Influence Of Test Temperature Research Articles

Correlation between charpy-V notch impact energy and KJIC of ferrite ductile iron in the transition-temperature region

Fracture toughness is an important index for the structural integrity assessment of ductile iron spent fuel transportation casks. Fracture toughness tests require a long test period, high cost, and difficult operation. Therefore, the Charpy V-notch impact energy value (KV) is considered to predict fracture toughness (KJIC).In this study, Charpy V-notch impact tests(−80 °C, −60 °C, −40 °C, −20 °C, 0 °C, 20 °C, 40 °C, 60 °C, 80 °C) and fracture toughness tests(−60 °C, −40 °C, −20 °C, 0 °C, 20 °C) of ferrite ductile iron(FDI) were carried out. A KJIC-KV model for FDI in the transition temperature region was proposed, taking into consideration the influence of test temperature(T) and yield strength(σ YS), then the proposed model was compared to the KIC-KV empirical equations of steel in the transition-temperature region, using the test data of FDI. The results indicate that the KJIC-KV model proposed in this work is more accurate and applicable for predicting fracture toughness values in the transition-temperature region than others, the residual between the estimated value of the KJIC-KV correlation model (KJIC-E) and the experimental value of KJIC(KJIC-T) was less than 4.1 MPa·m0.5, and the error was less than 5%.

Influence of testing temperature and pressure on the mechanical behavior of well cementing materials

In order to obtain insights into the mechanical responses of well cementing materials under various service conditions and provide more precise guidance for well cementing design, the mechanical behavior of a silica-enriched well cement system was investigated at various temperatures, pressures and drying conditions. Prior to mechanical testing, ultrasonic strength tests and a series of microscopic tests were conducted to verify that the silica-cement system cured at 150 °C/20.7 MPa exhibited stable properties with limited risk of strength retrogression. Triaxial tests conducted at ambient temperature (25 °C) demonstrate that the well cement exhibited an increase of peak strength and plasticity with increasing confining pressure, particularly under dry conditions. Additionally, brittle to ductile transition is more readily achieved for dried samples. However, the simultaneous application of both high temperature and high confining pressure (150 °C/30 MPa) resulted in reduced yield stress of the well cement, possibly because the weakening effect of high temperature overpowers the strengthening effect of high confining pressure. The peak strength and yield stress of the well cement increased significantly with the reduction of water content. The plasticity of the well cement increased upon the removal of evaporable water, but decreased with the removal of nonevaporable C–S–H bound water.

Review of the Hydrogen Permeation Test of the Polymer Liner Material of Type IV On-Board Hydrogen Storage Cylinders.

Type IV hydrogen storage cylinders comprise a polymer liner and offer advantages such as lightweight construction, high hydrogen storage density, and good fatigue performance. However, they are also characterized by higher hydrogen permeability. Consequently, it is crucial for the polymer liner material to exhibit excellent resistance to hydrogen permeation. International organizations have established relevant standards mandating hydrogen permeation tests for the liner material of type IV on-board hydrogen storage cylinders. This paper provides a comprehensive review of existing research on hydrogen permeability and the hydrogen permeation test methods for the polymer liner material of type IV on-board hydrogen storage cylinders. By delving into the hydrogen permeation mechanism, a better understanding can be gained, offering valuable references for subsequent researchers in this field. This paper starts by thoroughly discussing the hydrogen permeation mechanism of the liner material. It then proceeds to compare and analyze the hydrogen permeation test methods specified by various standards. These comparisons encompass sample preparation, sample pretreatment, test device, test temperature and pressure, and qualification indicators. Then, this study offers recommendations aimed at enhancing the hydrogen permeation test method for the liner material. Additionally, the influence of test temperature, test pressure, and polymer material properties on the hydrogen permeability of the liner material is discussed. Finally, the influences of the test temperature, test pressure, and polymer material properties on the hydrogen permeability of the liner material are discussed. Future research direction on the hydrogen permeability and hydrogen permeation test method of the liner material of the type IV hydrogen storage cylinder has been prospected.

