STUDIES ON THE EFFECT OF ARTIFICIAL AGEING HARDNESS ON TENSILE PROPERTIES AND IMPACT STRENGTH OF AL-6SI-0.5MG-2NI ALLOY
The effect of different scheduled artificial ageing hardness on the tensile and impact properties of Al-6Si-0.5Mg-2Ni alloy was studied. The solution treated Al-6Si-0.5Mg-2Ni alloy was aged isochronally for 1 hour at temperatures up to 300oC. The precipitation stages during ageing were monitored by hardness measurements. Tensile and impact properties were determined by standard tests. During artificial ageing, the yield and ultimate tensile strength were found to increase with ageing hardness; the maximum being attained at peak hardness. Ductility and impact toughness of the alloy, on the other hand decreased with ageing hardness, reaching the minimum at the highest hardness. The strength of Al- 6Si-0.5Mg-2Ni alloy was best at highest hardness but exhibits poor ductility and impact strength.
KEYWORDS: Al-6Si-0.5Mg-2Ni alloy; ageing; hardness; tensile properties; impact strength;
 Stadler F, Antrekowitsch H, Fragner W, Kaufmann H, Uggowitzer PJ.(2012) The influence of solution treatment on the high temperature strength of Al-Si foundry alloys with Ni. Metals 2012 edited by Carlos E., Suarez TMS.
 Shivkumar S, Keller C, Apelian D. (1990) Ageing behavior in cast Alâ€“Siâ€“Mg alloys. AFS Trans., 98:905â€“911.
 Kashyap KT, Murali S, Raman KS, SmurthyKS. (1993) Overview casting and heat treatment variables of Alâ€“7Siâ€“Mg alloy. Mater Sci., 9:189â€“203.
 LiYG, Yang Y, Wu YY, WangLY, Liu XF. (2010) Quantitative comparison of three Nicontaining phases to the elevated-temperature properties of Al-Si piston alloys. Mater. Sci. and Eng. A, 527: 132-7137.
 Apelian D, Shivkumar S, SigworthG. (1989) Fundamental aspects of heat treatment of cast Al-Si-Mg alloys. Am. Foundry Soc. Trans., 97:727-742.
 Shueiwan Juang H, Shyh-Ming W. (2008) Study on mechanical properties of A356 alloys enhanced with preformed thixotrophic structure. J. of Marine Sci. Tech., 16(4):271-274.
 AsgharZ, RequenaG, Kubel F. (2010) The role of Ni and Fe aluminides on the elevated temperature strength of an Al-12Si alloy. Mater. Sci. and Eng. A, 527:5691-5698.
 Stadler F, Antrekowitsch H, Fragner W, Kaufmann H, UggowitzerPJ. (2011) Theeffect of Ni on the high-temperature strength of Al-Si cast alloys. Mater. Sci. Forum, 690:274-277.
 Stadler F, Antrekowitsch H, Fragner W, Kaufmann H, Peter J, Uggowitzer (2012) Effect of main alloying elements on the strength of Al-Si cast alloys at elevated temperatures. Int. J. of Cast Metals Res., 25(4):215-224.
 LasagniF, LasagniA, MarksE, HolzapfelC, MÃ¼cklichF, DegischerHP. (2007) Threedimensional characterization of 'as-cast' and solution-treated Al-12Si(Sr) alloys by highresolution FIB tomography. Acta Mater., 55:3875-3882.