EXPERIMENTAL CHARACTERIZATION AND COMPUTER-BASED DESCRIPTION OF THE CARBURIZATION BEHAVIOR OF THE AUSTENITIC STAINLESS-STEEL AISI 304L

The carburization behaviour of the austenitic stainless steel AISI 304 L was studied in order to derive the necessary input data for a quanti tative description by means of a computer model based on the physical processes. Continuous thermogravimetry was applied to determine the ki netics of carbon uptake in gases of carbon activities of 0.3 and 0.9, respectively, in the temperature range from 800 degrees C to 950 degre es C. Detailed quantitative analysis of the corresponding microstructu ral changes, e.g. the depth of the zone of internal carburization. the phases formed and the dependence of the composition of the carbides a nd of the metal matrix on the distance to the surface, was carried out using optical, scanning electron and transmission electron microscopy . Selected results in combination with reasonable simplifications were used to adapt a computer programme regarding thermodynamics and kinet ics. A comparison between experimental data not used for this adaptati on and calculated data shows very satisfactory agreement illustrating the accuracy of the prediction method used.