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AL-6XN Alloy has proven to be resistant to a broad range of very corrosive processing environments. Exceptional corrosion resistance is obtained to chloride-induced corrosion in the forms of pitting, crevice and stress corrosion cracking. AL-6XN alloy also has excellent general corrosion resistance to various acids and salt solutions. This is achieved due to the higher levels of:
- Nitrogen – which retards the formation of chi phase during manufacturing and field welding
- Chromium – provides good resistance to oxidizing environments
- Molybdenum – improves resistance to chlorides.
AL-6XN alloy initially is more expensive than 300 series stainless steels. However, life-cycle costs for systems utilizing the alloy can be far less than the comparable costs of the initial installation, maintenance, and subsequent replacement of lesser alloys used in aggressive environments. In addition to material replacement, labor costs, and production downtime caused by system failures of 300 series stainless steels used in very corrosive environments, consideration must also be given to the associated costs of product contamination caused by corrosion related failures. Studies have shown the initial cost comparison of AL-6XN raw material to other alloys as follows:
304L stainless steel = factor of 1 (base)
316L stainless steel = 1.15 (x) 304L stainless steel
AL-6XN Alloy = 3 (x) 304L stainless steel
C-276 / C-22 = 5 (x) 304L stainless steel
When selecting materials for process systems, guidelines should be followed giving consideration to the service environment. The inclusion of corrosion control and the correct material selection is the most efficient and economical means for controlling corrosion and adding life to a piping system.
The toughness and ductility of the AL-6XN alloy provides for relative ease of fabrication in the shop or field environments. Satisfactory machining may be achieved by the selection of the correct tools and machine set-ups (see machining section). The low carbon and high nitrogen contents minimize the precipitation of carbides and secondary phases that can occur during welding. Field welding can be easily achieved provided that a suitable over-matched filler ring is used (see weld ring section) and the material has been properly cleaned and prepared for welding. Welding procedures are similar to those used with other austenitic stainless steels.
Central States Industrial (CSI) provides AL-6XN Alloy in the following product forms:
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