Publications
74 results found
Shao Z, Li N, Lin J, et al., 2018, Strain measurement and error analysis in thermo-mechanical tensile tests of sheet metals for hot stamping applications, Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, Vol: 232, Pages: 1944-2008, ISSN: 0954-4062
In order to conduct uniaxial tensile tests for hot stamping applications, tests are normally performed by using a Gleeble thermo-mechanical materials simulator so that rapid heating and cooling processes can be obtained. However, temperature gradients in a specimen tested on Gleeble are inevitable due to resistance heating principles and heat loss to grips and water-cooled jaws. In this research, a pair of purpose-built grips made of stainless steel with low thermal conductivity and significantly reduced contacting area for clamping, as well as a flat dog-bone specimen with maximised parallel length (80 mm) were designed, for the purpose of improving the temperature uniformity within the concerned gauge section area of the specimen. Uniaxial tensile tests on AA6082 were performed, after controlled heating and cooling processes, at constant deformation temperatures in the range of 400 ℃–500 ℃ and at constant strain rate in the range of 0.1–4/s, to simulate its hot stamping conditions. The digital image correlation system was adopted to enable strain distributions in specimens to be measured. The temperature distributions in specimens were investigated and an effective gauge length of 14 mm was specified accordingly to ensure temperature gradients less than 10 ℃ within it at all tested temperatures. True stress–true strain curves of AA6082 were obtained based on results of strain measurements along the defined effective gauge length and used to calibrate a set of advanced material model. Error analysis was carried out by using thermo-electrical and thermo-mechanical FE models on ABAQUS, in which the calibrated material constitutive equations were implemented via subroutines. The error of stress–strain curves of AA6082 measured based on the specified gauge length was investigated and quantified by analysing the distribution of axial strain and axial stress.
Jiang J, Hooper P, Li N, et al., 2017, An integrated method for net-shape manufacturing components combining 3D additive manufacturing and compressive forming processes, International Conference on the Technology of Plasticity (ICTP 2017), Publisher: Elsevier, Pages: 1182-1187, ISSN: 1877-7058
Additive manufactured (AM) or 3D printed metallic components suffer poor and inconsistent mechanical properties due to the presence of a large number of micro-voids, residual stress and microstructure inhomogeneity. To overcome these problems, a new forming process has been proposed, which effectively combines AM and compressive forming. The aim of this study is to prove the feasibility of this newly proposed method by providing preliminary results. Thus, we compared the tensile performance of hot-forged additive manufactured stainless steel 316L samples to none-hot-forged additive manufactured ones. Significant improvement in mechanical properties has been found in the tensile tests as well hardness test. In addition, our EBSD characterized grain orientation maps at each stage of the process revealed the corresponding microstructure revolution which provides insights into underlying mechanistic.
Shao Z, Li N, Lin J, 2017, The optimisation of cruciform specimen for the formability evaluation of AA6082 under hot stamping conditions, Procedia Engineering, Vol: 207, Pages: 735-740, ISSN: 1877-7058
The hot stamping and cold die quenching process is increasingly adopted to form complex-shaped structures of sheet metals in the automotive industry. However, it is difficult to obtain formability data of sheet metals under hot stamping conditions by using conventional experimental testing methods. In this study, a novel in-plane biaxial testing system, which is attached to a Gleeble materials thermo-mechanical simulator, had been developed for determining forming limit diagrams (FLDs) under hot stamping conditions. However, there is no standard of cruciform specimen geometries available for this type of biaxial tests. In this paper, the features of thickness reduction in the central region and slots in the arms of a type of cruciform specimen of aluminium alloy 6082 were verified first to increase strain uniformity of the biaxial loading zone on a cruciform specimen, based on the selective heating and cooling method. Finite Element (FE) thermo-electrical and thermo-mechanical models with UAMP and VUMAT subroutines were then implemented in ABAQUS 6.12 to optimise specimen dimensions so that fracture occurs in the concerned central region of the specimen during testing. By the use of the optimised specimen for AA6082 in the biaxial testing system, formability tests under the designated strain paths were conducted at specified hot stamping conditions. Strain fields in the gauge region of the cruciform specimens were measured using the digital image correlation (DIC) system and the experimental results were presented and analysed in order to verify the cruciform specimen design.
