Dear Mr. Bhandari,
Regarding minor repairs of Super Duplex Stainless Steel I would suggest to weld with a maximum interpass temperature of 150 °C.
One of my customers also manufactures Super Duplex Stainless Steel castings and as long as the part isn’t machined we prefer executing welding and afterwards perform solution heat treatment at 1130 °C followed by water quenching, but only for the full part and not local because of critical temperature areas as suggest by yourself.
After machining we only execute minor repairs by controlling interpass temperature with a maximum of 150 °C. In this way it’s not necessary to perform water quenching afterwards because the influence on surrounding material will be minimized. Of course manufacturer needs a qualified repair welding procedure for this because PWHT is an essential variable and testing need to include microstructure examination of HAZ and base material to ensure no precipitation takes place and/or sigma phase will be present.
Hope this will help you forward.
Met vriendelijke groeten / Best Regards
Herman Pieper
Pieper Quality Support & Inspection
Phone: +31 (0)521 380083
Fax: +31 (0)84 7539225
Cell: +31 (0)6 51691215
www.pieper-qsi.nl
Van: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] Namens Vikas Bhandari
Verzonden: woensdag 25 mei 2011 22:36
Aan: materials-welding@googlegroups.com
Onderwerp: [MW:11150] Weld Repair Procedure- 25% Duplex Casting
Hi
I have a weld procedure which the manufacturer of valves wants to use as a repair procedure for contingency purposes for 25% Super duplex casting.The procedure conducts solution annealing after welding. I think , for repair (allowing minor repair only,no more than 25% of wall thickness , not more than 10% of total surface area), localised solution annealing (1120 C) is neither possible nor desirable (more chances to form embrittle precipitates in the surrounding region). So the best solution is to weld (which will raise to temperature greater than 1120 anyways) the repair , followed by water quenching after completion of welding.
Please correct me if I am deviating form the facts.
Secondly, the proposed WPS shall be rejected as PWHT is not carried out in minor repair of 25 Cr Castings.
Your prompt response in this regard would be much appreciated.
Best regards
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1 comment:
Hi Vikas Bandari,
For SDSS 25% Chromium steel , you should not do excavation by welding
I have implemented this procedure in Manchester and I got a positive result.
SDSS is normally high toughness material in my case ASTM A 890 gr
6A
I have got many repairs which exceeds the casting repair criteria.obviously we dont have another casting if we reject this.
So i have implemented and succeeded
The procedure as follows
Keep with 4 Good PT technicians
First you completely clean by diluted acid.
Clean througly use Hindustani labours.
Apply Water washable Dye Penetrant dwell time is 30 min
There is a small point. During the 30 minutes yo keep on apply penetrant so that the surface area should be wet during 30 min
Use a high quality camel hair brush
Once cleaned by Water, just do dry air blow on the surface. Then apply developer by low pressurised
comressor.15bar
You can get a good fine indications.
well how do you repair.??
This is the complicated task
If you gouge finsih, your quality of material will gone. you never excavate the repair by welding
Use a good quality hard Tunsten Carbide Tip globe,needle grinding wheel
Use pneumatic grinders donot use electric grinders.
Use good experience grinders to remove the repair, and do PT so again you get indiactaion.In this manner you will clear the defect.
Then before welding clean properly so that no penetrant residues are not there.clean 2 times apply developer again, heat clean apply developer.
so finally the excavated area doesnot have any penetrant residues.
Now preheat upto 125 deg C Use good qulaity Welding by approved WPS.
If you practice in this manner No PWHT required after repair
Try this you can realise
The basic idea is donot heat the material SDSS, for localised repair.
After repair if possible go for X-ray or Co-60 RT
Navaneethan.S
NDT L3
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