Tensile test on steels at elevated temperatures

2020 ◽  
pp. 43-120
Author(s):  
Weiyong Wang ◽  
Venkatesh Kodur
Keyword(s):  
Tensile Test ◽  
Elevated Temperatures

Numerical Modelling of FRCM Materials Using Augmented-FEM

2019 ◽  
Vol 817 ◽  
pp. 23-29
Author(s):  
Santi Urso ◽  
Houman A. Hadad ◽  
Chiara Borsellino ◽  
Antonino Recupero ◽  
Qing Da Yang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Test ◽  
Failure Modes ◽  
Elevated Temperatures ◽  
The United States ◽  
Design Guidelines ◽  
Constitutive Law ◽  
Analytical Models ◽  
Fiber Reinforced Polymers ◽  
Fe Model

The use of externally-bonded composite materials for strengthening and rehabilitation of existing structures is among the most popular reinforcement techniques. Technologies, such as Fabric Reinforced Cementitious Matrix (FRCM) have been recently developed to address some of the issues of Fiber Reinforced Polymers (FRP), such as sensitivity to elevated temperatures and UV, impermeability, restricted application in presence of moisture or uneven substrate. For a detailed strengthening design with FRCM composites, the mechanical properties of the materials are required. Analytical models in literature discuss the interaction between the FRCM matrix and fabric using a fracture mechanics approach. These analytical laws were simplified using a trilinear curve in which a constant branch correlated to the friction is added. In the United States, “Acceptance Criteria AC434” includes the test methods to evaluate the mechanical properties of the FRCM through a direct tensile test which uses clevis grips. The material characterization per AC434 is in harmony with ACI 549.4R design guidelines. This study deals with the analysis of FRCM materials using 2D Augmented-Finite Element Method (A-FEM) approach. Constitutive material behaviors were used to implement on A-FE model, which can predict the failure modes of the composite material. The damage of the mortar was described by a trilinear curve, and the number and position of the cracks were fixed preliminarily. The fabric was modelled as a continuum layer attached to the mortar with no-thickness cohesive elements. The cohesive law between fabric and mortar was taken from the literature. The tensile test on the FRCM coupon with one layer of fabric was numerically modeled and compared to the experimental stress-strain curves. Results show that the numerical curves matched the experimental ones and capture the three branches of the FRCM constitutive law as well as the failure mode. This modelling tool will allow researchers to predict the constitutive law of an FRCM mater

A Modified Johnson–Cook Model to Predict Stress-strain Curves of Boron Steel Sheets at Elevated and Cooling Temperatures

2012 ◽  
Vol 31 (1) ◽  
Author(s):  
Nguyen Duc-Toan ◽  
Banh Tien-Long ◽  
Jung Dong-Won ◽  
Yang Seung-Han ◽  
Kim Young-Suk
Keyword(s):  
Tensile Test ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Boron Steel ◽  
Isotropic Hardening ◽  
Air Cooling ◽  
Stress Strain ◽  
Material Parameters ◽  
Hardening Law ◽  
Simulation Results

AbstractIn order to predict correctly stress-strain curve for tensile tests at elevated and cooling temperatures, a modification of a Johnson–Cook (J-C) model and a new method to determine (J-C) material parameters are proposed. A MATLAB tool is used to determine material parameters by fitting a curve to follow Ludwick and Voce's hardening law at various elevated temperatures. Those hardening law parameters are then utilized to determine modified (J-C) model material parameters. The modified (J-C) model shows the better prediction compared to the conventional one. An FEM tensile test simulation based on the isotropic hardening model for metal sheet at elevated temperatures was carried out via a user-material subroutine, using an explicit finite element code. The simulation results at elevated temperatures were firstly presented and then compared with the measurements. The temperature decrease of all elements due to the air cooling process was then calculated when considering the modified (J-C) model and coded to VUMAT subroutine for tensile test simulation. The modified (J-C) model showed the good comparability between the simulation results and the corresponding experiments.

On Phenomenon of Superplasticity in Fe3AL with Large Grains

1994 ◽  
Vol 364 ◽  
Author(s):  
Aidang Shan ◽  
Dongliang Lin
Keyword(s):  
Tensile Test ◽  
Strain Rate ◽  
Elevated Temperatures ◽  
Initial Strain Rate ◽  
Optical Microscope ◽  
Al Alloys ◽  
Initial Strain ◽  
Atomic Percent ◽  
Maximum Elongation ◽  
Grain Sizes

AbstractA variety of Fe3Al alloys including Fe-25Al, Fe-28Al, Fe-28Al-4Cr and Fe-28Al-2Ti (all in atomic percent) have been investigated by tensile test to find if these alloys could have superplasticity at elevated temperatures, the results revealed that all these alloys exhibited large elongations when the temperature is higher than 600°C. At 850°C , under appropriate initial strain rate, the elongation is all above 300%. For Fe-28Al-2Ti, the maximum elongation reached 585%. Maximum m values are all above 0.3. Initial grain sizes are bigger than 100μm but became finer after deformation. Fracture happened with necking but no cavities were found under optical microscope. Characteristics of this phenomenon were summarized and discussed.

