Relationships Between Processing, Microstructure, and Tensile Properties of Co–Cr–Mo Alloy

Abstract

Stellite alloy no. 21 was produced via rapid solidification processing (RSP) in a variety of particulate morphologies (coarse and fine powder, fibres, and ribbons), the various RSP forms showed similar fine microstructures with only slight differences in the scale of the microstructural features. These RSP particulates were consolidated by extrusion, dynamic compaction, and rapid omnidirectional compaction (ROC). Dynamic compaction proved to be unacceptable for this alloy because of non-uniform porosity and the inability to develop a metallurgical bond between particulates. A plot of elongation against yield strength depicted two yield strength-ductility relationships for the Co–Cr–Mo type alloys. As-ROC samples had a low yield strength-ductility relationship. However, after hot forging, the relationship shifted to a level comparable to similar material processed by conventional extruding and forging operations. Atomized powder size also affected the strength-ductility relationships of the extruded products. Decreasing powder size increased ductility without affecting yield strength. PM/0294