Effects of Co and Mo on the microstructure properties of GH4282 and the mechanical properties of metal bellows

Abstract In the present study, a new type of Ni-Cr-Co-Mo (GH4282) precipitation-hardening superalloy was prepared on the basis of GH4202 alloy. By adding Co and Mo elements to enhance the solution-strengthening effect, good creep resistance and toughness were obtained. The results show that the strength and microstructure stability of GH4282 alloy are significantly higher than those of traditional GH4202 alloy under the condition of 700~900°C. The precipitated phase of GH4282 alloy is dominated by γ′ phase, which contains M 23 C 6 , MC, and a small amount of M 6 C carbide. The precipitation is mainly distributed along the grain boundaries, and has good stability at temperatures below 900°C, which can effectively pin the grain boundaries. The thermal stability of the alloy is increased. The metal bellows made of GH4282 alloy have significantly higher fatigue life and high-temperature stability, the increase of Co and Mo element content leads to the enhancement of precipitation, and the combined effect of solution strengthening and precipitation strengthening leads to the above results.