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Up Topic Welding Industry / General Welding Discussion / Welding of ASTM A645 plates_Cracking
- - By Irik Gilimshin (*) Date 08-15-2017 07:30
Dear colleagues,
Please advise regarding the issue:
Storage tank made of ASTM A645 steel (plates) to be welded. But we've met a problem during qualification. On bend tests we have been facing cracks on bevels. GMAW is used, filler wire is OK Tigrod NiCRMo-3. Any strict requirements for pre-heating, interpass temperature and PWHT?
Thanks in advance
Parent - - By Tyrone (***) Date 08-15-2017 11:13
Hi Irik,
Welcome to the AWS Forum.

Need more information.
Gas
Voltage
Position
Coupon details

Clarification - You are using GMAW but using a Tig rod?
Parent - By Irik Gilimshin (*) Date 08-17-2017 08:19
Hi Tyrone,
thanks. 

Welding process: FCAW (Pulse) and GMAW
Welding equipment: Fronius TransPulse Synergic 4000 + VR 4000 https://www.fronius.com/en/welding-technology/products/manual-welding/mig/transpuls-synergic/transpuls-synergic/transpuls-synergic-4000
Filler material: sorry for typo, ESAB Shield-Bright NiCrMo-3 AWS 5.34 ENiCrMo3T1-4 http://www.esabna.com/us/en/products/index.cfm?fuseaction=home.product&productCode=412086&tab=2 and ESAB OK Autrod NiCrMo-3 AWS A5.14 http://www.esabna.com/us/en/products/index.cfm?fuseaction=home.product&productCode=12373&tab=2
Gas: 82%Ar+18%CO2 and 99,993% Ar
Base material: test plates ASTM A645 Gr.B, thck 10mm (~4")
Position: 1G (PA)
Current/Voltage: (different parameters) 140-170A/22-24V

I am sorry for the mistake, but (as mentioned by 803056) there is no fusion to groove face, observed after bend test. It's not cracking :red:
Results of tensile test and charpi are acceptable, but we have been failing with bend tests. Wrt C/V different parameters were tried, but no success.
Tomorrow ESAB guy is coming to clarify the issue.
Parent - By myhelmetsguide Date 10-17-2017 17:44 Edited 10-17-2017 21:31
yeah but main thing depends on the welder  that what is he doing and weld can't be hot enough so that it may fuse the part.
- - By 803056 (*****) Date 08-15-2017 22:59
If I understand correctly, the weld is not fusing to the groove face. When the bend test is performed, the weld is pulling away from the groove face.

If that is correct, then it is not a case of the weld cracking, it a case of the weld not fusing to the groove face. That isn't surprising if short circuiting transfer is used.

The corrective action involves checking the welding parameters to maximize the voltage and amperage to increase the heat input, but not high enough to change the transfer mode. This will increase the heat input which will help ensure fusion to the groove face. That isn't the end of the story. You also have to watch the welder's technique. The weld isn't "hot enough" to fuse to the base metal if the welder is simply depositing the weld without directing the gun at the groove face, back and forth with a roll of the wrist, as he is depositing the weld. If the welder is simply moving the gun down the groove and letting the weld metal "fill the groove", the groove faces will act as a mold to shape the weld deposit. The welder has to direct the gun toward the surface to be fused. In other words a small amount of weaving is needed to ensure the arc and the "heat" is directed to the groove faces.

Al
Parent - - By Irik Gilimshin (*) Date 08-17-2017 08:21
Hi 803056,
thanks a lot. but we still are not successful :cry:  

I am sorry for the mistake, but (you are correct) there is no fusion to groove face, observed after bend test. It's not cracking :red:
Results of tensile test and charpi are acceptable, but we have been failing with bend tests. Wrt C/V different parameters were tried, but no success.
Tomorrow ESAB guy is coming to clarify the issue.

pWPS details:
Welding process: FCAW (Pulse) and GMAW
Welding equipment: Fronius TransPulse Synergic 4000 + VR 4000 https://www.fronius.com/en/welding-technology/products/manual-welding/mig/transpuls-synergic/transpuls-synergic/transpuls-synergic-4000
Filler material: sorry for typo, ESAB Shield-Bright NiCrMo-3 AWS 5.34 ENiCrMo3T1-4 http://www.esabna.com/us/en/products/index.cfm?fuseaction=home.product&productCode=412086&tab=2 and ESAB OK Autrod NiCrMo-3 AWS A5.14 http://www.esabna.com/us/en/products/index.cfm?fuseaction=home.product&productCode=12373&tab=2
Gas: 82%Ar+18%CO2 and 99,993% Ar
Base material: test plates ASTM A645 Gr.B, thck 10mm (~4")
Position: 1G (PA)
Current/Voltage: (different parameters) 140-170A/22-24V
Attachment: IMG_7996.JPG (177k)
Parent - - By Tyrone (***) Date 08-17-2017 10:57
Yep, no sidewall fusion.

