Cast 22% Cr Duplex & ASTM G48a corrosion test

[bruv]

We have an enquiry for ASTM A995 J92205 cast 22%Cr duplex stainless. The client is requesting corrosion testing to ASTM G48 method A at 40C.

I have gone through our database and confirmed that we have never tested this material above 30C. The only exception to this are 2 occasions when the test house got it wrong and tested at 50C, with disastrous results.

Does anybody have experience of testing this alloy at 40C, and what results did you get?

In addition to this, what are your experiences of S32550/CD4MCuN at the same temperature?

 

[EdStainless]

Does your customer actually want A923C and they miss-speced this?

I would doubt that the cast alloy could pass 40C.

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Plymouth Tube

 

[bruv]

It's unlikely that they want A923C - they never have in the past (although our client isn't the end user). Plus, A923C calls out 25C for 22%Cr duplex and 40C only for the 25%Cr grades of duplex.

We also doubt that cast material will pass at 40C, but we are having a test done to see exactly what we get.

 

[metengr]

The literature I have indicates the ASTM G48 Practice A CPT for 2205 unwelded is about 34 deg C and the CCT is about 14 deg C.

 

[EdStainless]

They should be asking for a A923 to assure that there are no secondary phases in the material.
The big difference is that for a A923 test you must have freshly ground surfaces, to assure exposure of material.

I will be very surprised if you can pass a G48 at 40C.

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Plymouth Tube

 

[bruv]

So will I. I am having some material tested, to see exactly what results we do get.

On the subject of A923C, we have NEVER been asked to carry out testing to this spec. The industry standard seems to be G48A. Very often we are asked to supply 22%Cr duplex with charpy-v impact testing and ferrite count, but no corrosion test of any sort.

Does anyone ever ask, or get asked, to supply material meeting A923C requirements?

 

[metengr]

Does anyone ever ask, or get asked, to supply material meeting A923C requirements?

Yes, we ask as an owner/user.

 

[EdStainless]

923 isn't a corrosion test. It uses either impact toughness at low temp or a corrosion measurement to identify the presence of detrimental secondary phases.
It is verifying proper heat treatment.

People ask for this on heat exchanger tubing all of the time.
Every part, made by any method, in a 22 or 25 Cr duplex should always require this.

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Plymouth Tube

 

[bruv]

Better late than never, for your info, corrosion test results. All three test pieces taken from the same keel block.

30C - 0.3g/sq.m weight loss, no pitting
40C - 16 g/sq.m, pitting.
40C, after pickling - 7.5g/sq.m, pitting

I guess we don't get asked for A923C as we are very often working to Norsok requirements (or similar), where impact at -46C plus a micro is standard.