Ganapathy M, Li N, Lin J, et al., 2017, Investigation of a new hot stamping process with improved formability and productivity, ICTP 2017, Publisher: Elsevier, Pages: 771-776, ISSN: 1877-7058
In order to improve the drawability of boron steel and also to increase the productivity of hot stamping process, a new hot stamping process with pre-cooling has been proposed. Stress-strain behavior at various temperatures was investigated and compared with that in traditional hot stamping processes. Detailed studies were carried out on the strain hardening parameter, n, at different temperatures and deformation rates. To evaluate this concept, hot stamping experiments were performed with both conventional (without pre-cooling) and new process (with pre-cooling) for a scaled down B-Pillar automotive component. The new hot stamping process with pre-cooling was able to produce the B-Pillar at low temperature (500°C) with less thinning than the hot stamping carried out without precooling at high temperature (765°C). Also the in-die quenching time was reduced by about 60%, by adopting the new hot stamping process with pre-cooling, which would increase the productivity significantly for automotive mass production without compromising the part quality.
Ganapathy M, Li N, Lin J, et al., 2017, A Novel Grip Design for High-Accuracy Thermo-Mechanical Tensile Testing of Boron Steel under Hot Stamping Conditions, Experimental Mechanics, Vol: 58, Pages: 243-258, ISSN: 0014-4851
Achieving uniform temperature within the effective gauge length in thermo-mechanical testing is crucial for obtaining accurate material data under hot stamping conditions. A new grip design for the Gleeble Materials-Simulator has been developed to reduce the long-standing problem of temperature gradient along a test-piece during thermo-mechanical tensile testing. The grip design process comprised two parts. For the first part, the new design concept was analysed with the help of Abaqus coupled Thermal-Electric Finite element simulation through the user defined feedback control subroutine. The second part was Gleeble thermo-mechanical experiments using a dog-bone test-piece with both new and conventional grips. The temperature and strain distributions of the new design were compared with those obtained using the conventional system within the effective gauge length of 40 mm. Temperature difference from centre to edge of effective gauge length (temperature gradient) was reduced by 56% during soaking and reduced by 100% at 700 °C. Consequently, the strain gradient also reduced by 95%, and thus facilitated homogeneous deformation. Finally to correlate the design parameters of the electrical conductor used in the new grip design with the geometry and material of test-piece, an analytical relationship has been derived between the test-piece and electrical conductor.
Shao Z, Li N, Lin J, 2017, The comparison of two continuum damage mechanics-based material models for formability prediction of AA6082 under hot stamping conditions, 36th IDDRG Conference – Materials Modelling and Testing for Sheet Metal Forming, Publisher: IOP Publishing, ISSN: 1742-6588
The hot stamping and cold die quenching process has experienced tremendous development in order to obtain shapes of structural components with great complexity in automotive applications. Prediction of the formability of a metal sheet is significant for practical applications of forming components in the automotive industry. Since microstructural evolution in an alloy at elevated temperature has a large effect on formability, continuum damage mechanics (CDM)-based material models can be used to characterise the behaviour of metals when a forming process is conducted at elevated temperatures. In this paper, two sets of unified multi-axial constitutive equations based on material's stress states and strain states, respectively, were calibrated and used to effectively predict the thermo-mechanical response and forming limits of alloys under complex hot stamping conditions. In order to determine and calibrate the two material models, formability tests of AA6082 using a developed novel biaxial testing system were conducted at various temperatures and strain rates under hot stamping conditions. The determined unified constitutive equations from experimental data are presented in this paper. It is found that both of the stress-state based and strain-state based material models can predict the formability of AA6082 under hot stamping conditions.
Shao Z, Li N, Lin J, 2017, The comparison of two continuum damage mechanics-basedmaterial models for formability prediction of AA6082 underhot stamping conditions, Materials Modelling and Testing for Sheet Metal Forming IDDRG 2017
Shao Z, Li N, 2017, A Novel Biaxial Testing Apparatus for the Determination of Forming Limit under Hot Stamping Conditions, Journal of Visualized Experiments, Vol: 122, ISSN: 1940-087X
This protocol proposes a novel biaxial testing system used on a resistance heating uniaxial tensile test machine in order to determine the forming limit diagram (FLD) of sheet metals under hot stamping conditions.
