Aging of a Low Carbon Heat Resistant Cast Alloy

The changes in microstructure that take place during aging a low carbon heat resistant alloy at 750°C for a period of time of up to 1,000 h were studied by optical and scanning electron microscopy, X-ray diffraction and mechanical testing. The microstructure of the as-cast alloy consisted of an austenitic matrix and a network of Nb- and Cr-rich primary carbides that were identified by their tonality when viewed in backscattered mode in a scanning electron microscopy. Aging promotes precipitation of secondary carbides and the transformation of the Nb-rich particles. The mechanical properties are affected by the occurrence of the different phenomena