wherein {HEAD ~ the damaged location} of {TAIL ~ the region} near the surface contains a degradation of a microstructure whereby that at least a specific microstructural portion falls below a required concentration, 
of
wherein { HEAD ~ the damaged location } of { TAIL ~ the region } near the surface contains a degradation of a microstructure whereby that at least a specific microstructural portion falls below a required concentration ,
OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH