Mechanical Behaviors of Electrodeposited Bulk Nanocrystalline Metals and Alloys

2011 ◽  
Vol 683 ◽  
pp. 113-126
Author(s):  
S. Han ◽  
Jian She Lian ◽  
J.W. Mu ◽  
X.X. Shen ◽  
L.Y. Qin ◽  
...  
Keyword(s):  
Strain Hardening ◽  
High Strain ◽  
Rate Sensitivity ◽  
High Strength ◽  
Deformation Mode ◽  
Mechanical Tests ◽  
Metals And Alloys ◽  
Dual Phase ◽  
Bulk Nanocrystalline ◽  
High Strain Rate Sensitivity

Nanocrystalline (NC) metals and alloys always exhibit extremely high strength but quite limited ductility. This disappointing ductility might be caused by the preparation artifacts and the weak strain hardening ability of NC materials. In order to optimize the mechanical properties of NC metals and alloys , especially to enhance their ductility, and investigate the underlying deformation mechanism, nanocrystalline Ni, dual phase Ni-Co alloy and Cu were synthesized via electrodeposition and electro-brush deposition respectively, and then a series of mechanical tests were carried out. The results show that all the materials exhibit a combination of high strength and remarkable ductility. The high strength can be attributed to the “true” nanocrystalline grain sizes ranges from 15 to 30 nm. In addition, three factors are revealed to contribute to the enhanced ductility of these materials, respectively: (a) modified deformation mode (the tensile-relaxation cycle test) for nanocrystalline Ni, (b) high strain hardening and cooperative deformation for dual-phase Ni-Co alloy, and (c) high strain rate sensitivity for nanocrystalline Cu.

IMPROVED MECHANICAL PROPERTY OF ELECTRODEPOSITED NANOCRYSTALLINE NICKEL-COBALT ALLOY

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2285-2290 ◽  
Author(s):  
XIXUN SHEN ◽  
JIANSHE LIAN
Keyword(s):  
Strain Rate ◽  
High Strain ◽  
Rate Sensitivity ◽  
High Strength ◽  
Strain Rate Range ◽  
Nickel Cobalt ◽  
Average Grain Size ◽  
High Strain Rate Sensitivity ◽  
Small Activity ◽  
Very High

A bulk and dense nc Ni -24.7% Co with an average grain size of 15nm was fabricated by a direct current electrodeposition. This Ni -24.7% Co exhibits very high tensile strength of 1813MPa to 2232MPa with relatively good tensile ductility of 6.0%~9.6% under tensile test over a wide strain rate range of 0.417s-1 ~ 1.35×10-5s-1. The combination of high strength and good ductility should be attributed to the increased strain hardening ability induced by the addition of alloying Co element. The interaction of dislocation and grain boundaries is the rate-controlling deformation mechanism controlled in the Ni -24.7% Co based on its high strain rate sensitivity of 0.029 and small activity volume of ~14b3.

Superplastic Phenomenon in Sc2O3 Doped Zirconia Polycrystals to be Used for SOFC

2007 ◽  
Vol 551-552 ◽  
pp. 481-486
Author(s):  
Yoshinobu Motohashi ◽  
H. Ishimura ◽  
Y. Kobayashi ◽  
Takaaki Sakuma
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Strain Hardening ◽  
Microstructural Evolution ◽  
Superplastic Deformation ◽  
High Strain ◽  
Rate Sensitivity ◽  
Rate Region ◽  
Large Elongation ◽  
High Strain Rate Sensitivity

The 4mol%Sc2O3 doped ZrO2 (4ScSZ) showed a superplastic-like large elongation in a range of strain-rate at 1773K. The large elongation was caused by both of high strain-rate sensitivity and high strain hardening during the deformation. Ion conductivity of the 4ScSZ, deformed superplastically at a relatively high strain-rate region, was higher than that of non-deformed one, suggesting that superplastic deformation can improve its conductivity. These results are discussed with probable microstructural evolution.

scholarly journals Assessment of the Hardening Behavior and Tensile Properties of a Cold-Rolled Bainitic–Ferritic Steel

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6662
Author(s):  
Emilio Bassini ◽  
Antonio Sivo ◽  
Daniele Ugues
Keyword(s):  
Strain Hardening ◽  
High Strength ◽  
Dual Phase ◽  
Low Carbon ◽  
Soft Phase ◽  
Bending Tests ◽  
Ductile Materials ◽  
Hardening Behavior ◽  
Material State ◽  
Cold Rolled

