SEDL / STP / STP408-EB / STP46047S

Water Jet Impact Damage in a Cobalt-Chromium-Tungsten Alloy

Beckwith, D. J.
Metallurgist and head of materials group, English Electric Co., Whetstone, Leicester

Marriott, J. B.
Metallurgist and head of materials group, English Electric Co., Whetstone, Leicester

Pages: 14    Published: Jan 1967

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Abstract

The mechanism of water jet erosion in a wrought cobalt base alloy used for shielding steam turbine low pressure blades is shown to be a three-stage process. Detailed metallographic examination of lightly eroded polished surfaces has confirmed the presence of carbide/matrix interface cracking and slip line cracking during the initial stage. Similar damage is observed during conventional fatigue deformation. The relative importance of these two modes of cracking during the subsequent stage is indicated, and the over-all kinetics of the process are discussed in terms of the alloy structure and the nature of liquid jet impact.