One problem you may be encountering is that 18-8 is generic and includes several different austenitic stainless steel alloys, and I believe it includes type 303 alloy.
Type 303 stainless alloy is a free machining alloy that contains low melting point constituants (LMPC) that usually results in solidification cracking long the centerline of the weld bead. Type 303 ASS is often used for stainless steel bolts and nuts due to it's free machining characteristics. A change in the welding process will not eliminate the potential for cracking due to the use of LMPC used to promote the free machining characteristics.
You may have to purchase hardware made from 304 or 316 ASS alloys to prevent cracking. More expensive; yes, but easily welded.
Best regards - Al