Hard shot peening

Collisions of the shots which are small and hard balls of steel quickly through the Normal shot peening on the surface after carbonization and induction hardening will enhance the hardness of the parts and fatigue strength.

Treatment condition
Treatment condition

Collide the balls of steel on the
surface at high speed.
Air nozzle projection.

Metallographic structure

Retained austenite

The strain induced transformation by shot projection

Volume expansion

Compressive residual stress


Production mechanism of compressive residual stress

Production mechanism of compressive residual stress
  1. 1.Retained austenite
  2. 2.The strain induced transformation by shot projection
  3. 3.Volume expansion
  4. 4.Compressive residual stress

Distribution of compressive remaining stress
after shot peening (carbonization parts)

  • Hard shot peening
  • Usual shot peening
  • Without peening / No peening

Effect of compressive residual stress

  • TSCM620Carburizing + Hard shot peening
  • SCr420Carbonitriding + Hard shot peening
  • SCr420Carburizing + Usual shot peening
  • SCr420Carburizing
Compressive residual stress

Because the tensile stress on the surface can be reduced by high compressive remaining stress occurring from hard shot peening, the effect can see in improving fatigue life.



Hard shot peening machine
Hard shot peening machine

The factroy is able to do

Kaita Factory
Kaita Factory

9-9 Tsukimi-machi, Kaita-cho, Aki-gun,
Hiroshima-ken, 736-0034, Japan
Tel. +81-(0)82-822-2957
Fax. +81-(0)82-822-7294
Hofu Factory
Hofu Factory

26-1 Shintukiji-cho, Hofu-shi,
Yamaguchi-ken, 747-0824, Japan
Tel. +81-(0)835-25-3737
Fax. +81-(0)835-25-8626

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