Thermoviscoplastic constitutive relation for aluminium. The strain rate sensitivity decreased with increasing al content at the low strain rates. Through intensive analysis of the tensile stressstrain curves of a variety of steel sheets over a wide range of strain rates on the order of 102. The various combinations of alloying additions and strengthening mechanisms used for wrought aluminum alloys are shown in table 1. Effects of strain rate on tensile properties and fracture. Formability testing of aluminum sheet materials total. Strain rate and temperature effects on dynamic properties of. The high strain rate experiments were conducted using a split hopkinson bar apparatus. Dynamic tensile properties of steels and aluminum alloys for.
Quantumtocontinuum prediction of ductility loss in. The 5xxx series aluminum alloys containing solute mg atoms almg alloys can be cited as an example of materials that exhibit various strain rate sensitivity. Maniattya a department of mechanical, aerospace and nuclear engineering, rensselaer polytechnic institute, troy, ny 12180, usa b center for mechanical technology and automation, university of aveiro. The strain rate sensitivity of the hardness in indentation creep volume 22 issue 4 a. High strain rate properties of metals and alloys r. Enhanced roomtemperature formability in highstrength. Strain rate effects on mechanical properties in tension of aluminium.
The dynamic tensile tests were conducted using a tensile hopkinson bar apparatus 25, which was made of tool steel bars with a diameter of 16 mm and length of. The strain rate sensitivity index, mvalue, is being applied as a common tool to evaluate the impact of the strain rate on the viscoplastic behaviour of materials. The strain rate sensitivity parameter is determined as a function of temperature and plastic strain, and the strain rate and temperature range in which dynamic strain aging leads to negative strain rate sensitivity is mapped. Variation of strain rate sensitivity index of a superplastic. The variation in strain rate sensitivity with strain is reported for a number of aluminium alloys. Fatigue properties of aluminum alloys at various direct stress ratios part 1. Aluminummagnesium alloys exhibit negative strainrate sensitivity due to dynamic strain aging, causing reduced ductility at room temperature.
The almg alloy has been tested at various strain rates and testing temperatures because it exhibits high strength and corrosion resistance. Enhanced roomtemperature formability in highstrength aluminum alloys through pulsepressure forming ppf cop. Strain rate sensitivity of the commericial aluminum alloy aa51820. The effects of this variation on the maximum uniform plastic strain. Aermet 100, a modified 4340, modified hp9420, and a recently developed eglin afb steel alloy, es1c. Additionally, the level of damage was seen to increase with strain rate. Strain rate sensitivity is a very important aspect of material behavior. Low to high strain rate characterization of dp600, trip780, aa5182o by m. The stress corrosion sensitivity of the domestic and imported 7n01 aluminum alloys is researched by slow strain rate testing ssrt. The strain rate sensitivity was measured in constant strain rate tests as well as in strain rate jump tests.
The strain rate sensitivity is usually expressed by a differential function of stress and strain rate at specific plastic strain as shown by the following equation e. The present study examines the strainrate sensitivity of four high strength, high toughness alloys at strain rates ranging from 0. Aluminum alloys with identical plastic flow and different. Typical mechanical properties of wrought aluminum alloys at. Mechanical properties data for selected aluminum alloys. Suresh a, a department of materials science and engineering, massachusetts institute of technology, 77 massachusetts avenue, room 40140, cambridge, ma 029, usa b shenyang national laboratory for materials science, institute of metal research, chinese academy of sciences, shenyang. Effects of strain rates on tensile properties and fracture behavior of al6si0. Mechanical properties data for selected aluminum alloys 399 table a7. An experimental investigation on the dynamic compressive behaviour of the aluminium alloy, aa6063t6 in the strain rate range from 0. The strain rate sensitivity parameter is determined as a function of temperature and plastic strain, and the strain rate and temperature range in which dynamic strain aging leads to negative strain rate sensitivity is. Request pdf strainrate sensitivity of aluminum alloys aa1200 and aa3103 tensile tests are carried out for the aluminum alloys aa1200 and aa3103 at various strainrates in the range from 104. Strain rate dependence of material strength in aa5xxx.
Dynamic tensile properties of steels and aluminum alloys for a wide range of strain rates and strain. Cylindrical specimens of aa6063t6 are tested under universal testing machine at quasistatic 0. Strain rate sensitivity and the plasticity of aluminium alloys. This paper presents results from quasistatic and high rate tensile testing of three aluminum sheet alloys, aa5754, aa5182 and aa6111, all of which are candidates for replacing mild steel in automotive bodies. However, there is no significant difference with changing the temperatures except for 300oc. Strainrate sensitivity of aluminum alloys aa1200 and. Dynamic tensile properties of steels and aluminum alloys. Pdf the effect of strain rate on the mechanical properties of aa5xxx series. In general, starting from 102 s1 of strain rate thermal diffusion conduction and convection can be neglected and thermal softening can be evaluated under adiabatic assumption. Flow stress mpa strain rate 1sec comparison of higashi experiments results with model predicted flow stress. The characteristic equation which describes the superplastic behavior is usually written as 1 k b 6 k 4.
