High temperature corrosion resistant Ni-base alloy welded structure and heat exchanger

摘要

A Ni-based alloy welded structure and a heat exchanger having high temperature corrosion resistance are provided to be durable in a high temperature corrosion environment by covering a first welding metal with a second welding metal and exposing the second welding metal to the high temperature corrosion atmosphere. A Ni-based alloy welded structure having high temperature corrosion resistance is formed by welding a plurality of element members which are formed by a high-Si-Ni-based alloy having high-temperature corrosion resistance comprising Ni: 45 to 57wt%, Cr: 23 to 35wt%, Mo: 1 to 5wt%, Si: 3 to 6wt%, C: 0.05 to 0.5wt% and the remainder Fe and unavoidable impurities. A part(11) of the welded part is a first welding metal(WM1) having higher toughness than the high-Si-Ni-based alloy, and the rest(12,13,14,15) of the welded part is a second welding metal(WM2) having the same toughness as the high-Si-Ni-based alloy. The second welding metal is exposed to a surface which is exposed to the high temperature corrosion atmosphere. The second welding metal covers the first welding metal and is exposed to two sides of the welding part.