Characterization of Microstructural Features in Stainless Steels
Fig. 1.1: Pattern Quality Map depicting the microstructure of a stainless steel sample; map was acquired using eFlash XS EBSD detector mounted on JSM IT200 SEM.
Mechanical properties of raw metals and alloys are controlled through various sequences of thermo-mechanical forming processes, e.g. rolling, forging, extrusion, etc done at room or high temperatures. EBSD is commonly used to quantify the deformation state of grains in these materials which would define their properties and, when necessary, refine the forming parameters to achieve the desired properties. ESPRIT 2 provides an intuitive interface and all means necessary for this type of analysis to be successful, such as grain misorientation maps, subsetting options based on local misorientation and crystallographic texture representation options.
Fig. 1.2: Phase Distribution Map showing Ferrite phase in red and Austenite phase in green; phase ratio was 39% and 61% respectively; mapping time: 18:01min, Map size: 548,000pixels, zero solutions: 5.7%. No data cleaning applied!
Fig. 1.3: Grain Average Misorientation (GAM) Map indicating that certain regions/grains contain larger orientation change than others with values increasing from blue to red (15 degrees)
Fig. 1.4a: Subset of GAM Map for Austenite phase indicating that most grains contain little to no internal orientation changes; as the orientation change within a grain is often related to its deformation state, one can use such results to study the effect of parameters like temperature on the microstructure during thermomechanical manufacturing processes, e.g. hot rolling, extrusion or forging.
Fig. 1.4b: Subset of GAM Map for Ferrite phase indicating that the Ferrite grains contain large internal orientation changes; when comparing with Fig. 1.4a it appears like the stainless steel sample has been subjected to a thermomechanical forming process which led to dynamic recrystallization of the Austenite grains while the Ferrite grains experienced recovery only.