304 SST Solution soak?

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Yah Solution SoakI've done some reading and I believe that when I heat SST to a high temperature as in welding or brazing I gotta do a solution soak to correct the metallurgy that heating it screwed up..I understand that the "Solution Soak" is just  trade vernacular for an anneal and after welding the thing to do is a full anneal:The metal is heated to 1080°C and cooled rapidly in a 70°C water bath. and that's it. This will cause the Chromium to return to the surface of the steel allowing the natural precipitation of the passive layer. I am pretty sure that  no amount of Ascorbic acid passivation will do this  that only the heat treat anneal will accomplish the task. Is this all correct? What happens if I over shoot the temperature? And what color would that be when eyeballing the temp using a gas torch? My current app is 304 SST pipe fittings:  1/2" Nipple1/2" coupling a  pipe thread straight thread nut that fits the 1/2" pipe thread an O ring a SSt washer I am using Harris SaftySilv 56 to join the nipple and nut and coupling so that when I use the O ring there won't be any leaking through the  threads    which no o-ring will ever seal Here is  pix of the  problem I'm trying to solve:http://s1002.photobucket.com/albums/...1.jpg&newest=1Here is the coupler I've brazed togetherhttp://s1002.photobucket.com/albums/...inglabeled.jpgNote where the O ring goes.  There is no seal-able surface on the nipple 'cause it's all threads.  I don't want my SST fittings to rust in the pH 4.5 beer wort where they will be going.Last edited by Raul; 08-30-2010 at 08:12 PM.
Reply:Carbide precipitation is only a concern when the steel reaches a temperature of over 800deg for an extended period of time.  For the low heat involved in silver solder you shouldn't have any issues with precipitation.Have we all gone mad?
Reply:Originally Posted by sn0border88Carbide precipitation is only a concern when the steel reaches a temperature of over 800deg for an extended period of time.  For the low heat involved in silver solder you shouldn't have any issues with precipitation.
Reply:I still dont think it should be a problem, as brazing takes place from 450-650deg I believe.  And since the part is so small it can be done very quickly, so not much of a risk of overheating it.I dont see any reason that you would need to solution soak these parts.  You could passivate them to get the color back if thats what you desire.Have we all gone mad?
Reply:could you use a temp stick to gauge the temp u need. you can buy em at the welding supply instead of the eyeballing method lol! might take the geuss work outa that part.
Reply:Whats the expected service environment?I still dont think that this could be considered a problem, carbide precipitation happens from 800-1200F.  Even if you overheated the part and made it into that range, it shouldnt stay there for more than a few seconds provided you are competent with the brazing process.Have we all gone mad?
Reply:Originally Posted by sn0border88Whats the expected service environment?
Reply:Originally Posted by dyrvalecould you use a temp stick to gauge the temp u need. you can buy em at the welding supply instead of the eyeballing method lol! might take the geuss work outa that part.
Reply:According to the chart which Zapster recently posted, the melting range for that alloy is 1175 to 1200*F so the parts will get into the range of concern, but should not be there long enough to do any real damage, I suspect.  Annealing by torch "at 1080" might not be too bad for a welded joint, but for a silver soldered one, you risk ruining the joint itself by worrying about the base metal.
Reply:Originally Posted by RaulI brazed 'em together today, and dunked 'em into water when still hot, and then did an abrasive polish job on them and now they are soaking in Citric Acid for passivation.
Reply:Originally Posted by sn0border88Nothing wrong with that, im sure it will work well for you.
Reply:Let me ask a dumb question here.   What are the consequences of not performing the solution soak?  Suppose I get it red hot, and hold it at a high temperature for a minute or more, and then let it cool gradually?  What properties of the stainless have I damaged?   Corrosion?  Strength (yield)?  Toughness?If you lose corrosion resistance, could you not partially make that up with passivating?I have heard about this problem, but I have not understood it.  If somebody can point me to a good source to read more I would appreciate it.Thanks,RichardSculptures in copper and other metalshttp://www.fergusonsculpture.comSyncrowave 200 Millermatic 211Readywelder spoolgunHypertherm 600 plasma cutterThermal Arc GMS300 Victor OA torchHomemade Blacksmith propane forge
Reply:Originally Posted by rafergusonWhat are the consequences of not performing the solution soak?  Suppose I get it red hot, and hold it at a high temperature for a minute or more, and then let it cool gradually?  What properties of the stainless have I damaged?   Corrosion?  Strength (yield)?  Toughness?