scholarly journals Strain rate sensitivity of the aluminium-magnesium-scandium alloy - Scalmalloy®

2021 ◽  
Vol 250 ◽  
pp. 05014
Author(s):  
Puneeth Jakkula ◽  
Georg Ganzenmüller ◽  
Florian Gutmann ◽  
Stefan Hiermaier
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Testing Machine ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Image Correlation ◽  
Strain Rates ◽  
Rate Dependency ◽  
Strain Rate Dependency ◽  
Scandium Alloy

This work investigates the strain rate sensitivity of the aluminiummagnesium-scandium alloy Scalmalloy, which is used extensively for additive manufacturing of lightweight structures. This high strength aluminium alloy combines very good weldability, machinability and mechanical strength: it can be heat-treated to reach nominal ultimate tensile strengths in excess of 500 MPa. We report tensile tests at strain rates ranging from 10−3 /s to 103 /s at room temperature. It is well known that Al-Mg alloys exhibit a negative strain rate dependency in combination with serrated flow caused by the Portevin-Le Chatelier effect, which describes the interaction of Mg solutes with dislocation propagations. In contrast, in Al-Sc alloys, the flow stress increases with increasing strain rate and displays positive strain rate dependency. Additionally, the presence of Sc in the form of Al3-Sc provides a fine-grained microstructure which allows higher tensile and fatigue strength. This research shows how these combined effects interact in the case of Scalmalloy, which contains both Mg and Sc. Tests are performed at quasi-static, intermediate and high strain rates with a servohydraulic testing machine and a Split-Hopkinson tension bar. Local specimen strain was performed using 2D Digital Image Correlation.

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.

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.

Mechanical Anisotropy and Strain Rate Dependency Behavior of Ti6Al4V Produced Using E-Beam Additive Fabrication

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Leila Ladani ◽  
Jafar Razmi ◽  
Soud Farhan Choudhury
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Mechanical Anisotropy ◽  
Rate Dependency ◽  
Out Of Plane ◽  
Degree Of Anisotropy ◽  
Strain Rate Dependency

Anisotropic mechanical behavior is an inherent characteristic of parts produced using additive manufacturing (AM) techniques in which parts are built layer by layer. It is expected that in-plane and out-of-plane properties be different in these parts. E-beam fabrication is not an exception to this. It is, however, desirable to keep this degree of anisotropy to a minimum level and be able to produce parts with comparable mechanical strength in both in-plane and out-of-plane directions. In this manuscript, this degree of anisotropy is investigated for Ti6Al4V parts produced using this technique through tensile testing of parts built in different orientations. Mechanical characteristics such as Young's modulus, yield strength (YS), ultimate tensile strength (UTS), and ductility are evaluated. The strain rate effect on mechanical behavior, namely, strength and ductility, is also investigated by testing the material at a range of strain rates from 10−2 to 10−4 s−1. Local mechanical properties were extracted using nanoindentation technique and compared against global values (average values obtained by tensile tests). Although the properties obtained in this experiment were comparable with literature findings, test results showed that in-plane properties, elastic modulus, YS, and UTS are significantly higher than out-of-plane properties. This could be an indication of defects in between layers or imperfect bonding of the layers. Strong positive strain rate sensitivity was observed in out-of-plane direction. The strain rate sensitivity evaluation did not show strain rate dependency for in-plane directions. Local mechanical properties obtained through nanoindentation confirmed the findings of tensile test and also showed variation of properties caused by geometry.

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 Strain Rate Sensitivity of the Additive Manufacturing Material Scalmalloy®

2021 ◽  
Author(s):  
Puneeth Jakkula ◽  
Georg Ganzenmüller ◽  
Florian Gutmann ◽  
Aron Pfaff ◽  
Jörg Mermagen ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Strain Rate ◽  
Yield Stress ◽  
Strain Rate Sensitivity ◽  
Mass Density ◽  
Rate Sensitivity ◽  
Heat Treating ◽  
Tensile Tests ◽  
Strain Rates ◽  
Interesting Candidate

This 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 /s 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 A New Explanation for the Effect of Dynamic Strain Aging on Negative Strain Rate Sensitivity in Fe–30Mn–9Al–1C Steel

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3426 ◽  
Author(s):  
Jia Xing ◽  
Lifeng Hou ◽  
Huayun Du ◽  
Baosheng Liu ◽  
Yinghui Wei
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Dynamic Strain Aging ◽  
Strain Aging ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Dynamic Strain ◽  
Strain Rates ◽  
Dislocation Arrangement ◽  
Hall Plot

In this study, the evolution of the mechanical properties of Fe–30Mn–9Al–1C steel has been determined in tensile tests at strain rates of 10−4 to 102 s−1. The results show that the strain rate sensitivity becomes a negative value when the strain rate exceeds 100 s−1 and this abnormal evolution is attributed to the occurrence of dynamic strain aging. Due to the presence of intergranular κ-carbides, the fracture modes of steel include ductile fracture and intergranular fracture. The values of dislocation arrangement parameter M were obtained using a modified Williamson–Hall plot. It has been found that once the strain rate sensitivity becomes negative, the interaction of dislocations in the steel is weakened and the free movement of dislocation is enhanced. Adiabatic heating promotes the dynamic recovery of steel at a high strain rate.

