Shrinkage on 4"x6" HSS

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I am building a single stringer stair for my home. The eng. has approved 4x6 HSS with 1/4 inch wall for the stringer with the 4" being the width and 6" being the height of the stringer. I need to weld wedges of the same size HSS to the top of the stringer for the tread support. If I put that much heat every foot or so on either side of the wedge, will I end up with a banana shaped stringer from heat shrinkage?Thanks in advance!
Reply:Yes it will. HSS is very reactive to heat. I suggest some pre welding heat on the opposite side of where you want to weld the wedges. Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Hmm. Makes perfect sense. So heat it red hot on the same points underneath that i will weld on top?Thanks!
Reply:You can heat pre-weld, or post-weld.Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Somewhere between a talent contest and guessing game. It's all based on what you know has happened in the past and what you think is going to happen this time.  Just remember what happens in the middle will have a bigger impact than what happens near the ends. Proceed slowly."The things that will destroy America are prosperity at any price, peace at any price, safety first instead of duty first, the love of soft living and the get rich quick theory of life." -Theodore Roosevelt
Reply:Great advice! Thanks folks. I've never welded only on one side of HSS so ...... The other option I thought could use plate( instead of wedges of the same HSS) and run the plate up the sides so there is equal heat on both sides....Wish me luck!Last edited by rustysweldshoppe; 04-07-2013 at 03:37 PM.
Reply:Knowing where to put the heat is easy. Knowing how much heat to apply is the trick! Something this small I would use a #2 or #3 cutting tip in your O/A torch. I would also use a spray bottle of water for cooling. When cooling, the metal is still moving if you can feel heat with your hand.Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Groovy. Thank a bunch!