Welding SA387 Gr22 to SA516 GR70 - N

[muld0020]

I was wondering if anyone has a recommendation (pros/cons/discussion) for filler materials for SAW SA387 GR22 (P5A Gr1) to SA516 GR70 Normalized (P1 Gr2). I am working to ASME Sec IX and ASME Sec VIII D1 and D2 vessels.

I need to expand a weld procedure to incorporate the dissimilar weld metals with PWHT. I'm not certain if it is better to use a low carbon weld wire or a "B3" low alloy filler. My thought would be that using the carbon steel electrode the weldment may be more ductile and cracking less likely. If I incorporated our FCAW, SMAW, and GTAW process would the same (Low Carbon vs B3) still be true.

(I apologize for the brand specific materials)
We currently use for P5A material: LA93 W/ 880M flux : F7P0-EB3R-B3-H8
We currently use for P1 Gr2 materials: LA71 W/ 888 flux : F7P8-EM14K-H4

My best guess for the filler for P5A - P1GR2 : LA71 w/ 880M : F7P8-EM14K-H8

 

[metengr]

You can use either a carbon steel electrode, a 1.25%Cr - 1/2% Mo electrode or a 2.25% Cr - 1% Mo electrode for joining P-No 1 to P-No 5A base materials. I would not use a low carbon weld metal given the fact that after PWHT there is a loss in strength properties, which is the reason why the low carbon electrodes have been classified in a lower strength category.

Because of the use of Grade 22, PWHT will be required. I would use either a 1.25% Cr- 1/2%Mo weld metal or matching weld metal with the Grade 22 base material.

 

[weldstan]

Echoing metengr, we recently performed chemical analysis of deposited weld metal of an E71T-1 flux cored wire with the following results. C = 0.03%, Mn = 1.05%. After PWHT at 1300F, do not expect to have 70Ksi tensile properties of the weld metal.

 

[muld0020]

Thank you for the input. I appreciate it.

I looked at the product data sheet on the SAW filler/flux combination LA71 w/ 880M : F7P8-EM14K-H8

The published data in PWHT condition is 63ksi yield, 80ksi tensile, 31% elongation and 121ft-lbs @ -80F

The 80ksi would be stronger than the SA516 GR70, would you still shy away from the low carbon approach on the SAW? Any other reasons besides getting the strength above the 70KSI for the SA516 GR70?

 

[metengr]

What is the application that requires the DMW? Again, you can use what you mentioned above or higher alloy that matches the Grade 22 base material. The electrode formulations today have improved over the years and have increased weldability.

 

[weldstan]

F7P8-EH14 will have no difficulty meeting 70 Ksi tensile properties after PWHT at 1300 F.