Influence Of Deformation Temperature Research Articles

Influence of Deformation Temperature on the Formation of Contacts in Titanium Powder Ribbons Produced by Symmetric and Asymmetric Rolling

Influence of Deformation Temperature on the Formation of Contacts in Titanium Powder Ribbons Produced by Symmetric and Asymmetric Rolling

Influence of Deformation Temperature On Flow Stress and Dislocation Structure of 2A12 Aluminum Alloy Under Quasi-Static and Dynamic Compression

Influence of Deformation Temperature On Flow Stress and Dislocation Structure of 2A12 Aluminum Alloy Under Quasi-Static and Dynamic Compression

Springback prediction of 7075 aluminum alloy V-shaped parts in cold and hot stamping

In this paper, the springback behavior of high strength aluminum alloy 7075 is studied by experiments and finite element (FE) simulation. Firstly, an analytical model is established to predict the springback angles and analyze the springback trend. The springback experimental tests are conducted by using the V-shaped stamping dies. The influence of deformation temperature, punch radius, and blank holder force on the springback angles is studied. Finally, an FE simulation model is performed to investigate the deformation characteristics and springback process of the aluminum alloy sheet. The results show that the change of springback angles is direct proportional to the punch radius. The springback angles increase with the decreasing deformation temperature and the increasing blank holder force. The stress relaxation that occurs during the die holding stage is the primary reason of reducing the springback compared with cold stamping. Low blank holder force will cause side wall curl, which results in the deviation of forming size. The FE simulation model considering stress relaxation is capable of precisely predicting the change of springback angles, and the simulation results exhibit good consistency with the experimental results.

Study on A New Deformation Resistance Model and High Temperature Flow Behaviour of High Cr N80 Steel

The purpose of this paper is to discuss a new deformation resistance model and high temperature flow behaviour of high Cr N80 steel. Through the single-hit hot compression test with true strain 0.7 at strain rate 0.1s-1,1s-1,10s-1,40s-1 from deformation temperature 700°C to 1200°C by Gleeble-3500 thermomechanical simulator, the flow stress curves of the dynamic recovery type are obtained. The influence of deformation temperature, strain rate on the flow stress is systematically analysed. Furthermore, a new and highly precise Zhou Jihua-Guan Kezhi deformation resistance model of high Cr N80 steel is established through the test data. The calculated results of the model are in good agreement with actual test results. The correlation coefficient (R) is 0.993. Most of residual errors between the measured values and the predicted values by the model are within ±30MPa.

Molecular dynamics simulation-based study of creep–ratcheting behavior of nanocrystalline aluminum

In the present study, molecular dynamics simulations have been performed to investigate the creep–ratcheting deformation behavior of nanocrystalline aluminum (NC Al) having an average grain size of ~ 8 nm. The influence of deformation temperature on creep–ratcheting behavior has been studied and associated with underlying mechanisms based on the structural evolution of the material identified. The vacancy concentrations, strains and dislocation densities have been evaluated at the end of each stage of creep–ratcheting process for two ratcheting stress ratios and three different temperatures. In the mean time, the microstructural and defect evolution has been investigated. Accumulation of creep–ratcheting strain is found to increase with the deformation temperature in the range of temperature investigated: 10–467 K. Cyclic hardening dominates in the initial stages of creep–ratcheting, whereas cyclic softening dominates in the final stages at a higher temperature. The creep–ratcheting plots exhibit a primary and steady state regions at room temperature (300 K). In addition, a tertiary region is also perceived at high temperature (467 K). The NC Al specimen is also found to be damaged earlier at a higher temperature (i.e., 467 K) than at 10 K and 300 K. The highest dislocation density is attained for room temperature creep–ratcheting deformation. Finally, it is seen from the dislocation analysis that the Shockley partial and full dislocations are the driving dislocations for the creep–ratcheting deformation process.

