scholarly journals A Yield Stress Model for a Solution-Treated Ni-Based Superalloy during Plastic Deformation

2018 ◽  
Vol 37 (9-10) ◽  
pp. 849-856 ◽  
Author(s):  
Yan-Xing Liu ◽  
Y.C Lin
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Yield Stress ◽  
Deformation Temperature ◽  
Strengthening Effect ◽  
Stress Model ◽  
Compression Tests ◽  
Forming Process ◽  
Yield Behavior ◽  
Solution Treated

AbstractUp to now, there are few reports on the yield behavior of Ni-based superalloy during plastic deformation. However, an accurate yield stress model is significant for simulating the plastic forming process by cellular automaton or finite element methods. Therefore, the yield behavior of a solution-treated Ni-based superalloy is studied by hot compression tests. In order to evaluate yield stresses from the measured flow stress curves, the yield process is analyzed in terms of dislocation theory. Then, yield stresses at different deformation temperatures and strain rates are clearly determined. The experimental results show that the yield stresses are highly sensitive to deformation temperature and strain rate. The determined yield stress almost linearly increases with the increase of the logarithm of strain rate or the reciprocal of deformation temperature. A yield stress model is developed to correlate the yield behavior of the studied solution-treated Ni-based superalloy with deformation temperature, strain rate, and strengthening effect of alloying elements. The developed model can well describe the yield behavior of the studied solution-treated Ni-based superalloy.

scholarly journals Compressive Properties and Constitutive Model of Semicrystalline Polyethylene

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2895
Author(s):  
Kebin Zhang ◽  
Wenbin Li ◽  
Yu Zheng ◽  
Wenjin Yao ◽  
Changfang Zhao
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Yield Stress ◽  
Dynamic Compression ◽  
Molecular Structures ◽  
Strengthening Effect ◽  
Compression Tests ◽  
Compression Process ◽  
Softening Effect ◽  
Constitutive Parameters

The mechanical properties of polyethylene (PE) materials are greatly influenced by their molecular structures, environmental temperature, and strain rate. In this study, static and dynamic compression tests were performed on two semicrystalline PE materials—ultrahigh molecular weight polyethylene (UHMWPE) and high-density polyethylene (HDPE). The stress–strain curves of HDPE and UHMWPE under uniaxial compression at temperatures of −40–120 °C and strain rates of 0.001–5500 s−1 were obtained. The research findings suggest that both the UHMWPE and HDPE showed significant strain rate-strengthening effect and temperature-softening effect. In particular, HDPE exhibited better compression resistance and high-temperature resistance. The relationships between the yield stress and temperature and between the yield stress and strain rate for both materials were fitted, and the Cowper–Symonds constitutive model was built while considering the temperature effect. The parameters of the constitutive model were obtained and input into LS-DYNA software to simulate the dynamic compression process of HDPE. The simulation result was consistent with the test result, validating the accuracy of the constitutive parameters.

Formability of Explosive Welded Mg/Al Bimetallic Bar

2016 ◽  
Vol 716 ◽  
pp. 114-120 ◽  
Author(s):  
Sebastian Mróz ◽  
Piotr Szota ◽  
Teresa Bajor ◽  
Andrzej Stefanik
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Process Parameters ◽  
Metal Forming ◽  
Explosive Welding ◽  
Physical Modelling ◽  
Main Process ◽  
Compression Tests ◽  
Welding Method

The paper presents the results of physical modelling of the plastic deformation of the Mg/Al bimetallic specimens using the Gleeble 3800 simulator. The plastic deformation of Mg/Al bimetal specimens characterized by the diameter to thickness ratio equal to 1 was tested in compression tests. The aim of this work was determination of the range of parameters as temperature and strain rate that mainly influence on the plastic deformation of Mg/Al bars during metal forming processes. The tests were carried out for temperature range from 300 to 400°C for different strain rate values. The stock was round 22.5 mm-diameter with an Al layer share of 28% Mg/Al bars that had been produced using the explosive welding method. Based on the analysis of the obtained testing results it has been found that one of the main process parameters influencing the plastic deformation the bimetal components is the initial stock temperature and strain rate values.

The Influence of the Bauschinger Effect on the Yield Stress, Young’s Modulus, and Poisson’s Ratio of a Gun Barrel Steel

2005 ◽  
Vol 128 (2) ◽  
pp. 179-184 ◽  
Author(s):  
J. Perry ◽  
M. Perl ◽  
R. Shneck ◽  
S. Haroush
Keyword(s):  
Plastic Deformation ◽  
Yield Stress ◽  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Bauschinger Effect ◽  
Young's Modulus ◽  
Poisson's Ratio ◽  
Compression Tests ◽  
Residual Stress Field ◽  
Gun Barrel

