Damage mechanisms in silicon nitride rolling tools applied in caliber rolling copper and steel wires

Among various kinds of metal forming processes, rolling is the most primary and important one. The rolling industry, however, is still dominated by tools made of steels or cemented carbides. These conventional materials exhibit severe drawbacks in service, such as excessive wear, thermal fatigue, high adhesion affinity to some metals and environmental related corrosion. There is an increasing need to develop advanced materials that meet the requirements for such challenging applications. High quality silicon nitride is acknowledged as a ceramic of first choice for applications where resistance to wear, fatigue and chemical corrosion are limiting factors in lifetime and performance. The application of silicon nitride in rolling tools have demonstrated extended tool lifetime and improved product surface quality. However, it is still limited in some fields such as caliber wire rolling, where some issues concerning the damage mechanisms, damage initiation and evolution as well as the wear behavior of the tool still needs substantial elaborations and deeper understanding.