For 800H below 787℃, use 82 (ER NiCr-3) welding wire. RA 330-04 (N08334) welding wire has a matching thermal expansion coefficient and higher strength. If you want to obtain the maximum mechanical strength, it is best to use welding wire 617 (ERNiCrCoMo-1) or welding rod 117 (ENiCrCoMo-1).
In order to avoid stress relaxation that may occur in 800H welded parts above 538℃ and cause grain boundary cracking, post-weld heat treatment is required at 899℃. The holding time is one hour per 25 mm of material thickness (at least half an hour/25 mm thickness), and then air cooling.
Material standards UNS American standard: N08811, N08810 W. Nr./EN European standard: 1.4958, 1.4959 ASTM: B 409, B 408, B 407 ASME: SB-409, SB-408, SB-407 Code Case 1325
800H alloy has the following characteristics:
- Excellent corrosion resistance in aqueous media at extremely high temperatures up to 500°C
- Good resistance to stress corrosion
- Good processability
Incoloy 800H metallographic structure:
800H is a face-centered cubic lattice structure. The extremely low carbon content and the increased Ti:C ratio increase the stability of the structure and the maximum resistance to sensitization and intergranular corrosion. Low-temperature annealing at around 950°C ensures a fine-grained structure.
Incoloy 800H corrosion resistance:
800H is resistant to corrosion by many corrosive media. Its high nickel content gives it good resistance to stress corrosion cracking under aqueous corrosion conditions. The high chromium content gives it better resistance to pitting and crevice corrosion cracking. The alloy has good resistance to nitric acid and organic acid corrosion, but limited corrosion resistance in sulfuric acid and hydrochloric acid. In addition to the possibility of pitting corrosion in halides, it has good corrosion resistance in oxidizing and non-oxidizing salts. It also has good corrosion resistance in water, steam, and mixtures of steam, air, and carbon dioxide.
Application areas
- Nitric acid condenser – resistant to nitric acid corrosion
- Steam heating tube – good mechanical properties
- Heating element tube – good mechanical properties
For applications up to 500°C, the alloy is supplied in annealed state