The strainrate sensitivity of the hardness in indentation creep volume 22 issue 4 a. The strainrate sensitivity of high strength hightoughness. In order to examine the strainrate sensitivity, tensile tests were carried out at a dynamic strain rate of 1. The strain rate sensitivity parameter is determined as a function of temperature and plastic strain, and the. The thermo mechanical responses of the material were determined during uniaxial compression experiments at different strain rates, ranging from 10. The present study examines the strain rate sensitivity of four high strength, high toughness alloys at strain rates ranging from 0.
It has been found that aa5754 sheet exhibits negative rate sensitivity up to a strain rate of 0. Blatberwiek university of minnesota september 1953 g materials laboratory contract no. The mgrich alloy exhibits lower strain rate sensitivity and a different variation of this parameter with the stress haasen plot relative to. Tensile tests are carried out for the aluminum alloys aa1200 and aa3103 at various strainrates in the range from 104 s1 to 1 s1. The constitutive response of all of the aluminum alloys tested showed only mild strain rate sensitivity. The results for the various alloys are interpreted in terms of the development of the. Thus, the material properties at those strain rates are important. However, the plastic flow of some materials is sensitive to strain rate, which is known as material strain rate sensitivity, or viscoplasticity 3. At strain rates above 1500 s1 there was substantially higher work hardening and strain rate sensitivity compared with that observed for the quasistatic tests at. Determination of stress corrosion cracking resistance of. Strength, strainrate sensitivity and ductility of copper. Strain rate sensitivity of an aluminium alloy under.
Analysis of strain rate behavior of an al 6061 t6 alloy. Experimental tests in this work the material al 6061 t6 is experimentally characterized over a range of strain rates from 104 s1 up to 104 s1 in compression. High strain rate behaviour of aluminium alloy sheet. The strainrate sensitivity was shown to decrease with increasing aluminium solute level in the matrix.
Lsdyna theoretical manual, livermore software technology. Constitutive model w variable strain rate sensitivity. Mgrich and sirich aluminum alloys from the aa6xxx class are considered to demonstrate that standard heat treatments can be used to produce materials with identical plastic flow yield stress and strain hardening and different strain rate sensitivity. The ends of the specimen were lubricated with aluminum foil to. However, the aa5xxx series aluminum alloys primarily exhibited the. An aluminum alloy al 2024t351, which is an alcumg alloy with face centered cubic structure, was used in the current study. The dynamic mechanical behavior, fracture characteristics, and microstructural evolution of highstrength weldable aluminumscandium alsc alloy were investigated using a compressive split hopkinson pressure bar at strain rates of 1. The strength ranges achievable with various classes of wrought and cast alloys are given in tables 2 and 3.
Pdf strain rate dependence of material strength in aa5xxx. When gradients in strain exist, materials which harden with increasing strain rate will distribute deformation more uniformly because additional deformation in areas of high strain rate, such as neck, will require greater stress. The formability of a material depends upon the strain hardening and strain rate hardening of the material. The unique combinations of properties provided by aluminum and its alloys make aluminum one of the most versatile, economical, and attractive metallic materials for a broad range of usesfrom soft, highly ductile wrapping foil to the most demanding engi. Strainrate sensitivity of diecast magnesiumaluminium. Low to high strain rate characterization of dp600, trip780. Single highstrainrate pulse or multiple lower strain rate pulses minimize risk by broadening the temperstrain rate window 11 heattreatment or yield strength commercialization risk wtemper xx days aging lack of ppf supply chain wtemper supply timing.
Stressstrain behaviour of aluminium alloys at a wide range. Strength, strainrate sensitivity and ductility of copper with nanoscale twins m. The chemical composition of the alloy is listed in table 1. On certain aspects of strain rate sensitivity of sheet metals. Pdf effects of strain rate on mechanical properties in tension of a.
Evaluation of tensile properties of 5052 type aluminum. Strain rate sensitivity versus temperature as shown in fig. In the dynamic strain rate range, it is known that the flow stress starts to increase rapidly. For additional information on standards for aluminum alloys and their applications, please refer to the following. Alloy and yield strength specimen 24 c 75 f 196 c 320 f 253 c 423 f 269 c 452 f condition mpa ksi design. In the strain rate jump tests the rate was changed by one or two orders of magnitude in separate tests and both the instantaneous and the steady state rate sensitivity were. The strainrate sensitivity of the hardness in indentation. They are manufactured by a sequence of hot, then cold, forming operations rolling for sheets combined with intermediate andor final annealing. The aim of this paper is to evaluate the effects of various strain rates on the tensile properties of al6si0. Tests were performed at quasistatic rates using an instron apparatus and at strain rates of 600 to 1500 s1 using a tensile split hopkinson bar. Typical mechanical properties of wrought aluminum alloys. Strainrate sensitivity of aluminum alloys aa1200 and aa3103.
