Welding 4130 with 100K Min Yield Strength 2

[jmec87]

We've been welding 4130 steel with 75 ksi minimum yield for sour service oil and gas applications quite successfully for a while. We're now looking at welding 4130 steel with 100 ksi minimum yield for a standard service oil and gas application. The standard service application has no H2S, so we don't need to meet NACE MR0175, but we still want to PWHT to relieve the residual stresses from welding. We need to maintain the 100 ksi minimum yield strength in the weld and base metal after welding and PWHT.
We're planning on using E12018-M filler metal in order to hit the required yield strength. Most of the filler metal data sheets that I've found for E12018-M don't give a recommended PWHT. Is E12018-M suitable for PWHT? If so, what is the lowest suitable temperature? (We need to stay below the tempering temperature of the steel).
Can anyone share any experience they've had welding 4130 with 100 ksi min yield?
Is there a similar alloy (such as 4330 or 8620) that is better for welding when 100 ksi min yield is required?

 

[metengr]

If you are thinking of using E12018-M, have you looked at AWS SFA 5.5, and have you reviewed Table 3? If not, I would encourage you to do this. Second, you should be qualifying a welding procedure, which means you can weld a coupon, PWHT and determine if the selected filler metal is acceptable or other is required. Your selection of PWHT should be based on the original tempering temperature - 50 deg F to avoid altering the bulk mechanical properties of the base material (4130).

 

[jmec87]

Thanks metengr. I'll have a look at SFA 5.5. We're planning on qualifying the weld procedure, including welding the coupon, PWHT, and mechanical and charpy testing. I want to make sure our PWHT is reasonable before we try the qualification. We currently have material available which was tempered at 1000°F. If we PWHT 50°F below that, we'll be at 950°F, which seems too low to be an effective PWHT. Can you suggest a minimum PWHT temperature for 4130? Or do you think 950°F will be fine if the base material was tempered at 1000°F?

 

[metengr]

jmec87;
Try and run a coupon and evaluate the mechanical properties. If your tempering temperature is too high you will soften (lower the strength) the surrounding 4130 base material. This is why I use 50 deg F below the original tempering temperature.

 

[TVP]

I agree with metengr. Use 950 F as a starting point for PWHT.