Heat treatment of Super Duplex 2507

[Kaysuns Ltd.]

thread330-462459

I haven't seen such a serious and earnest technical discussion in a long time, thank you. As a material supplier, we are struggling with whether or not to do heat treating for orders of A928 S32750 super duplex welded pipe.
It is a fact that most super duplex welded pipes and butt-weld fittings to A815, the manufacturer does not do heat treatment. This is not just because of cost, but because of the nature of duplex steel. It will be deformed too easily when heated. Especially for thin wall thickness pipes and fittings, once heat treated they can be completely deformed or even scrapped, which is a huge challenge for the manufacturer. And in practice, there is a few complaints caused by the lack of heat treatment.

 

[EdStainless]

If you can pass A923 and mediocre corrosion resistance is fine then use A928.
For real corrosion resistance you should insist on full anneal and quench.
Such as is required in A789 and A790.
The allowance to skip anneal if the plate meets the anneal requirements is bogus.
Though it sill needs to be marked HT-0 so that everyone knows that it isn't annealed.
The real problem with unannealed pipe is where the butt welds cross the seam welds.
You end up with a zone that will not meet the A923 requirements.

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P.E. Metallurgy, consulting work welcomed

 

[Kaysuns Ltd.]

Thanks for your suggestions. As I said, super duplex 2507 welded pipe is easily deformed during heat treatment and is very difficult to repair. I think I need to discuss this with the customer

Kaysuns Ltd. - Stainless Steel & Duplex.

 

[EdStainless]

It sounds like you need to invest in manufacturing methods.
I have annealed a lot of duplex pipe and tube over the years.
Much of it with wall thickness less than 2% of the OD.
With duplex the anneal temp is critical as it changes the A:F ratio.
And with superduplex a hard quench is often needed as the walls get thicker.

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P.E. Metallurgy, consulting work welcomed