Our mate TomC is talking about a 3" radius spring , will that work ?Yes, a 6" radius can be bent with the right piece of wood.
I have NO experience steam bending Cherry. This 1/4" thick piece of Hackberry I steamed is bent around a 2x4 end which is considerably less radius that your 6" radius. Being it was cut fresh, all that's required is to bring the wood to temperature since we aren't attempting to add moisture back. This piece was steamed for about 20 minutes.
For ease of steam bending a fresh cut from the tree will be the easiest and have the best success rate. Next would be air dried wood followed by Kiln dried. I don't even attempt Kiln dried and avoid air dried when possible.
Research steam bent wood stirrups and you'll see old white Oak and Hickory bent with real sharp radii. You can bet those were bent fresh cut and the convex of the bend was the outside of the tree to avoid grain blow out.