scholarly journals Strain Rate Sensitivity of Tensile Properties in Ti-6.6Al-3.3Mo-1.8Zr-0.29Si Alloy: Experiments and Constitutive Modeling

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1591 ◽  
Author(s):  
Jun Zhang ◽  
Yang Wang ◽  
Bin Zhang ◽  
Hanjun Huang ◽  
Junhong Chen ◽  
...  
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Full Range ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Strain Rate Change ◽  
Complex Deformation ◽  
Rate Dependent ◽  
Single Stress ◽  
Cavitation Fracture

The complex deformation usually involves wide strain-rate change. However, few efforts have been devoted to investigate the effect of strain rate history on the tensile behavior of α + β titanium alloy. In present paper, tensile tests of Ti-6.6Al-3.3Mo-1.8Zr-0.29Si alloy were carried out under both constant and variable strain-rate conditions within the region from 10−3~500 s−1. A single stress pulse experimental technique was utilized to conduct the recovery tests. The strain-rate history effect was examined. It is found that the flow stress is independent on the strain rate history, though the alloy exhibits obvious positive strain rate sensitivity. The Taylor-Quinney coefficient of the plastic work converted to heat is proved as 0.9 at high strain rates. The cavitation fracture mechanism is revealed by microstructural observation over the full range explored. In basis of the experimental results and other pulished literatures, empirical Khan-Huang-Liang constitutive model was suitably modified to account for the strain-rate dependent behavior. Good agreement is achieved between the modeling prediction results and experimental data.

scholarly journals Experimental study of the stress state and strain rate dependent mechanical behaviour of TRIP-assisted steels

2021 ◽  
Vol 250 ◽  
pp. 05003
Author(s):  
A. Pontillo ◽  
C. Lonardi ◽  
S. Chandran ◽  
F. Vercruysse ◽  
L. Corallo ◽  
...  
Keyword(s):  
Strain Rate ◽  
Plane Strain ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Image Correlation ◽  
Strain Rates ◽  
Plane Shear ◽  
Rate Dependent ◽  
Stress States

This paper presents an investigation into the effect of different stress states and strain rates on the austenite-to-martensite transformation during plastic straining of a Q&P steel. Different stress states are imposed to the steel using purposed-designed samples. The sample geometries, including in-plane shear, dogbone and plane strain samples, are optimised by finite element modelling. Tensile tests are performed at different strain rates of 0.001 s-1, 10 s-1 and 500 s-1. Digital image correlation is used to capture the strain fields during the entire deformation process. The mechanical results indicate a positive strain rate sensitivity for both the shear and plane strain specimens and a negative strain rate sensitivity for the dogbone sample. In addition, the influence of the strain rate on the strain level is more pronounced for the shear than for the plane strain specimens and for the dogbone samples.

scholarly journals Strain-Rate-Dependent Deformation Behavior and Mechanical Properties of a Multi-Phase Medium-Manganese Steel

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 344 ◽  
Author(s):  
Simon Sevsek ◽  
Christian Haase ◽  
Wolfgang Bleck
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Deformation Behavior ◽  
Rate Sensitivity ◽  
Manganese Steel ◽  
Strain Rates ◽  
Rate Dependent ◽  
Medium Manganese Steel ◽  
Multi Phase

The strain-rate-dependent deformation behavior of an intercritically annealed X6MnAl12-3 medium-manganese steel was analyzed with respect to the mechanical properties, activation of deformation-induced martensitic phase transformation, and strain localization behavior. Intercritical annealing at 675 °C for 2 h led to an ultrafine-grained multi-phase microstructure with 45% of mostly equiaxed, recrystallized austenite and 55% ferrite or recovered, lamellar martensite. In-situ digital image correlation methods during tensile tests revealed strain localization behavior during the discontinuous elastic-plastic transition, which was due to the localization of strain in the softer austenite in the early stages of plastic deformation. The dependence of the macroscopic mechanical properties on the strain rate is due to the strain-rate sensitivity of the microscopic deformation behavior. On the one hand, the deformation-induced phase transformation of austenite to martensite showed a clear strain-rate dependency and was partially suppressed at very low and very high strain rates. On the other hand, the strain-rate-dependent relative strength of ferrite and martensite compared to austenite influenced the strain partitioning during plastic deformation, and subsequently, the work-hardening rate. As a result, the tested X6MnAl12-3 medium-manganese steel showed a negative strain-rate sensitivity at very low to medium strain rates and a positive strain-rate sensitivity at medium to high strain rates.

