AFS Magnesium Div. developing new heat treatment method to reduce time, cost.

The AFS Magnesium Div. 6 Research Committee, Schaumburg, Ill., presented new developments in magnesium heat treatment cycles that can lead to significantly lower costs of magnesium cast components.

As part of committee discussions dating to last year, Eck Industries Inc., Manitowoc, Wis., and Technomics LLC, Plymouth Minn., began preliminary investigations on the fluidized bed heat treatment of magnesium alloys in January. The committee noted that magnesium alloys typically require long solution and aging cycles to achieve the desired mechanical properties, and this can add increased costs to heat treated magnesium castings. Thus, Eck and Technomics began to examine methods to reduce cycle times. Magnesium alloy AZ91E was chosen for the development because of its common use in many markets, and it usually requires a solution and age heat treatment of 32-40 hrs.

Using a combined solution and aging time of as little as 8-10 hrs., the minimum requirements of the alloy's mechanical properties were met. By heat treating in a shorter time frame, the heat treat costs for magnesium components can be one-third their current costs and less than the costs of conventionally heat treated aluminum castings.

Currently, the committee plans further investigations to improve the new heat treat development. Eck and Technomics have planned additional cycle development work to maximize mechanical properties of this alloy, and other magnesium alloy systems will be investigated, as well.