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Up Topic Welding Industry / Technical Discussions / Crash course in Metalurgy
- - By John T. (*) Date 06-05-2002 20:33
I have recently been deemed head of our Q.A. program, and am desperatly trying to keep up with the requirements of AISC. One of which is checking in material (making sure the mill is providing the correct material and that it performs as specified). Herein lies the problem, I've run across a chemical report on S that was .002 % over the maximum spec'ed in the ASTM. We are dealing with A500 Gr.B, welded, 4"x4"x.1875" tube, to be used as stuctural support for canopies in a building. My question is what effect will this have, will it be a structural concern or more about weldability? The mill assures me this will have little if any effect on either. My engineer dosent want to commit one way or the other and I would like to hear a solid answer, hence my return to the best resource there is, this forum. Thanx in advance
Parent - - By MBSims (****) Date 06-05-2002 21:28
Which max sulfur limit was exceeded, heat analysis or product analysis?

My initial feeling is that this small amount of sulfur over the limit will not cause a problem and may be able to be justified depending on Mn content. If the mill test reports show that the material met the mechanical testing requirements (tensile, yield & elongation), there should be no structural concern. But, you have a product that does not meet specified requirements and you know it doesn't. Is your company willing to accept the possibility of being found negligent if a failure occurs and folks find out you knew in advance the product did not meet the specs?

Marty
Parent - - By John T. (*) Date 06-05-2002 22:10
Heat analysis, my fellings exactly you know as well as I that all we or I am trying to do is limit the liability to my employer, it's wrong thats all there is to it. I get a funny feeling when I ask these kinds of questions and look at the faces of my superiors, pride, fear...... I've done all I can do, I believe.

Please tell me more about the Mn content justifying the S.
Parent - By MBSims (****) Date 06-06-2002 02:10
The heat analysis limit is 0.035% max S, and product analysis limit is 0.045% max. Have you thought about having chemical analysis performed (by the mill or a local test lab) on a sample of the tube steel and comparing it to the product analysis limit?

Marty
Parent - - By MBSims (****) Date 06-06-2002 12:16
On your other question abount Mn and S:

At melting temps (such as during welding) S can combine with Fe to form iron sulfide. This has a lower freezing temp than the iron, so it is last to freeze and can create a film between grain boundaries that has little strength. This is generally not a problem if S is less than about 0.05%. If Mn is present in a ratio of at least 1.75 parts Mn to 1 part S, the S will combine with it to form manganese sulfide stringers in the material. These stringers have less effect on strength than the iron sulfide. So if you have 0.037% S, then Mn would need to be at least 0.065% to tie up the sulfur.

Marty
Parent - By John T. (*) Date 06-06-2002 12:40
Thanks again for the response, It really helps to be able to turn to an un-biased resource for information that would other wise be almost impossible to attain.

The Mn amount was .320
Parent - - By Michael Sherman (***) Date 06-06-2002 10:09
John, I often have to supply mill certs with products I fabricate. If the certs do not meet the customers specs they will reject it. Anytime I receive material from a supplier that does not meet the specs I asked for, I send it back. Period. There is no harm or foul in this, the supplier did not give the customer (me) what I asked for. If I accept the wrong material and then fabricate something out of it, I will most likely end up using that product as a flower pot in the front yard and one thing I don't need is a $50,000 flower pot!! Your boss probably does not need one either. One other thing, if your engineer does not want to commit, this tells me that the responsibilities are falling squarely on your shoulders. Your engineer should be one of your best resources, if he will not commit, why should you? When the customer specifies a particular material, why would you sell him something different without his approval? My apologies for such a long opinion.

Respectfully,
Mike Sherman
Shermans Welding
Parent - - By CHGuilford (****) Date 06-06-2002 14:24
John,
I'm thinking that since your engineer won't commit to a decision, as Mike Sherman said, the decision seems to be yours ( but not necessarily). I know that rejecting material for such a small percentage beyond allowable limits can put you underfire from many directions and it sounds like you won't have any/much support. One thing you can do is to contact the customer, explain everything you can learn, and let him make the decision. Then if the material is rejected, all the production people, vendors, or others need to know is that your company won't be paid for it. If the vendor resists, he can do the research as to why the material should not be rejected. Either way, all you are trying to do is identify a non-conformity and seek a resolution everyone can accept.
Hope this helps
CHGuilford
Parent - By John T. (*) Date 06-06-2002 21:30
Thanx, I had determined from the begining of this ordeal that I would be out of pocket (or the company anyway) for the cost of product ananlysis. As it turns out the probable severity of the matter finnaly set in to the powers that be, and also the vendor that supplied the product.
So in turn I started getting too much help from every direction, the supplier is requesting that I send him two 1" samples so that he may perfom the product analysis, and my production supervisor is laying the smack down on anyone who even looks at material before it has been relased for production.

As for the engineer, well he still needs a spine transplant.

All is well, Thanks again for the help, Everyone!
Up Topic Welding Industry / Technical Discussions / Crash course in Metalurgy

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