In Situ Testing and Heterogeneity of UFG Cu at Elevated Temperatures

2015 ◽  
Vol 1127 ◽  
pp. 67-72
Author(s):  
Martin Petrenec ◽  
Petr Král ◽  
Jiří Dvořák ◽  
Milan Svoboda ◽  
Vàclav Sklenička
Keyword(s):  
Elevated Temperature ◽  
Tensile Test ◽  
Grain Growth ◽  
Elevated Temperatures ◽  
Tensile Deformation ◽  
Constant Strain Rate ◽  
Electron Back Scatter Diffraction ◽  
Coarse Grained ◽  
Ultrafine Grained

Experiments were conducted to investigate deformation-induced processes during in-situ tensile test at elevated temperature. Consequently the microstructure after creep loading was examined by 3D Electron Back Scatter Diffraction (EBSD) technique. The billets of coarse-grained copper were processed by equal-channel angular pressing (ECAP) at room temperature using a die that had an internal angle of 90° between the two parts of the channel and an outer arc of curvature of ~ 20°, where these two parts intersect. The pressing speed was 10 mm/min. To obtain an ultrafine-grained (UFG) material, the billets were subsequently pressed by route Bc by 8 ECAP passes to give the mean grain size ~ 0.7 μm. The constant strain-rate test in tension was performed at 473 K using testing GATAN stage Microtest 2000EW with EH 2000 heated grips which is configured for in-situ electron back scatter diffraction (EBSD) observations. Microstructure was examined by FEG-SEM TESCAN MIRA 3 XM equipped by EBSD detector HKL NordlysMax from OXFORD INSTRUMENT. The tensile test was interrupted by fast stress reductions after different deformation step and observation of microstructure changes was performed. Despite of a considerable interest in ECAP processing method, there are not many works documenting microstructure evolution and changes during creep testing and determining creep mechanisms of ultrafine-grained materials processed by ECAP. It was found that creep resistance of UFG pure Al and Cu is considerably improved after one ECAP pass in comparison with coarse grained material, however, further repetitive pressing leads to a noticeable deterioration in creep properties of ECAP material. Recently it was observed the coarsening of the grains in microstructure of ECAP copper during creep at elevated temperature. It was suggested that creep behaviour is controlled by storage and dynamic recovery of dislocations at high-angle boundaries. In the present work was found that ultrafine-grained microstructure is instable and significant grain growth has already occurred during heating to the testing temperature. Static recrystallization during heating led to the formation of high fraction of special boundaries Σ3 and Σ9. The tensile deformation at 473 K led to the additional grain growth and formation of new grains. Microstructure was investigated also by 3D EBSD.

Evaluation of Changes of Mechanical Properties of Selected Cr-Ni-Mo Steels for Heavy Forgings during Long Time Annealing

2017 ◽  
Vol 891 ◽  
pp. 149-154
Author(s):  
Jakub Horník ◽  
Petr Zuna ◽  
Jaroslav Malek
Keyword(s):  
Mechanical Properties ◽  
Fracture Surface ◽  
Tensile Test ◽  
Temperature Interval ◽  
Dwell Time ◽  
Elevated Temperatures ◽  
Processing Temperature ◽  
Long Time ◽  
Grain Boundary Embrittlement ◽  
Boundary Embrittlement

The effect of long dwell time at elevated temperatures on two types of steels used for production of heavy forgings was evaluated. Microstructural changes and mechanical properties were monitored in temperature interval of 200 - 700 °C in order to avoid the possibility of grain boundary embrittlement during long dwell time at the processing temperature. Samples of the evaluated steels 26NiCrMoV14-5 and 22CrNiMoWV8-8 were being austenitized for 2 hours at temperature of 1200 °C and oil quenched. Subsequently the annealing at selected temperatures for 100 hours was applied. Tensile test, hardness and impact energy measurements were used for the evaluation. The results of mechanical testing, structural and fracture surface analyses indicate that for steels 26NiCrMoV145 and 22CrMoNiWV8-8 there exist a temperature interval of 300 - 400 °C and 500 600 °C respectively showing the toughness decrease.

Mechanical Properties and Fracture Behavior of Hot Extruded Mg-5Al-3Ca-xNd Alloys at Elevated Temperature

2013 ◽  
Vol 334-335 ◽  
pp. 199-202
Author(s):  
Hyeon Taek Son ◽  
Kwang Jin Lee ◽  
Yong Hwan Kim
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperature ◽  
Tensile Test ◽  
Intermetallic Compounds ◽  
Grain Growth ◽  
Fracture Behavior ◽  
Elevated Temperatures ◽  
Fine Grain ◽  
Nd Addition ◽  
Fracture Behaviors

In this study, effects of Nd addition on mechanical properties and fracture behaviors of as-extruded Mg-5Al-3Ca based alloy were investigated by a tensile test at elevated temperatures. For all temperatures, addition of Nd elements resulted in further increase of strength both yield and ultimate strength compared to the Mg-5Al-3Ca alloy. At 150°C, the ductility in Nd-added alloys is lower than that of no-Nd addition alloy. However, at 250°C, the ductility in Nd-added alloys is improved for no-Nd addition alloy because of fine grain and suppression of grain growth by formation of thermally stable Al2Nd intermetallic compounds.

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