EVALUATING THE EFFECTIVENESS OF SPECIAL HEAT TREATMENT CARRIED OUT ON AZ91 MAGNESIUM ALLOY TO PREVENT THE GRAIN GROWTH

Properly conducted heat treatment of cast magnesium alloys is a very important tool in increasing the mechanical properties of castings. Nevertheless, during high temperature annealing of castings made from magnesium alloys, some disadvantageous changes occur in them, mainly rapid alloy oxidising and excessive grain growth. The latter effect is particularly dangerous for metals crystallising in the hexagonal system. To prevent this effect, special heat treatment is applied to the most popular magnesium-based alloy, i.e. AZ91. The aim of this article has been investigation of the effectiveness of a special heat treatment of the alloy, compared with standard route. A method to evaluate the effectiveness of this treatment was measurement of the grain size and testing of mechanical properties.

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