Characterization of Hot Deformation Behavior and Dislocation Structure Evolution of an Advanced Nickel-Based Superalloy

The hot deformation behavior of an advanced nickel-based Haynes282 superalloy was systematically investigated employing isothermal compression tests in the sub-solvus and super-solvus temperature with various strain rates. The influence of deformation temperature and strain rate on the microstructure was studied by transmission electron microscope. The results reveal that the interaction between work hardening and dynamic softening did not reach equilibrium under lower deformation temperature and higher strain rate. The active energy of alloy is around 537.12 kJ/mol and its hot deformation constitutive relationship equation was expressed. According to the processing map and microstructure observations, two unsafe flow instability domains should be avoided. The optimum hot processing condition for homogeneous and fine dynamic recrystallization grains are obtained. TEM micrograph observations indicated that deformation temperature and strain rate affected recrystallization by affecting the evolution of dislocation substructures within the alloy. The nucleation and growth of DRX grains can be promoted by the relatively high deformation temperature and low strain rate. The main mechanism of dynamic recrystallization nucleation preferred to discontinuous dynamic recrystallization and the typical feature of discontinuous dynamic recrystallization showed grain boundary migration nucleation. The findings improve the understanding of hot deformation behavior and dislocation substructures evolution of the superalloy, which benefits the accurate control of microstructures of nickel-based superalloys, and tailors the properties of final components used in the land-based gas turbine.

Hot Deformation Behavior and Microstructure Characterization of an Al-Cu-Li-Mg-Ag Alloy

The flow behavior of an Al-Cu-Li-Mg-Ag alloy was studied by thermal simulation tests at deformation temperatures between 350 °C and 470 °C and strain rates between 0.01–10 s−1. The microstructures of the deformed materials were characterized by electron backscattered diffraction. Constitutive equations were developed after considering compensation for strains. The processing maps were established and the optimum processing window was identified. The experimental data and predicted values of flow stresses were in a good agreement with each other. The influence of deformation temperature and strain rates on the microstructure were discussed. The relationship between the recrystallization mechanism and the Zener–Hollomon parameter was investigated as well.

Study on constitutive model and dynamic recrystallization softening behavior of AZ80A magnesium alloy

The microstructures of as-cast AZ80A magnesium alloy before and after homogenization treatment were studied. The flow behaviors of the homogenized alloy under different deformation conditions were studied by isothermal compression tests. Based on the flow stress-strain curves of the homogenized alloy, the constitutive model was established by the strain compensation method. The strain rate sensitivity index maps with different strains were constructed to quantify the dynamic recrystallization softening behavior of the homogenized alloy. Based on this, the influence of deformation temperature and strain rate on strain rate sensitivity index and dynamic recrystallization microstructure evolution were studied. The results show that both increasing homogenization temperature and holding time are beneficial for the β-phases to dissolve and alloying elements to diffuse. It is concluded that the proper homogenizing parameter of as-cast AZ80A magnesium alloy is 683 K for 20 h. Both the increase of deformation temperature and the decrease of strain rate are beneficial to the increase of strain rate sensitivity index. The region with an index greater than 0.22 corresponds to dynamic recrystallization softening zone and has good deformation properties.

Influence of deformation temperature on the microstructure and thermal stability of HPT-consolidated Cu-1%Nb alloys

Ultrafine grained Cu–Nb alloys with minimal additions of 1wt.% Nb were prepared by using HPT at ambient temperature (˜20°C) and elevated temperature (˜200°C). The microstructure, thermal stability and properties were investigated. The results indicated that compared with the Cu-1%Nb alloy processed at ambient temperature, the sample processed at 200°C shows higher density and higher thermal stability, which contributed to its higher electrical conductivity and tensile strength after annealing treatment.

A phenomenon of strain induced bainitic transformation and its effect on strength enhancement in a lightweight transformation-induced-plasticity steel