A Study on Rate Sensitivity of Impedance in TRIP Steel during Deformation at Various Strain Rate under Two Kinds of Deformation Mode

2014 ◽  
Vol 566 ◽  
pp. 140-145
Author(s):  
Daiki Inoshita ◽  
Takeshi Iwamoto
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Trip Steel ◽  
Testing Machine ◽  
Rate Sensitivity ◽  
Deformation Mode ◽  
Tensile Tests ◽  
Material Testing ◽  
Trip Steels ◽  
Material Testing Machine

TRIP steel possesses excellent mechanical properties dominated by strain-induced martensitic transformation (SIMT). For automotive industries, if TRIP steel can be applied to shock absorption members, it can be considered that the weight of automobile can be reduced. However, the strain rate sensitivity of TRIP steels has not been fully understood because the strain rate sensitivity and the deformation mode dependency of SIMT are still unclear. Therefore, it is important to reveal these sensitivity and dependency for confirming a reliability of TRIP steel. Therefore, in this study, it is attempted to estimate the amount of produced martensite in TRIP steel by measuring the inductance of TRIP steel. The specimen made of TRIP steel is used as a core of a prototype coil manufactured in this study. Then, the compressive and tensile tests are conducted by using a material testing machine and a drop weight testing machine using the specimen inside the coil. The inductance of the coil with the deformed specimen are measured continuously during the tests.

The effect of minor element concentrations on the strain rate sensitivity and ductility of commercial purity aluminium sheet

1980 ◽  
Vol 295 (1413) ◽  
pp. 130-130
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Minor Element ◽  
Tensile Tests ◽  
Plastic Instability ◽  
Alloy Sheet ◽  
Second Phase ◽  
Commercial Purity ◽  
Aluminium Sheet

Minor element levels vary considerably in commercial purity ( ca .99.5 % Al) aluminium alloy sheet obtained from various sources. Minor elements may be present in solution or as second phase particles formed during solidification or subsequent processing. The present work is largely concerned with the effects of elements in solution on strain-rate sensitivity and ductility. Recent treatments of plastic instability in tensile tests incorporate the strain rate sensitivity and note its importance in determining the strain at which instability occurs (Ghosh 1977; Marciniak 1974). Tensile properties have been determined on a range of aluminium sheet samples. The results show that small increases in solute concentration can result in a change from positive (flow stress increasing with strain rate) to negative strain rate sensitivity. The rate sensitivity was found to be strain dependent and this had led to a reconsideration of the effect of strain rate sensitivity on ductility. The work suggests that it is not the absolute value of the rate sensitivity that determines its effect on the strain to plastic instability, but rather the sign of its variation with strain. If this is positive then the strain to instability exceeds that expected in the absence of rate sensitivity; if the slope is negative the opposite trend is observed.

Strain Rate Sensitivity of Commercial Aluminum Alloys

2019 ◽  
Author(s):  
R.C. Picu
Keyword(s):  
Plastic Deformation ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Solid Solutions ◽  
Elevated Temperatures ◽  
Rate Sensitivity ◽  
Solute Diffusion ◽  
Rate Dependent ◽  
Ultrafine Grained ◽  
Using Data

This article presents a review of the strain rate-dependent mechanical behavior of aluminum and its commercial alloys. The importance of strain rate sensitivity (SRS) stems from its relation with ductility and formability. Plastic deformation is stable and localization less likely in alloys with higher SRS. After discussing the basic formulation used to interpret experimental data, the methods used to measure the SRS parameter are presented. This is followed by a brief review of the main mechanisms that render the flow stress sensitive to the deformation rate, including mechanisms leading to positive and negative SRS. The generic dependence of the SRS parameter on the strain, temperature, and strain rate are further presented using data for pure Al. The effect of alloying is analyzed in the context of solid solutions and precipitated commercial alloys. Results on solid solutions are discussed separately at low and elevated temperatures in order to evidence the role of solute diffusion on SRS. This article ends with a brief discussion of the grain size dependence of SRS, with emphasis on recent efforts to produce nanocrystalline and ultrafine-grained materials by severe plastic deformation.

Hot Deformation Behaviour of Low Alloyed Steel

2012 ◽  
Vol 706-709 ◽  
pp. 2794-2799 ◽  
Author(s):  
Cecilia Poletti ◽  
S. Großeiber ◽  
Sergiu Ilie ◽  
Hans Peter Degischer
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Hot Deformation ◽  
Power Efficiency ◽  
Deformation Behaviour ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Alloyed Steel ◽  
Strain Rates ◽  
Low Alloyed Steel

