Effect of Strain Rates on the Transformation Behavior of Ni-Ti Alloy

2007 ◽  
Vol 539-543 ◽  
pp. 3231-3236
Author(s):  
Hidefumi Date
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Liquid Nitrogen ◽  
Testing Machine ◽  
Martensite Phase ◽  
Reverse Transformation ◽  
Strain Rates ◽  
Ti Alloy ◽  
Compressive Test ◽  
Transformation Temperatures

In order to clarify the effect of strain rates on phase transformation behaviors of Ni-Ti alloy, a compressive test using a cylindrical specimen of polycrystalline Ni-Ti alloy of Ti-50.69 at% Ni was carried out at a high strain rate and a low strain rate. The transformation temperatures were determined by a differential scanning calorimeter (DSC) using a sample cut from a compressed specimen. The transformation temperatures of the specimens before deformation were Ms= 303 K, Mf = 287 K, As = 297 K and Af = 319 K, respectively. The compressive test was carried out using specimen heated from liquid nitrogen temperature to room temperature. A universal testing machine as a static test apparatus and a Split Hopkinson Bar apparatus for a dynamic test were used. The specimen had a reoriented martensite phase after deformation because the superelastic effect was not observed upon unloading. Two reverse transformations during heating and a forward transformation during cooling were observed by DSC measurement. The first reverse transformation corresponds to that of thermal-induced martensite by immersion in liquid nitrogen and the second reverse transformation corresponds to that of reoriented martensite with slips in a polycrystalline matrix introduced by plastic deformation. The reverse transformation of the martensite phase with a slip exhibited strong strain rate dependency. Plastic strains and strain rate had strong influence on the shape recovery. The interaction between the temperature elevation by a conversion of plastic work and slip generated by dynamic plastic deformation is a complicated problem.

An Investigation of the Dynamic Recrystallisation Behaviour of Magnesium AZ31 Alloy at 450°C Using Plane Strain Compression Testing as a Tool

2012 ◽  
Vol 715-716 ◽  
pp. 164-169
Author(s):  
Bradley P. Wynne ◽  
R. Bhattacharya ◽  
Bruce Davis ◽  
W.M. Rainforth
Keyword(s):  
Strain Rate ◽  
Plane Strain ◽  
Testing Machine ◽  
Az31 Alloy ◽  
Plane Strain Compression ◽  
Strain Rates ◽  
Basal Texture ◽  
Magnesium Az31 ◽  
Dynamic Recrystallisation ◽  
Double Hit

The dynamic recrystallisation (DRX) behaviour of magnesium AZ31 is investigated using a plane strain compression (PSC) testing machine at 450°C. The variables included strain rate, double hit including intermittent anneal and double hits with different strain rate at each hit. The alloy shows higher peak stress and strain with increasing strain rates. Predominant basal texture with different intensities are observed at different strain rates. The annealing treatment between double tests leads to strong basal texture. Reversal of strain rate during double hit results in similar flow curves. This shows that in AZ31 alloy, DRX mechanism is independent of the initial microstructure and only depends on the test condition viz. temperature, strain rate and total equivalent strain.

Superplasticity in a 5024 Aluminium Alloy Processed by Severe Plastic Deformation

2012 ◽  
Vol 735 ◽  
pp. 353-358 ◽  
Author(s):  
Anna Mogucheva ◽  
Diana Tagirova ◽  
Rustam Kaibyshev
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Strain Rate ◽  
Aluminium Alloy ◽  
Initial Strain Rate ◽  
Strain Rates ◽  
Superplastic Behaviour ◽  
Angular Pressing ◽  
Elongation To Failure ◽  
Zr Alloy

The superplastic behaviour of an Al-4.6%Mg-0.35%Mn-0.2%Sc-0.09%Zr alloy was studied in the temperature range 250-500°C at strain rates ranging from 10-4 to 10-1 s-1. The AA5024 was subjected to equal channel angular pressing (ECAP) at 300°C up to ~12. The highest elongation-to-failure of ∼3300% was attained at a temperature of 450°C and an initial strain rate of 5.6×10-1 s-1. Regularities of superplastic behaviour of the 5024 aluminium alloy are discussed.

