2205 Duplex 625 Clad

[MrGezus]

Hello all and thank you in advance for any information that you can provide.

I am going to be running a coupon in the next few days overlaying 625 inconel on duplex.

Codes:

ASME SECTION IX​

NACE MR0175​

ASTME562​

API 6A​

API 6D​

DNV-OS-E101​

I have done several cladding procedures in the past using P1 materials and 4130. I have not yet had to do one using a duplex. I've been doing some research and this is what I've come up with so far.

Preheat >300°F
Use 309L Butter Layer
PWHT - TIME AND TEMPERATURE UNKNOWN
625 finish layer.

I understand that using 625 directly on duplex can harm your ferrite content and I may fail bends. So a butter layer is preferable. However, I have never performed any sort of heat treatment on duplex.

Any suggestions?

 

[Guest102023]

I'm glad to hear you have never performed any sort of heat treatment on duplex! Time and temperature for any duplex SS should be 0 hours at Room Temperature.

Ferrite content in the Duplex SS HAZ is a function of 12/8 cooling time, not filler metal composition. Not sure why it would need a 309 butter layer, unless the combination of 625 and 2205 mechanical properties is somehow problematic for a bend test. Whatever you do, I advise using a wraparound bend jig.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[EdStainless]

Unless you are trying to fix the damage from the buttering pass, then you need full solution anneal and rapid quench.

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P.E. Metallurgy, Plymouth Tube

 

[metengr]

There should be no PWHT on duplex stainless steel because it is impractical in your situation. A solution anneal and quench will distort the vessel during fabrication, and ruin it. What you have stated is acceptable using a butter with no preheat and limiting the maximum interpass below 350 deg F.

 

[Don56]

Brimstoner, just curious, what do you mean by 12/8 cooling time?

 

[EdStainless]

I believe that he is referring to temperature range.
The duplex alloys have a number of microstructural issues that need to be watched.
Solidification and initial cooling rates will impact austenite/ferrite ratio.
Time spent coming through 1800-1200F will impact formation of intermetallics (chi and sigma).
Carbides can form in the range of 1500-800F. These first two happen over a few minutes. So welds need to be below 800F is less than 90 sec, with 60 sec being better.
The range of 1000-600F is where alpha prime (885 embrittlement) will form (also leading to increased hardness and reduced toughness). This typically takes 10 min or more to form.

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P.E. Metallurgy, Plymouth Tube