Tool steel parts that are processed and hardened at high temperatures can be protected from oxide buildup and scaling by creating a controlled atmosphere around them. One conventional methods is by using a furnace, which is either vacuumed or has the air inside replaced with neutral, non-reacting gases.
Steel tool foil for heat treatment
A more economical and highly effective way of protecting heat treated steel parts is by wrapping these with secured steel tool foil. Heat treatment foil is a sheet of steel which resists the precipitation of chromium carbide as well as other reactions during the heat treatment. Such foil, used in the needed size, can be folded and wrapped around the parts to work on, as to create an airtight package. Once it’s well sealed with a double edge, the foil no longer allows the air to come in.
The importance of a vent
Experts do recommend to leave a 5-mm vent in order to prevent expansion and tearing because of heated air. The vent is small enough to be helpful and not detrimental. To make sure there is only little air left inside, you can squeeze it out carefully by pressing the foil. This needs to be performed with great care, as the wrap can be easily torn.
Limiting oxygen reactivity
As long as there is no excess oxygen inside the package, you can rest assured that the reactions will not be damaging. It’s the same that happens inside ovens or furnaces – the air is taken out, to prevent oxidation. Some oxygen may still be left, but not enough to lead to unwanted effects.
How to select the foil to work with
Manufacturers produce steel tool wrap foil of various degrees, which give these more or less heat resistance. Thus, before you purchase, you need to select not only the right size, but also the desired heat resistance. Note that, in case you are opting for a double wrap, you will have to use slightly high temperatures for your steel components.
Because steel is reactive under high temperature treatment, protecting it is a necessary measure. Wrapping is not only effective, but is a method easy to employ and costs less than the other ones.