A Study on the Effect of Test Temperatures on Tensile and Fracture Behavior of SS 316LN

Abstract In the present study, the influence of test temperatures in the range of 25°C–550°C on the deformation and fracture behavior of SS 316LN has been investigated. The tensile properties and fracture toughness (J1c) of SS 316LN have been evaluated in this temperature range. From tensile properties, strain energy density was estimated as a function of plastic strain and strain-hardening parameters. The fracture tests (J-R curves) are conducted in this temperature range to determine fracture toughness and tearing resistance. From the fracture tested specimens, fractographic studies were carried out to further understand crack initiation mechanisms. From the results of fracture toughness in the temperature range of 350°C–450°C, an attempt to understand the deformation mechanism was made based on an empirical equation.

Tribo-oxide Competition and Oxide Layer Formation of Ti3SiC2/CaF2 Self-Lubricating Composites during the Friction Process in a Wide Temperature Range.

Ti3SiC2/CaF2 composites were prepared by the spark plasma sintering (SPS) process. Both the microstructure of Ti3SiC2/CaF2 and the influence of test temperature on the tribological behavior of the Ti3SiC2/CaF2 composites were investigated. The synergistic effect of friction and oxidation was evaluated by analyzing the worn surface morphology. The results showed that Ti3SiC2/CaF2 were still brittle materials after adding CaF2, which was in agreement with Ti3SiC2. The hardness, relative density, flexural strength and compressive strength of the Ti3SiC2/CaF2 composites were slightly lower than those of Ti3SiC2, and the addition of CaF2 decreased the decomposition temperature of Ti3SiC2 from 1350 to 1300 °C. Simultaneously, as the temperature of the test increased, the friction coefficient of Ti3SiC2/CaF2 showed a downward trend (from 0.81 to 0.34), and its the wear rate was insensitive.

Quasi-static perforation response of inter-ply hybrid polypropylene composites at various temperatures

This study is motivated by the lack of knowledge in the research of mechanical characterization of thermoplastic composites (TPCs) with additional fiber hybridization. To enhance the mechanical properties of long glass fiber-reinforced polypropylene (PP) composite, hybridization via alkaline-treated aramid and carbon fabrics is performed. High performance fabrics modified with 10 wt.% sodium hydroxide (NaOH) aqueous solution are incorporated into the PP composite as reinforcements. Herewith, four arrangements (hybrid composites) for two different reinforcements and two different stacking configurations and the monolithic composite are separately investigated in terms of quasi-static perforation behavior. Failure mechanisms are also evaluated at macro level by visual observations and micro scales through a scanning electron microscopy (SEM). The experimental results provide a basis for selecting fiber-enabled hybridization and lay-up configuration with improved perforation resistance. Moreover, the influence of test temperature is reported for three different values as 20°C, 60°C, and 100°C. Based upon the results, the maximum penetration force of hybrid configuration with single-layered aramid fabric reinforcements is approximately 15.5% higher than that of single-layered carbon fabric reinforcements at 60°C test temperature. It is further observed that the absorbed energy improves as the number of fabrics is increased in both aramid and carbon reinforcements. The test temperatures significantly affect the failure mechanisms of TPCs. A smaller damaged area at the penetrated faces of the hybrid structures is obtained by comparison with the monolithic TPCs.

Flexural Performance of Emulsified-Asphalt-Modified ECC for Expansion Joint Use

The concrete transition zone plays an important role in bridge expansion joint structure, which provides a good connection between the expansion joint installation and bridge decks. However, the premature deteriorations of concrete transition zone are found to be the major diseases of expansion joint during service life. Therefore, a material with high ductility, superior durability, and low modulus/stiffness is highly desired for transition zone. Engineering cementitious composites (ECC), a kind of high-performance concrete featuring the prominent ductility and durability, are a promising material for transition zone of expansion joint. This paper introduces a specific ECC material for transition zone, which is modified by emulsified asphalt (EA-ECC), and has the high deformation ability and low modulus/stiffness. The flexural mechanical properties including flexural stress-load displacement relation, flexural secant stiffness, and elastic modulus of the EA-ECC’s matrix were investigated experimentally. The microstructures of EA-ECC were observed via scanning electron microscope (SEM) imaging. Additionally, the influence of test temperature on flexural mechanical properties of EA-ECC was also investigated. It is found that the ultimate flexural stress of EA-ECC reduces gradually with increasing EA content. Conversely, the flexural deformation capacity shows an increasing trend with EA content. Additionally, incorporating EA significantly reduces the flexural secant stiffness and elastic modulus of EA-ECCs. The research results concluded that incorporating EA in ECC can significantly improve the flexural deformation ability accompanied by relatively lower modulus, which is likely to reduce the impact load on transition zone caused by vehicle bumping and prolong the service life of the whole bridge expansion joint structure.

