Re: [MW:24045] Re: PQR - WPS - PWHT P91 to CS

When welding together two steels of different strength it is recommended to select a filler matching the strength 

of the weaker of the two. The lower strength filler metal would provide such benefits as better ductility, improved

weld ability, and lower cost.

Sometimes one can compensate for the reduced strength of the filler metal by increasing the section of the weld

performed, beyond the strict minimum. This practice is called over welding with under matching filler metal.

Preheat is needed in general for carbon content higher than 0.30% or for Hardness equal to or higher than 30 HRC. 

Post Weld Heat Treatment (PWHT) may be needed too in those cases.

For high strength steels one should specify low hydrogen filler metals to reduce susceptibility to cracking.

Requirements for filler metals exhibiting minimum Charpy V-notch (CVN) test value at given low temperatures are 

spelled out in certain Codes.

If stress relieving is required, it may reduce the weld strength. To maintain the strength required from the structure, 

one may need to use low alloy steel filler metals instead of low carbon steel.

Special requirement steels like weathering steels, low alloy steels and quenched and tempered steels may need special consideration  at times.

In conclusion the properties required from the structure to be welded (to perform adequately in service) will condition 

the choices available in the selection of appropriate filler metals.

 

sridhar

From: 'c sridhar' via Materials & Welding <materials-welding@googlegroups.com>

To: "materials-welding@googlegroups.com" <materials-welding@googlegroups.com>
Sent: Sunday, 3 January 2016 5:36 PM
Subject: Re: [MW:24041] Re: PQR - WPS - PWHT P91 to CS

The temp of SR for CS could be 620 ± 20 for carbon content beyond 0.25 % 

and 600 ± 20 for lesser carbon .

 

The soaking time should be 60 minutes.

 

C Sridhar.

---

 

---

From: Vishwas Keskar Welding Manager Pune India <vvkeskar123@gmail.com>
To: Materials & Welding <materials-welding@googlegroups.com>
Sent: Saturday, 2 January 2016 10:05 PM
Subject: [MW:24039] Re: PQR - WPS - PWHT P91 to CS

CS  with Gr 91 - PQR can be successful. But CS will not withstand the high operating temperature (>535 Deg C  or greater).

On Saturday, October 20, 2012 at 3:59:03 PM UTC+5:30, Tunisian Quality Engineer wrote:

Dear eorxperts,

  Need your support.

We performed one PQR P91 grade ( P number 15E) to Carbon steel (P number 1) welded GTAW/SMAW ER90S-B9 / E9015-B9, 11mm thickness, PWHT @ 740°C - 40 minutes.

PQR and related WPS already approved by our client. but the Owner consulting agency sent to us some comments :

1- No possible to weld P91 directly to CS shall add transition material P11 grade : We answer that it's design issue and i requested some explain / calculation from design.

2- Should use filler metal compatible with lower grade material : i answer that can make choice of  filler metal between to material grades (included) so we can weld with lower, heigher or iontermediate filler metal when mechanical properties is ok and don't have ebjection from project spec.

3- this is the main issue : PWHT @ 740 °c is heigher than lower critical temperature for CS so we must perform PWHT in intermediate Temperature : in this case if will do like this WPS will not supported by Prepared PQR;

PQR approved by Client and weld already done, i propose to perform hardness test, PMI and metallographic replic in production ( just one weld) to confirm.


Need your support .



Regards.





--

زكرياء غراب
GHRAB Zakaria

--
You received this message because you are subscribed to the Google Groups "Materials & Welding" group.
To unsubscribe from this group and stop receiving emails from it, send an email to materials-welding+unsubscribe@googlegroups.com.
To post to this group, send email to materials-welding@googlegroups.com.
Visit this group at https://groups.google.com/group/materials-welding.
To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/bc81d634-8aab-4878-aa1e-bef0d0f9e748%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

--
You received this message because you are subscribed to the Google Groups "Materials & Welding" group.
To unsubscribe from this group and stop receiving emails from it, send an email to materials-welding+unsubscribe@googlegroups.com.
To post to this group, send email to materials-welding@googlegroups.com.
Visit this group at https://groups.google.com/group/materials-welding.
To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/245037819.5913487.1451822767613.JavaMail.yahoo%40mail.yahoo.com.
For more options, visit https://groups.google.com/d/optout.