Induction heat treatment uses electromagnetic induction to precisely target a particular area of metal to be hardened. It’s a quick process with cycle times that are often less than a minute. Induction also offers less distortion than some other heat treating processes, especially when only the targeted area is heated.
What is heat treatment process types?
The workpiece is placed in the center of an alternating magnetic field where it experiences resistance to eddy currents, which create Joule heating. This leads to the phase transformation of the metal into martensite, causing the material to become harder. The workpiece is then quenched to temper the brittle martensite into tougher tempered martensite, allowing it to have more ductility and strength.
Depending on the frequency of the alternating current, deeper or shallower heating into the workpiece can be achieved. Lower frequencies produce Joule heating at a greater depth, while higher frequencies only reach to the surface of the workpiece. This is why many treaters use a range of frequencies to optimize the hardening of a variety of materials and workpiece shapes.
Induction is particularly useful for the field heat treatment of ferro-magnetic materials, including iron and its alloys. This is due to the fact that induction can be used to directly heat an item without having to move it into a furnace chamber. This allows for much faster processing times and tighter control over the heat-treating of a part.