Removal of surface carbides from spark-machined molybdenum and tungsten
- 36 Downloads
When reactive metals such as molybdenum and tungsten are shaped by electrical discharge machining in the kerosene-based electrolytes generally employed for the process, they become covered with a thin, multiply-melted surface layer which contains carbide phases of variable composition. This surface layer is sometimes undesirable because its chemical and mechanical properties are different from the base metals. It has been demonstrated that the carbide can be removed by a high-temperature anneal in a reducing atmosphere. The anneal also removes surface cracks on molybdenum introduced by the machining, but the heat treatments employed here did not remove surface cracks on tungsten. The high-temperature anneal had the unfortunate side effect of inducing a significant degree of grain coarsening in the metals.
KeywordsPolymer Atmosphere Mechanical Property Carbide Heat Treatment
Unable to display preview. Download preview PDF.
- 1.N. C. Welsh,J. Inst. Metals 88 (1959–60) 103.Google Scholar
- 3.“Handbook of Chemistry and Physics”, 49th Edn Ed. R. C. Weast (Chemical Rubber Co., Cleveland, OH, 1968) p. B220.Google Scholar
- 4.A. Y. Nakonechnikov, L. V. Pavlinov andV. N. Bikov,Fiz. Metal. i Metalloved. 22 (1966) 234.Google Scholar