Comparative Study of the Dynamic Behavior of AA2519 Aluminum Alloy in T6 and T8 Temper Conditions

2019 ◽  
Author(s):  
Adewale Olasumboye ◽  
Gbadebo Owolabi ◽  
Olufemi Koya ◽  
Horace Whitworth ◽  
Nadir Yilmaz
Keyword(s):  
Plastic Deformation ◽  
Aluminum Alloy ◽  
Stress Response ◽  
Flow Stress ◽  
Yield Strength ◽  
Strain Rate ◽  
High Strain ◽  
Second Phase ◽  
Strain Rates ◽  
High Strain Rates

Abstract This study investigates the dynamic response of AA2519 aluminum alloy in T6 temper condition during plastic deformation at high strain rates. The aim was to determine how the T6 temper condition affects the flow stress response, strength properties and microstructural morphologies of the alloy when impacted under compression at high strain rates. The specimens (with aspect ratio, L/D = 0.8) of the as-cast alloy used were received in the T8 temper condition and further heat-treated to the T6 temper condition based on the standard ASTM temper designation procedures. Split-Hopkinson pressure bar experiment was used to generate true stress-strain data for the alloy in the range of 1000–3500 /s strain rates while high-speed cameras were used to monitor the test compliance with strain-rate constancy measures. The microstructures of the as received and deformed specimens were assessed and compared for possible disparities in their initial microstructures and post-deformation changes, respectively, using optical microscopy. Results showed no clear evidence of strain-rate dependency in the dynamic yield strength behavior of T6-temper designated alloy while exhibiting a negative trend in its flow stress response. On the contrary, AA2519-T8 showed marginal but positive response in both yield strength and flow behavior for the range of strain rates tested. Post-deformation photomicrographs show clear disparities in the alloys’ initial microstructures in terms of the second-phase particle size differences, population density and, distribution; and in the morphological changes which occurred in the microstructures of the different materials during large plastic deformation. AA2519-T6 showed a higher susceptibility to adiabatic shear localization than AA2519-T8, with deformed and bifurcating transformed band occurring at 3000 /s followed by failure at 3500 /s.

scholarly journals Review of Intermediate Strain Rate Testing Devices

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 894
Author(s):  
Trunal Bhujangrao ◽  
Catherine Froustey ◽  
Edurne Iriondo ◽  
Fernando Veiga ◽  
Philippe Darnis ◽  
...  
Keyword(s):  
Strain Rate ◽  
Measurement Techniques ◽  
Testing Machine ◽  
Hydraulic Testing ◽  
Manufacturing Processes ◽  
Strain Rates ◽  
General Description ◽  
Intermediate Strain Rate ◽  
Friction Stir ◽  
Rate Testing

Materials undergo various loading conditions during different manufacturing processes, including varying strain rates and temperatures. Research has shown that the deformation of metals and alloys during manufacturing processes such as metal forming, machining, and friction stir welding (FSW), can reach a strain rate ranging from 10−1 to 106 s−1. Hence, studying the flow behavior of materials at different strain rates is important to understanding the material response during manufacturing processes. Experimental data for a low strain rate of <101 s−1 and a high strain rate of >103 s−1 are readily available by using traditional testing devices such as a servo-hydraulic testing machine and the split Hopkinson pressure bar method, respectively. However, for the intermediate strain rate (101 to 103 s−1), very few testing devices are available. Testing the intermediate strain rate requires a demanding test regime, in which researchers have expanded the use of special instruments. This review paper describes the development and evolution of the existing intermediate strain rate testing devices. They are divided based on the loading mechanism; it includes the high-speed servo-hydraulic testing machines, hybrid testing apparatus, the drop tower, and the flywheel machine. A general description of the testing device is systematically reviewed; which includes the working principles, some critical theories, technological innovation in load measurement techniques, components of the device, basic technical assumption, and measuring techniques. In addition, some research direction on future implementation and development of an intermediate strain rate apparatus is also discussed in detail.

