EFFECT OF THE T6 HEAT TREATMENT ON CHANGE OF MECHANICAL PROPERTIES OF THE AlSi12CuNiMg ALLOY MODIFIED WITH STRONTIUM

The paper presents test results concerning an effect of the heat treatment on microstructure and mechanical properties of eutectic EN AC-AlSi12CuNiMg (EN AC-48000) alloy according to the EN 1706: 2010 (tensile strength - R-m, hardness - HB 10/1000/30) modified with strontium. Solution heat treatment and ageing treatment temperature ranges were selected on base of heating (melting) curves recorded with use of the ATD method. Temperatures of the solution heat treatment were 500, 520, and 535 degrees C +/- 5 degrees C, while the solution time ranged from 0.5 to 3 h (0.5; 1.5 and 3 h). Temperature of the solution heat treatment amounted to 180, 235 and 310 degrees C, while the ageing time ranged from 2 to 8 h (2, 5 and 8 h). Obtained results have enabled determination of optimal parameters of the T6 heat treatment in aspect of improvement of tensile strength R-m and hardness HB of the alloy, with reduced time of individual treatments and determination of mathematical relationships enabling prediction of these mechanical properties.