Effect of Strain Rates on the Mechanical Behavior of Cu Thin Films of Various Thicknesses

2013 ◽  
Vol 284-287 ◽  
pp. 94-97
Author(s):  
Kuan Jung Chung ◽  
Chi Feng Lin ◽  
W. C. Chiang
Keyword(s):  
Thin Film ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Strain Rate Sensitivity ◽  
Testing Machine ◽  
Rate Sensitivity ◽  
Strain Rates ◽  
Tensile Testing Machine ◽  
Cu Film ◽  
Cu Thin Film

The objective of this study is to investigate the mechanical behavior of copper thin film with different thicknesses subjected to varying strain rates. A micro-force tensile testing machine (MTS Tytron 250) was used to test the polyimide samples coated with different thicknesses of copper (500 nm, 750 nm, 1000 nm, and 1500 nm). The experiments were conducted by applying test vehicles to different strain rates (1.6×10-4s-1, 1.6×10-3s-1, and 1.6×10-2s-1). The experimental results showed the strain rate and the thickness have obvious influence upon the mechanical properties of Cu thin film. The yield stress increases as increasing the strain rate or decreasing the thickness of Cu film. For considering the strain rate sensitivity m, the strain rate sensitivity m is found that it increases as decreasing the thickness to imply that Cu film has high strain-rate response at low thickness.

Strain Rate Sensitivity of Die Steel under Compressive Loads

2012 ◽  
Vol 585 ◽  
pp. 412-416
Author(s):  
Nilamber K. Singh ◽  
Maloy K. Singha ◽  
Ezio Cadoni ◽  
Narinder K. Gupta
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Split Hopkinson Pressure Bar ◽  
Testing Machine ◽  
Rate Sensitivity ◽  
Gauge Length ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Static Tests ◽  
Die Steel

An experimental investigation on the strain rate sensitivity of die steel (D3) has been presented in this paper at different rates (0.001-2500s-1) of uni-axial compression. Quasi-static tests (0.001s-1) of the material are conducted on universal testing machine (UTM), whereas, the experiments at high strain rates are performed on split Hopkinson pressure bar (SHPB) apparatus. The effects of gauge length of the specimen on the material properties of the material are studied at different strain rates. The material parameters of existing Cowper-Symonds and Johnson-Cook material models are determined and the suitability of the models is examined.

scholarly journals Compressive Behaviour of Additively Manufactured Periodical Re-Entrant Tetrakaidecahedral Lattices at Low and High Strain-Rates

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1196
Author(s):  
Michaela Neuhäuserová ◽  
Tomáš Fíla ◽  
Petr Koudelka ◽  
Jan Falta ◽  
Václav Rada ◽  
...  
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
High Speed ◽  
Mechanical Response ◽  
Split Hopkinson Pressure Bar ◽  
Deformation Behaviour ◽  
Rate Sensitivity ◽  
Image Correlation ◽  
Strain Rates ◽  
Static Compression

Compressive deformation behaviour of additively manufactured lattice structures based on re-entrant tetrakaidecahedral unit-cell geometry were experimentally investigated under quasi-static and dynamic loading conditions. Specimens of four different structures formed by three-dimensional periodical assembly of selected unit-cells were produced by a laser powder bed fusion technique from a powdered austenitic stainless steel SS316L. Quasi-static compression as well as dynamic tests using split Hopkinson pressure bar (SHPB) apparatus at two strain-rates were conducted to evaluate the expected strain-rate sensitivity of the fundamental mechanical response of the structures. To evaluate the experiments, particularly the displacement fields of the deforming lattices, optical observation of the specimens using a high-resolution camera (quasi-static loading) and two synchronised high-speed cameras (SHPB experiments) was employed. An in-house digital image correlation algorithm was used in order to evaluate the anticipated auxetic nature of the investigated lattices. It was found that neither of the investigated structures exhibited auxetic behaviour although strain-rate sensitivity of the stress–strain characteristics was clearly identified for the majority of structures.

Sign in / Sign up

Export Citation Format

Share Document