Howmet Turbine Components Corporation

Robert J Smickley

Louis E Dardi

A method of refining the microstructure of metals which undergo a phase transformation at high temperatures by diffusing a solute material into the metal at a temperature below the normal transformation temperature. The solute induces the phase transformation and removal of the solute at a temperature near the transformation temperature reverses the transformation. These phase transformations refine the microstructure of the metal so treated. The method is particularly useful to Group IVB metals i.e. Zr, Hf and Ti.

Microstructural refinement of cast metal

The microstructure of titanium is refined by inducing a high temperature transformation from .alpha.+.beta. to .beta. and back to .alpha.+.beta. by diffusing hydrogen into and then out of the metal while maintaining the metal above the temperature of hydride formation. The titanium is heated to a temperature just below the .alpha.+.beta. to .beta. transformation temperature, and hydrogen is diffused into the metal thereby inducing the phase change. The hydrogen is diffused out of the metal again inducing a phase change. When the hydrogen has been removed, the metal is allowed to cool to room temperature.

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Whitehall, MI, United States of America

Robert J Smickley