Dissolution of Iron-Chromium Carbides during White Layer Formation induced by Hard Turning of AISI 52100 Steel

The (Fe, Cr)(3)C carbide morphology in the surface region of hard turned bainitic AISI 52100 steel was investigated using both experimental techniques and simulations, where microstructural analysis was correlated with analytical studies of the carbide dissolution kinetics using DICTRA(1). The experimental results showed that for both predominantly thermally and mechanically induced white layers no significant carbide dissolution took place down to a depth of 20 mu m below the machined surfaces. This was confirmed by the analytical results from DICTRA, which showed that no significant carbide dissolution should take place during hard turning given the short contact times. Within the hard turned surfaces up to similar to 12% of the carbides were elongated, indicating plastic deformation of the carbides during machining.