What's this defect?

[500e]

Vega Tescan
Tend to agree with Bspark
http://www.tescan.com/en/other-products/special-products/mira3-amu

 

[Michael elliott]

It's a TIG weld, 321ss with 347 filler. TWI were sent the material and micros but couldn't suggest a cause so thought I would ask here. Thanks

 

[Richard.]

Don't both those grades require a form of pwht?
Was this done?

 

[MichaelV]

It's a TIG weld, 321ss with 347 filler. TWI were sent the material and micros but couldn't suggest a cause so thought I would ask here. Thanks

Michael - It must be rather unusual if TWI can't offer a view. Have you tried the technical line at the BSSS in Sheffield? I'm not sure if Alan Harrison is still there, but it would be worth checking in there.

Michael

 

[MichaelV]

Michael - details here: http://www.bssa.org.uk/technical_information.php
M

 

[TechnicAl]

Michael - It must be rather unusual if TWI can't offer a view. Have you tried the technical line at the BSSS in Sheffield? I'm not sure if Alan Harrison is still there, but it would be worth checking in there.

Michael

Alans retired. Im trying to recall the new guys name.......Lewis I think.........its BSSA

 

[TechnicAl]

It's a TIG weld, 321ss with 347 filler. TWI were sent the material and micros but couldn't suggest a cause so thought I would ask here. Thanks

Where is the crack? Is it centre of the weld, across the weld, alongside the weld
What welding process was used
Is it a single pass or multi.........fillet or butt........has it cracked after / during welding or in-service?
Do you know all the details of the welding procedure........

as much detail as possible and we may be able to suggest something

 

[MichaelV]

Alans retired. Im trying to recall the new guys name.......Lewis I think.........its BSSA

Thanks TechnicAl - I always found him a very helpful chap. Have you a view on whether it's knife-line attack, albeit at a high magnification?
Michael

 

[Michael elliott]

It's was a single pass butt weld. Cracks are across the weld. Failed inspection after welding so hadn't gone through any pwht. Failed again after rework.
Thanks Michael, I'll give them a call.

 

[MichaelV]

Michael - I've messaged you directly with another contact that may be able to help.
Good luck in resolving it - I'm sure many would be very interested to learn more if you're in a position to discuss it at a later date.
M

 

[TechnicAl]

It's was a single pass butt weld. Cracks are across the weld. Failed inspection after welding so hadn't gone through any pwht. Failed again after rework.
Thanks Michael, I'll give them a call.

Across.......thats unusual

have you got a photo of the whole weld....not high magnification

was it a vee or a square edge

was it a single pass against a copper backing bar

 

[Michael elliott]

Thanks for your help Michael

I'll post a photo tomorrow.
It was a square edge, not sure of the backing bar material

 

[TechnicAl]

has the weld sunk?

 

[Michael elliott]

No sinking

 

[TechnicAl]

Its not easy to make cracks in 347. Its highly crack resistant. So its not an obvious answer

As much information as possible please.

 

[Paul The Pie Eater]

Is that San Andreas?

 

[voipio]

Are there any other images available, e.g. visible light micrographs, or etched cross-sections through the weld? It is probably down to excessive shrinkage during cooling. There appear to be inclusions in the weld, so could be impurities with higher thermal expansion coefficients, and there are hints of crystallisation being present, although the crack itself doesn't appear to follow any crystal planes, following more of an amorphous profile. Could there have been significant vibration during welding?

 

[TechnicAl]

Are there any other images available, e.g. visible light micrographs, or etched cross-sections through the weld? It is probably down to excessive shrinkage during cooling. There appear to be inclusions in the weld, so could be impurities with higher thermal expansion coefficients, and there are hints of crystallisation being present, although the crack itself doesn't appear to follow any crystal planes, following more of an amorphous profile. Could there have been significant vibration during welding?

Bloody hell mate, youve lost me..............Whats an "amorphous profile"

 

[NickyEng]

Bloody hell mate, youve lost me..............Whats an "amorphous profile"

No crystal grain structure in the metal more like glass

 

[rikrobson]

So its a butt crack.

#Goes off sniggering in the corner