A broadband metamaterial absorber with temperature scalability to 400 °C

A broadband metamaterial absorber intended for applications at elevated temperatures was designed and fabricated. Its performance was measured over a temperature range from room temperature to approximately 400 °C. The absorber consists of a lossy resistive frequency selective surface (RFSS) on a dielectric substrate and a metallic ground plane with high-temperature stability scalable to approximately 400 °C. The top RFSS layer, made of conductive composites, was prepared using a mixture of graphite microflakes and water glass, and it showed good chemical and thermal stability up to 400 °C. Its sheet resistance was adjustable over a wide range with different proportions of graphite flakes and decreased gradually with increasing temperature. The metamaterial absorber demonstrated broadband absorption with a reflection coefficient of less than −10 dB in the X-band frequency range (8.2–12.4 GHz), resulting in the absorption of more than 90%. The influence of testing temperature on the reflection coefficient was correlated with the variation in the sheet resistance. The proposed metamaterial absorber is a promising candidate for use in high-temperature microwave absorption applications.

Self-heating of metastable 304L austenitic stainless steel under cyclic loading: Influence of initial martensite volume fraction, testing temperature and pre-strain

In this study, special attention is paid to the thermal response of the austenitic stainless steel 304L under cyclic loading tests (i.e., self-heating tests) in different conditions. The cyclic behavior of the 304L austenitic stainless steel can be influenced by martensitic transformation. Hence, the role of martensitic transformation in the self-heating behavior of this material is studied. For this purpose, self-heating tests are performed on pre-strained specimens at a wide range of temperatures from 100 °C to −130 °C, which leads to different initial volume fractions of martensite ranging from 0% to 45%, respectively. Furthermore, the influence of the testing temperature and a pre-strain at room temperature on the self-heating curves is investigated. The results demonstrate that the decrease in the test temperature from room temperature to - 30 °C as well as the increase in the pre-strain values from 0% to 30% at room temperature, result in a shift of the self-heating curves to the right. It could mean that the fatigue limit of the material is improved.

An alternative of crack length extension in R-curve analysis of asphalt concrete

This study applies the Digital Image Correlation (DIC) technique to capture the displacement field on the specimen surface in the SC(B) fracture test of asphalt concrete for the construction of R-curves. Previous research, utilizing a displacement method, did not capture the micro-cracking that occurs during the formation of the cohesive zone in a fracture specimen. A Crack Opening Displacement Matrix (CODM) is defined based on the DIC displacement field. Five CODMs are used as alternatives of crack length extension to construct the displacement-based R-curve for asphalt concrete. The cohesive energies and energy rates are determined by those displacement-based R-curves. The influences of test temperature, loading rate, aggregate size, and polymer modification on cohesive energies and energy rates are then investigated. The following lists the major findings of the this study: (1) The cohesive energies determined by displacement-based R-curve are generally lower in value compare to the cohesive energy determined by crack-extension-based R-curve, which indicates the displacement-based R-curve and its cohesive energy may separate crack initiation and propagation by invisible micro crack; whereas the crack- extension-based R-curve separate the crack initiation and propagation by visible crack; (2) The test temperature is statistically significantly impacting on cohesive energies; loading rate is significantly impacting on cohesive energy determined by the R-curve using the CODM that is distant from the crack tip; (3) Higher loading rate, lower test temperature and larger aggregate size may lead to higher energy rate; but these trends are not statistically proved in this study. In all, the crack length and CODMs quantify the crack extension in different ways (length growing and wideness opening). Thus, by complementing the existing displacement-based R-curve, the R-curve system of both CMOD and CODM has the potential to fully characterize the fracture behaviour of asphalt concrete.

Study of the tensile behaviour of tungsten wires from ambient temperature to 320 °C in relation to their microstructure

The tensile test results have been interpreted in terms of the microstructure typical of drawn tungsten wires; the influence of test temperature between 25 °C and 320 °C is significant and is linked to the dependence of the mechanical behaviour of tungsten versus temperature and to the development with increasing temperature of a necking zone in which damage and rupture take place in two stages, a localized damage controlled first by the hoop stress associated to the notch effect linked to necking and rupture under the axial stress and the notch effect just mentioned.

