American Welding Society Forum
I need to do a PQR / WPS to ASME section IX. The PQR will be a complete joint penetration weld.
On this job, I will be welding 4130 to 4130, 4130 to 4140 and 4140 to 4140. To me, its basically the same materials except the 4140 has more carbon.
I know ASME section IX does not cover this material, but the customer want to use this code and use the material as unassigned material.
The customer also wants to use 70,000 PSI filler metal. For the tensiles, the customer is ok if the test meet the min. specified tensile of 70,000 PSI.
For PQR testing: any unassigned metal to the same unassigned metal qualifies the unassigned metal to it self.
My question is:
1) Can I considered 4130 and 4140 the same unassigned material?
2) Do I use 4140 to 4140 for PQR testing? Since 4140 has the most carbon content, we can then weld 4130 since it has less carbon content.
3) Should I use 4130 to 4140 for PQR testing? Since the weld and procedure will be tested on 4130 and 4140 in the same joint, can I then weld 4130 to 4130, 4130 to 4140 and 4140 to 4140?
I seem to recollect ASTM A387 includes the chrome molybdenum steels. There are several grades so you would have to verify the carbon content was high enough to match the 4130 and 4140.
If I understand you correctly, if I use 4140 to 4140 for a PQR. No extra test required, just the bends & tensiles.
I could then write a WPS for welding: 4130 to 4130, 4130 to 4140 & 4140 to 4130, as long as the carbon content of the test samples for the PQR was as high or higher than the 4130 or 4140 to be welded?
Yes or NO
If you are welding to D1.1 or ASME, the answer is "no", you are only qualified for the material you joined.
AISI does not include published mechanical properties for any of their base metals with an assigned AISI numbers. The reason is pretty simple, the mechanical properties are dependent on the chemistry, manufacturing process, and state of heat treatment. The AISI material specifications only warrants the chemistry, they do not include the state of heat treatment or manufacturing process (think hot rolled versus cold rolled). That being the case, how do you know if you passed the tensile tests or not? That's why most welding standards do not list AISI materials.
Why are they using a high strength low alloy steel that is heat treatable to increase the tensile strength to more than 100ksi and then weld it with 70ksi filler metal? Strange, very strange. Do they plan of doing a heat treatment to the finished weld? Stress relief, normalize, anneal, quenched, quenched and tempered? What is the state of heat treatment when you weld the coupon? They said they will accept 70ksi for the UTS, but what are they expect to do with the weldment after they receive it?
A change in the carbon content of 0.1% is significant in my world.
You'll have to review your welding standard very carefully.
Good luck my friend.
This job is not a pressure vessel. The reason for the 4140 / 4130 is because of wear and some strength.
Its actually a piece of mining equipment. I know there are other codes for this.
The customer is in the oil industry and they wanted to stick with ASME section IX.
The reason for the 70xxx filler is:
1) don`t need full strength
2) less chance of cracking with 70xxx filler.
3) better fatigue strength with 70xxx filler.
Most of the welds are fillet welds, and using a larger fillet weld could have the same strength as the 100xxx or 111000 filler.
What are you using as the minimum tensile strength? 70 ksi?
If you are not bound by a code, you’re free to do what ever your customer asks you to do. As the Owner, they call the shots.
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