Zheng K, Lee J, Politis DJ, et al., 2017, An analytical investigation on the wrinkling of aluminium alloys during stamping using macro-scale structural tooling surfaces, International Journal of Advanced Manufacturing Technology, Vol: 92, Pages: 481-495, ISSN: 0268-3768
Structural surface texturing is believed to be a promising approach to modify tribological and thermal performances of tooling for sheet-stamping processes. However, a fundamental study on the surface-texturing design and resulting material deformation is currently lacking. In this paper, an advanced analytical buckling model specifically for the utilisation of textured tools at macro-scale, comprising dislocation-driven material model, isotropic yield criteria, bifurcation theory and Donnell-Mushtari-Vlasov (DMV) shell structure theory, was established. The developed analytical buckling model was validated by cylindrical deep-drawing experiments. Further finite element (FE) simulations with the implementation of material model via user-defined subroutine were also used to validate the bucking model for large surface texture designs. Effects of theoretical assumptions, such as yield criterion, boundary condition and test-piece geometry, on the accuracy of model prediction for wrinkling were investigated. It was found that the von Mises yield criterion and hinged boundary condition exhibited more accurate predictions. In addition, the DMV shell theory made this model most representative for large structural texturing designs. Furthermore, the implementation of induced shear strain component has an important effect on precisely predicting the wrinkling occurrence. The advanced analytical models developed in this study combine various classical mechanics, structure stability and material modelling together, which provides a useful tool for tooling engineers to analyse structural designs.
Li N, Zheng J, Zheng K, et al., 2017, A fast ageing method for stamped heat-treatable alloys, WO2017021742 A1
Shao Z, Li N, Lin J, 2017, A New Damage Model for Predicting Forming Limits under Hot Stamping Conditions, The International Conference on Plasticity, Damage, and Fracture 2017
Shao Z, Li N, Lin J, et al., 2017, Formability evaluation for sheet metals under hot stamping conditions by a novel biaxial testing system and a new materials model, International Journal of Mechanical Sciences, Vol: 120, Pages: 149-158, ISSN: 0020-7403
Hot stamping and cold die quenching has been developed in forming complex shaped structural components of metals. The aim of this study is the first attempt to develop unified viscoplastic damage constitutive equations to describe the thermo-mechanical response of the metal and to predict the formability of the metal for hot stamping applications. Effects of parameters in the damage evolution equation on the predicted forming limit curves were investigated. Test facilities and methods need to be established to obtain experimental formability data of metals in order to determine and verify constitutive equations. However, conventional experimental approaches used to determine forming limit diagrams (FLDs) of sheet metals under different linear strain paths are not applicable to hot stamping conditions due to the requirements of rapid heating and cooling processes prior to forming. A novel planar biaxial testing system was proposed before and was improved and used in this work for formability tests of aluminium alloy 6082 at various temperatures, strain rates and strain paths after heating, soaking and rapid cooling processes. The key dimensions and features of cruciform specimens adopted for the determination of forming limits under various strain paths were developed, optimised and verified based on the previous designs and the determined heating and cooling method [1]. The digital image correlation (DIC) system was adopted to record strain fields of a specimen throughout the deformation history. Material constants in constitutive equations were determined from the formability test results of AA6082 for the prediction of forming limits of alloys under hot stamping conditions. This research, for the first time, enabled forming limit data of an alloy to be generated at various temperatures, strain rates and strain paths and forming limits to be predicted under hot stamping conditions.
Ganapathy M, Li N, Lin JG, et al., 2017, Test-Piece and Test-Rig Designs to Obtain High Accuracy Experimental Data for Boron Steel at Hot Stamping Conditions, 3rd International Conference on Advanced High Strength Steel and Press Hardening (ICHSU), Publisher: WORLD SCIENTIFIC PUBL CO PTE LTD, Pages: 109-113
Kong XX, Li N, O'Keeffe R, et al., 2017, Experimental Investigation on the Accuracy of Uniaxial Tensile Data of AA6082 Under HFQ (R) Conditions, 3rd International Conference on Advanced High Strength Steel and Press Hardening (ICHSU), Publisher: WORLD SCIENTIFIC PUBL CO PTE LTD, Pages: 390-394
Li N, Lin J, Balint DS, et al., 2016, Modelling of austenite formation during heating in boron steel hot stamping processes, Journal of Materials Processing Technology, Vol: 237, Pages: 394-401, ISSN: 0924-0136
A physically-based material model has been developed to describe the austenite formation in a manganese-boron steel during heating in hot stamping processes. The equations were formulated based on three austenite formation mechanisms: nucleation, growth and impingement. It is able to characterise the phase transformation process under both non-isothermal and isothermal conditions, where the effects of heating rate and soaking temperature on the austenite formation have been rationalised. Heat treatment tests of the manganese-boron steel were performed on a Gleeble 3800 subjected to various heating conditions (heating rate: 1 K/s − 25 K/s, soaking temperature: 1023 K − 1273 K). The dimensional changes of specimens associated with the phase transformation, which was measured using a high resolution dilatometer, has been quantitatively related to the volume fraction of austenite formation. The experimental data was used to calibrate and validate the equations. Good agreement between the experimental and predicted results has been obtained. Further analysis has been made to illustrate the significance of the model in applications.
