Welding of dissimilar metals

[Rilley Chellah Mulenga]

Good day experts ,

we encountered  a challenge trying to reducers of 108 duplex steel to mild steel and welding 108 duplex stainless steel steel to 304 stainless schedule 80, what is the best filler rods i can use when using TIG 

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Thanks & kind regards

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[Vishwas Keskar]

What is the 108 duplex steel ?

Pl inform Duplex garde?

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[Rilley Chellah Mulenga]

The duplex steel grade is  SAF 2507

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[Yasin Tamay]

Hi Mulenga,

I currently have such a calculation. I used it in my previous works. There are 3 alternatives for you. It can be used as an alloy and transition wire. Don't forget to check your own calculations and the FN region. The De Long diagram is good.

1. ErNiCr3 SFA A5.14 >> Since the Cr Ni ratio will be high, the Ferrite ratio in Duplex should not fall below 30%.
2. Duplex ER2209 SFA A.9 >>> Seems ideal. Since there will be a combination of 304 different materials, there will be some loss of chemical properties of the superduplex. In fact, you get a complete Duplex.
3. Superduplex ER2594 SFA A5.9 >>> Definitely the best. The amount of Cr in the weld metal will increase. The amount of Ni also to a very small extent. In both options, you remain in the Austenite+Ferrite region. Don't forget to do a cost calculation according to the importance of the job. <<<

Maybe I don't need to say it, but use 100% Ar as Shielding and Backing gas. If you have the opportunity, 2.5% Nitrogen for Backing can prevent root darkening. This also provides better corrosion resistance. O2 max 250 ppm !!
You should keep the heat input to a minimum, use values as low as you can. (interpass should be max 50°) All these are information that will definitely work for you for butt welds. Good work.

21 Ekim 2025 Salı tarihinde saat 09:43:03 UTC+3 itibarıyla Rilley Chellah Mulenga şunları yazdı:

[Mohd Siraj]

use same duplex electrode or filler wire.