70S-2 vs 70S-6

By jon20013 (*****)

Date 10-07-2005 01:29

Both are, for all intents, identical. One has slightly more deoxidizing agents than the other, but you may use both as equals.

By rhoople47 (**)

Date 10-07-2005 01:34

The 70S-6 has better scavaging properties then the S-2. It has higher silicon,and manganese deoxidizer levels, with better arc characteristics. It will not have any adverse effects on your welding. Hope this helps, and I'm sure there are others out there that will have more to add.

By SWP

Date 10-07-2005 15:08

I think its one of the AWS welding handbooks that lists the chemical composition and welding characteristics of the various solid wires, E70S-2, 3, 6. E70S-6 has the most deoxidizers for highest quality welds, and due to higher silicon is more fluid than E70S-2. If you did a side by side test, I belive you would see a real difference between the fluidity and weld appearnce of S-2 and S-6 spray or pulsed spray welds. Have you compared these yourself?
I worked with automated stations at my last employer, that ran thousands of pounds/year of S-3 and S-6 in the pulsed spray mode. The welds were safety critcal and 100% helium leak tested. We only started using S-6 when needed to fix one troublesome joint that was more prone to porosity, but changed a number of other factors at the same time, so can't say that the S-6 soley fixed the porosity. As far as weld characteristics and final appearnce, S-3 and S-6 were identical for our application.

By got2weld Date 11-18-2005 00:54

If E70S-2 is used with PQR, can E70S-6 be used on WPS/WPQ?

By MBSims

Date 11-18-2005 04:52

If this is a ASME IX WPS, the manganese for the ER70S-6 must be limited to 1.6% maximum in order for it to be considered A-No. 1. AWS A5.18 permits >1.6% Mn for the ER70S-6.

By jon20013 (*****)

Date 11-18-2005 10:22

Marty, EXCELLENT technical point! That one little point evaded me until recently! Unfortunately it was only found by a customer review of my WPS... My 70S-6 in stock was less than 1.6% but I had to add that clarification to the WPS.

By Shane Feder (****)

Date 05-07-2007 22:43

Marty / Jon,
If AWS 5.18 allows Mn up to 1.85% and ASME IX QW-422 requires an A1 to have a maximum of 1.60% Mn what A number will you have for an ER 70S-6 with 1.70% Mn,
Your thoughts would be appreciated,
Regards,
Shane

By jon20013 (*****)

Date 05-08-2007 03:02

I spoke with Walt about that one quite some time back Shane and according to Walt, it wouldn't have an A Number. At least thats my recollection... shaking off a few cobwebs, lol!

By john baxter (*)

Date 05-08-2007 04:07

S-2 is triple deoxidised S-6 double deoxidised. Procedure wise very little difference. S2 is A1 S6 may not be for the stated reasons but this does not matter as from an essential variable point of view this only applies to special processes I think (compare QW404.5 to QW 404.37).

By MBSims

Date 05-08-2007 04:06

It would fall outside the range of A-No. 1 and not fit any of the other A-Nos., so it would have no A-No. However, ASME IX permits several ways to determine A-No. for bare wire used for GTAW/GMAW:
1) chemical analysis of the weld deposit of the PQR,
2) chemical analysis of an all weld metal sample prepared according to the filler metal spec,
3) the specification chemical composition or mfr's certificate of conformance.

If the 1.7% comes from chemical analysis of the bare wire, then perhaps a PQR test plate can be run to determine if the actual weld deposit Mn content is below 1.6%. No other tests would be needed (tensiles, bends), just as deposited weld metal chemistry. Just following the words in the last paragraph of QW-404.5, you could run a PQR with ER70S-6 and just refer to the AWS classification (ER70S-6) on the PQR and WPS with no reference to A-No. Doesn't make a whole lot of sense for this case, but it would meet the wording of ASME IX. I think we really should have the Mn limit expanded in QW-442 for A-No. 1 to include the Mn range for ER70S-6. I'll ask at the meeting next week if this has previously been discussed.

