EBSD Study of Creep‐Induced Lattice Misorientation in MgO‐Particle‐Reinforced Austenitic Steel Composites

Creep in compression experiments at 900°C are conducted on coarse‐grained steel‐ceramic composites reinforced with different volume fractions of recycled magnesia particles. Strain accumulation within the austenitic steel matrix is characterized through detailed electron back‐scattered diffraction (EBSD) analysis using the parameters kernel average misorientation (KAM) and grain reference orientation deviation (GROD). The creep resistance is significantly improved by increasing the volume fraction of ceramic reinforcements. Subgrain formation in the steel matrix is identified as the dominant creep mechanism. Both parameters KAM and GROD are suitable for evaluating lattice misorientation in the as‐sintered and creep‐deformed microstructures. Higher ceramic volume fractions increase the average lattice misorientation in the as‐sintered states. Under the same applied creep stress, the unreinforced steel matrix and composite variants show comparable misorientation distributions. An increase in the applied stress significantly shifts the distributions to higher misorientation values. High‐resolution electron channeling contrast imaging (ECCI) is used to confirm that KAM mapping reliably identifies subgrain structures within the steel grains. Average subgrain sizes range from 2 to 4 µm and decrease moderately with increasing creep strain. No significant differences in subgrain size are observed between the unreinforced steel and the composite variants.