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

before treatment

Large and nonuniformity structure
before treatment (hot forging)

after treatment

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



Continuous furnace
Continuous furnace
Car bottom furnace
Car bottom furnace

The factroy is able to do

Numata Factory
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
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
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

Contact Us

Nagato Heat Treatment (Thailand) Co., Ltd.
7 /379 Moo 6, Tambol Mabyangporn, Amphur Pluakdaeng, Rayong, Thailand
Tel. +66-(0)38-027-473  Fax. +66-(0)38-027-475