THERMAL TREATMENT OF CASTINGS OUT OF ALUMINIUM ALLOY PRODUCED BY HIGH PRESSURE DIE-CASTING PROCEDURE Russian patent published in 2010 - IPC C22F1/04 

FIELD: metallurgy.

SUBSTANCE: thermal treatment procedure is designed to decrease or prevent bubble formation. There is produced a casting by high pressure die-casting procedure causing gas or other internal porosity in the casting. The casting is made out of dispersed-solidifying aluminium alloy containing from 4.5 to 20 wt % Si, from 0.05 to 5.5 wt % Cu, from 0.1 to 2.5 wt % Fe, from 0.01 to 1.5 wt % Mg, not necessarily - at least one from Ni up to 1.5 wt %, Mn up to 1 wt % and Zn up to 3.5 wt %, and aluminium and unintentional impurities - the rest. The following stages of heat treatment are carried out to decrease or prevent formation of bubbles in a casting. The casting(a) is heated to and within an interval of temperature of treatment to solid solution wherein soluble elements are transited to solid solution. Heating is carried out (i) to and within the interval 20-150°C below temperature of solidus for casting alloy and (ii) during less, than 30 minutes. Further, the casting is cooled (b) starting from an interval of temperature at stage (a) by quenching the casting in a liquid quenching medium at temperature between 0°C and 100°C. Ageing (c) of a quenched casting from stage (b) is performed in the interval of temperature of natural or artificial ageing from 0°C to 250°C, thus producing a casting which has been subjected to solidification or hardening.

EFFECT: production of castings with decreased bubble formation or without bubbles, also structure elements made out of these castings maintain dimension uniformity and possess improved mechanical properties.

20 cl, 32 dwg, 17 tbl