Understanding the microstructure-properties relationship of low-temperature carburized austenitic stainless steels through EBSD analysis

The purpose of this paper is to explore the potential applicability of electron backscatter diffraction (EBSD) technique to reveal the correlation between phase transformation and hardness. First of all, EBSD was used to create kernel average misorientation (KAM) maps of the modified surface layers to identify the internal strains. Moreover, the preferential sites for precipitation of chromium-compound during annealing were identified. We prove here that EBSD can provide useful information to distinguish the main hardening mechanisms within modified surface layers at different annealing conditions. When combined with nano-indentation, X-ray diffraction (XRD) and glow discharge optical emission spectrometry (GDOES), an effective bridge between macro and microanalysis can be obtained. Solid solution hardening was found to be the dominant mechanism in as-carburized materials, with pre-existing strain promoting a higher supersaturation. In the annealed materials, the alloy composition and surface finish can also dictate the preferential sites of precipitation and can therefore affect the residual hardening.