Re: [MW:17961] PQR for Welding Weldox 700

Dear Mr. Ramin

Thanks for your valuable feed back. But am afraid I have checked with SSAB manufacturer of this plate and am told that PWHT is not mandatory unless the design calls for. 

However I agree with you regarding the transfer method.

The heat input has been very low as the welding speed was good, but. This too fast may also be the reason for insufficient slag covering over the weld puddle and exposure to atmosphere. 

Another possibility may be the low heat input the heat has immediately dissipated to the base metal and the plate has served as a heat sink thereby leading to a hard micro structure. 

Regards

Rudolf

Sent from my iPhone

On 18 Jun, 2013, at 2:03 PM, Ramin Kondori <raminkondori@gmail.com> wrote:

Dear Rudolf:

Of course it will fail...
This is a Q&T steel...
Along with heat input control, a 35 mm Thick Weldox-700 plate shall definitely require stress relief after welding.

But be careful...

The holding temp shall not exceed that of base metal during manufacturing.
do not apply stress relieve at 600, 620 or so...
Check the plate certificate and you will find the heat treatment parameters there, the PWHT temp shall not exceed the tempering temperature of your weldox-700 plate.

Try to keep heat input around 1.0 KJ/mm. Lower heat input is better.

You are using FCAW...

Not saying that it is wrong but sometimes in Q&T steels, you have to use pulsed arc or spray transfer to get good impact results and for this reason, MIG works better (in case you failed with FCAW).

Good Luck

Ramin Kondori

Sr. QA/QC Engineer

SINOPEC

r.kondori@petroyada.com
+98-2123592322
+98-9132150320

On Sat, Jun 15, 2013 at 6:02 PM, rudolf <rudolf.jude@gmail.com> wrote:

Dear Community Members.

We have done a PQR coupon for welding Weldox 700E. The material Thickness was 35 mm. Double V Groove Butt Joint. 2G position. Code AWS D1.1

The following parameters were followed

Process = FCAW

Electrode wire = Esab Dual Shield II 110 

Gas = 80 % Argon 20% Co2

Gas Flow = 20 lpm

Preheat to 103 C

Interpass temp around 150 C

Current Settings 

DCEP CV

Amps 200 amps 24 Volts for root pass 

Amps 180 to 160  24 Volts for hot, fill and capping.

The heat input recorded was between .8 to 1.5 kj/mm

The wire feed rate was 10 m/min

We did a charpy test on weld metal however it failed.

The results were average of 8 kj absorption at -40 C

At 1mm and 5mm from fusion line the absorption was 80 to 130kj

Intend to do a re charpy test @ -18 C.

Though the client has not specified Charpy requirements and specifications. Wanted to do it for future requirements if any.

Request you to please share your opinion,

WHAT COULD BE THE REASON THE CHARPY @ WELD METAL IS SO LOW, and in the absence of specific requirements for CVN what should be the impact values.

AWS D1.1 does not state any values for Yield strength above 355 MPA, but leaves the onus on the client to specifiy.

Please advise.

Thanks

Rudolf

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