Friction stir spot welding of AA6061-T6 and Cu with preheating: Strength and failure behavior at different test temperatures

In the current study, the influence of test temperatures was investigated on lap shear strength and fracture behavior of dissimilar and similar friction stir spot-welded (FSSW) joints between Cu and AA6061-T6 sheets prepared without and with employing additional heating. Formation and distribution of intermetallic compounds (IMCs) in Cu-AA6061 FSSW joints was further appraised. An increase in maximum lap shear force was observed in Cu-AA6061 and Cu-Cu joints when preheating was employed. Lap shear force decreased with increase in test temperature for Cu-AA6061 joints prepared without preheating; however, for joints prepared employing preheating, the lap strength increased from 25 to 50 °C following a slight drop at 100 °C test temperature. For Cu-Cu joints, lap shear force also increased with test temperature for the range studied in the present work. X-ray diffraction, and energy dispersive spectroscopy analysis illustrates the formation of IMCs in the form of Al2Cu and Al4Cu9 in Cu-AA6061 and oxides in Cu-Cu joints. The interface failure from IMC rich regions in dissimilar joints was observed whereas similar joints failed under plug failure. Intermittently, thick IMC layer was observed in dissimilar Cu-AA6061 joint prepared with preheating. Presence of tearing/rupture from oxide dominated intermetallic region observed in Cu-AA6061 FSSW joints whereas dimples and micro-voids were noted in Cu-Cu joints.

АНИЗОТРОПИЯ ХАРАКТЕРИСТИК МАЛОЦИКЛОВОЙ УСТАЛОСТИ МОНОКРИСТАЛЛИЧЕСКИХ ЖАРОПРОЧНЫХ НИКЕЛЕВЫХ СПЛАВОВ

The low cycle fatigue of heat-resistant nickel alloys with a single crystal structure VZHM7 and VIN3 was studied. The tests were carried out under conditions of monitoring the complete deformation in the cycle, loading of the type «tension-compression» occurred according to a sinusoidal law with a frequency of 0,5 Hz. For both alloys, tests were carried out for three crystallographic orientations ([001], [011], [111]) at two temperatures: 500 and 850 °C. Regression lines were constructed, the limits of limited endurance were found on the basis of 104 cycles. The influence of test temperature and crystallographic orientation on the endurance limit of alloys and RMS is analyzed.

Failure Mechanism and Mechanical Characteristics of NiCrBSi Coating

Mechanical properties of NiCrBSi coatings on plain carbon steel substrate prepared by HVOF (High velocity flame spraying) were studied in this work. Sprayed coatings with average thicknesses of 0.25 mm, 0.5 mm and 1 mm were prepared on preheated steel strips and steel strips without preheating. Chemical analysis of the coatings cross‑section offered information about material structure and distribution of chemical elements within the coating. Hardness of the coating was measured with the aim to reveal the influence of coating thickness and coated substrate preheating on coating hardness. Similar hardness was observed regardless coating preparation conditions and thickness. Bend test was used for characterization of failure character of NiCrBSi thermally sprayed coatings under different thermal conditions. Higher coating thickness was beside cracking, accompanied also by coating delamination from the substrate, while also some influence of testing temperature (laboratory temperature vs. ‑50 °C) on coating failure characteristics were observed. No influence of the coating preparation conditions on the coating pull‑off strength was observed.

Influence of test temperature on impact toughness of X70 pipe steel welds

Impact toughness of the base metal and welds of the pipe steel of the X70 strength class was investigated and high values were defined. It was particularly important that impact toughness of the weld at temperatures of -40 °C and -20 °C was identical to that of the base material. For specimens W1 and W2 cut from the heat zone of weld by different metods (milling (W1) and plasma method (W2)) at a temperature of -40 °C, it was 1.14 and 1.5 times lower than that of the base metal, respectively. The method of cutting the specimens (milling, or plasma cutting) did not affect the impact toughness of the pipe steel and its welds in the investigated temperature range.

Key Test Conditions for Volatile Organic Compound (VOC) Testing of Non-metallic Parts in Vehicles

VOCs in Automobile will pose a threat to the health of passengers. Nowadays, more and more people are focusing on the VOCs. Different OEMs and parts units use different VOCs test methods according to their actual situation. Some of the test methods may exist with low performance and low reliability. In this paper, the influence of test temperature and time on the test results are studied, and a reasonable test draft of VOCs in nonmetallic structures is put forward, which will provide technical support and basis for OEMs select suitable VOCs detection methods.