The Bauschinger effect (BE) was originally defined as the phenomenon whereby plastic deformation causes a loss of yield strength restraining in the opposite direction. The Bauschinger effect factor (BEF), defined as the ratio of the yield stress on reverse loading to the initial yield stress, is a measure of the magnitude of the BE. The aim of the present work is to quantitatively evaluate the influence of plastic deformation on other material properties such as Young’s modulus and Poisson’s ratio for gun barrel steel, thus extending the definition of the Bauschinger effect. In order to investigate the change in this material’s properties resulting from plastic deformation, several uniaxial tension and compression tests were performed. The yield stress and Young’s modulus were found to be strongly affected by plastic strain, while Poisson’s ratio was not affected at all. An additional result of these tests is an exact zero offset yield point definition enabling a simple evaluation of the BEF. A simple, triphase test sufficient to characterize the entire elastoplastic behavior is suggested. The obtained experimental information is readily useful for autofrettage residual stress field calculations.

Influence of plastic deformation temperature on the structure and mechanical properties of low-alloy copper alloys with Co, Ni and B

2017 ◽  
Vol 84 (2) ◽  
pp. 49-57 ◽  
Author(s):  
B. Grzegorczyk ◽  
W. Ozgowicz
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Strain Rate ◽  
Minimum Temperature ◽  
Deformation Temperature ◽  
Tensile Testing ◽  
Copper Alloys ◽  
Testing Machine ◽  
Temperature Range ◽  
Ductility Minimum

Purpose: This work presents the influence of chemical composition and plastic deformation temperature of CuCoNi and CuCoNiB as well as CuCo2 and CuCo2B alloys on the structure, mechanical properties and, especially on the inter-crystalline brittleness phenomenon and ductility minimum temperature effect in tensile testing with strain rate of 1.2·10-3 s-1 in the range from 20°C to 800°C. Design/methodology/approach: The tensile test of the investigated copper alloys was realized in the temperature range of 20-800°C with a strain rate of 1.2·10-3 s–1 on the universal testing machine. Metallographic observations of the structure were carried out on a light microscope and the fractographic investigation of fracture on an electron scanning microscope. Findings: Low-alloy copper alloys such as CuCo2 and CuCo2B as well as CuCoNi and CuCoNiB show a phenomenon of minimum plasticity at tensile testing in plastic deforming temperature respectively from 500°C to 700°C for CuCo2, from 450°C to 600°C for CuCo2B and from 450°C to 600°C for CuCo2B and from 500°C to 600°C for CuCoNiB. Practical implications: In result of tensile tests of copper alloys it has been found that the ductility minimum temperature of the alloys equals to about 500°C. At the temperature of stretching of about 450°C the investigated copper alloys show maximum strength values. Originality/value: Based on the test results the temperature range for decreased plasticity of CuCoNi and CuCoNiB as well as CuCo2 and CuCo2B alloys was specified. This brittleness is a result of decreasing plasticity in a determined range of temperatures of deforming called the ductility minimum temperature.

Effect of Hot Deformation Parameters on Flow Behavior and Microstructure of Ti-6Al-4V-0.2O Alloy

2017 ◽  
Vol 898 ◽  
pp. 137-143
Author(s):  
Lin Xiang ◽  
Bin Tang ◽  
Hong Chao Kou ◽  
Jie Shao ◽  
Jin Shan Li
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Temperature ◽  
Dynamic Recovery ◽  
Volume Fraction ◽  
Flow Behavior ◽  
Strain Rates ◽  
Compression Tests ◽  
Height Reduction ◽  
Deformation Parameters

Isothermal compression tests were conducted to investigate the effect of hot deformation parameters on flow behavior and microstructure of Ti-6Al-4V-0.2O alloy. The experimental results show that the strain rate and height reduction have little effect on the volume fraction of primary α at a deformation temperature of 860 ̊C. At a deformation temperature of 940 ̊C, the volume fraction of primary α at a high strain rate (10s-1) is about 10% less than that at low strain rates (0.01s-1~1s-1). It may be one of the reasons for the significantly discontinuous yielding phenomenon. Another reason is that the dislocation density decreased suddenly due to the dynamic recovery. With the increasing strain rate and the decreasing deformation temperature, the volume fraction of irregular secondary α increases and lamellar secondary α decreases. And with height reduction increasing, the irregular secondary α increases firstly and then tends to be steady because of dynamic recovery and recrystallization.

scholarly journals Dynamic Constitutive Model for Reactive Powder Concrete with Standard Curing

2018 ◽  
Vol 2 (1) ◽  
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Steel Fiber ◽  
High Strength ◽  
Reactive Powder Concrete ◽  
Strengthening Effect ◽  
Compression Tests ◽  
Softening Effect ◽  
Impact Compression ◽  
Reactive Powder

In view of the disadvantages of steam curing of reactive powder concrete (RPC), RPC with standard curing (SCRPC) is proposed. SC-RPC is an ultra-high strength concrete material prepared with high strength cement, silica fume, and gypsum by standard curing. In this study, quasi-static and impact compression tests were performed to investigate the mechanical properties of SC-RPC. The results show that steel fiber and the strain rate significantly affect the compression performance. Nevertheless, the Holmquist–Johnson–Cook (HJC) constitutive model is mainly used to analyze the dynamic response of brittle materials, such as common concrete, under shock and impact. Therefore, based on the quasi-staticand impact compression tests and the HJC constitutive model for concrete, by analyzing the steel fiber strengthening effect under quasi-static uniaxial compression, strain rate hardening, and the damage softening effect under SHPB impact compression, the steel fiber strengthening factor Kf , dynamic increase factor DIF, and revised damage variable D are introduced, and a modified HJC constitutive model for RPC with standard curing is proposed.

