Welding of AISI 4140 to EH36 as per AWS D1.1

[laurudolphy]

Dear Forum Members

I have a job to weld AISI 4140 200mm Solid Bar to EH 36 100mm Plate. It is fillet weld and the throat is 18mm. The construction code is AWS D1.1
But Iam afraid I dont have a qualified PQR. However I have the following PQRS
PQR that I have earlier qualified is EH36 to EH36 max thickness 50 mm. FCAW process with PWHT
WELDOX to WELDOX unlimited thickness FCAW without PWHT.

I assume AISI 4140 is unlisted material and EH36 is Group 2.

I request your advise. Can I use any of the above PQR and write a new WPS.
What is the consumable that I have to use. Is E8018 a good choice.

If I have to develop a new PQR and WPS,

What is the thickness of the coupon that I have to use. (I will be doing groove weld in 3G Position, even though the job calls for fillet weld in 1G position)
I am aware of the thickness limitations vis a vis the coupon thickness for groove welds, but for fillet welds do the same thickness limitations apply?

What are the welding precautions I have to take care, in terms of pre heat, interpass temperature, PWHT, Soak time and temperature. Have I got to soak the coupon for the time considering the thickness of the coupon, or considering the thickness of the actual job. Any precautions to take to wrap with thermal blanket to facilitate slow cooling.
I have not received the material yet and not reviewed the MTC, however if the material is received in Normalized condition I think I can proceed with the welding, but if the material is Quenched and Tempered, do I have to do annealing before welding.

Your advise will be highly appreciated.

Thanks

[arweldcon]

AISI 4140 is indeed an unlisted material instead only the ASTM A 131 grade EH36 and ABS grade EH36 are group 2, the other xxx grade EH36 types are unlisted.

You cannot use the existing PQRs to write a new WPS since the base metal of production welding can not be covered by them and thus a new qualification is required. Relating to the filler metal, AWS: E8018-B2 H4R is a good choice to join the different parent materials when the weld needs a PWHT. There are also FCAW consumables special for 4140 materials (full basic wire) for which you could have a look at internet.

Use a test coupon of at least 1" thickness that covers T=1/8” – unlimited (with impact requirement it covers T=5/8” – unlimited). Test position 3G can be a choice if impact requirements are applicable on the project (the 3G test position covers "All" welding positions according to table 4.6 point 6). If there are no impact requirements required table 4.1 is applicable. This means if you need the 1G position, a 1G or a 2G test is mandatory according table 4.1, 3G test coupon qualifies then only vertical up according table 4.1.

If you weld a 3G test coupon, you shall be aware of the current, voltage and travel speed restrictions of table 4.5 since from an economical point of view it’s better to qualify the needed flat welding position and thus you can use the maximum current and travel speed for that position having the highest deposit. AWS D1.1 qualifies also fillet welds on butt welds, so there is no need for separate qualification of fillet weld.

For fillet weld the same thickness limitations are applicable if the fillet weld is qualified on a butt weld (with impact requirement impact T=5/8” – unlimited) butt that is not an issue with this thicknesses.

As for some welding precautions that you have to take care, you shall preheat at 200- 250°C and keep the interpass temperature lower than 325°C as well as if there is impact test requirement, you shall PWHT the coupon the same time that is necessary for the production thickness (see table 4.6, point 8, PWHT). PWHT temperature is depending on delivery condition of material, so you need the MTC. Heating up maximum up to 315°C free, then 55°C/hour till soaking temperature (the maximum metal thickness is 200 mm and the calculated heating rate had to be 25.5°C/hour but as specified in section 5.8 of AWS D1.1 "the rates of heating and cooling need not be less than 55°C/hour"). Cooling down maximum 55°C/hour till 315°C then cooling down free in still air or in insulation. Soaking time 2,5 minute per mm of total weld thickness "t" as specified in table 5.2 (in this case "t" is throat thickness of the welding).

No annealing prior to welding required.

