ASME IX QW407.4

[DiplingAndre]

Dear all,
I have a question regarding ASME IX (2010) QW 407.4.
"QW-407.4 For ferrous base metals other than P-No. 7,
P-No. 8, and P-No. 45, when a procedure qualification test
coupon receives a postweId heat treatment exceeding the
upper transformation temperature or a solution heat treatment
for P-No. lOH materials, the maximum qualified base
metal thickness, T, shall not exceed 1.1 times the thickness
of the test coupon."

So for my understanding. When I weld a Duplex/Superduplex (P10H) test coupon and give him a solution annealing, which is required by the product standard my qualified thicknes is limited to 1.1xt?!
If I don't do a soloution heat treatment the thicknes is 2xt?

Can anybody tell me if my understanding is correct and if it's like this the technical reason for it?
Solution heat treatment is only to eliminate sigma phases and doesen't touch the basic structure or change the ferrite/austenite ratio.

Thanks in advance!

 

[metengr]

What QW-407.4 means is this.... when you weld a procedure qualification coupon and subject the coupon to a post weld thermal treatment that either exceeds the upper critical transformation temperature OR the original solution treatment temperature per the original material specification requirements, the thickness limit for the qualified procedure is 1.1x coupon thickness.

Why? Because if you exceed the upper transformation temperature or the original solution treatment temperature you are altering the bulk mechanical and corrosion properties of what was originally supplied by the material specification, especially the balance of phase constituents required for duplex stainless steel alloys.

Look at rules required for subcritical post weld heat treatment in ASME B&PV Code. For a subcritical post weld thermal treatment you are not affecting bulk mechanical properties.

 

[DiplingAndre]

Hello metengr,
tzhanks for your quick response.
Your view seems logical but where can I find a proof for this interpretastion. The ASME is not very clear.

 

[SJones]

Solution heat treatment is only to eliminate sigma phases and doesen't touch the basic structure or change the ferrite/austenite ratio.

You may find that this statement is not quite correct.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[DiplingAndre]

Are you sure. I don't think that a quick heating up to 1040°C and rapid quenching can change the ferrite/austenit ratio due to holding times of some minutes.

Nevertheless is there a Para or clarification which helbs me to proof this interpretation?

 

[metengr]

Induction heating can certainly result in very rapid heating and altering of phase constituents.