From: sudhakar kuppuswamy
Sent: 09-10-2014 08:43 AM
To: google welding
Subject: Re: [MW:22078] Super Duplex stainless Steel weld (UNS S32750)- ASTMA923 Method C Testing
Hello Azam,
Meeting the acceptance criteria of ASTM A923 Method C for weldments in as welded condition is HIGHLY IMPOSSIBLE.
The intention of doing ASTM A 923 Method C on DSS/SDSS material is to detect the formation of detrimental intermetallic phases during manufacturing, i.e. to ensure how effectively the SOLUTION ANNEALING heat treatment is carried out by the manufacture.
Of course, if the weldments are subjected to SOLUTION ANNEALING then the requirements can be meet, but lot of practical difficulties are there in doing so at site conditions!!.
During welding we cannot avoid formation of INTERMETALLIC PHASES completely , because of slow cooling from higher temperatures, particularly in multiple pass welding i.e in thick sections the percentage of intermetallic phase formed will high when compared with thin sections.
But you can convince the client, by request for a technical deviation; you can substantiate the deviation by putting forward the following points.
- Successful Impact test results, (Intermetallic phases deteriorate the toughness of the material )
- Successful Pitting corrosion test as per ASTM G48 Method A ( without any pitting on the test sample)
- Delta Ferrite Count within acceptable limits,
- Hardness values within limits as per NACE requirements.
--Dear Experts,
Pls share your experience on super Duplex Stainless steel weld:
We run PQR for SDSS material UNS S32750 Pipe to Pipe Single "V "butt weld, All the testing result in line with requirement like Tensile, Hardness, Macro, Ferrite to Austenitic ratio, ASTM G48 but ASTM A923 Method C testing is not meeting the requirement
Acceptance Values
20.1 The corrosion rate is calculated in accordance with the
weight loss and total surface area (see Note 5). Unless
otherwise specified, the calculated corrosion rate shall not
exceed 10 mdd (see Note 6).
NOTE 5—The corrosion rate is calculated in accordance with the
following: corrosion rate (mdd)
= weight loss (mg)/[specimen area (dm2) × time (days)]
Even if sample will meet the requirement of ASTM G48 and Shell DEP 30.10.6018-Gen. it will not pass ASTM A923 Method C. ASTM A923C requirement is looking likemore stringent compare to ASTM G48.We prepare sample size 50 mm*10mm*thickness (3.4 mm). Pls share your expertise.
Thanks & Regards,
Mohd. Azam
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