By Shane Feder (****)

Date 05-08-2007 04:35

Mr John Baxter,
Is that the same John Baxter who keeps on appearing on Americas Most Wanted.
Or is that The AWS Most Wanted.
Welcome to the forum John,
Regards,
Shane

By js55

Date 05-08-2007 14:35

If I may, I'm not sure it is accurate to say that one or the other is more highly deoxidized. Though it is more often understood as S2 being more highly deoxidized due to the triple deox Ti, Zr, and Al, which, as far as I know more readily bond with O2 than the Si or Mn of the 6 (the same reason 321 SS fillers are seldom used-if even available-the same reason Al must be AC welded, and quickly after preping-and the same reason Zr and Ti alloys are so sensitive to purging).
But it depends. I think you would have to venture into thermochemical reaction studies to verify one way or the other. Not my bailiwick to be sure. 2 is often recommended for material with highly oxidized layers, such as rust. But the triple deox elements will build up in multipass applications causing visible non metallic deposits.
6 will generally demonstrate higher strength and lower ductility. But they are most often readily interchangeable. The most important issue being exactly what Marty posted. Make sure than within the context of your WPS that you are actually using an A-1 chemistry. Not that it risks the viability of your weld, but you will have violated your procedure.
Just one of those quirks caused by the fact that the Section IX guys aren't the same ones as the A5 guys.
And Walt and Marty are correct, there aint no A# with high Mn S6.

By wolfpack51 Date 08-31-2007 22:51

This is a battle I have pesonally fought several times while I was welding pipe. The 70 S 6 wire is superior to the S 2 wire in regards to the actual welding. The S6 wire is cleaner and flows much better, very similar to stainless steel. The wall that I always hit was that the QC people were not capable of interpreting the code well enough accept the possibility that S6 did conform to the WPS. According to the 2001 QW-442 A-numbers the Mn is listed in the Ferrous Weld Metal Analysis as 1.60. This should mean that the 70-S 6 wire is acceptable as long as its Mn is 1.60 or less. The actual certs on the wire used should show this. If this argument is a reality then is means that one can list the A number for 70 S 6 wire as a A-1. Qw 404.5 in the 2001 edition states: "The weld composition may be determined by any of the following: (b) For SMAW, GTAW, and PAW-from the chemical analysis of the weld deposit prepared according to the filler metal specification, or from the chemical composition as reported either in the filler metal specification or the manufature's or supplier's certificate of compliance.

The reason to use 70 S 6 over 70 S 2 in my opinion as a welder and a CWI is for the quality of the weld. In many projects that I was on the reject rate for welds being radiographed were higher while using the 70 S 2 wire. When economics and schedules became in jepordy the management listened to the welders and qualified personel and switched to the 70 S 6 wire. The results were improved welds with fewer rejects.

The key thing that I use when using 70 S 6 is the actual wire certs.. Keep the Mn at or under 1.6 and keep the Si at or under 1.0. This has always been acceptable in situations that I encountered.

Good luck on this issue

By darren

Date 09-01-2007 00:20

down here on the floor the s-2 does not eat all the crud that is left on the metal as well as the s-6. less precleaning and better results from the average or new welder.
i will definitely be using some of this info to inform qc and the management so as to be able to use the s-6 and keep from following up on the structural welds with concerns about poor quality welds. the islands of si come right off so there is no real extra cleaning time.
darren

By js55

Date 09-04-2007 13:49

I would have to disagree that S-6 should be viewed as a higher quality wire. This is a subjective judgement based upon application and not an inherent property of the wire itself. Its different. Thats all.
In fact, were your application one where the trip deox of Ti, Al, and Zr, is valuable then the S-2 would certainly be argued as better.
Were you to apply it to an application where its higher viscosity (a reason why so many inexperienced welders may have a problem with it) is valuable, as in wide gaps (a reason why inexperienced welders may be helped by it), or out of position work then S-2 would be considered higher quality. Were a specific maximum of hardness to be a concern S-2 would be considered higher quality. It all depends upon the application. And that is the very reason there are choices.
If one were to argue for lesser quality, S-3 (with lower Si/Mn AND no trip deox)might be a preferrable choice since its very invention was based upon S-6 heats that missed. And so Lincoln was successful in the creation of a new classification they could market as opposed to the expense of remelting. But this is still only an evaluation based upon a knowledge of its introduction, not necessarily an engineering evaluation of its application.