Microstructure evolution, transformation behavior and mechanical property are examined for a Fe-0.35C-1.1Mn-4.1Al-0.38Si (in wt%) ferrite-based lightweight transformation induced plasticity (TRIP) steel under tensile deformation at room temperature (25 °C) to 450 °C. The influence of deformation temperature and strain on mechanical stability of retained austenite leads to the occurrence of various transformations in the TRIP steel. From room temperature towards 150 °C, strain induced martensitic transformation (SIMT) takes place resulting in the formation of twin-type martensite, and it is progressively suppressed with increasing deformation temperature. A phenomenon of strain induced bainitic transformation (SIBT) of retained austenite is observed at higher deformation temperatures, and it is enhanced with increasing deformation strain and temperature ranging from 150 °C to 300 °C. During the SIBT, the formation of carbide-free bainite with high dislocation density is primarily attributed to the increased carbon diffusivity. The occurrence of the SIBT reveals the significant importance of the diffusion-associated mechanism for the bainitic transformation. Above 300 °C, the activation of dislocation movement in retained austenite gradually replaces the SIBT with increasing deformation temperature. The highest tensile strength obtained at 300 °C indicates the strength enhancement due to the SIBT.

Dynamic recrystallization behavior of Gd-containing Mg alloy under torsion deformation

The thermal deformation behavior of Mg-11.95Gd-4.5Y-2Zn-0.37Zr alloy was investigated by torsion tests under different deformation conditions. Electron backscattered diffraction (EBSD) technique was used to study the effect of deformation temperature and strain rate on the dynamic recrystallization grain (DRX) and texture evolution during torsion deformation. The results indicate that the equivalent stress-strain curve of the alloy under hot torsion is similar to the curve under thermal compression. A predictive model for the critical strain (εc) and the Z parameter of the investigated Mg-alloy during torsion deformation has been established. The influence of deformation temperature on the DRX and grain size distribution is significantly different in different temperature regimes. We have observed that the grain size distribution is significantly wider at higher temperatures. Moreover, the distribution of pole density is relatively uniform under different torsion deformation conditions. The torsion has significantly declined the texture and the maximum texture intensity decreased with the decrease in grain size under different deformation conditions.

A novel heat-triggered shape-memory polymer based on ethylene–vinyl acetate copolymer/nitrile–butadiene rubber thermoplastic vulcanizates

Achieving considerable shape-memory effects is a challenge for typical sea-island structured polymer blends. In this article, we successfully fabricated a novel heat-triggered shape-memory polymer (HSMP) based on ethylene–vinyl acetate copolymer/nitrile–butadiene rubber (EVA/NBR) thermoplastic vulcanizates (TPVs) via dynamic vulcanization. The influence of deformation temperature ( Td), recovery temperature ( Tr), and recovery time on the shape-memory behavior of the EVA/NBR (weight ratio = 80/20) TPV was investigated systematically. The shape-memory result of the EVA/NBR (weight ratio = 80/20) TPV demonstrated that when the Td was close to the melting temperature ( Tm) of the EVA phase (76°C), the TPV could obtain a good shape fixity ratio (>95%) and an excellent shape recovery ratio (>95%) at 100% stretch ratio. A shape-memory mechanism was proposed for this HSMP. The dynamic mechanical analysis results under temperature sweep mode showed that with increasing EVA content in TPVs, the tan δ decreased, while the storage modulus increased. The morphology observation showed that the cross-linked NBR particles were dispersed evenly in the etched surface of EVA/NBR TPV with an average diameter of approximately 2–6 μm. The longitudinal stretching surface of the EVA/NBR TPV exhibited the banding-like texture microstructure during the stretching process.

Structure formation of nitrogen-containing austenitic 04Kh20N6G11M2AFB steel. Part 1: Influence of deformation temperature and strain rate on the dynamic recrystallization

The paper determines values of the deformation threshold necessary for the initiation and development of dynamic recrystallization in the investigated deformation temperature and strain rate. Analysis of diagrams shows that the deformation resistance increases with decreasing of temperature, while a weak peak is observed at temperature 1000–1200°C, when dynamic recrystallization starts. The structure of high-strength corrosion-resistant nitrogen-containing austenitic steel 04Kh20N6G11M2AFB after hot deformation with strain rate 0.1, 1.0 and 10 s-1 in the temperature range 900–1200°С has been studied by EBSD analysis and transmission electron microscopy.