Hot deformation of a continuously cast low alloyed steel is studied by means of hot compression and tensile tests carried out after austenitization between 700–790 °C at 3x10-4– 0.3 s-1of strain rate. The ferrite transformation at the applied cooling rate was determined at 710°C by means of dilatometry. The compressive flow data obtained by using a Gleeble®1500 machine are evaluated to obtain the strain rate sensitivity and the processing maps using different models. The tensile data are used to determine the ductility of the material with different deformation parameters. A new calculation method is used for the instability parameter derived from the dynamic materials model. The strain rate sensitivity does not predict any instability but all the others instability parameters do, including the new one. Pores are formed at the prior austenitic grain boundaries at low strain rates, causing a decay of ductility in the tensile samples. A minimum in the ductility was observed for low strain rates at 750°C. Low strain rates and low temperatures increase the formation of more ferrite than without deformation at the corresponding heat treatments without deformation. In these conditions, the deformation is concentrated in the softer ferrite phase. Low power efficiency was calculated at high strain rates, where no dynamic recrystallization takes place. The domains with similar efficiency of power dissipation are correlated to deformation induced ferrite formation and ferrite recovery. These domains vary with the increasing strain.

scholarly journals Strain Rate Sensitivity of the Additive Manufacturing Material Scalmalloy®

2021 ◽  
Author(s):  
P. Jakkula ◽  
G. Ganzenmüller ◽  
F. Gutmann ◽  
A. Pfaff ◽  
J. Mermagen ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Strain Rate ◽  
Yield Stress ◽  
Strain Rate Sensitivity ◽  
Mass Density ◽  
Rate Sensitivity ◽  
Heat Treating ◽  
Tensile Tests ◽  
Strain Rates ◽  
Interesting Candidate

AbstractThis work investigates the influence of strain rate on the stress/strain behaviour of Scalmalloy. This material is an aluminium–scandium–magnesium alloy, specifically developed for additive manufacturing. The bulk yield stress of the material processed by Selective Laser Melting is approximately 340 MPa which can be increased by heat-treating to approximately 530 MPa. These numbers, combined with the low mass density of 2.7 g/cm3, make Scalmalloy an interesting candidate for lightweight crash-absorbing structures. As this application is inherently dynamic, it is of interest to study the loading rate sensitivity, which is difficult to predict: Al–Sc alloys exhibit classic strain rate sensitivity with an increased yield stress at elevated strain rates. However, Al–Mg alloys are known to show the contrary effect, they exhibit less strength as strain rate is increased. To answer the question how these effects combine, we study the dynamic behaviour at four different strain rates ranging from 10−3 to 1000 /s using servo-hydraulic and split-Hopkinson testing methods. The resulting data is analysed in terms of strain rate sensitivity of tensile strength and failure strain. A constitutive model based on a simplified Johnson–Cook approach is employed to simulate the tensile tests and provides good agreement with the experimental observations.

scholarly journals High strain rate in situ micropillar compression of a Zr-based metallic glass

2021 ◽  
Author(s):  
Rajaprakash Ramachandramoorthy ◽  
Fan Yang ◽  
Daniele Casari ◽  
Moritz Stolpe ◽  
Manish Jain ◽  
...  
Keyword(s):  
Metallic Glass ◽  
High Strain Rate ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
High Strain ◽  
Deformation Behaviour ◽  
Rate Sensitivity ◽  
Propagation Speed ◽  
Atomic Scale ◽  
Complex Deformation

Abstract High strain rate micromechanical testing can assist researchers in elucidating complex deformation mechanisms in advanced material systems. In this work, the interactions of atomic-scale chemistry and strain rate in affecting the deformation response of a Zr-based metallic glass was studied by varying the concentration of oxygen dissolved into the local structure. Compression of micropillars over six decades of strain rate uncovered a remarkable reversal of the strain rate sensitivity from negative to positive above ~ 5 s−1 due to a delocalisation of shear transformation events within the pre-yield linear regime for both samples, while a higher oxygen content was found to generally decrease the strain rate sensitivity effect. It was also identified that the shear band propagation speed increases with the actuation speed, leading to a transition in the deformation behaviour from serrated to apparent non-serrated plastic flow at ~ 5 s−1. Graphic abstract

Strain Rate Sensitivity of Ultrafine Grained FCC- and BCC-Type Metals

2006 ◽  
Vol 503-504 ◽  
pp. 781-786 ◽  
Author(s):  
Johannes May ◽  
Heinz Werner Höppel ◽  
Matthias Göken
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Testing Temperature ◽  
Ultrafine Grain ◽  
Ultrafine Grain Size ◽  
Ultrafine Grained

The dependence of the strain rate sensitivity (SRS) of α-Fe and Al 99.5, as typical representatives of fcc- and bcc-type metals, on the testing temperature and with respect to the microstructure is investigated. In particular, the differences between conventional grain size (CG) and ultrafine grain size (UFG) are pointed out. UFG Al 99.5 generally shows an elevated SRS compared to CG Al 99.5. In case of α-Fe the SRS of the UFG state is decreased at room temperature, but increased at 200 °C, compared to the CG state. It is shown that the SRS also influences the ductility of UFG-metals in tensile tests.

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