Ferrite test done on 1.4462 duplex material for structural application

[vellingiri]

My understanding about Duplex S.S is mostly used in pressure vessels. Ferrite content testing is important quality test for its welding because mostly it has to perform in corrosive environment with high thermal stresses.

But,we are using Duplex SS (EN std. 1.4462)in rolling stock underframe where the environment is not highly corrosive and stresses are present due to static/ dynamic loading only.

Can anybody suggest what is the relevance of ferrite tests done on Duplex SS welds for application in structures.

 

[metengr]

vellingiri;
Confirmation of the necessary ferrite content for strength, corrosion resistance, forming and weldability.

 

[vellingiri]

Hi Metenger,

Thanks for your reply...

Since the Ferrite content value is more than 70 % and I would like to know the consequences on the product of the same.

Is there any destructive or non destructive test know about the consequences on the product ? especially about corrosion resistance and toughness ?

 

[EdStainless]

Very high ferrite numbers can also result in poor ductility at low temp. Are these frames ever going to be used below freezing? If so you need to qualify with low temp impact testing. A923 should always be specified for qualification of welds in duplex grades.

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Plymouth Tube

 

[vellingiri]

Hi Edstainless,

The operating temp is -10 to +50

 

[vellingiri]

Hi Edstainless,

Practically We can consider the operating temp as 0 to +50 deg. C

 

[EdStainless]

I would still require A923 to assure that there have not been detrimental secondary phases introduced. I am suspicious.
What weld filler was used?
Impacts at -40 will tell you quickly if the material is sound.

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Plymouth Tube

 

[dig1]

70%+ ferrite is high and I would be worried about this under a fatigue condition because the high ferrite generally has low impact strengths associated with it.

What filler metal was used? I assume 2209.

How thick is the material?

Was the ferrite measured in the heat affected zone (I assume so)? What was the ferrite in the deposited weld metal and the base material?

Was a pre-heat applied?

Normally, I have seen ferrite in the 55-65% range in the HAZ for a reasonable range of thickness (6 mm to 50 mm) with reasonable welding procedures and practices. I have however seen numbers has high as 80% (this was rejected).

I agree with Ed Stainless that I am suspecious of the numbers.

Thanks,

Patrick

 

[vellingiri]

Hi All,

Thanks..

 

[EdStainless]

Another reason to care:
If you are way off of the normal ratio you are much more likely to form detrimental secondary phases. While these phases normally take many minutes to form, under high ferrite conditions they may form in under a minute. Their presence would lower corrosion resistance and ductility enough that reliability could be impaired.

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Plymouth Tube