Heat treatment plays a crucial role in enhancing the mechanical properties of castings, making them stronger, more durable, and better suited for demanding applications.  

 

At Mabrey Precision Castings, we specialize in heat treatment processes designed to refine the microstructure of our sand and die-cast components, improving their strength, hardness, and wear resistance. In this blog, we’ll explore the importance of heat treatment, the different methods used, and how it enhances the performance of castings across various industries. 

 

Heat treatment, depending on the specification, consists of three key steps: Solution Heat Treatment to dissolve alloying elements, Quenching to lock in the structure, and Aging to enhance strength through precipitation hardening. 

The purpose is to heat the aluminium and aluminium alloy castings to the required temper designation as per drawing. Castings are kept at that temperature for a designated period of time so as to obtain the desired product structure and mechanical properties. 

 

This method involves heating aluminium alloy castings that to a specified high temperature near to the mushy state (solid solution state) typically 540C and holding them there for a nominated period of time for optimum performance, prior to quenching in water, typically at 80C pending requirement. 

 

This process enables the second phase or other soluble components in the casting such as Magnesium to dissolve fully into the aluminium matrix for maximum efficiency, forming a supersaturated solid solution, then locking in place by the following quench. 

 

Times and temperatures can vary pending the cross-sectional area of the casting and alloy type and temper requirement. 

Following on from Solution heat treatment, the castings are then cooled quickly using a fast-quenching method boiling water in our case, but in some cases a polymer quench is required for stability. 

 

This process creates an unstable state, because the solute atoms are in a higher energy state and can precipitate at any time, however, the material at this stage has higher ductility and can undergo cold working or straightening processes. 

 

Note: The casting will gradually try to revert to its’ natural state if left at room temperature for extended periods, so refrigeration can be required, especially on thin-walled cast parts. 

 

Our system allows for this time and castings are age hardened within in a short period of time following solution heat treatment. 

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After solution heat treatment and quenching, the material is held at room temperature or a higher temperature for a certain period of time. 

 

The unstable supersaturated solid solution will decompose, and the second phase particles will precipitate (or settle) from the supersaturated solid solution and distribute around the alpha (AL) aluminium grains, resulting in a strengthening effect called precipitation (or settlement) strengthening. 

 

Heat treatment is more than just an optional finishing step—it is a critical process that unlocks the full potential of cast components. Whether it’s stress relief, improved machinability, or enhanced wear resistance, the right heat treatment can significantly impact performance and longevity. 

 

Typical conditions are as follows: 

Note we are now using en-ac specifications, but most engineers will understand the older British Standard. 

At Maybrey Precision Castings, we combine expertise with precision-controlled processes to ensure our castings meet the highest standards. 

 

If you require high-quality, heat-treated castings tailored to your application, get in touch with our team today.