Welding Stainless Steel 316- Quenching or Not?

Discussion in 'Materials' started by raf pali, Jun 22, 2018.

  1. raf pali
    Joined: Mar 2012
    Posts: 71
    Likes: 1, Points: 8, Legacy Rep: 12
    Location: Australia

    raf pali Junior Member

    Some time back I heard that SS welding should be quenched. I vaguely remember is to avoid precipitation of atoms or some thing of the like.
    I did a search on the net and found little about it and some confusing info too.
    Does anyone here know of it please?
     
  2. Ad Hoc
    Joined: Oct 2008
    Posts: 5,675
    Likes: 247, Points: 63, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    You can do whatever you like, with, anything you like.

    But, in doing this, what is your objective...?...what do you have to gain or achieve...since your question is far too vague.
     
  3. raf pali
    Joined: Mar 2012
    Posts: 71
    Likes: 1, Points: 8, Legacy Rep: 12
    Location: Australia

    raf pali Junior Member

    I'm not a pro steel worker, just want to do it right when I have to weld SS. My question implies, as you say, is there anything to gain or achieve in quenching SS? Thanks
     
  4. Ad Hoc
    Joined: Oct 2008
    Posts: 5,675
    Likes: 247, Points: 63, Legacy Rep: 2488
    Location: Japan

    Ad Hoc Naval Architect

    But doing "something" has an objective...what is yours.

    Since to quench or not to quench....everyone has a reason why they wish to do it. It might simply be because the fabby doesn't like hot steel about the place, each reason, in design, is different for everyone and needs to be addressed as to WHY....
    Thus, you have not stated your reason why.
     
  5. alan craig
    Joined: Jul 2012
    Posts: 178
    Likes: 7, Points: 28, Legacy Rep: 14
    Location: s.e. england

    alan craig Senior Member

    raf pali likes this.
  6. raf pali
    Joined: Mar 2012
    Posts: 71
    Likes: 1, Points: 8, Legacy Rep: 12
    Location: Australia

    raf pali Junior Member

    Thank you Alan, your post lead to learn that there are a number of issues when welding these materials.
    Here is about Sigma Phase Embrittlement of Stainless Steel in FCC Service - OnePetro https://www.onepetro.org/conference-paper/NACE-06578
    Here more in depth about
    Intergranular corrosion - Wikipedia https://en.wikipedia.org/wiki/Intergranular_corrosion
    It mentions precipitation of chromium carbide at the grain boundaries.
    From the article: "...
    quenching it in water, leading to dissolution of the chromium carbide in the grains and then preventing its precipitation..."
     
  7. alan craig
    Joined: Jul 2012
    Posts: 178
    Likes: 7, Points: 28, Legacy Rep: 14
    Location: s.e. england

    alan craig Senior Member

    Interesting articles. But also welds solidify then shrink due to cooling putting stresses into the material; quenching could make this worse. Lots to read up about, or you could just ignore it all and practice until your welds look nice!
     
  8. raf pali
    Joined: Mar 2012
    Posts: 71
    Likes: 1, Points: 8, Legacy Rep: 12
    Location: Australia

    raf pali Junior Member

    I had a welding splitting like a piece of glass as soon as the rod was lifted.
    It was a "fat" weld between two 1" DIA bars side by side.
    I wonder if the great shrinkage due to accumulation of heat was the cause.
    If that's the case, to avoid such a shrinkage ratio, would be to do one short weld and cool then another short weld and so on.
     
  9. JanAF
    Joined: May 2018
    Posts: 5
    Likes: 0, Points: 1
    Location: Stockholm, Sweden

    JanAF Junior Member

    It primarily depends on what material it was. Cast iron (and also some high tensile steel) will crack when cooling down, is very hard to weld because shrinking when cooling, creates tension beyond breaking strain. Regular 316 stainless is very tough, will deform instead. I have never seen 316, welded with proper rod, crack after welding, even on thick pieces.
     
  10. alan craig
    Joined: Jul 2012
    Posts: 178
    Likes: 7, Points: 28, Legacy Rep: 14
    Location: s.e. england

    alan craig Senior Member

    I can confirm never seen 304 or 316 crack after welding, but if you weld a tee with (for example) 304 1" square tube, the tube forming the top of the tee will bend towards the weld, so huge residual stresses in a very tough material.
     
  11. Rick hambric
    Joined: Jul 2018
    Posts: 11
    Likes: 0, Points: 1
    Location: Georgia—USA

    Rick hambric Junior Member

    3rd gen fabricator/ AWS cert inspector here. Joined just to answer this conundrum.
    Anytime you quench a weld and the base materials, you are adding stress to the weld and the blended base material surrounding the weld. The weld itself will always have a different contraction rate compared to the base material. So quenching any weld and especially brittle metals such as stainless will create stress fractures on the molecular level, and leave you with a product that is not as strong as it could have been. If you ar wanting to create a stronger product, then encapsulate it in sand post weld and slowly bring the temp down evenly rather than shock it.
     
  12. fallguy
    Joined: Dec 2016
    Posts: 1,048
    Likes: 35, Points: 48, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    Can you explain the sand encapsulating?

    Are you setting the item in sand and covering it with sand?

    I am assuming the sand is bone dry as well? Otherwise, quench effect?

    Thanks.
     

  13. Rick hambric
    Joined: Jul 2018
    Posts: 11
    Likes: 0, Points: 1
    Location: Georgia—USA

    Rick hambric Junior Member

    Cover it 100% with sand. Depending on how big your part is, that can be done in a bucket, barrell, or for large pieces... in a hole but then a backhoe is needed. The sand acts as an insulator and retains the heat so The whole product gets heated and cools equally therefore relieving stress. You are basically giving the product a low tempering.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.