Quenching SS Welds

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A comment came up in this thread that cautioned against spraying a hot weld with water.  http://www.weldingweb.com/vbb/showthread.php?t=9810Figured this is one of those old welders wisdoms that deserves some discussion and clarification.  Somewhere you were told/taught, "never quench a weld in water, it'll harden it/crack it/ whatever"!   Well I say, you are perfectly safe in quenching 300 series stainless steel welds.  They will not harden or crack, and quenching can actually be beneficial to the steel.   Does anyone know why it will not harden, and in what way could quenching be beneficial to the stainless?
Reply:Does anyone know why it will not harden, and in what way could quenching be beneficial to the stainless?
Reply:Originally Posted by pulserin what way could quenching be beneficial to the stainless?
Reply:300 series stainless is non-hardingChuckASME Pressure Vessel welder
Reply:some metals are very finiky with heat, i prefer to let anything i weld cool naturally.
Reply:300 series stainless steels should be cooled rapidly to reduce the effects of carbide precipitation which makes the more prone to corrosion.
Reply:This is cool!! ...zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Originally Posted by zapsterThis is cool!! ...zap!
Reply:quenching stainless steel actually anneals the metal, copper also
Reply:So generally when I complete a weldement in 300 series SS ,throwing it into a water sink will decrease carbide preciptation on the weld surface???Idealarc 300\300 TIG AC\DC
Reply:You guys pretty much quenched this topic!  1.  Yep, 300 series SS is not hardenable by heat treatment.  It is austenitic in structure, and stays austenitic when heated and quenched.Carbon steel on the other hand is hardenable by heat treatment.  It changes structure from ferritic to austenitic upon heating (above about 1300 F) and alloying elements such as carbon readily dissolve and diffuse throughout the structure. Upon rapid cooling (quenching) however, the carbon becomes trapped and bound up within metal structure as it attempts to change back to ferritic.  This forces the formation of a new structure, martensite, which is highly stressed by the trapped carbon, and thus is hard and brittle.Reheating the quenched and hardened steel, called tempering, will release some of the trapped carbon, reducing hardness and brittleness, and increasing toughness and impact strength.2.  Quenching 300 SS helps limit carbide precipitation.Carbide ppt, also called sensitization, is the formation of chromium carbides during the heating cycle of welding (800 - 1500 F).  The carbides rob the protective Chromium from the grain boundaries within the steel and make it susceptible to intergranular corrosion.  Keeping the SS heat affected zone (HAZ) small by limiting heat input, and cooling between passes helps minimize carbide ppt.  The low carbon grades of SS, 304L, 308L, etc. have lower carbon to help prevent carbide ppt.  Stabilized grades 321 and 347 have Titanium and Niobium (Columbium) additions which are stronger carbide formers than Chromium so the Cr remains as a corrosion protective element.lorenzo: A+ on carbide pptChopper 5: A+ on non-hardenable76GMC1500: A+ on carbide pptChenS, the carbide ppt occurs between the grains throughout the metal that has been exposed to the detrimental temperature and time.  It is primarily a issue in the HAZ next to the weld metal.  In a corrosive atmosphere the metal next to the weld with "dissolve" away, leaving grooves like wagon tracks along the weld edges.drivethruboy54:  B+ on SS & copper annealing.  It is the heating that anneals the metal.  In the case of steel it would have to be slow cooled to remain annealed.  As you say, both SS and copper remain annealed after quenching since they are non-hardenable by heat treatment.Thanks for the comments,
Reply:very intresting stuff..
Reply:I just wanted to add that Carbide Precipitation can be controlled after welding is completed and dosen't have to be addressed at the time of welding. By bring the weldment to the range of 1850F to 2100F then quenching the weldment during the cooling cycle through the temp range 1400F to 800F.  The downside to this high temperature thermal treatment is that the weldment may distort if it is too large to be accommodated in a furnace.NO.... I did not google my original answer..... nor did I google the information in this post...._________________Chris
Reply:Also, using stablized grades such as 321 and 347/348 as well as low carbon modified, anything followed by an L such as 304L or 316L reduces/eliminates the problems of carbide precipitation.
Reply:Some photos of corrosion gone rampant in weld HAZ with carbide precipitation.http://i56.photobucket.com/albums/g1...arbideppt1.jpghttp://i56.photobucket.com/albums/g1...arbideppt2.jpghttp://i56.photobucket.com/albums/g1...rCorrosion.jpg
Reply:Very cool pictures.
Reply:Originally Posted by pulserA comment came up in this thread that cautioned against spraying a hot weld with water.  http://www.weldingweb.com/vbb/showthread.php?t=9810Figured this is one of those old welders wisdoms that deserves some discussion and clarification.  Somewhere you were told/taught, "never quench a weld in water, it'll harden it/crack it/ whatever"!   Well I say, you are perfectly safe in quenching 300 series stainless steel welds.  They will not harden or crack, and quenching can actually be beneficial to the steel.   Does anyone know why it will not harden, and in what way could quenching be beneficial to the stainless?
Reply:I'll check out your thread on distortion control.Thanks for adding that dimension to the SS quenching topic.
Reply:Thanks for the info guys! Is there a post on here that explains metaluurgy sp?? for AL,CS,Ti ,Mg??