Since other members wrote, that my my original question here Shuttle main engines RS-25 refurbishment/material damage was too broad I modified it to asked just one thing, while the other questions I will asked later.
There was some thread here on Space Stack-Exchange about RS-25 refurbishment, but I am interested now, how this refurbishment look from the point of material damage of SSME hardware.
In the early years of the shuttle, SSME needed months of refurbishment and turbopumps must be from safety reasons completely disassembled into small parts. In 30 years of Shuttle program, SSME went through 5 mayor redesign/overhauls but even in 2010 they needed detailed inspections after each flight and some parts refurbishment/replacement. (Quote from Daniel Dumbacher, deputy director of the Exploration Launch Office at NASA's Marshall Space Flight Center, Huntsville, Ala..)
My question :
On those parts of 2010 version of SSME (latest redesign/overhaul version) that needed refurbishment/replacement after each flight, was there some material damage, some cracks, erosion of the surface, etc. For example cracks, erosion of the surface inside pre-burner, combustion chamber or rocket nozzle as a result of heat and pressure of combustion process? Or simply cracks as result of mechanical stresses on engines, turbopumps during ascend ?