Aerospace Material Specification 5806 is a corrosion and heat resistant iron-nickel alloy in welding wire form.
Fe: 42% | Ni: 38% | Co: 15% | Cb: 3% | Ta: 3% | Ti: 1.4% | Al: 0.92%
Further reading: AMS 5802 Corrosion Heat.
Further reading: corrosion and heat resistant steel welding.