High-Temperature Wear Behavior Of A Newly Developed Hot-Forging Cast Die Steel

Cast hot-forging dies as a new alternative for production of hot-forging dies reveal obviously economical and advanced features, compared with tradition machining dies from forged stock. Owing to high utilization ratio of materials, low finish allowance, short process time and high life, the cast hot-forging dies have been currently applied abroad. However most of hot-forging dies are manufactured in traditional way through machining from forged stork in home. This is mainly because the cast hot-forging dies give lower life and bad stability of quality, which is disadvantage in batch process. Therefore elevation of life is one of technical problems to need solving for large-scale production and application of cast hot-forging dies.Currently lives of domestically-made cast hot-forging dies are rather apart from the foreign counterparts (6000-10000 times or above). The key is to improve the high-temperature wear resistance of the cast hot-forging steels.The cast hot-forging die steels and processes have been normally selected on the basis of HRC andαK. Namely the basis of alloying composition design and processes optimization for cast hot-forging die steels is elevation of toughness. And toughness index is simply selected as impact toughness, because of neglecting effects of work condition and failure patterns of cast hot-forging dies. It is clear that the toughness index is taken as the basis of alloying design, thus wear resistance and life of cast hot-forging dies reduced. The advantage of cast material as the hot-forging die can't be exerted. Therefore extensive application and lives exaltation of cast hot-forging dies are directly hindered. Cosequently optimization of alloying composition design of the cast steels is key for cast hot-forging dies with long lives.The researches on high temperature wear resistance of cast hot-forging die steels are sparsely reported. Especially, influence laws and action mechanism of composition, microstructures and properties on high-temperature wear and high-temperature oxidation wear mechanism are not clearly known. So enough theoretic instruction can not be provided for alloying composition design and processes optimization of the cast hot-forging steels.Many studies have been made on high-temperature oxidation wear. Oxide formation, growth and delamination and their function on wear have been known. However high-temperature oxidation wear mechanism is not perfect. Tao, Tenwick...