Welding on high P steel

[EngMan40]

The following are the results of chemical analysis:
C:0.11
Mn 0.46
P 0.08
S 0.42
Si 0.02
Cr 0.008
Ni 0.005
The P content is high, how to determine the weldability of this steel?

 

Taken separately, the high P and high S are not necessarily problematic; taken together I am less sure. I would expect it to hold together but would not ask it to perform any kind of critical function. Check with applicable and possibly governing steel standards, because this analysis does not conform to any known grade.

Is this a legacy steel from old equipment you are refurbishing?


"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[gtaw]

It looks like a free machining steel. Don't be surprized if the welds crack right down the center of the weld bead.

Best regards - Al

 

[CWEng]

You might take a look at AWS D1.7 which has some guidelines for weldability and testing.

 

thanks gtaw, I had not considered free-machining grades.

I had some exposure to this many years ago in an investigation into failing automotive pulley spot welds.
Very difficult to make this kind of steel stick together without benefit of filler metal.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[weldstan]

It is highly prone to hot cracking. Can be brazed though.

 

[gtaw]

The use of a low hydrogen welding practice using low heat input to limit diluting the base metal with filler metal (low voltage, low amperage, stringers only) is the best route relative to welding. I like the brazing alternative if possible,

Best regards - Al

 

[kingnero]

I have no practical experience with this, but I would try an austenitic filler (if the conditions allow this), and see if those are capable of retaining the harmful alloying elements. I guess it's worth a shot.
First bet would also be brazing, though. You can do almost everything with silver...

 

[gtaw]

The austenitic microstructure isn't very tolerant of the low melting point constituents. But it is worth a try.

Best regards - Al

 

[kingnero]

Ni-based fillers are notorious for that, however (and this comes from first hand experience) I've used 307 and 312 succesfully on dirty steel that had all kinds of contaminants on it (think buckets and shovels of mining equipment with god knows how many previous repairs and fillers types used... But admittedly, likely not as much S and P).
I guess it's worth a try, even if it comes with no guarantee...

 

[gtaw]

Generally, both S and P are held to 0.04% maximum to ensure ease of welding. If the numbers are correct, the S is about 10 times higher than the recommended upper limit. I will be surprised if the welds don't crack during solidification. Check the S to verify the decimal point is correct.

Let us know how it goes.



Best regards - Al

 

[kingnero]

Just throwing this out here, would the 6% Mn from a 307 filler not bond with the S ?

 

[EdStainless]

King, the Mn will for MnS, but large sheets of MnS in the welds will not be good either.
If you have ever tried to weld on wrought iron you have an ides of what will happen here.
Melting as little base metal as possible is important.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy

 

[EngMan40]

sorry for the typo, the S is 0.042 not 0.42!

 

Funny, because that's how I read it, as 0.042.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[gtaw]

Just a tad bit of difference between 0.42 and 0.042% sulfur. If it is really only 0.042 sulfur there should be a problem with weldability, assuming the balance is Fe.

Best regards - Al