Fatigue Characteristics of Nano-Structured Tool Steel Under Load Variation by Ultrasonic Cold Forging Treatment
Recently, the use of high strength steels (HSS) for automotive applications has been drastically increased not only to enhance the safety and durability of vehicles, but also lighten the weight for a high degree of fuel efficiency, In the side trimming operation in the production of HSS and mild steel, knife breakage and burr frequently occur. In addition, such breakage and bad quality of strip cutting face are affected by yield as well as by reduced productivity and reliability on production line [1–5]. This study examined the variation of mechanical properties of nano-structured surface by ultrasonic cold forged tool steel (SKD-61). Same ultrasonic cold forging treatment (UCFT) process was applied to produce the trimming knife. Their effectiveness and reliability of the UCFT were successfully verified through the field test by trimming process in cold rolling line of POSCO.
KeywordsHigh Strength Steel Severe Plastic Deformation Fatigue Limit Ultrasonic Vibration Compressive Residual Stress
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