At thermal junctions of aluminium alloy castings and at points where risering proves to be difficult there appear internal or external
shrinkages, which are both functionally and aesthetically inadmissible. Applying the Probat Fluss Mikro 100 agent, which is based on
nano-oxides of aluminium, results in the appearance of a large amount of fine microscopic pores, which compensate for the shrinking of
metal. Experimental tests with gravity die casting of AlSi8Cu3 and AlSi10Mg alloys have confirmed that the effect of the agent can be of
advantage in foundry practice, leading to the production of castings without local concentrations of defects and without the appearance of
shrinkages and macroscopic gas pores. Also, beneficial effect on the mechanical properties of the metal has been observed.
An analysis has been carried out of the influence of annealing time at the preheating temperature of 650 °C on the change in hardness and alloy structure of lamellar graphite cast iron in the working as well as in the laboratory conditions. This preheat temperature is common during reclaiming welding of castings with complex shapes. The changes in unalloyed cast iron EN-GJL 200 to EN-GJL 300 according to ISO 1690 standard and cast iron with low amount of elements such as Sn, Cu, Cr, and Mo and their combinations were assessed. It was found that the cast iron of higher strength grades has better hardness and structural stability. Cast iron alloyed with chromium or its combinations has the highest stability. In unalloyed cast iron, a partial degradation of pearlite occurs; in alloyed cast iron the structural changes are not conclusive.
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