Hardening is a method to cool down rapidly with oil and water after making the steel glow. Generally, a good hardness can be expected from hardening and the abrasion resistance will be improved. However, hardening is not enough as it can be fragile and unstable, so heat it again to a certain temperature. That is called tempering. The steel will be toughened by tempering at approximately 600°after hardening. Also, when conducted together, hardening and tempering are referred to as thermal refining.

Metallographic structure and treatment condition

Large and nonuniformity structure before treatment (hot forging)

Structure of ferrite + perlite is uniformed after treatment (standard structure)

Equipment

Continuous furnace

Car bottom furnace

The factroy is able to do

Numata Factory 2-23-1 ohzuka-nishi, , Asaminami-ku, Hiroshima-shi, 731-3167, Japan Tel. +81-(0)82-848-6021 Fax. +81-(0)82-848-6301	Shiwa Factory 190-1 Aza Fukasako, Kanmuri, Shiwa-cho, Higashi-Hiroshima-shi, 739-0265, Japan Tel. +81-(0)82-420-5511 Fax. +81-(0)82-420-5615
Kurose Factory 175-1 Ichiida, Kurose-cho, Higashi-Hiroshima-shi, 739-2626, Japan Tel. +81-(0)823-82-3068 Fax. +81-(0)823-82-3069