delta ferrite question

By 803056

Date 10-27-2007 21:54

How are you determining you ferrite numbers?

Al

By darren

Date 10-27-2007 21:57

i do not know i just received this info
i do know they were sent away for lab testing.

By 803056

Date 10-27-2007 22:17

Different methods can provide different results.

Ferrite numbers has proven to be more consistent than the old method where the percentage of ferrite was determined, but still there are variations.

Did you run the diluted weld deposit chemistry through the WRC diagram to see where your chrome equivalency and nickel equivalency plotted? You can play with the filler metal composition and your heat input to achieve different diluted chemistry. Use your macro-etch to determine the dilution of you weld deposit. The chemistry of the weld will affect you ferrite numbers.

Also, provide as much information as you can. What you have provided is a little, no make that very sparse on details.

Best regards - Al

By darren

Date 10-28-2007 04:15

i will do my best to get the qc agent to get on board the forum. thanks for your patience.
darren

By CWI555

Date 10-28-2007 08:11 Edited 10-28-2007 08:19

the .76 number will be at risk for hot cracking. the other is likely to be fine. They either did a ferritescope measurement, or a chemical analysis. Either way, Al is right in that the FN number is better. However; Lincoln and Avestas make specific fillers for controlling Ferrite (3-6) you may want to contact one of their reps. Don't get the kobe, as they design theirs to be 8-12 FN.

Regards,
Gerald

By darren

Date 10-30-2007 09:33

i spoke to the qc agent and he is rendering the info so as to post. has to get clearance from customer first

By darren

Date 11-01-2007 09:39

heres what i got
1) As per UW--35, maximum reinforcement permitted for Category 'A' weld (Long seam) in 17mm thick material is 2.4mm.
2) Assuming the base metal removal is 0, that will leave
a maximum permitted weld overlay thickness of 5.4mm.
3.0mm Thickness of Clad
+2.4mm Maximum Reinforcement
5.4mm Maximum WOL Thickness
-- Test Depth Per Shell Standard 3.4mm Theoretical Test Thickness
3) Initial PQR Test Results:
ESF 40--3AW FCAW Weld Overlay Thickness = 5.9mm
Test Depth per Shell =--2Omm
Test Face Distance from Fusion line = 3.5mm
Side Bends = Pass
Ferrite = 10.5 FN (fail)
Chromium = 19.2%
Nickel = 12.0%
Moly =2.94% (fail)
Carbon =027%
ESF 40--3PWHT FCAW Weld Overlay Thickness = 58mm
Test Depth per Shell =--2.Omm
Test Face Distance from Fusion line = 3.8mm
Side Bends = Pass
Ferrite = 6.96 FN
Chromium = 18.8%
Nickel = 12.2%
Moly = 2.96% (fail)
Carbon =025%
ESF 41--3AW SAW Weld Overlay Thickness 4.8mm
Test Depth per Shell =--2.Ornm
Test Face Distance from Fusion line = 2.8mm
Side Bends = Pass
Ferrite = 1.56 FN (fail)
Chromium = 15.6% (fail)
Nickel = 11.2%
Moly = 2.57% (fail)
Carbon = .037%
ESF 41--3PWHT SAW Weld Overlay Thickness = 4.5mm
Test Depth per Shell =--2.Omm
Test Face Distance from Fusion line = 2.5mm
Side Bends = Pass
Ferrite = .76 FN (fail)
Chromium = 15.7% (fail)
Nickel = 11.3%
Moly = 2.56% (fail)
Carbon = .037%
it is the saw that is the problem

By js55

Date 11-01-2007 15:35

Well your first problem is clearly the increased dilution you are getting from the SAW process. Note that all your alloy percentages are lower. Your gonna have to turn the heat down (specifically the amps) on the SAW to get your alloys back up.
The increased dilution would also increase C which is a very strong austenite forming element. And this could be driving your FN down.

By CWI555

Date 11-01-2007 16:06

I believe your correct on this one.