Shao Z, Li N, Lin J, et al., 2016, Development of a new biaxial testing system for generating forming limit diagrams for sheet metals under hot stamping conditions, Experimental Mechanics, Vol: 56, Pages: 1489-1500, ISSN: 0014-4851
Conventional experimental approaches used to generate forming limit diagrams (FLDs) for sheet metals at different linear strain paths are not applicable to hot stamping and cold die quenching processes because cooling occurs prior to deformation and consistent values of heating rate, cooling rate, deformation temperature and strain rate are not easy to obtain. A novel biaxial testing system for use in a Gleeble testing machine has been adopted to generate forming limits of sheet metals, including aluminium alloys, magnesium alloys and boron steel, under practical hot stamping conditions in which heating and cooling occur. For example, the soaking temperature is about 900 °C and the deformation temperature range is 550–850 °C for boron steel [1] and the soaking temperature is about 535 °C and the deformation temperature range is 370–510 °C for AA6082 [2]. Resistance heating and air cooling were introduced in this pioneering system and the thermal analysis of different heating and cooling strategies was investigated based on a type of cruciform specimen. FE models with a UAMP subroutine were used to predict temperature fields on a specimen in ABAQUS 6.12. Digital image correlation (DIC) system was used to record strain fields of a specimen by capturing images throughout the deformation history and its post-processing software ARAMIS was used to determine forming limits according to ISO standards embedded in the software. Heating and cooling strategies were determined after the analysis. Preliminary results of forming limit curves at the designated temperatures are presented in order to verify the feasibility of this new method.
Li N, Shao Z, Lin J, et al., 2016, Investigation of uniaxial tensile properties of AA6082 under HFQ® Conditions, Key Engineering Materials, Vol: 716, Pages: 337-344, ISSN: 1013-9826
© 2016 Trans Tech Publications, Switzerland. For a metal forming process, the uniaxial tensile properties of a material are the most fundamental and important properties to investigate. Solution heat treatment, forming and in-die quenching (HFQ®) is a patented process to form complex shape panel components using aluminium alloys at high efficiency and low cost. A Gleeble materials thermo-mechanical simulator was used to conduct uniaxial tensile testing of AA6082 under HFQ® conditions. A set of grips were specially designed to reduce the heat loss of specimen during testing in a Gleeble and allow the strain measurement by using digital image correlation (DIC) system. A large dog-bone specimen with parallel length of 80mm was designed to minimise the temperature gradient along the gauge section. Temperature gradient was measured and uniaxial tensile tests were conducted at the range of deformation temperature of350-535 °C and the range of strain rate of 0.1-4/s. The uniaxial tensile properties of AA6082 at different temperatures and strain rates under HFQ® conditions were summarised and the viscoplastic response of the material was discussed.
Yang L, Li N, Wang B, et al., 2016, Unified constitutive modelling for two-phase lamellar titanium alloys at hot forming conditions, Manufacturing Review, Vol: 3, ISSN: 2265-4224
In this paper, a set of mechanism based unified viscoplastic constitutive equations have been established for two-phase titanium alloys with initial lamellar microstructure, which models the softening mechanisms of the alloys in hot forming conditions. The dislocation density, rotation and globularization of lamellar α-phase and their effects on flow behaviour can also be modelled. The values of material constants in the equation set have been calibrated, according to stress-strain curves and globularization fractions of lamellar α-phase obtained from compression tests at a range of temperatures and strain rates, using a genetic algorithm (GA) based optimisation method. Based on the determined constitutive equations, flow stress and globularization evolution of Ti-17 and TA15 alloys at different temperatures and strain rates were predicted. Good agreements between the experimental and computed results were obtained.
