Use of the ABI technique to measure the mechanical properties of aluminium alloys: effect of chemical composition on the mechanical properties of the alloys

Abstract

The effects of the chemical composition on the microstructure and mechanical properties were investigated using automated ball-indentation tests, scanning electron microscopy and energy dispersive X-ray analysis. It was observed that the mechanical properties change with the presence of the eutectic and varying excess content of elements. In this work, the automated-ball-indentation (ABI) technique was compared with the standard mechanical tests. The ABI method is based on controlled multiple indentations into a polished surface by a spherical indenter under load. The indentation depth is progressively increased to the maximum, user-specified limit, with intermediate partial unloading. This technique allows to measure the yield strength, stress-strain curve, strength coefficient and strain-hardening exponent. For all these test materials and conditions, the ABI-derived results were in very good agreement with those obtained with the conventional, standard test methods. Keywords: Al-alloys, microstructure, mechanical properties, ABI tests Vpliv kemijske sestave na mikrostrukturo in mehanske lastnosti je bil preiskovan z avtomatskim preizkusom vtiskovanja krogle, z vrsti~no elektronsko mikroskopijo in z energijsko disperzijsko rentgensko analizo. Opa`eno je bilo, da se mehanske lastnosti spreminjajo s prisotnostjo evtektika in s spreminjanjem vsebnosti prese`nih elementov. V prispevku je bila preverjena metoda avtomatskega vtiskanja kroglice (ABI) z obi~ajnimi mehanskimi preizkusi. ABI metoda temelji na kontroliranih ve~kratnih vtiskih kroglastega vtiska~a v polirano povr{ino. Globina vtiskov progresivno nara{~a do maksimalne, z uporabnikom dolo~ene meje, s takoj{njo vmesno razbremenitvijo. Ta tehnika omogo~a merjenje meje plasti~nosti, krivulje napetost-raztezek, koeficienta trdnosti in eksponenta napetostnega utrjevanja. Za vse pogoje preizku{anja materiala so dobljeni ABI rezultati skladni z rezultati, dobljenimi iz obi~ajnih metod preizku{anja.

Use of the ABI technique to measure the mechanical properties of aluminium alloys: effect of heat-treatment conditions on the mechanical properties of alloys

“…4,5 As shown previously 6 , the results obtained with this method achieve good compatibility with those of the conventional methods.…”

“…[11][12][13] After the solution treatment, the excess silicon from the d-phase dissolves in the a-aluminum solid solution. 6 As it can be seen from Table 2 and Figure 5f, this process improves the hardness even after the homogenization.…”

“…6 Two types of heat treatment were applied. The first type was the solution treatment, carried out in an electric resistance furnace.…”

“…For the presented series of alloys, we used the following value of this coefficient -2.8. 6 For the determination of the yield strength (R p0.2 ), the methodology proposed in 7 , together with Equation (3), was used. The Meyer hardness was calculated with Equation (4):…”