For plain stainless rod the typical specification is ASTM A276-304/316 and this can be specified in various conditions for the required mechanical properties. Cond A - Fult = 70 ksi, Fy = 30 ksi.
If you need higher strength you can use 17-4 in a heat treated condition based on ASTM A564 Type 630.
If you are attempting to follow a bolt specification use ASTM F593 and F594 - typical threading manufactures and Fastenal will provide SS bolts/washers/nuts to this specification.