Quality control and assurance program for duplex stainless steels, field experience
- FMC Corp., Santa Clara, CA (United States)
- FMC Corp., Princeton, NJ (United States). Engineering Services
Duplex stainless steels have proven to be cost effective alternatives to more highly alloyed materials in chloride environments in which conventional 300 series austenitic stainless steels suffer from stress corrosion cracking. However, improper welding of these alloys can cause significant reduction in their corrosion resistance. Close monitoring of welding during fabrication and tight quality control is necessary to ensure that sound weld metal microstructure is obtained with optimum corrosion resistance. One of FMC`s primary applications for duplex stainless steels has been in large scrubbers units in chemical processing plants. In the fabrication of these scrubbers, training of the fabricators and welders was necessary as a part of the total quality control and assurance program. Corrosion testing was performed on coupons removed from each welding procedure qualification test plate and from run-off tabs removed from production welds. The corrosion tests were performed in ferric chloride. Although ferric chloride is not a realistic service environment for these alloys, it has been widely used for screening purposes and successfully indicates the presence of undesirable microstructures. Two deposited weld microstructures were identified as being most susceptible to pitting in the samples examined. These were areas with high ferrite containing precipitates and reheated areas of multiple pass welds with a high secondary austenite content. Field experience showed that relying only on monitoring and controlling the welding heat input, preheat and interpass temperatures, may not be sufficient for ensuring the corrosion resistance of the finished weldment and additional corrosion testing should be done. The materials tested were weldments of alloy 2205 (UNS S31803) and alloy 255 (LTNS S32550).
- OSTI ID:
- 80125
- Report Number(s):
- CONF-940222-; TRN: IM9532%%252
- Resource Relation:
- Conference: Corrosion 94: National Association of Corrosion Engineers (NACE) international annual conference, Baltimore, MD (United States), 28 Feb - 4 Mar 1994; Other Information: PBD: 1994; Related Information: Is Part Of Corrosion/94 conference papers; PB: 5005 p.
- Country of Publication:
- United States
- Language:
- English
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