American Welding Society Forum
I noticed that filler metals usually have an option of say ESAB Coreshield 8, then they also offer a Coreshield 8 Ni-H5.
What is the purpose of the nichel? extra strength and what else?
I see the H5 is a lower hydrogen content.
Extra strength, no. More corrosion resistance.
Giovanni S. Crisi
Sao Paulo - Brazil
I believe it can also increase toughness at low temperature use.
This post is a little old, but thought you may still be interested in an answer.
I had a look, and see that the Coreshield 8 Ni has 1% Nickel. Typically the 1% Ni consumables are for obtaining better fracture toughness than the normal carbon steel fillers. The main mechanism for achieving this is that the weld metal has a finer grain structure due to the Nickel addition. Most of the time, for more critical structural welds, we tend to use the 1% Ni filler materials, although the one's we normally specify are the 80kSi fillers. Also, we (so far) never use the self shielded FCAW consumables, as they tend to produce lower quality weld deposits when compared to the gas assisted consumables. I notice that the Coreshield 8 Ni is a 70 kSi filler, so does actually not give the designer a higher strength to work with. I also see that the Carbon content is significantly lower in the Coreshield 8-Ni filler (0.03%) compared to the normal Coreshield 8 (0.17%) so while the Ni would typically add to the strength, this tendancy has been reduced by reducing the C content. Theoretically this should give an improved toughness, with comparable strength, with good resistance to forming martensitic microstructures that could lead to hydrogen cracking. I see that ESAB recommends this filler for root runs in constrained joints, so this all seems to make sense.
The H5 designation will have more to do with the flux than the Ni addition. Again, given that their market is for a filler to reduce the probability of hydrogen cracking as far as possible, this choice of flux makes sense.
It will be good to get some feedback regarding people's experience with self shielded FCAW these days. Have these wires improved enough to give deposits suitable for critical "primary steel" off-shore structures?
Hope this helps.
The hardening influence of nickel is rather low. Based on a carbon equivalency formula that is in common use here in the US, the influence of nickel is about 1/15th that of carbon. So, the nickel content would have to be 0.15% to provide the same hardenability as 0.01% carbon. So, 1% nickel would have the same influence as 0.07% carbon. Add to that the other alloying elements, and you get a better idea of the total hardenability of the alloy system.
I do agree that nickel is often added to improve notch toughness at lower temperatures.
The AWS D1.5 Bridge Code does permit the use of specific classifications of self-shielded FCAW provided the WPS is qualified by testing per 5.13. The testing required is more strenuous than for gas shielded FCAW.
Best regards - Al
I think you are agreeing with me. Nickel would tend to increase the strength, but by lowering the carbon, this tendency is negated, ensuring that you end up with a filler with less strength. This will reduce the stress in the HAZ as compared to a higher strength filler, reducing the chance of HAZ cold cracking. According to the manufacturer's literature, the "typical" strength values for the Ni containing consumable is actually lower when compared to that shown for the "standard" non-Ni bearing filler.
Interesting about the bridge code. I have not previously used the bridge code, so not sure what extra testing is called for. What would the additional testing be for self-shielded FCAW?
Ladies and Gentlemen,
I have five patents in welding involving underwater welding / welding in damp environments. In the past the Lincoln Fleet Weld electrodes had a drop of nickel in them to achieve a surface tension / heat capacity benefit on the puddle and resulting weldment. This yielded smoother weldment. It is part of my welding consumables. Lincoln has used other ways to get the benefit than expensive nickel. I hope this is helpful
Len Andersen firstname.lastname@example.org
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I had originally asked because my old employer was quoting a job the required the higher Ni in the filler wire and I wanted to know the difference between the regular FCAW and the Ni option.
this was for structural buildings, D1.1
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