Are you refering to bending stress or shear stress?

I do not recall seeing such info I usually use Goodman and SN curves based on 0.9 of yield stress for bending or 0.577 of bending for shear stresses. Remeber that spring wires can not be tested using the standard/ideal rotating bending tests. The spring manufacturing process leaves tool marks on the wire which affect fatigue life.

Try contacting the wire house.  A few years back this grade was being drawn by both National Standard and Bradford.

If I pull some old data sheets I find that for this size the strength should be 330-360ksi.
We estimated that Fatigue endurance limit is 38-40% of UTS.
The rest of the data:  Torsional yield - 55% UTS;
Yield in tension - 75% of UTS (though for CH900 I would expect this to be 85-90%); E=29.5Mpsi, G=11Mpsi

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.
http://www.trenttube.com/Trent/tech_form.htm

Haldex Garphyttan has some fatigue data for this grade.  Use the following links for more information:

http://www.read-eurowire.com/haldex.htm

http://www.hgse.haldex.com/ver02/global/showTxt.asp?mainDeptID=50&subDeptGrpID=71&subArtID=155&subArtSubCatID=74