[laurudolphy]

Thanks Arweldcon for your reply and advise,

The Client has revised the drawing and now the weld geometry is a T Joint Full Pen, where a 4140 Hollow Tube 200mm OD, 150 mm ID is welded to a 120 mm EH 36 Plate. I intend to use a FCAW with shielding gas. The big question lies in preparing the coupon, where as the 4140 is a tube and eh 36 is a plate, how do i prepare the coupon,

I agree with you that 4140 is unlisted material and eh36 is group 2, so it is wps is going to qualify "Specific Unlisted Material to Group 2". Am I right i saying that?
If so, can i buy a similar tube 25mm wall thickness (API 5L X52 Pipe ) and weld to 4140 tube.

There is no impact requirement, Due to the thickness of the EH36mm plate I feel it will be done in the Flat position, So i would qualify with 1G Position.

As this is a full penetration weld and the back side cannot be accessed for grinding or gouging, Can I have the root till the capping in FCAW or is it required for me to have the root run in Argon Welding.

You have mentioned that PWHT would depend on the delivery condition of the material....Would you mind please elaborating on this. Material condition if Normalized, Q and T, etc.

I could not understand clearly the heating/soaking temperatures that you have suggested. Using a 25mm coupon but simulating for 120mm thickness (larger size of the actual job), What is the temperature to which it has to be heated and I understand the soaking time is 2.5 minutes/mm which means it is 45 minutes.

Regarding Preheating, as the actual job is 25 mm tube welded to a 120 mm thick plate, can i preheat to a max of 325 deg C, as the plate is quite thick, am afraid that it would act as a heat sink.

Your comments will be highly appreciated.

Thanks again

[wgadmin]

For the PQR, please note that you have to use the base metals intended for the production welding (AISI 4140 to EH36) since according to table 4.8 in case of welding unlisted steel to steel listed in table 3.1, the qualification covers only the specific combination of steels listed in the PQR (the qualification test shall be done as specified in table 4.2). So, you don't need to purchase extra materials, instead you could use the existing base metals for the qualification as well.

I agree that the best position is 1G.

I suggest you fill the root using GTAW process (suggested filler metal: SFA 5.28 ER80S-B2) and the cup using FCAW process (suggested filler metal: SFA 5.29 E81T1-B2C/B2M H4).

As for the relationship between PWHT and delivery condition of the material, If for example the material's delivery condition is "quenched and tempered", it means that for some reason this metal should be harder than normal and thus if you do PWHT above the lower critical temperature then the material will lose its specific characteristics.

As for the "thickness simulation" relating to the PWHT, the AWS D1.1 requires when there is impact requirement the PWHT to be done based on production weld thicknesses (table 4.6, point 8). In your case it does not make sense because there is not impact requirement (but also because you may use the same thicknesses both for qualification and for the production welding).

As for the PWHT procedure please have a look at par. 5.8 of AWS D1.1. The temperature of the furnace shall not exceed 315°C at the time the welded assembly is placed in it. Above the 315°C the heating shall be done at a rate not greater than 55°C per hour. After a maximum temperature of 600°C is reached on quenched and tempered steel, or a mean temperature range between 600-650°C is reached on other steels, the temperature of the assembly shall be held for at least 62.5 minutes as results by the table 5.2 (the calculation is based on weld thickness, t=25 mm). Above 315°C cooling shall be done at a rate not greater than 55°C per hour. Then cooling down free in still air or in insulation.

Regarding the preheating at 325°C, please note that there is no reason for such high preheat temperature since because of silicon existence such high temperature may lead to hot cracking.

[laurudolphy]

Thanks Giorgos, for the clarification. I feel I have just touched the tip of the ice berg. Thanks again.
Regards
Rudolf

[laurudolphy]

Hi, Giorgos,
Further to my question, as mentioned earlier, due to non availability of 4140 hollow tube, the client has accepted a substitute for ST 52 / S355J2H hollow tube. The weld geometry remains the same, T Joint 200mm Tube 25mm Wall thickness welded to a 120 mm EH 36 Plate. It is Single bevel full penetration.

I already have a Qualified Procedure for 25mm eh36 plate to 25mm eh36 plate in 3g position. Single V Groove Joint with back gouging. CJP

My query is...

