Metengr,
Special circumstances make us to consider the use of T91 in waterwall application. We may be able to find a way to heat treat it after welding, but don't know if there are unexpected problems down the road.
Not too sure. Most likely, these "cracks" are just crack-like, the material in these areas were melted during welding, but re-solidified when the heat was removed to leave no voids in the material, therefore the fatigue strength will probably not impaired. However, if the melted area is subject...
It depends on whether the material has residue stress in it to start with. If the residue stress is negligible, it should not shrink -- my personal opinion.
Henk,
Stress relieving 300 series s.s at 775F will only remove the peak stresses and aid in dimensional stability. The stress removal process is really slow at this low temp., one source recommended that the soak time be 4 hrs per inch.
If 1900F solution annealing has already done, will re-solution annealing at higher temperature, say 2100F, fully restore the material's creep strength?
You do not have to know the actual yield and shear strength.
It seems that although a coefficient of friction of this AlTiN, .4, is not too impressive, it will serve your purpose well as you mentioned that you only need a coeeficient of .2 to .3.
Section II, Part D, Appendices 1& 2 give the basis for determining the allowable stresses for materials listed in Part D. One may use the procedures provided in these appendices to estimate the allowable stresses for new materials, BUT the allowables so derived can NOT be used for designing...