The automotive field is continuously researching safer, high-strength, ductile materials. Nowadays, dual-phase (DP) steels are gaining importance, since they meet all these requirements. Dual-phase steel made of ferrite and bainite is the object of a complete microstructural and mechanical characterization, which includes tensile and bending tests. This specific steel contains ferrite and bainite in equal parts; ferrite is the soft phase while bainite acts as a dispersed reinforcing system. This peculiar microstructure, together with fine dispersed carbides, an extremely low carbon content (0.09 wt %), and a minimal degree of strain hardening (less than 10%) allow this steel to compete with traditional medium-carbon single-phase steels. In this work, a full pearlitic C67 steel containing 0.67% carbon was used as a benchmark to build a comparative study between the DP and SP steels. Moreover, the Crussard–Jaoul (C-J) and Voce analysis were adopted to describe the hardening behavior of the two materials. Using the C-J analysis, it is possible to separately analyze the ferrite and bainite strain hardening and understand which alterations occur to DP steel after being cold rolled. On the other hand, the Voce equation was used to evaluate the dislocation density evolution as a function of the material state.

Strain rate sensitivity and strain hardening response of DP1000 dual phase steel

2018 ◽  
Vol 115 (5) ◽  
pp. 507
Author(s):  
Onur Çavusoglu ◽  
Hakan Gürün ◽  
Serkan Toros ◽  
Ahmet Güral
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Strain Hardening ◽  
Strain Rate Sensitivity ◽  
Dual Phase Steel ◽  
Rate Sensitivity ◽  
Dual Phase ◽  
Significant Difference ◽  
Load Carrying ◽  
Hardening Coefficient

In this study, strain hardening and strain rate sensitivity behavior of commercial DP1000 dual phase steel have been examined in detail at temperatures of 25 °C, 100 °C, 200 °C and 300 °C, at strain rates of 0.0016 s−1 and 0.16 s−1. As the strain rate has increased, the yield strength has increased but no significant change in tensile strength and strain hardening coefficient has been observed. As the temperature has increased, the yield and tensile strength has decreased in between 25 and 200 °C but it has showed an increase at 300 °C. The strain hardening coefficient has increased in parallel with temperature increase. It has been seen that the strain rate sensitivity has not been affected by temperature. No significant difference in the hardening rate has appeared in between 25 and 200 °C, but the highest value has been calculated at 300 °C. It has been determined that the fracture behavior has occurred earlier and load carrying capacity on necking has reduced with the increase of strain rate and not significantly affected by temperature.

scholarly journals QUASISTATIC STRAIN RATE’S EFFECT TO THE PROPERTIES OF ADVANCED STEELS FOR AUTOMOTIVE INDUSTRY

2016 ◽  
Vol 22 (1) ◽  
pp. 14 ◽  
Author(s):  
Emil Evin ◽  
Miroslav Tomáš ◽  
Marek Výrostek
Keyword(s):  
Strain Rate ◽  
Testing Machine ◽  
Rate Sensitivity ◽  
High Strength ◽  
Strength Properties ◽  
Major Influence ◽  
Sensitivity Index ◽  
Dual Phase ◽  
Deformation Properties ◽  
Low Alloyed Steel

The paper presents the findings of the strain rate effect, described in constitutive material models by strain rate sensitivity index m, to the strength and deformation material properties. These were evaluated from stress-strain diagrams recorded at tensile test using PC controlled testing machine TiraTEST 2300 according to STN EN ISO 6892-1. The high strength low alloyed steel H220PD, dual phase steel DP 600 and Trip steel RAK 40/70 were investigated at strain rates = 0.0021, 0.083 and 0.125 s<sup>-1</sup>. The results indicate major influence of the strain rate to the strength properties while only minor influence have been found when evaluate the deformation properties. The results also shown single phase materials are more sensitive to the strain rate than dual phase materials.

scholarly journals Large Deformation Behavior of High Strength Steel Under Extreme Loading Conditions: High Temperature and High Strain Rate Experiments and Modeling

2018 ◽  
Vol 183 ◽  
pp. 01053
Author(s):  
Xueyang Li ◽  
Christian C. Roth ◽  
Dirk Mohr
Keyword(s):  
Strain Hardening ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
High Strength ◽  
Fracture Initiation ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Temperature Dependent ◽  
Split Hopkinson ◽  
Pressure Bar

Plasticity and fracture experiments are carried out on flat smooth and notched tensile specimens extracted from DP800 steel sheets. A split Hopkinson pressure bar testing system equipped with a load inversion device is utilized to reach high strain rates. Temperature dependent experiments ranging from 20°C to 300°C are performed at quasi-static strain rates. The material exposes a monotonic strain hardening behaviour with a non-monotonic temperature dependency. The rate-independent material behaviour at room-temperature is described with a non-associated Hill’48 plasticity model and an Swift-Voce strain hardening. A machine learning based model is used multiplicatively to capture the rate and temperature responses. A good agreement between measured and simulated force-displacement curves as well as local surface is obtained. The loading paths to fracture are then extracted to facilitate further development of a temperature dependent fracture initiation model.

Sign in / Sign up

Export Citation Format

Share Document