Effect of Testing Temperature on Sulfide Stress Cracking of Low Alloy Steel

In this study, effects of environmental temperature on susceptibility to sulfide stress cracking (SSC)—a type of hydrogen embrittlement (HE) occurring in sour environments—of low alloy steels were investigated from the perspective of hydrogen entry, absorption, and accumulation. SSC susceptibility was evaluated using a double cantilever beam (DCB) test and a four-point bend (4PB) test in sour environments at several testing temperatures. 4PB test specimens included notched and un-notched specimens to investigate influences of stress concentration and local stress. In the case of evaluation methods using specimens with high-stress concentration area, a decrease in testing temperature from room temperature to 4°C significantly increased SSC susceptibility. Hydrogen entry and absorption behaviors were also evaluated at several testing temperatures using a hydrogen permeation test. The hydrogen concentration at the plastic deformed area increased remarkably with decreasing testing temperature. It is considered that the influence of testing temperature is due to hydrogen concentration at the stress concentration area with plastic deformation. In a low temperature condition, the degree of hydrogen accumulation at the crack tip areas of a DCB specimen or crack initiation site of a 4PB specimen could be higher than that in a higher temperature condition. When steels are applied to low temperature conditions with H2S, a prior material evaluation reproducing both environmental temperature and actual stress condition is needed.

Influence of surface oxidation on the radiative properties of ZrB2-SiC composites

The spectral emissivities of ZrB2-20 vol.% SiC composites with various surface components of ZrB2/SiC (ZS1), silica-rich glass (ZS2) and porous zirconia (ZS3) were measured using infrared spectrometer in the wavelength range from 2.5 to 25.0μm. The relationship between surface oxidation (associated with surface component, thickness of oxide scale, testing temperature as well as roughness) and the radiative properties of ZrB2-SiC composites were investigated systematically. Surface component affected the radiative properties of composites significantly. The total emissivity of ZS1 varied from 0.22 to 0.81 accompanied with surface oxidation in the temperature range 300–900°C. The emissivity of ZS2 was about 1.5 times as that of ZS3 under the same testing conditions. The oxide scale on specimen surface enhanced the radiative properties especially in terms of short-wave range, and the emissivity in the long-wave range gradually increased with the thickness of oxide scale within a certain range. The influence of testing temperature and surface roughness was also investigated. The testing temperature had a little effect on radiative properties, whereas effect of surface roughness could be negligible.

Influence of test temperature on cyclic deformation behavior of a near α titanium alloy

Low cycle fatigue behavior of titanium alloy Timetal 834 has been studied at 300°C, 450°C and 600°C under fully reversed constant total strain amplitudes (Δεt/2) ranging from 0.4% to 1.2%. The alloy exhibited initial cyclic softening followed by cyclic hardening at 450°C for Δεt/2≥0.4% while at 300°C and 600°C, cyclic softening followed by cyclic stability was noticed in the cyclic stress response curves for Δεt/2>0.4%. Precipitate shearing was observed to be the micro-mechanism responsible for cyclic softening at all test temperatures. However, dislocation-dislocation and dislocation – solute interaction was observed to be the micro-mechanism responsible for cyclic hardening only at 450°C. TEM observations revealed that the severity of planar slip is found to peak at 450°C.

Fatigue of NiTi shape memory wires

In the present work, an innovative methodology for characterizing structural fatigue of NiTi superelastic wires is proposed. It consists in, firstly, performing low speed nearly isothermal pseudoelastic cycles in a limited region of the wire specimen. This results in the stabilization of the pseudooelastic behavior accompanied by a decrease in the stresses for forward and reverse transformations which allows obtaining an equivalent to a geometric dog-bone shaped specimen due to the reduced transformation stresses in the pre-cycled region. In a second stage, by limiting the transformation active zone to the pre-cycled region, the deformation speed can be increased to practical values avoiding any transformation activity outside that region. In that way, grip induced failures resulting in artificially shorter fatigue lives might be completely avoided thus allowing an accurate characterization of the true structural fatigue. Additionally, strain controlled experiments on wires in fully austenite and fully martensite states have been performed. Resulting fatigue lives in these cases were at least two orders of magnitude higher compared with the pseudoelastic fatigue indicating the decisive role played by the stress induced transformation in determining fatigue life. The influence of testing temperature and deformation rate on fatigue life has also been evaluated