Experimental investigation on static recrystallization behavior of a low carbon Nb–V–Ti microalloyed steel

2021 ◽  
Vol 118 (2) ◽  
pp. 202
Author(s):  
Fei Li ◽  
Liwen Zhang ◽  
Chi Zhang ◽  
Qing Yang ◽  
Chaoqun Li ◽  
...  
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Deformation Temperature ◽  
Static Recrystallization ◽  
Microalloyed Steel ◽  
Pipeline Steel ◽  
Low Carbon ◽  
Compression Tests ◽  
X70 Pipeline Steel ◽  
Deformation Parameters

The static recrystallization (SRX) behavior of a low carbon Nb–V–Ti microalloyed steel X70 was investigated by two-pass hot compression tests. The compression tests were carried out at deformation temperatures of 1000–1150 °C, strain rates of 0.01–5 s−1, pre-strains of 0.1–0.2 and interval times of 1–50 s. The effects of deformation parameters on SRX behavior were analyzed. The experimental results showed that deformation temperature, pre-strain and strain rate had significant influence on SRX fraction, while initial grain size had a smaller impact. The effects of deformation parameters on SRX microstructure were discussed, and the microstructure evolution process was analyzed. Higher deformation temperature, strain rate and pre-strain lead to larger SRX fraction. The kinetics and recrystallized grain size models for SRX of X70 pipeline steel were developed. Comparison between the predicted results and the experimental ones indicated that the established equations could give a reasonable description for SRX behavior of X70 pipeline steel.

Hot Workability Analysis of Extruded Mg-Zn-Mn-Y Magnesium Alloys with Different Phases

2012 ◽  
Vol 184-185 ◽  
pp. 1010-1016
Author(s):  
Wei Wei He ◽  
Kun Zhang ◽  
Min Huang ◽  
Sheng Long Dai
Keyword(s):  
Strain Rate ◽  
Magnesium Alloys ◽  
Power Dissipation ◽  
Rate Sensitivity ◽  
Processing Maps ◽  
Hot Workability ◽  
Compression Tests ◽  
Secondary Phases ◽  
Forming Process ◽  
Power Dissipation Efficiency

Workability, an important parameter in magnesium alloys forming process, can be evaluated by means of processing maps on the basis of dynamic materials model, constructed from experimentally generated flow stress variation with respect to strain, strain rate and temperature. To obtain the processing maps of extruded Mg-Zn-Mn-Y magnesium alloy with different secondary phases (I-phase and W-phase), hot compression tests were performed over a range of temperatures 523–673 K and strain rates 0.001~10s-1. The response of strain-rate sensitivity (m-value), power dissipation efficiency (ζ-value) and instability parameter (n-value) to temperature and strain rate were evaluated. By the superimposition of the power dissipation and the instability maps, the dynamic recrystallization (DRX) and instability zones were identified and validated through micrographs. The observations were performed in order to describe the behavior of the material under hot forming operation in terms of material damage and micro-structural modification.

An Experimental Study on Lubrication Behavior of Glass Lubricants during Hot Plastic Deformation of Ni-Based Alloys

2012 ◽  
Vol 591-593 ◽  
pp. 960-964
Author(s):  
Rui Li ◽  
Chao Yang Sun ◽  
Qing Dong Zhang
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Friction Factor ◽  
Flow Behavior ◽  
Compression Tests ◽  
Hot Plastic Deformation ◽  
Ring Compression ◽  
Specimen Material ◽  
Inconel 690 ◽  
Lubrication Performance

Friction factor and flow behavior of melt glass lubricants A5 and up68/2886 during hot plastic deformation of Ni-based alloys Incoloy800H and Inconel 690 were studied by using ring compression tests. The results indicated that glass up68/2886 had higher mobility than glass A5. Friction factor between interfaces went up with temperature in sufficient lubrication, but the opposite in inadequate lubrication, and the friction factor went down with strain rate under both conditions. Besides, yield strength of specimen material also slightly influenced lubrication performance of glass lubricants in inadequate lubrication. Low friction factor about 0.1 was still obtained in inadequate lubrication by using glass up68/2866, therefore excellent performance could be expected when glass up68/2886 was used properly such as at higher strain rate.

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