Volume 54, Issue 9

Tungsten carbide-cobalt hard metal produced by additive manufacturing offers opportunities to meet the increasingly complex requirements of high-performance machining. Besides a high level of design freedom and the easy integration of functional properties, the additive manufacturing of hard metals also offers potential for cost savings and conservation of resources. A window of favorable process parameters for laser beam melting was established using commercially available carbide powder with 17 % Co content, which serves to build carbide samples by laser-based additive manufacturing. Compared to conventionally manufactured carbides, deviations can still be noticed with regard to microstructural and mechanical properties. However, bending strengths of > 1 000 MPa and fracture toughness in the range of 10–12 Mpa √m are promising for the future additive manufacturing of WCCo hard metals.

Metallographic examinations using light and electron microscopy, EBSD analysis, and X-ray diffractometry were performed on four steels with different austenite content as part of a materialography student project. The aim was to provide a qualitative and quantitative determination of the austenite content present in each case. Different color etching techniques revealed the microstructure in different contrasts, austenite and delta ferrite phases could be differentiated, and the residual austenite could be determined in overaged steel using light and scanning electron microscopy (SEM). The areas revealed by color etching with a size of only a few μm in the light microscope could be correlated in the SEM and were identified by EBSD analysis.

The present paper deals with the microstructure-properties correlations of industrial electrical steel for efficient electric energy converters. The metallographic evaluation of quality is important for the understanding and the further development of this class of materials. For this purpose, a comparison between electrical steel sheets of the same quality, but from different manufacturers, was performed in terms of grain size, texture and composition.

Silicon carbide is a superior material for the manufacturing of semiconductors. This is where the project on the gaseous phase synthesis of SiC components made of carbon precursors comes in. On the basis of graphite substrates and a reaction with thermally evaporated silicon monoxide in the CVI process (chemical vapor infiltration), silicon carbide with strongly process dependent structural composition is formed. The process can be used for the coating of C substrates as well as for the manufacturing of complex components. With the help of new approaches in process development and via detailed materialographic microstructural analysis, the understanding of gaseous phase synthesis was promoted. The transition of different carbon structures in equivalent silicon carbide structures was verified.