Material Structure Determines Successful Hardening
In the photo to the right, the white area of the part has been treated and appears to be sufficiently hardened.
However, upon measuring, only area ① had reached the minimum required hardness of HRC46.
Inspection by microscope of area ③ shows that most of the structure is ferrite and only a small portion is pearlite.
Ferrite does not harden even after repeated heating and quenching. For stable hardening, a minimum of 70% pearlite is required, especially in cast metal.
This sample material had low pearlite in some areas.
IH hardening, which hardens stell in a short time, can be affected by such insufficient composition.
As in this case, the raw material affected the hardening quality.
The quality of cast iron can vary from lot to lot and must be considered.
At Fuji Denshi, we examine material using our x-ray metal analyzer to ensure quality hardening can be achieved.