Variable strain rate sensitivity in an aluminum alloy. Aluminum alloys are important technological materials primarily due to their advantageous strength to weight ratio. Tanimura department of mechanical engineering, college of engineering, university of osaka prefecture, mozuumemachi, sakai, osaka 591, japan technical research laboratories, sumitomo light metal. Tests with constant nominal strainrate and strainrate jump tests are conducted, and the instantaneous rate sensitivity and the rate sensitivity of strain hardening are investigated. In this study, strain rate sensitivity is evaluated for several different grades of steel. Sem images of chip obtained during the drilling of aluminum alloys at 0. Enhanced roomtemperature formability in highstrength aluminum alloys through pulsepressure forming author. The formulations reported extend the validity of the rusinekklepaczko model for the definition of particular aspects of the behaviour of aluminium alloys, namely the negative strain rate sensitivity and the viscous drag. Here, the authors develop an atomistically informed. Strain rate sensitivity of the commericial aluminum alloy.
Oct 16, 2017 the strain rate sensitivity index, mvalue, is being applied as a common tool to evaluate the impact of the strain rate on the viscoplastic behaviour of materials. In aluminium alloys positive values of strain rate sensitivity are associated with the phenomena responsible for dynamic recovery. Aluminum magnesium alloys exhibit negative strain rate sensitivity due to dynamic strain aging, causing reduced ductility at room temperature. The strength ranges achievable with various classes of wrought and cast alloys are given in. Nanostructured alfe alloys produced by ebeam deposition. Yielding and fracture in tungsten and tungstenrhenium alloys. The mechanical behavior of the commercial aluminum alloy aa5182o is investigated at temperatures ranging from. Conclusions the strain dependence of the strain rate sensitivity is an additional factor which needs to be considered when discussing the effects of strain rate on plastic deformation. In this study, constitutive parameters using the power law constitutive equation are determined for six different strength steels and two aluminum alloys over different strain ranges, including approximations of the postuniform elongation range. This implies the diagram of figure 2 is partially inaccurate in this range of strain rate. Machining and machinability of aluminum alloys 381 materials chip form at 31.
Typical mechanical properties of wrought aluminum alloys at various temperatures age lines were constructed to represent the typical behavior. Dramatic increases in the elongation to failure were observed with increases in strain rate as well as greater reduction in area. In this paper the strain rate sensitivity of alloys 800h and 617 determined from strain rate jump tests are compared for the temperature range 650 to c. Strain rate dependence of the material strength in 5xxx. Evaluation of mechanical properties of aluminium alloy aa. Strain rate sensitivity m values of the alloys at different temperatures at the strain rate of of 5 x 104 s1.
Walley2 the high strain rate dependence of the flow stress of metals and alloys is described from a dislocation mechanics viewpoint over a range beginning from conventional tensioncompression. Strain rate sensitivity of the commercial aluminum alloy. It was cleared that the aluminum alloys belonging to the one group exhibit the positive strain rate sensitivity and the aluminum alloys belonging to another group exhibit the negative sensitivity or almost non. Strain rate sensitivity is an important material property in the formability of sheet metal. Similar observations regarding rate sensitivity of aluminium alloys, now in tension, were reported by. Aluminium alloys in marine applications 37 alcan marine 3. The strainrate effect in diecast magnesiumaluminium based alloys under quasistatic strain rates ranging from 10.
Effects of strain rate on mechanical properties in tension of a. The relationship of the temperature dependence of the measured strain rate sensitivity to the tensile curves for both alloys is determined. Altenpohl, aluminum, technology, applications, and environment, the aluminum. Compressive strainrate sensitivity of magnesiumaluminum. We have tested numerous aluminum alloys 6061, 2024, 8090 at strain rates of 0. Tensile behaviour of commercial aluminium alloys used in armour. Materials science and engineering a 390 2005 334343 strain rate sensitivity of the commercial aluminum alloy aa5182o r. Also included are the strain rate sensitivity exponent, m, determined at di.
Furthermore, the strain rate sensitivity parameter, determined as a function of plastic strain and the strain rate at room temperature, is compared for the three alloys. The mvalue, as a constant number, has been frequently taken into consideration for modeling material behaviour in the numerical simulation of superplastic forming processes. The mgrich alloy exhibits lower strain rate sensitivity and a different variation of this parameter with the stress haasen plot relative. Strain rate and temperature effects on dynamic properties. Compression strainrate sensitivity of magnesiumaluminum. Sep 29, 2010 mgrich and sirich aluminum alloys from the aa6xxx class are considered to demonstrate that standard heat treatments can be used to produce materials with identical plastic flow yield stress and strain hardening and different strain rate sensitivity. Increasing the strain rate also has the effect of increasing the yield stress as well as the ductility.
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