Andrew James conducted PhD research from 2015-2019 investigating crack initiation in carburised 316H stainless steel subjected to cyclic loading. He used 2D X-ray diffraction on small-scale tensile samples to analyze phase-specific and hkl-specific strain evolution in the oxide. He also measured bulk hkl information to inform mechanistic models of crack initiation. Through testing samples under monotonic loading and using a specialized loading rig, he was able to identify and classify small cracks. Observation of cracks post-test under SEM revealed both ductile failure in the bulk material and brittle failure in the oxide layer.

1. Mechanistic Understanding of Crack Initiation
in Carburised 316H Stainless Steel
Subjected to Cyclic Loading
Andrew James
PhD Researcher 2015-2019
Solid Mechanics Research Group

2. 2D X-ray diffraction on
small scale tensile samples
Phase-specific
strain evolution
hkl-specific
strain evolution
Above: Strain evolution measured in oxide.
Below: Bulk hkl information measured to
inform mechanistic models
Above: Sample tested under
monotonic loading
Below: Loading rig used in
experiment

3. Identification and classification
of small cracks Left: Magnified view of
ductile failure region
Right: One of
the main
surface cracks
showing brittle
failure in oxideAbove: Surface cracking
observed post test under SEM