Structure Formation of the Nitrogen-Containing Austenitic 04Kh20N6G11M2AFB Steel at Hot Deformation: Part I. Influence of Deformation Temperature and Strain Rate on the Process of Dynamic Recrystallization

Structure Formation of the Nitrogen-Containing Austenitic 04Kh20N6G11M2AFB Steel at Hot Deformation: Part I. Influence of Deformation Temperature and Strain Rate on the Process of Dynamic Recrystallization

The effect of phthalide cardo structure on the shape memory performance of high-temperature resistant epoxy resins

The novel high-temperature resistant shape memory (SM) materials which were prepared based on diglycidylether of bisphenol A (DGEBA) epoxy resin with a chain-extended aromatic diamine containing phthalide cardo structure (BAPP) as curing agent. The influence of deformation temperature and loading rate on the deformability, and the dependence of shape recovery ratio (Rr) and shape fixity ratio (Rf) on the fixed deformation temperature, imposed deformation load, shape fixity cooling rate and number of cycles were investigated by dynamic mechanical analyzer (DMA) in comparison with these of the common aromatic amine-cured epoxy systems. The deformability, Rr and Rf could be improved markedly by changing the SM programming conditions. The results demonstrate the incorporation of phthalide groups plays an important role on the improvement of SM performance of epoxy networks.

Effect of Deformation Temperature on Microstructure Evolution and Mechanical Properties of Low‐Carbon High‐Mn Steel

This work addresses the influence of deformation temperature in a range from −40°C to 200°C on the microstructure evolution and mechanical properties of a low‐carbon high‐manganese austenitic steel. The temperature range was chosen to cope at the time during sheet processing or car crash events. Experimental results show that yield stress and ultimate tensile strength gradually deteriorate with an increase in the tensile testing temperature. The dominant mechanism responsible for the strain hardening of steel changes as a function of deformation temperature, which is related to stacking fault energy (SFE) changes. When the deformation temperature rises, twinning decreases while a role of dislocation slip increases.

ВЛИЯНИЕ ТЕМПЕРАТУРЫ ДЕФОРМАЦИИ НА СТРУКТУРУ И СВОЙСТВА ПРЕССОВАННЫХ ПРОФИЛЕЙ СПЛАВА В-1341 СИСТЕМЫ Al–Mg–Si

ВЛИЯНИЕ ТЕМПЕРАТУРЫ ДЕФОРМАЦИИ НА СТРУКТУРУ И СВОЙСТВА ПРЕССОВАННЫХ ПРОФИЛЕЙ СПЛАВА В-1341 СИСТЕМЫ Al–Mg–Si

Investigation on the preparation and mechanical properties of porous Cu35Ni15Cr alloy for a molten carbonate fuel cell

AbstractThe preparation process of porous Cu35Ni15Cr alloy was studied in this paper. The effect of ball milling time and sintering temperature on the porosity of Cu35Ni15Cr alloy was identified. It was found that 18 h ball milling and 950 °C sintering are the most promising parameters for the preparation of porous Cu35Ni15Cr alloy. The products have a ~62 % porosity. The alloy consists of an α phase and β phase. The influence of deformation temperature and loading rate on the mechanical properties of Cu35Ni15Cr alloys was investigated. The results show that with decreasing deformation temperature, the yield strength and elastic modulus of the porous alloy increase. With the increase of loading rate, the yield strength of these alloys shows an increasing trend, but the elastic modulus is on a steady level.

Experimental investigation of boron steel at hot stamping conditions

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 1500MPa boron steel at different strain rates of 0.01–5.0s−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.

Influence of deformation temperature on recrystallization in a Ni-based single crystal superalloy

The influence of deformation temperatures on recrystallization in a Ni-based single-crystal superalloy was investigated. Electron back-scattered diffraction (EBSD) was used to determine if recrystallization could occur. The deformation dislocation microstructure was examined by transmission electron microscopy (TEM). Critical annealing temperatures for recrystallization of compressed samples with around 5% plastic strains were determined. The results indicated that deformation temperature had an important influence on the recrystallization behavior. Samples deformed at around 980°C have the highest propensity for recrystallization. The recrystallization nucleation mechanism in this alloy was discussed. Low misorientations are induced in deformed samples, even at elevated deformation temperatures. Annealing twinning through stacking faults plays a significant role in recrystallization at low plastic strains.