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.

scholarly journals INFLUENCE OF TEMPERATURE AND STRAIN RATE ON SUPERPLASTICITY KINETICS OF COMPOSITE AZ61-F MAGNESIUM MATERIALS

2018 ◽  
Vol 24 (3) ◽  
pp. 200
Author(s):  
Michal Besterci ◽  
Song-Jeng Huang ◽  
Katarína Sülleiová ◽  
Beáta Ballóková
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Superplastic Deformation ◽  
Strain Rates ◽  
Maximum Strain ◽  
Influence Of Temperature ◽  
Angular Pressing ◽  
Micromechanisms Of Fracture ◽  
The Mean ◽  
Kinetics Of

Micromechanisms of fracture of AZ61-F composites in the zone of quasi-superplastic deformation were analyzed and quantified in this work. Deformation of AZ61-F magnesium alloys with 1 wt.% of Al<sub>2</sub>O<sub>3</sub> phase was tested at a temperature of 473 K and different strain rates. It was shown that at the temperature of 473 K and the highest strain rate applied from 1<em>× </em>10<em><sup>−</sup></em><sup>2</sup> to 1 <em>× </em>10<em><sup>−</sup></em><sup>4</sup> s<em><sup>−</sup></em><sup>1</sup>, a significant growth of ductility was observed. The mean dimples diameter of the ductile fracture decreased with the decreasing strain rate. The grain size of 0.7 μm was reached by severe plastic deformation using equal channel angular pressing (ECAP). Secondary Mg<sub>17</sub>Al<sub>12</sub> and Al<sub>2</sub>O<sub>3</sub> phases were identified. The maximum strain was reached at the temperature of 473 K and strain rate of 1 <em>× </em>10<em><sup>−</sup></em><sup>4</sup> s<em><sup>−</sup></em><sup>1</sup>.

Tensile Behavior of Unidirectional Carbon Reinforced Composites for Aerospace Structures under Varying Strain Rates

2015 ◽  
Vol 798 ◽  
pp. 357-361 ◽  
Author(s):  
Haris A. Khan ◽  
Mehr Nigar ◽  
Imran Ali Chaudhry
Keyword(s):  
Strain Rate ◽  
Volume Fraction ◽  
Testing Machine ◽  
Tensile Modulus ◽  
Failure Behavior ◽  
Strain Rates ◽  
Loading Rates ◽  
Matrix Volume ◽  
Versus Strain ◽  
Fiber Reinforced Laminates

This paper focuses on progressive damage investigation and failure analysis of carbon fiber reinforced laminates under varying strain rates in tensile mode. Samples specimen prepared for experiments were made from unidirectional ply with 70/30 fiber-matrix volume fraction and cross-ply (0°-90°) balanced stacking. These laminates were subjected to uniaxial longitudinal tensile loading in a Universal Testing Machine (UTM) with varying strain rates. Results acquired from the experiments were used to plot stress versus strain curves for different strain rates. These plots were subsequently analyzed to investigate the effect of varying loading rates on the mechanical properties and failure behavior of these composites. Experimental data revealed a considerable increase in the tensile strength with increasing strain rate. The tensile modulus and strain to failure were also found to exhibit slight increase with the increasing strain rate.

