There is a UNS Numbering System cross-reference guide, I believe available through ASM.
It's base listing is the UNS system, but there are then cross reference lists to ASTM, ANSI, etc.
Also, you should recall the basics behind ASTM numbers and UNS.
ASTM numbers are based primarily on mechanical property, whereas UNS is based on chemical composition. Hence, there isn't a straight one-for-one correlation.