SA516 micro structure Island type feature filled with scale:

[ahsinnaqvi]

Kindly can someone help me identifying this feature?? Is it a crack or some other feature resulted from in service application.

 

[metengr]

Looks like a large, non-metallic inclusion or slag pocket.

 

[weldstan]

Non-metallic inclusion. Where is it located through the thickness? Are there any more similar?

 

[EdStainless]

And what is the product (how was it made)? and what is the orientation of this?
If it is near the surface of a hot formed product then you look one place, but if it is down the center of a long product that is different.

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P.E. Metallurgy, Plymouth Tube

 

[ahsinnaqvi]

This feature was developed adjacent to the welded region in riser containing an upper conical shaped section which is connected at the large end of the cone to a cylindrical sleeve that fits around and overlaps a portion of the lower riser in FCC reactor system.

 

[ahsinnaqvi]

"Non-metallic inclusion. Where is it located through the thickness? Are there any more similar?"
Yes there were more, grinding the surface upto one mm resulted in the removal of these partially rust filled inclusions.
Thanks for the response.

 

[EdStainless]

Either slag from the melting and casting, or scale that was rolled in in hot working are the most likely.

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P.E. Metallurgy, Plymouth Tube

 

[weldstan]

So they are at the surface. We used to call these flaws skin laminations. They were deemed to be a combination OF NMI and scale. They were quite prevalent on SA-516 back in the '70s.