I'm about to weld the joints for a open web steel joist in a shop. All of the members are hollow square tube (aka HSS). This is going to be an "architecturally exposed" steel joist, meaning is has to be pretty. The wall thickness is 3/16". All fillet welds. The steel making up the tube is ASTM A500 grade B which is known to have some brittleness problems. What kind of TIG filler should I use?
--zeb