Mechanical Characteristics of Nano-Structured Tool Steel by Ultrasonic Cold Forging Technology

  • Suh, Chang-Min (School of Mechanical Engineering, Kyungpook National University) ;
  • Song, Gil-Ho (Technical Research Center, POSCO) ;
  • Suh, Min-Soo (School of Mechanical Engineering, Kyungpook National University) ;
  • Pyoun, Young-Shik (Dept. of Mechanical Engineering, SunMoon University) ;
  • Kim, Min-Ho (School of Mechanical Engineering, Kyungpook National University)
  • Published : 2006.11.16

Abstract

Ultrasonic cold forging technology (UCFT) utilizing ultrasonic vibration energy is a method to induce severe plastic deformation to a material surface, therefore the structure of the material surface becomes a nano-crystal structure from the surface to a certain depth. It improves the mechanical properties; hardness, compressive residual stress, wear and fatigue characteristics. Applying UCFT to a rolling process in the steel industry is introduced in this study. First, the UCFT specimens of a tool steel (SKD-61/equivalent H13) are prepared and tested to verify the effects of the UCFT in a variety of mechanical properties, the UCFT is applied to the trimming knives in a cold rolling process. It has been determined that UCFT improves the mechanical properties effectively and becomes a practical method to improve productivity and reliability by about two times compared with the conventionally treated tooling in the trimming process in a cold rolling line.

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