Breakdown Behavior of Eutectic Carbide in High Speed Steel During Hot Compression

The evolution of eutectic carbide in as-cast M2 high speed steel was investigated with hot compression test and metallographic examination. Initial rodlike or irregular eutectic carbides were broken into smaller particles during hot deformation by thermomechanical disintegration, while diffusion-controlled phase transformation was not remarkable. Combining with numerical simulation, the relationship between breakdown ratio of carbide network and deformation parameters was obtained. Strain was the most important driving force to shatter eutectic carbides and disperse products. Furthermore, critical strain values were obtained, beyond which carbide network disappeared, and fractured carbides kept a stable profile and they were deformed with matrix coordinately. A higher temperature or lower strain rate resulted in a lower critical strain.