What is Induction Hardening - Overview by Ameritherm
This video from Ameritherm
explains the basics of Induction Hardening. Many types of steel are treated
with heat to increase toughness and resistance to wear. The effectiveness of
this process depends on the steel's carbon content. When the steel is heated
above its transformation temperature (720°C), the carbon changes the steel's
crystalline structure to an austenite. The harder, more brittle steel is then
quickly cooled or quenched.
To make the steel less brittle and more usable, another process called tempering
is used; the steel is slowly heated to just below the transformation temperature
and then slowly cooled.
There are two general types of hardening processes: through- hardening treats
the entire part, while case-hardening generally treats the part surface area
and some of the interior area, according to the depth of hardening requirements
for a specific application.
Modern induction heating provides reliable, repeatable, non-contact and energy-efficient
heat in a minimal amount of time. For hardening, induction provides the necessary
control and accuracy to focus the heat to a specific area of the part. Solid
state systems are capable of heating very small areas within precise production
tolerances, without disturbing individual metallurgical characteristics.
For case-hardening, typical frequencies are 450 kHz for case-depths of 0.030"
to 0.080"; thicker case-depths of 0.100 to 0.150" are typically hardened
at 10 kHz. It is important to heat the part quickly with high power density,
and then quench the part rapidly to prevent the inside of the part from exceeding
the transformation temperature. Through hardening is generally defined more
by the time required to heat through the part than the by the frequency of the
Typical RF power supplies for hardening range from 5 to 120 kW, depending
on the material and application requirements.
Run time: 1.21 mins