The main steam pipeline has the characteristics of low service temperature and large wall thickness.Besides good durability and oxidation resistance

it also has higher requirements on the processing

welding

fatigue and other properties of candidate materials. The new Ni-based and Ni-Fe-based superalloys represented by Inconel740 H

GH984 G

CCA617

Haynes282

HR6 W and other alloys developed by relevant institutions at home and abroad are considered as the main candidate materials for the key components of advanced ultra-supercritical coal-fired power sets because of their excellent high temperature stress rupture strength and oxidation resistance.By comprehensively considering the dimensional characteristics and use environment of the main steam pipe

this article summarizes the composition and microstructure

durability

steam oxidation resistance

fatigue resistance

stress relaxation

weldability and processing performance of the above six alloy materials in detail. It is concluded that

although Inconel740 H alloy has been used in high-temperature components of thermal power units

the problem of its welding and filling materials still needs further research. Haynes282 alloy has a low thermal expansion coefficient

and its welding performance is better than that of Inconel740 H alloy. It is a potential candidate material for the main steam pipeline. For the candidate materials for the main steam pipe of the 700 ℃ ultrasupercritical unit

a large number of experimental studies are still required before actual production.