Magnesium Alloy Forging Temperature Range and Heat Treatments
Magnesium alloys are a family of light-weight materials used in a variety of applications, from medical devices to automobile parts. These alloys have excellent strength-to-weight ratios and are often chosen for their quick response time and elevated melting points. As with any metal alloy, there are advantages and disadvantages associated with using magnesium alloys. Prior to using these alloys, manufacturers must consider the forging temperature range and associated heat treatments.
The temperature range for forging magnesium alloys depends on the particular alloy’s composition. Generally, the melting point of pure magnesium is 924°C (1,700°F). Depen ding on the type of alloy being used, the forging temperature can range from 600°C (1,112°F) to 950°C (1,742°F). If the alloy is heated to a temperature above 1,000°C (1,832°F), there is a risk of the alloy starting to oxidize, which would reduce its strength. Furthermore, if the forging temperature is too low, the alloy may not attain the desired physical properties.
Once the forging temperature is determined, heat treatments can be carried out to further improve the properties of the alloy. Heat treatment is a process wherein the material is heated and held to a specific temperature, followed by quenching and a series of tempering steps if necessary. Heat treating provides a variety of benefits such as reducing internal stresses, improving strength, improving ductility and toughness and improving the corrosion resistance of the alloy.
The heat treating of magnesium alloys is divided into two categories: solution treatment and age hardening. Solution treatment is a heat treatment in which the alloy is heated to a temperature where all the solid solution constituents of the alloy are present in the liquid state. The temperature used depends on the composition of the alloy and is usually in the range of 450-550°C (842-1,022°F). After the solution treatment is complete, the alloy is quenched in water.
Age hardening is a heat treatment process consisting of aging the alloy at a temperature below its recrystallization temperature. The temperature depends on the type of alloy being used and can vary from 100-300°C (212-572°F). Age hardening produces a very fine, strain hardening matrix that improves the mechanical properties of the material.
In summary, different magnesium alloys may require different forging temperature and heat treatment ranges depending on their composition. Forging temperatures must be within the recommended range in order to avoid the undesirable oxidation of the alloy. Heat treatment provides the additive benefit of improving the mechanical properties of the alloy and should be selected to meet the application requirements.
