Integrated Rapid Solidification and Heat Treatment using Computerized Electron Beam Processing

Martensitic refinement is observed in rapidly solidified high speed steel (M7) by introducing a short ‘thermal arrest’ during cooling. This is accomplished using microcomputer controlled electron beam deflection for the generation of preselectcd scanning patterns. Such a tcchnique provides a high degree of control over short-duration heating at high temperatures and thus facilitates the use of fast reaction rate kinetics. By programming a ‘thermal arrest’ in the austenite range it has been found possible to obtain a distribution of fine carbides within the solidification cells. These carbides, it was found, result in refinement of the martensitic structure.