Microstructure and Failure Analysis of Austenitic Fe-Ni Alloys and Ni-Cr-Fe Alloys for Furnace Materials and Fixtures

The heat-treating industry is in need of heat-treatment furnace materials and fixtures that have a long service life and reduced heat capacity. Failure mechanisms on the effect of prolonged exposure to carburization heat treatment have been investigated. RA330, RA602CA, 316L and Inconel 625 alloys were selected to study the anti-corrosion properties. The alloys were exposed to 0.7%C carburizing atmosphere at around 900 degree Celsius for a range of times. Based on failure analysis of those components that were used in carburization furnace application, it was found that the primary reason for failure was the excessive carburization that leads to “metal dusting” and subsequent cracking. In this paper the failure analysis of industrial components will be presented. In addition, the preliminary analysis of microstructural development during long term exposure experiments in an industrial carburizing furnace will be presented. These samples were characterized using optical and scanning electron microscope and x-ray diffraction.