Influence on mech/chem prop. when welding with exessive curr

Date 01-05-2011 15:17

Pvertongen,

WELCOME TO THE AWS WELDING FORUM!!

Now, I am not a metallurgist, but let me ask a couple of questions:

1) Is there a specific code that is being adhered to? D1.1, D1.8, API 1104, etc.

2) You asked about excessive current, to me that means the amps range called out on the WPS? Yes or no?

3) You say Heat Input is higher than the Max allowed by the WPS? Only because the amps were exceded or does it also call out a maximum interpass temperature and that was exceded?

4) If a max interpass temp is called out, what is it?

5) What material are we talking about?

6) What welding process are we talking about?

7) What joint design are we talking about?

These questions will greatly assist responders in getting you a more specific answer to your question.

Basically, there are many effects upon the mechanical and chemical properties of steel if proper procedures are not followed. But to be anywhere near specific there needs to be more information share.

Have a Great Day, Brent

By ravi theCobra (**)

Date 01-05-2011 19:57

I think this is a come - on !

Is Pevertogen the new cutting fuel replacing MAPP ?

Or is it a new gas that can be used for welding ?

Either way I 'm interested -

By ssbn727 (*****)

Date 01-05-2011 23:37

It can vary, but you really need to be more specific in the details regarding your query as Brent mentioned earlier. ;)

So if you're looking for a vague answer, then I just gave you one... However, if you are looking for a specific answer, then you need to give us more details that are specific towards your query. ;)

I also "WELDCOME YOU TO THE WORLD'S GREATEST WELDING FORUM!!! :) :) :)" And look forward to more specificity regarding your query. ;)

Respectfully,
Henry

By pvertongen Date 01-06-2011 08:11

Dear all,
Please find some more details in relation to my question from yesterday.
I am reviewing filler metal material certificates (solid wire ER316L - AWS A5.9-06) and checking compliance with our Purchase Order specification. Acceptance of the filler metal has to be in compliance with RCC-MR RS2000. The test specimen (CS with SS buttering) was prepared in compliance with NF EN 15792-1. Welding process is TIG (141). The Amp range from WPS used is 80-200 A. The TP Inspector who witnessed the welding allowed the welder to use a current from 240 Amp without any justification or clarification I can trace back on the cert.. In yesterday`s mail I made the link with the Heat input because the current is an important factor in this equation.
before we allow our contractor to purchase huge amounts of filer metal I want to assess the possible consequences of this ''non conformity'' on the mechanical properties and chemical composition as a results on the tests performed on the as welded specimen

regards
pat

By js55

Date 01-06-2011 13:43 Edited 01-06-2011 13:45

If you are talking test specimens, especially for filler metals, the increased amperage is a 'who cares' if the specimen passes the tests. The problems may begin with service. And even then its generally a who cares.
With stainless steels there will be segregation of elements and varying carbide precipitation issues but you cannot at the fabricaiton stage anticipate if this is a problem or not. This is a design engineering issue.
Mechanically you cannot even distinguish any problems from a normal testing scatter band. If you were dealing with ferritics you may argue a problem with toughness but this is not a problem with austenitics unless you get way down the temp scale to the -250F range.
The primary concerns in service would be corrosion related but I caution once again you cannot anticipate what those issues will be and I would not recommend designing you procedures around the most stringent requirements.
You may indeed have a violation of a specification and should deal with that in the proper manner but metallurgically and mechically until you get to service you don't have a problem as I see it, if you passed the tests.
Also, since you seem to be using this for buttering keep in mind that whatever carbide or element segregation problem you may encounter due to welding parameters with the SS it will still have better corrosion resistance than the carbon steel it is welded to, so again its probably a 'who cares'.
One more thing, if your heat input is the variable of concern then heat input is the variable of concern, and by this I mean that amperage is irrelevent if you have reduced voltage or increased travel speed to accomodate and the heat input remains unchanged.