Stainless steel requires less amperage than carbon steel.  
The one amp per one thousandths rule of thumb works pretty well on carbon steel.  But stainless only requires about 2/3 of one amp for every one thousandths of thickness.

For all you metric folks, your rule of thumb is 40 amps per 1mm.

So for this 1/16" thick (1.6mm) stainless , about 45 amps worked very well.   If you do the math, that works out to 0.7 amps per one thou.

1,6X40=64A carbon steel

(2/3=0.7) Stainless steel 

64X0.7=44,8 A=1,6mm Stainless steel