Great site, thanks in advance.
I must weld approx. 20 downhill mountain bicycle frames of Reynolds 953 Stainless Steel. Reynolds has provided me with samples of tubing, and also their proprietary filler wire.
The bikes take extreme abuse, but must be very light, hence, the <1mm thickness. The welds must be applied to both butted and lugged joints. They must look great under paint, be strong, and deal with the heat sink aspect of a tube fitting inside a thicker lug. Many fabricators making only 1 or 2 frames use bronze or silver solder, but because of the number, I think TIG is the way to go. I have no experience with TIG on stainless steel, so I could use help in all areas: welder, torch, gas mixture, purging, heat treating, mar-aged (yes or no), cooling, on & on. I know this is a difficult weld under the best of circumstances, but round tubes with interrupted welds make it even more difficult. I would appreciate any help or comments you could provide. In advance, thank you for any help you can provide.
as for the welder, a miller dynasty 200dx or similar inverter with pulse settings will be best.
as for the torch, A #25 water cooled from tectorch, ck, or weldcraft.
also an oversize cup like the big pyrex one from ck will help the look of the welds greatly.
gas mixture ....argon will be fine,
purging, purge the back side of all welds with argon.
heat treating is a design issue that i cant answer. this material can be welded aged, or aged after welding...depending on properties needed,
mar-aged (yes or no), cooling, on & on.
here is the thing on maraging stainless... it will not get hard and brittle from welding. but some loss of strength will occur in the haz if the tubing is in the aged state prior to welding. you have to determine if this is acceptable. its the same as welding heat treated aluminum like 6061. a lot of bike makers dont heat treat age the bike after welding because the weld area is more rigid just due to design.