Nickel and Nickel Alloys
Two main groups
- solid solution alloys (e.g. IN200, Hastelloy)
- can be fusion welded in the annealed condition
- HAZ does not harden so no pre/post heat needed
- precipitation hardening alloys (e.g. IN738)
- fusion weld in the solution treated condition and then heat treat to precipitation harden
- surfaces must be well cleaned before welding
- liquation cracks can occur on reheating