Compressive Deformation of ZK60 Magnesium Alloy at Elevated Temperature

2007 ◽  
Vol 353-358 ◽  
pp. 631-634 ◽  
Author(s):  
Chun Yan Wang ◽  
Kun Wu ◽  
Ming Yi Zheng
Keyword(s):  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Flow Behavior ◽  
Testing Machine ◽  
Mechanical Twinning ◽  
Dislocation Slip ◽  
Strain Rates ◽  
Lower Temperature ◽  
Zk60 Magnesium Alloy

The high temperature compressive tests of squeeze casting ZK60 magnesium alloy with temperatures of 573-723K and strain rate in the range of 0.001-1s-1 were performed on Gleeble-1500D thermal simulator testing machine. Optical microscopy was performed to elaborate on the dynamic recrystallization (DRX) grain growth. TEM findings indicate that mechanical twinning, dislocation slip, and dynamic recrystallization are the materials typical deformation features. Variations of flow behavior with deformation temperature as well as strain rate were analyzed. Analysis of the flow behavior and microstructure observations indicated that flow localization was observed at lower temperature and higher strain rates, which should be avoided during mechanical processing. Dynamic recrystallization occurred at higher temperature and moderate strain rates, which improved the ductility of the material. The optimum hot working conditions for ZK60 alloy were suggested.

Measurement on Strain Rate Sensitivity Properties of Rice Husk (Rh)/Linear Low Density Polyethylene (Lldpe) Composites under Various Loading Rates

2015 ◽  
Vol 754-755 ◽  
pp. 77-82
Author(s):  
Mohd Firdaus Omar ◽  
Nur Suhaili Abdul Wahab ◽  
Hazizan Md. Akil ◽  
Zainal Arifin Ahmad ◽  
N.Z. Noriman
Keyword(s):  
Strain Rate ◽  
Thermal Activation ◽  
Testing Machine ◽  
Rate Sensitivity ◽  
Applied Strain ◽  
Strain Rates ◽  
Static Compression ◽  
Loading Rates ◽  
Compression Properties ◽  
Great Dependency

In this study, LLDPE/RH composites were tested under various strain rate loadings (0.001/s, 0.01/s and 0.1/s) using the universal testing machine. Static compression properties of LLDPE/RH composites with different filler contents of 5 wt%, 10 wt%, 15 wt%,20 wt% and, 30 wt% RH were investigated. Results show that the yield stress, ultimate compressive strength and the rigidity properties of LLDPE/RH composites were strongly affected by both filler contents and strain rate loadings. Apart from that, the rate of sensitivity of LLDPE/RH show great dependency towards applied strain rate, where it was increased with increasing strain rates. Unfortunately, the thermal activation values show contrary trend. Visually, from the post damage analysis, the results show that applied strain rates affected the deformation behavior of tested LLDPE/RH composites.

Hot Workability of Ultrafine-Grained Aluminum Alloy Produced by Severe Plastic Deformation of Al6063 Powder and Consolidation

2010 ◽  
Vol 667-669 ◽  
pp. 979-984 ◽  
Author(s):  
Hamed Asgharzadeh ◽  
Abdolreza Simchi ◽  
Hyoung Seop Kim
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Deformation ◽  
Grain Structure ◽  
Al Alloy ◽  
Strain Rates ◽  
Hot Workability ◽  
Ultrafine Grained

Al6063 powder was subjected to severe plastic deformation via high-energy mechanical milling to prepare ultrafine-grained (UFG) aluminium alloy. Uniaxial compression test at various temperatures between 300 and 450 °C and strain rates between 0.01 and 1 s-1 was carried out to evaluate hot workability of the material. Microstructural studies were performed by EBSD and TEM. The average activation energy and strain rate sensitivity of the hot deformation process were determined to be 280 kJ mol-1 and 0.05, respectively. The deformation temperature and applied strain rate significantly affected the grain structure of UFG Al alloy. A finer grain structure was obtained at lower temperatures and higher strain rates. The formation of highly misoriented and equiaxed grains also revealed that dynamic recrystallization occurred upon hot deformation. Furthermore, elongated grains with high dislocation density were observed that disclosed partial dynamic recrystallization of the aluminum matrix.

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