Application of Laser Peening for Cold Work Steel

Forming technology using dies is utilized by various industries because of its reasonable price and high productivity. Cold forging technology is used in the automotive industry because it can make high precision products. However, die lifespan is a major concern because dies make up the largest proportion of manufacturing costs in cold forging. To improve die life, one can ensure the die’s exact physical properties through fundamental material development, or improve the die’s fatigue life through surface reforming. Laser peening technology mainly progressed as a technology for fatigue life improvement of aerospace parts. As a result, there is much literature about special materials (ex. Titanium, Inconel alloy). On the other hand, there is little literature about tool steel, which is used for cold forging and die-casting. In this study, basic research was conducted to determine the possibilities of laser peening as technology to improve the fatigue life of cold forging dies. As a result, fatigue strength improvement of JIS-SKD11 needs post-polishing because of Roughening of surface, besides, irregular position of chromium carbide inner material occur large variation of fatigue life.