Wire drawing failures and tungsten fracture phenomena

For usual drawing conditions of tungsten wire the following fracture phenomena are relevant: transgranular cleavage, intergranular brittle fracture and ductile fracture. The paper describes the correlations between fracture morphology and the main influencing drawing parameters, especially the ratio between drawing and flow stress, reduction in area, die geometry and the corresponding stress distribution, back pull stress, lubrication and slippage on the drawing drum. The special importance of the correct drawing temperature is considered by an analysis of the microstructural dependent ductile-brittle transition temperature as well as the polygonization temperature. The most detrimental splitting behaviour of tungsten wire is treated as a special case of intergranular brittle fracture.