Try all the things Al mentioned.  I also think it's heat and technique related.
I expect the ESAB rep to say the same things.

1G is the position that most welder's here fail.

PS - Try a slight backhand/drag to get more penetration.
Parent - By Irik Gilimshin (*) Date 08-17-2017 11:26
ok, we'll see tomorrow. today we welded one more test coupon via normal MIG process, it looks better. Waiting for mechanical results.
thanks Tyrone! keep well:wink:
- - By 803056 (*****) Date 08-17-2017 22:36
I've used that filler metal before. It is like welding with toothpaste. It doesn't flow or wet easily. The welder has to direct the arc toward the groove face with a roll of the wrist. Simply moving back and forth like a typical weave will not promote good fusion to the groove face.

I also suspect the gas mix. You are using a lot of CO2 in your mix. I typically limit the CO2 to 12, possibly 13%.

Make sure you remove the oxide between weld bead with an abrasive wheel or rotary file. Cleaning with a wire brush may not be aggressive enough.

Best regards - Al
Parent - By Irik Gilimshin (*) Date 08-18-2017 02:43
Thanks a lot, Al!
We'll follow your recommendations. I keep you informed
Parent - - By Irik Gilimshin (*) Date 08-20-2017 09:54
ok, we welded more test coupons by ESAB welder using Mig 4004i Pulse+Feed3004w+OK Autrod NiCrMo-3+Argon 99,993%. Your recommendations have been followed-up, but no success. :sad: ESAB took A645 plates for further testing.
So, what are root causes supposed:
- gas mixture? Could He+Ar mixture improve it?
- magnetization? This material is susceptible to magnetization, which affect weldability.
- is GMAW/FCAW applicable for welding of A645 in general? Is SMAW/SAW helpful to fix the issue?
- any additional heat treatment activity?
- others?

So, plan A - to continue and  "play" with welding parameters, plan B - to switch to SMAW/SAW...:confused:
Parent - - By 803056 (*****) Date 08-20-2017 14:19 Edited 08-20-2017 14:24
This material should not be that difficult to weld. The steel contains 5 to 5 1/2 nickel and is intended for cryogenic service, but the nickel content is low enough that it should not present any specific welding issues.

I mentioned the CO2 content used in your original post was rather high, but 99% argon on a steel alloy with FCAW? That seems to be moving to the extreme even if you are using GMAW. What gas mix is recommended by the filler metal manufacturer? 

Without knowing the application, it is tough to make a recommendation for the filler metal. I am curious as to why you are using a nickel alloy filler metal that contains 22% Cr, 65% Ni, and less than 1% Fe if the steel plate only contains 5% nickel? Would a type 309 or 310 filler metal work as well at a considerable cost savings?

I checked the web site you listed. The welding parameters seem to be on the low side of the ranges listed by the manufacturer. As far as pulsing, I don’t think I would try that if you are using FCAW. Make sure you have the right polarity when welding with nickel alloys or even nickel bearing steel filler metal.

From your descriptions of the problems your heat input is simply too low. The description of the face bend failures seem to support  incomplete fusion if the heat input is too low.

If the shielding gas mix SG-AC-20% is what the manufacturer recommends, I would go back to that. I like the argon to be a little richer, but why argue with success? If the manufacturer uses a leaner mix and it works, stick with it. I would start at mid range of the parameters (voltage, amperage, etc.)  listed by the manufacturer and increase or decrease the parameters after seeing the test results. Pay close attention to the wire feed speed and the electrode extension. I  hate it when the manufacturer lists amperage, but not wire feed speed or electrode extension. Amperage is as much aq function of WFS and EE more than anything else when welding with any semi-automatic welding process.

Good luck my friend.

Al
Parent - By Irik Gilimshin (*) Date 08-20-2017 17:17
Dear Al, pls see my comments in bold

This material should not be that difficult to weld. The steel contains 5 to 5 1/2 nickel and is intended for cryogenic service, but the nickel content is low enough that it should not present any specific welding issues. Fully agree

I mentioned the CO2 content used in your original post was rather high, but 99% argon on a steel alloy with FCAW? We've used FCAW also. As per ESAB recommendations for Shield-bright NiCrMo-3, 80% Ar + 20% CO2 mixture is recommended. But FCAW provided worse quality of weld That seems to be moving to the extreme even if you are using GMAW. What gas mix is recommended by the filler metal manufacturer? GMAW --> we used NiCrMo-3+Ar99%. ESAB also poposed using of He+Ar mixture. Used welding equipment Aristo Mig 4004i pulse http://mam.esab.com/assets/1/BDBA5CC688D14EBE822C00D265DF8E7D/doc/28443B5C679B4F83BFD20ED2DAC020FB/ARC_23314-en_US-FactSheet_Main-01.pdf