1. The thickness qualified is unlimited as per table 4.2 (metric standard)........ Hence I presume for thickness this PQR is acceptable. Am I right?
2. Because I have used a plate to prepare the PQR and as per table 4.1 note b, plates qualify for pipe of OD 600 mm and above......Hence I presume this PQR cannot be used to prepare a WPS as the Job to be welded is OD 200 mm. Am I right?
3. The PQR coupon was welded in 3G position........... Hence I presume, the WPS will be valid for only Vertical Position (3G) as per table 4.1. Am I right?
4. The PQR was back welded after back gouging....... Can I use the PQR to prepare a WPS, but without back gouging. Instead can I use a BACKING PLATE.
What is the meaning of Table 4.5 34) The omission, but not inclusion, of backing or backgouging....This is an essential variable.

Does it mean that my PQR above (with backgouging done on coupon) .... in a WPS - OMISSION of Back gouging and INCLUSION of Backing plate allowed?

OR

does it mean a PQR coupon welded WITHOUT Back gouging but WITH BACKING PLATE........in a WPS - OMISSION of Backing Plate and INCLUSION of Back gouging allowed?

OR

Simply said, Omission (Backgouging, Backing Plate) is allowed, BUT Inclusion (Backgouging, Backing Plate) is not allowed. Inclusion calls for re-qualification. OR Omission (Backgouging, Backing Plate) is NOT allowed, BUT Inclusion (Backgouging, Backing plate) is Allowed. Omission calls for re-qualification.

5. EH 36 is a group II material,the PQR qualifies for Group II to Group II material...... ST 52 / S355J2H is a material that is NOT listed in Table 3.1, However on the internet the equivalent of ST 52 / S355J2H is API 5L X 52 material, and API 5L X52 is group II material. Can I say that this PQR can be used to develop a WPS to weld material ST 52 / S355J2H to EH 36.?

6. The PQR Coupon weld geometry was Single V full penetration with back gouging..... Can I use this geometry to weld Single Bevel WITH Backing plate?

I am seeking advise on each point, I am not touching on current parameters, heat input, electrode classification, etc.. which are more or less straight forward.

My apologies for this long query. Thank you in advance for you advise.

[Ballbearing]

Rudolf,
If you qualified your PQR with backing or backgouging you cannot delete (omit) this.
If you qualified your PQR without backing or backgouging you can add (include) this.

The material you have noted S335J2H is not acceptable as a substitute for a Group II material per AWS D1.1 as it is an unlisted material.

However, the code does allow the Engineer (the Owners delegated Representative) to accept alternatives to the code in certain circumstances,

1.4 Responsibilities
1.4.1 Engineer’s Responsibilities. The Engineer shall
be responsible for the development of the contract documents
that govern products or structural assemblies produced
under this code. The Engineer may add to, delete
from, or otherwise modify, the requirements of this code
to meet the particular requirements of a specific structure.
All requirements that modify this code shall be incorporated
into contract documents.
Regards,
BB

[laurudolphy]

Thanks Ballbearing.

To sum up from your reply.

Proposed material cannot be used, however the onus is on the Engineer who may permit usage of the same.

Addition of Backing/ Backgouging does not require re qualification. Deletion is not allowed. If deletion is to be done, then it has to be re qualified.

However in my case, lets say if the material, thickness, etc were not a issue. As the PQR was made out of a plate with back gouging, Can I

1. Delete Back gouging and insert backing plate? ( Its a combination of both deletion and addition)

To drift away from your reply, but in continuation to my post,

When the PQR coupon was welded with plate Groove details were Single V (60 deg included angle) CJP with back gouging. Can i prepare a WPS where the groove detail is SINGLE BEVEL (45 degree) CJP with backing plate?

Not withstanding the above, If at all I cannot use the existing PQR/WPS, I would have to prepare a new test coupon. and I would have to roll eh36 mm plate to form a pipe of 200 mm dia (I am not sure how to roll into such a small diameter), prepare an edge by bevelling the edge to 45 deg and do all the required tests. Instead of Rolling do I have any options like buying a pipe itself?

The actual job is 25 mm Hollow Tube welded to a Flat 120mm Plate. T Joint CJP. Can i use 12.5 mm thickness coupons and will it qualify me for the said job, or do i have to use a 25 mm coupon in order to qualify me for unlimited thickness as the plate is 120 mm?

Iam just trying to understand better, and asking myself a lot of if's, why's and but's.

Thanks for your patience in reading and looking forward to your advise.

Regards
Rudolf