Heat Treatable Swivel Materials ?

For oil/gas drill ship, i'm building a swivel joint for burner boom which need to swing regularly, but found it's hard to put heat treatment which need for increasing hardness of the inner surface of the swivel, because of material itself . i used to make it with S45C for ordinary swivel, but for burner boom situation, it changed to SM490YB for high pressure sour gas use...it can be welded well to the STPG38 (or ASTM a106,gr B) pipes, good for shock/impact resist and sourgas resist, etc...but i found it very difficult to harden inner face of swivel by heat treatment for friction resistance... Any alternative materials for swivel or treatment for SM490YB ?