Magnesium alloy plate manufacturers tell you five common defects that are prone to occur during heat treatment of magnesium alloys: oxidation, over-burning, bending and deformation, abnormal grain growth and uneven performance.

Oxidation
If the magnesium alloy workpiece is heat treated without using protective gas, local oxidation will occur or even fire in the furnace. Magnesium alloy plate manufacturers tell you that 0.5%~1.5%SO2 (volume fraction) or 3%~5%Co (volume fraction), or CO2 protection containing 0.5%-1.5%SF6 (volume fraction) is usually introduced into the heat treatment furnace gas, or inert gas to avoid oxidation of magnesium alloy workpieces. Inert gases are less used due to their high cost. In addition, it is necessary to ensure that the furnace chamber is clean, dry and sealed.
burnt
When the heating speed is too fast, the heating temperature exceeds the solution treatment temperature limit of the alloy, and there are many low melting point substances in the alloy, the magnesium alloy workpiece is prone to overburning. Usually, the heating time from 260℃ to the solution treatment temperature should be more than 2h, and the furnace temperature fluctuation should be controlled within the range of ±5℃, and the zinc content should be reduced to the specified lower limit to avoid the damage of magnesium alloy workpieces. Burnt.
Bending and Deformation
The absence of fixtures or supports during heat treatment, lack of workpiece support, and uneven heat distribution can all cause bending and deformation of magnesium alloy workpieces. In order to reduce or eliminate the bending and deformation of magnesium alloy workpieces, the following aspects need to be paid attention to. Magnesium alloy plate manufacturers tell you that workpieces with thin sections and long spans need support; for workpieces with complex shapes, fixtures or forming brackets should be used; for workpieces with uneven wall thickness, the thin-walled parts should be wrapped with asbestos. At the same time, it is necessary to place the workpieces in the furnace reasonably to ensure good circulation of the furnace atmosphere and uniform distribution of heat. Residual stresses in castings can be removed by annealing. In addition, the heating rate should be kept moderate during the heat treatment.
abnormal grain growth
The use of cold iron in the layer-by-layer solidification results in too fast local cooling. If the internal stress is not pre-eliminated in the subsequent heat treatment, it is easy to cause abnormal grain growth in the magnesium alloy. Magnesium alloy plate manufacturers tell you that stress relief treatment before heat treatment, proper selection of cold iron during casting and intermittent heating method during solution treatment can effectively avoid abnormal growth of magnesium alloy grains.
Uneven performance
Uneven furnace temperature, insufficient thermal cycle in the furnace or inaccurate furnace temperature control, insufficient solution treatment time for thick section workpieces and uneven cooling rate of workpieces are the main reasons for the uneven performance of magnesium alloy workpieces. Magnesium alloy plate manufacturers tell you that the main measures to prevent the uneven performance of magnesium alloys are: use standard thermocouples to calibrate the furnace temperature; the thermocouples that control the furnace temperature should be placed in the place where the furnace temperature is required to be uniform; Thermal cycle; regularly check the temperature control device of the heating furnace to ensure that it is working properly; appropriately extend the solution treatment time for thick-section workpieces to obtain a completely uniform structure; perform secondary heat treatment if necessary.
Magnesium alloy plate manufacturers tell you that the above is about the defects that are prone to occur in the heat treatment of magnesium alloys, and it is also what we need to pay special attention to!