Dissimilar welds

[leedrong]

Hi ~!Specialist

Anyone who know the suitable welding rod material for
welding 9cr to A410 stainless steel ?
We failed qualification test using 309 welding rod .
The cost is too fuge when we use Inconel welding rod
(ER NiCr-3 )because calculated required welding rod is 3000 kgs.

Waiting helpful replies.

 

[ijzer]

Because welds to 9Cr require PWHT , you have to use ERNiCr-3

 

[metengr]

You might want to consider buttering the 9Cr and 410 SS sides of the weld joint using ERNiCr-3, PWHT and fill the remainder of the buttered weld joint using 309 ss with no PWHT. It may help to offset the cost.

 

[deanc]

Agree with metengr

 

[leedrong]

Many Thanks ~!
The failed section and area was bonded area of 410ss side on bend and tensile test.
Still I want try welding with 309L welding rod without buttering.
when I fail again ,second try will be Buttering both side with 309L and PWHT and welding with 309L.
How about my plan .

 

[metengr]

It appears from your second post that you did not PWHT after welding. You need to PWHT the 9Cr and 410 SS weld joint. The reason that the failure occurred on the 410 ss side of the weld joint is because of the untempered martensite formation in the HAZ. I would butter the 9Cr and 410 SS sides of the weld joint with 309L and PWHT. Then finish the weld joint.

 

[leedrong]

We did PWHT after Inconel buttering on 9cr and weld using 309L with 410.
But the result was crack along weld boundary Inconel butter weld with 309L at 120 angle during bend test.
Do We need to use Inconel welding rod instead of 309L?
Is it final applicable choice ?

 

[metengr]

leedrong;
Please go back and follow the suggestion in buttering BOTH sides of the weld joint (9Cr, 410 SS) using ENiCr-3. IMPORTANT - Butter layer should be 1/4" in thickness to avoid base metal dilution effects, PWHT the coupon, then finish the weld joint using E309 with NO PWHT.

 

[GRoberts]

I might be missing something in this thread, but since the joint has to recieve PWHT anyway, why not weld the joint with 410 filler metal and PWHT everything at once? The filler metal should be metallurgically compatible with both materials, and is cheaper than austenitic stainless or nickel based filler metal.

On a side note, are you using transverse or longitudinal bends? With the large strength difference between the materials (with the weld having a lower yield strength), side bends stand little chance of passing. Especially if you are bending with a plunger type machine instead of a wrap-around type bending fixture.