Effects of pouring temperature on the microstructure

tensile properties and stress rupture properties of K465 nickel base superalloy were investigated. The results reveal that with the increase of pouring temperature in the range of 1 420 ℃ to 1 520 ℃

the grains are coarsened without significant change in the morphology and distribution of carbides

and the content of W element in MC carbide is increased with the γ′ phase growing. After the standard heat treatment（1 210 ℃×4 h）

the irregular shape of γ′ phase is converted to the cubic shape

and the size is obviously refined. Moreover

the size and morphology of γ′ phase in the alloys with different pouring temperature are almost the consistent after the heat treatment. With the increase of pouring temperature

the strength of the alloys tends to be decreased with increasing in elongation

and the stress rupture properties are improved. After that

the crack initiation and propagation mainly occur near the grain boundaries. Finally

the mechanism that pouring temperature affects the mechanical properties of the alloy was discussed.