It’s a technology installed at Mazda corporation and it has a patent.
From the induction hardening after carbonization hardening, the crystal grains are refined and grain boundary property during carbonization is improved, as an example, the gear improves in shock strength and conflicting of sporing strength improves at the same time and the strength of the gear gets stronger.

Comparison between carburizing + induction hardening products and conventional carburizing hardening products

	Crystal grain size	Fracture morphology
Carburizing + Induction hardening	Gc No.11	Intercrystalline fracture
Conventional carburizing	Gc No.8	Grain boundary fracture

The factroy is able to do

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