Li N, Wang L, Lin J, et al., 2016, A method for forming a part from aluminium alloy, GB2536193A
A method of forming a part from aluminium alloy by rolling the alloy to form a sheet at a first manufacturing plant and cutting or stamping a blank from the sheet, solution heat treating the blank and placing the blank between dies where it is cooled shaped at a second manufacturing plant. The alloy can be a 6xxx series alloy such as 6082 which is heated to a solution heat treatment temperature in the range 520-575 0C in 30 seconds or less, a 7xxx series alloy such as 7075 with solution heat treatment at a temperature in the range 460-520 0C, a 2xxx series alloy or a 5xxx series alloy.
Zuo B, Wang B, Li Z, et al., 2016, An investigation of involute and lead deflection in hot precision forging of gears, International Journal of Advanced Manufacturing Technology, Vol: 88, Pages: 3017-3030, ISSN: 1433-3015
A theoretical model is presented in the paper for predicting involute profile deflection in hot precision forging of gears. This model is a function of a number of material and processing parameters, including the thermal expansion of the die, thermal contraction of workpiece, elastic expansion of the die during forging, and workpiece recovery after ejection. To improve the accuracy of the hot forged gear tooth, an equation set to define modified involute that is used to design the die tooth has been proposed based on the model. The distribution of deflection along the involute was also predicted using the commercial FE code, PRO-E. The deflection characteristic of the toothed die through the tooth width was analyzed by combining the theoretical method and FEM to investigate the non-uniform deflection. The dimension of the forged gears was measured using a gear measurement machine WGT3000. A close agreement between predicted and measured tooth involute profiles was obtained, which validated the involute deflection prediction model. The measured lead error also verified the model for deflection non-uniformity through the tooth width. The results can provide a guide for die tooth designs to improve the dimensional accuracy of hot forged gear teeth.
Shao Z, Bai Q, LI N, et al., 2016, Experimental investigation of forming limit curves and deformation features in warm forming of an aluminium alloy, Proceedings of the Institution of Mechanical Engineers Part B - Journal of Engineering Manufacture, Vol: 232, Pages: 465-474, ISSN: 0954-4054
The determination of forming limit curves and deformation features of AA5754 aluminium alloy are studied in this article. The robust and repeatable experiments were conducted at a warm forming temperature range of 200 °C–300 °C and at a forming speed range of 20–300 mm/s. The forming limit curves of AA5754 at elevated temperatures with different high forming speeds have been obtained. The effects of forming speed and temperature on limiting dome height, thickness variation and fracture location are discussed. The results show that higher temperatures and lower forming speeds are beneficial to increasing forming limits of AA5754; however, lower temperatures and higher forming speeds contribute to enhancing the thickness uniformity of formed specimens. The decreasing forming speed and increasing temperature result in the locations of fracture to move away from the apexes of formed specimens. It is found that the analysis of deformation features can provide a guidance to understand warm forming process of aluminium alloys.
Lin J, Zheng K, Wang L, et al., 2016, Material and Process for Preparing and Forming an Aluminium Alloy Material, WO/2016/067045
Shao Z, Li N, Politis D, et al., 2016, Analysis on Experimental Techniques for Generating FLD at ElevatedTemperatures, 2nd International Conference on Advanced High Strength Steel and Press Hardening (ICHSU2015), Publisher: World Scientific
The evaluation of the formability of sheet material is of great importance for forming complex-shapecomponents in automotive applications. However, for hot and warming forming conditions, thisusually requires formability tests with specialist devices and testing procedures and is difficult toobtain accurate and comparable results due to the lack of testing standards. In this paper, the conceptand development of strain-based forming limit diagram (FLD) are introduced. The testing methodsto experimentally determine the FLD, classified into formability tests and planar tensile tests, arewidely reviewed. The applications of both types to obtain FLD at elevated temperatures for differentforming processes are introduced, and the advantages and disadvantages of the methods areanalysed.