By js55

Date 11-01-2007 16:19

Overlay is tough with SAW, unless you've done it awhile. Some are doing it easily and successfully every day, but it takes some dialing in for consistent results. The usual dilution tolerance is around 25%. Less is preferrable. 15% to 20% for fusion processes. Yet SAW will generally give you 25% to 50%. So you have to run it cold. Or, you have to punch the alloy content of the weld metal, the choice usually taken for production sake.
I would suggest, if your going to be doing overlays on a regular basis you take a look at single pass techniques and alloys, GMAW-P, possibly even ESW, and/or some strip technologies.

By darren

Date 11-01-2007 20:25

we are doing the coupons with an esab dc only machine but the job will be done on a powerwave 1000. what are your thoughts on ac as part of a solution.
we still have a 4.5 volt 'leak' in our powerwave that we cannot identify except it is part of the powerwave unit itself. that is however a separate matter.
will find out our parameters for the saw welds
we have a company investigating this, but the qc manager has gotten me on board to give me an opportunity to learn and see what i can offer so i REALLY APPRECIATE the help.
it is part of improving myself and hopefully my career.
thanks
darren

By js55

Date 11-01-2007 21:19

Control of the AC waveform can help. The downside to increasing the percentage of straight polarity (marketed as improving deposition rate) has always been reduced penetration. Which is exactly what your are looking for with overlays and reducing dilution. Sorta gettin the best of both worlds I would say. Make sure your procedures are exacting though. I wouldn't push the assistance of the AC waveform too far or you could end up with lack of fusion. Your bead appearance may suffer as well and smooth transitions between beads is very important for corrosion services. I would say that if you're gettin down to <10% dilution with SAW your gettin risky. I know some are gettin less, but without more experience I think its a little aggressive.

By 803056

Date 11-03-2007 00:57

I'm on the road this week so I don't have access to all my references. The reference you need for this work is the latest from Kotecki and Lipold (forgive me if the spelling is incorrect).

There is a modified WRC diagram for calculating Creq and Nieg for determining the ferrite numbers for dissimilar metals, i.e., carbon steel/low alloy steels to austenitic stainless steels.

I'm not sure what the ESF means, I'm assuming it is the sample number or PQR identification of different tests you have run. Are you determining the ferrite numbers for each filler metal, i.e., the layer of 309 and then the layer of 317?

The dilution with any welding process is a function of the depth of fusion. If you are obtaining too much penetration (and too much dilution with base metal) reduce the amperage and cut back the voltage slightly, but not so much you are getting an unstable arc and incomplete fusion. The same is true with the FCAW.

How many layers of each (309 and 317) are you depositing? You should shoot for 18 Cr and 8 Ni as minimums on the transition layer and you should hit those numbers easily with 309. The final layer(s) made with 317 should be OK if you are using a minimum of two layers of the 317.

Good luck - Al

By darren

Date 11-04-2007 03:05

esf is just an abbreviation for our companies name

By ssbn727 (*****)

Date 11-03-2007 04:09

Anybody remember "Variable Polarity" SAW???

Respectfully,
Henry

By Stephan (***)

Date 11-04-2007 15:47

Hey Henry,

great discussion...

I am pursuing it devotionally.

As a bloody layman in SAW and additionally to your question please allow me to ask:

"What kind of power sources are actually used in Submerged Arc Welding?"

Are there Inverters being used to making it feasible to vary the AC-balance?

Thanks a lot for a short advice and my best regards,
Stephan

By js55

Date 11-05-2007 14:18

The Lincoln AC/DC 1000 can not only vary the AC balance in duration but amplitude as well. This allows you to vary the duration (the the EN side) to enhance deposition while at the same time increasing amplitude (on the EP side)to restore some penetration. My experience has been that arc destabilization and bead appearance are the limiting factors

By Stephan (***)

Date 11-05-2007 18:23

Hmmmm!

I must admit...

These are pretty fine and... extraordinary suitable properties!

Thanks Jeff!

By darren

Date 11-05-2007 22:17

weve spent no time doing any testing on those features. i do however tend to think that unless there is a lot of experience behind this newer saw process then it just holds us back.
a pure ac or dc source with an experienced operator can keep up to or exceed an inexperienced operator with all the bells and whistles. and way less failures.
does it make sense to of set the balance in one direction and offset the amplitude in the other, or have you found that you offset both parameters to the same inclination ie both for more penatration or more deposition?