Without knowing the application, it is tough to make a recommendation for the filler metal. I am curious as to why you are using a nickel alloy filler metal that contains 22% Cr, 65% Ni, and less than 1% Fe if the steel plate only contains 5% nickel? Would a type 309 or 310 filler metal work as well at a considerable cost savings? Client's chosen NiCrMo-3. FYI: ethylene tank, design temperature is -105 C degree. Supplier requirements for weld metal: yield > 430MPa, tensile > 690 MPa, elong > 32%, charpi > 70J at - 196 C

I checked the web site you listed. The welding parameters seem to be on the low side of the ranges listed by the manufacturer. As far as pulsing, I don’t think I would try that if you are using FCAW. Make sure you have the right polarity when welding with nickel alloys or even nickel bearing steel filler metal. pls find enclosed pict with the last welding parameters on a.m. Aristo

From your descriptions of the problems your heat input is simply too low. The description of the face bend failures seem to support  incomplete fusion if the heat input is too low.

If the shielding gas mix SG-AC-20% is what the manufacturer recommends, I would go back to that. I like the argon to be a little richer, but why argue with success? If the manufacturer uses a leaner mix and it works, stick with it. I would start at mid range of the parameters (voltage, amperage, etc.)  listed by the manufacturer and increase or decrease the parameters after seeing the test results. Pay close attention to the wire feed speed and the electrode extension. I  hate it when the manufacturer lists amperage, but not wire feed speed or electrode extension. Amperage is as much aq function of WFS and EE more than anything else when welding with any semi-automatic welding process. we will try our best.
thanks a lot, Al
Parent - - By Irik Gilimshin (*) Date 08-20-2017 17:29
also tried with other parameters (pls see attached)
Parent - - By 803056 (*****) Date 08-20-2017 18:20
Perfect, now we have something to work with. The photographs help.

The photograph of the groove is interesting. The groove looks tight. I would open it up to 45 to 60 degrees. It appears you are welding an open root joint (no backing). Try opening the root opening to 1/4 inch and use a 6 mm thick by 25 mm backing composed of the same material as the plate. If need be, simply cut a strip of the base metal as backing.

I suspect you will need a fairly long electrode extension (contact tip to work distance). From the test record I saw, you are using GMAW, 1.2 mm diameter electrode. The voltage 28-30, the amperage; around 100 to 110 amps. The electrode extension might need to be on the order of 12 mm.

The voltage seems to be on the high side, but the current is on the low side. That isn't surprising considering the high percentage of nickel in the electrode. However, try increasing the wire feed speed, reduce the voltage to about 25 to 26 V, and play with the electrode extension. See if you can get a smooth stable arc.

Don't weave the electrode. Try stringer beads. Again, clean between weld beads to remove any and all oxide with an abrasive disk or carbide rotary file.

Personally, I find using the high nickel electrodes difficult with GMAW.

Did you by chance contact the steel manufacturer and ask them for recommendations on what filler metal they recommend? The high nickel based alloy filler metal causes my stomach to tie into knots. They are too expensive and too difficult to weld with, especially under field conditions.

Good luck.

Al
Parent - - By Irik Gilimshin (*) Date 08-20-2017 18:36
What is about magnetizm? Does it affect GMAW/FCAW too much? SMAW gave us proper mechanical results, but complicated welding because of magnetic blow. SMAW done with OK 92.45 http://www.esab.co.uk/gb/en/products/index.cfm?fuseaction=home.product&productCode=410099&tab=2
Parent - - By 803056 (*****) Date 08-20-2017 18:49
Any ferromagnetic material can be magnetized and yes, suffer the effects of arc blow. The higher the amperage, the greater the problem.

Al
Parent - By Irik Gilimshin (*) Date 08-20-2017 18:52
highly appreciated your experience!:cool:
Parent - - By Irik Gilimshin (*) Date 08-30-2017 17:30 Edited 08-30-2017 17:34
Hello, Al!
So, we finalized the issue, only 60% of test specimens are acceptable --> no reproduceable success. Also our material engineering dept. says: "Ni-alloy steel welding of LNG tanks that GMAW / FCAW have the risk of poor sidewall fusion. There are several recommendations on GMAW like which arc types to use - spray arc, short circuiting arc or pulsed arc - depending on targeted effect like weld deposit rate, weld position, distortion, etc. In addition to the generally known issues with side wall fusion when using GMAW / FCAW, one significant problem that is frequently encountered with the nickel steels is that of residual magnetism causing arc blow".
Therefore, we've excluded GMAW/FCAW and switched to SMAW/SAW.

http://www.twi-global.com/technical-knowledge/job-knowledge/welding-of-ferritic-cryogenic-steels-100/
http://www.ozmetalsan.com/images/catalog/72595ESAB_LNG_Tanklarinin_Kaynagi_-_EN.pdf

Thanks for your support.
Parent - By MBSims (****) Date 09-15-2017 22:49
Have you considered 75% argon / 25% helium for the GMAW shielding gas?
Up Topic Welding Industry / General Welding Discussion / Welding of ASTM A645 plates_Cracking

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