Li N, Lin J, Balint D, et al., 2016, Experimental characterisation of the effects of thermal conditions on austenite formation for hot stamping of boron steel, Journal of Materials Processing Technology, Vol: 231, Pages: 254-264, ISSN: 0924-0136
The formation of austenite in manganese-boron steels during selective heat treatment has great significance in the application of innovative hot stamping processes. Heat treatment tests were designed according to the thermal cycle of industrial heating and hot stamping processes and were conducted on a Gleeble 3800 thermomechanical testing system. Specimens were subjected to non-isothermal (heating rates: 1 K/s–25 K/s) and isothermal (soaking temperatures: 1023 K–1173K) temperature profiles. A high-resolution dilatometer was employed to detect the dimensional change of the specimens associated with austenitization. The dilatometric measurement was quantitatively related to the volume fraction of austenite. By analysing the evolution curves of austenite fraction, the effects of heating rate and temperature on the progress of austenite formation under both non-isothermal and isothermal conditions were investigated and characterised, improving the current understanding of the mechanisms that control austenite formation in manganese-boron steels.
Li N, Politis D, Foster AD, et al., 2016, Prediction of thinning behavior for complex-shaped, lightweight alloy panelsformed through a hot stamping process*, 2nd International Conference on Advanced High Strength Steel and Press Hardening (ICHSU2015):, Publisher: World Scientific
This paper provides an overview of hot stamping of light alloys using a method known as HFQ®forming. We present a new method of forming complex shaped automotive components through theuse of a hot stamping process for high strength AA6082 alloy. In particular, the component selectedfor study is a complex automotive door inner component that could not be conventionally formedfrom such a strong alloy. The forming process is described and the post-formed thicknessdistribution is presented. An FE simulation is given to demonstrate the potential to predict theforming process and to provide guidance as to the final component thicknesses.
Matsumoto T, Shi X, Li N, et al., 2016, An Investigation of Deformation Effects on Phase Transformation in Hot Stamping Processes
Shao Z, Li N, Politis D, et al., 2016, Analysis on Experimental Techniques for Generating FLD at Elevated Temperatures, International Conference on Hot Stamping of UHSS (ICHSU2015)
Li N, Sun C, Guo N, et al., 2015, Experimental investigation of boron steel at hot stamping conditions, Journal of Materials Processing Technology, Vol: 228, Pages: 2-10, ISSN: 0924-0136
The effect of deformation temperature and strain rate on the fracture and strain hardening of boron steel was investigated through the analysis of large amount of experimental data tested using a Gleeble (3800) materials simulator. These features were further modelled by using a set of unified viscoplastic damage constitutive equations. To study the deformation behavior, isothermal uniaxial tension tests of 1500 MPa boron steel at different strain rates of 0.01–5.0 s−1 and different deformation temperatures of 550–850 °C were performed on a Gleeble 3800 materials simulator. Considering the difference between the deformation of the necking cross section and the centre measuring cross section of specimen at necking stage, a correction method of measuring strain at the necking cross section was developed. In addition, by taking temperature rise during deformation into account, a correction method of measuring stress was proposed. The true stress-strain curves were obtained based on the two corrections methods. The influence of deformation temperature and strain rate on the fracture and hardening was analyzed. A set of unified constitutive equations was adopted and determined from experimental data. The correlation between the numerical-computed and experimental true stress-strain data is presented. The average relative error is within the range of allowable experimental conditions and the predicted and experimental values can almost be consistent.
Ganapathy M, Li N, Lin J, et al., 2015, Analysis of new Gleeble tensile specimen design for hotstamping application, 4th International Conference on New Forming Technology, Publisher: EDP
Hot tensile testing is useful to understand the material behavior at elevated temperatures. Hence it is of utmost importance that the test condition is accurate enough to derive stress-strain data in fully austenitic state and to ensure homogeneous deformation throughout the gauge length of the specimen. But present limitation of standard Gleeble hot tensile sample geometry could not be used to achieve a uniform temperature distribution along the gauge section, thus creating errors of experimental data. In order to understand the effect of sample geometry on temperature gradient within the gauge section coupled electrical-thermal and thermo-mechanical finite element analysis has been carried out using Abaqus, with the use of viscoplastic damage constitutive equations presented by Li [1]. Based on the experimental study and numerical analysis, it was observed that the new sample geometry introduced by Abspoel [2], is able to achieve a better uniformity in temperature distribution along the gauge length; The temperature deviation along the gauge length within 25 ∘C during soaking and 5 ∘C after cooling and onset of deformation); also the strain deformation is found to be almost homogeneous.
This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.