2020 Volume 92 Issue 2 Pages 75-82
Microstructures in as-cast state, after thermal shock and creep test of austenitic heat resistant cast steel with tungsten were investigated using scanning electron microscopy, energy dispersive X-ray spectrometry, X-ray diffractometry and X-ray photoelectron spectroscopy. The results indicate that tungsten dissolves in austenitic matrix and promotes the microstructural refinement of primary carbides. In addition, crystalized tungsten carbide is also detected. Furthermore, W substitutes for Fe and Cr in the primary chromium carbides, improving thermal stabilization. As a result, primary carbides are difficult to decompose at elevated temperature. Microstructures which provide both of solid solution strengthening and dispersion strengthening are effective for enhancing high temperature properties of austenitic heat resistant cast steel.
