrust loss. Historical incidents, such as early 1940s jet engine turbine blade failures in the I-40 engine, stemmed from thermal shock during rapid acceleration, where uneven heating induced stresses that exceeded blade material limits, contributing to early development challenges.^[37]^[38]^[39] Standard testing evaluates thermal shock resistance through quench methods, such as ASTM C1525, which measures a ceramic's survival under repeated water quenching from elevated temperatures (e.g., 200–1200°C). Specimens are heated and rapidly cooled, with resistance assessed by the maximum ΔT endured before a 20% strength reduction or visible cracking occurs; this quantifies the critical ΔT for practical applications in refractories and engine components.^[40]

Applications and Mitigation

Engineering Design Considerations

In engineering design, thermal stress analysis is integrated into finite element methods to predict and mitigate deformations and failures under temperature-induced loads. Software such as ANSYS Mechanical couples thermal and structural modules, allowing engineers to simulate heat transfer alongside mechanical stress, ensuring that designs account for transient temperature gradients that could lead to warping or cracking.^[41]^[42] Material selection plays a critical role in managing thermal stress, prioritizing coefficients of thermal expansion (α) and toughness to match application demands. For precision instruments requiring dimensional stability, low-α alloys like Invar (α ≈ 1.2 × 10^{-6} K^{-1}) minimize expansion mismatches, while high-toughness materials such as 24CrNiMo low-alloy steel are chosen for shock-prone components like high-speed railway brake discs to resist fracture under rapid heating.^[43]^[44] Thermal stress considerations are paramount in diverse applications, including aerospace reentry vehicles where nosetips endure extreme gradients up to 2000 K, necessitating ablative coatings to limit structural loads. In power plants, turbine blades face cyclic thermal stresses exceeding 1000°C, requiring single-crystal nickel alloys for creep resistance. Electronics design addresses PCB warpage from reflow soldering, where mismatched α between copper and substrates can induce significant bending, mitigated through symmetric layering. A notable case is the design refinement for space telescope mirrors in the 1990s, where NASA addressed temperature-induced distortions by incorporating measured coefficients of thermal expansion into thermoelastic models, ensuring optical stability across orbital thermal cycles from -150°C to 100°C.^[45]^[46]^[47]^[48] Design codes like the ASME Boiler and Pressure Vessel Code (BPVC) Section VIII provide guidelines for evaluating thermal stresses in pressure vessels, categorizing them as secondary stresses with allowable ranges based on stress linearization and limits such as 3S_m to prevent fatigue under thermal cycling.^[49]^[50] As of 2025, advances in additive manufacturing enable tailored thermal gradients through functionally graded materials (FGMs), reducing residual stresses by up to 50% in components like turbine blades via controlled deposition of compositionally varied layers.^[51]^[52]

Prevention and Control Strategies

Design strategies to mitigate thermal stress often incorporate mechanisms that accommodate material expansion and contraction without inducing excessive strains. Expansion joints, for instance, are widely used in bridges and pipelines to allow controlled movement due to temperature variations, thereby releasing thermal deformations and preventing cracking.^[53] Similarly, slots or compliant fixtures, such as flexible supports or bellows, enable free thermal expansion in constrained structures like building facades or piping systems, reducing localized stress concentrations.^[54] Pre-stressing techniques, where components are intentionally loaded in compression prior to service, counter anticipated thermal expansion loads; this method has been applied in structural steel beams by heating high-strength cover plates during welding to induce beneficial residual stresses.^[55] Process controls during manufacturing play a crucial role in managing thermal stresses by controlling heating and cooling rates. Gradual temperature ramps, such as slow heating to avoid steep gradients, are standard in welding and casting to minimize residual stresses. Annealing, a post-processing heat treatment, effectively relieves these stresses in steel by holding the material at approximately 600°C for one to two hours, allowing atomic diffusion to redistribute dislocations without altering the microstructure significantly.^[56]^[57] Material treatments enhance resistance to thermal stress through tailored surface modifications or integrated buffers. Thermal barrier coatings (TBCs), typically yttria-stabilized zirconia applied to turbine blades, provide insulation with low thermal conductivity, reducing substrate temperatures by up to 200°C and mitigating stress from hot gas exposure.^[58] Phase-change materials (PCMs), such as paraffin-based composites embedded in matrices, buffer temperature fluctuations by absorbing latent heat during phase transitions, thereby dampening gradients and associated stresses in applications like electronic enclosures or concrete structures.^[59] Real-time monitoring enables proactive control of thermal stresses using integrated sensors. Thermocouples measure local temperatures to track ΔT, while strain gauges capture total deformation; thermal stress is then estimated via the relation

\sigma = E (\epsilon_{\text{total}} - \alpha \Delta T)

where E is the modulus of elasticity, \epsilon_{\text{total}} is the measured strain, \alpha is the thermal expansion coefficient, and \Delta T is the temperature change.^[60] This approach allows for immediate adjustments, such as altering cooling rates, in dynamic environments like aerospace components. As of 2025, advanced techniques leverage artificial intelligence for optimized thermal management in additive manufacturing of heat exchangers.^[61]

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ASME Section VIII BPV Code & the Pressure Vessel Safety Factor
ASME Section VIII standards regulate design safety. Understand how material properties impact pressure vessel allowable Stress, materials and safety factor.
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Role of additive manufacturing in developing functionally graded ...
Aug 20, 2025 · The tailored FGM counterpart material gradient makes these materials less stress-concentrated and improves the resistance against crack ...
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Thermal and residual stress distributions of additively manufactured ...
The proposed model can be used to predict the thermal and mechanical properties of FGM parts fabricated by the SLM process and optimize SLM process parameters ...
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Review Article Mitigation of thermal effects in bridges
The most common engineering practice for releasing thermal deformation in bridges involves using bearings and expansion joints. In the case of straight girder ...<|separator|>
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[PDF] Expansion Joint Considerations for Buildings - steelwise
May 2, 2011 · For these reasons, the bear- ing style connection and the double column are the preferred methods for stress release due to thermal loading.
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Thermal Prestressing of Structural Steel - AISC
The thermal prestressing method discussed in this article consists of shop welding heated high strength steel cover plates to the bottom flanges of beams and ...
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Stress relieving on metal products - Heat treatment - Bodycote Plc
The stress relieving temperature is normally between 550 and 650°C for steel parts. Soaking time is about one to two hours. After the soaking time the ...
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stress relief of steels | Total Materia
Carbon steels are typically stress relieved by holding them at a temperature of 1100 to 1250°F (600 to 675°C) for 1 hour per inch (25 mm) of thickness.
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[PDF] Thermal-barrier coatings for more efficient gas-turbine engines
Introduction. Thermal-barrier coatings (TBCs) are refractory-oxide ceramic coatings applied to the surfaces of metallic parts in the hottest.
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Phase change material-based thermal energy storage - ScienceDirect
Aug 18, 2021 · The analysis shows that the PCM buffers heat spikes from the heat source and reduces the transient peak heat loads by 50% for the heat rejection ...
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[PDF] Measurement of Thermal Expansion Coefficient Using Strain Gages
When a resistance strain gage is installed on a stress-free specimen of any test material, and the temperature of the material is changed, the output of the ...
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Recent advances in artificial-intelligence enhanced additive ...
This study presents a comprehensive and critical review of state-of-the-art research on the applications of additive manufacturing in thermal management.