The article presents results of heat treatment on the high chromium cast iron. The study was carrying out on samples cut from the casting
made from chromium cast iron. Those were hardened at different temperatures, then tempered and soft annealed. The heat treatment was
performed in a laboratory chamber furnace in the Department of Engineering Alloys and Composites at Faculty of Foundry Engineering
AGH. At each stage of the heat treatment the hardness was measured by Vickers and Rockwell methods, and the microscope images were
done. Additionally based on images from the optical microscope the microstructure was assessed. Based on these results, the effect of
hardening, tempering and soft annealing on the microstructure and hardness of high chromium cast iron was studied. Next the effects of
different hardening temperatures on the properties of high chromium cast iron were compared. The study led to systemize the literature
data of the parameters of heat treatment of high chromium cast iron, and optimal conditions for heat treatment was proposed for casts of
similar properties and parameters.
The paper presents research on the effects of soft annealing parameters on a change of the impact strength KC and Brinell hardness (HB)
of the EN AC-AlSi11 alloy. The research has been performed according to the trivalent testing plan for two input parameters –
temperature in the range between 280°C and 370°C and time in the range between 2 and 8 hours. The application of such heat treatment
improves the plasticity of the investigated alloy. The improvement of the impact strength KC by 71% and the decrease of the hardness HB
by 20% was achieved for the soft annealing treatment conducted at a temperature 370°C for 8 hours, compared to the alloy without the
heat treatment. A change of the form of eutectic silicon precipitations which underwent refinement, coagulation and partial rounding, had
a direct effect on the hardness HB and impact strength KC. The results obtained were used to prepare space plots enabling the temperature
and time for soft annealing treatment to be selected with reference to the obtained impact strength KC and hardness HB of the alloy with
the heat treatment.