Effect of low angle grain boundaries on mechanical properties of DD5 single crystal Ni-base superalloy at medium temperature and high temperature

Abstract

The effects of low angle grain boundaries on the tensile properties and stress rupture properties of second generation single crystal superalloy DD5 at medium temperature and high temperature were investigated. The test plates were prepared by using seeds and processed into mechanical samples. The results show that the tensile strength at 760 ℃ is higher than 1100 MPa, the elongation is higher than 8% and the percentage reduction of area is higher than 14% when the angle is below 14.8°. The tensile strength, elongation and percentage reduction of area are decreased when the angle is above 14.8°. But the yield strength shows no difference. The tensile strength at 980 ℃ is higher than 760 MPa, the yield strength is higher than 630 MPa, the elongation and percentage reduction of area are decreased quickly when the angle is below 19.4°. The elongation is 1.4%, the percentage reduction of area is 2.8% when the angle is 19.4°. The rupture life at 870 ℃/551 MPa is higher than 110 h, the elongation is higher than 19.8% and the percentage reduction of area is higher than 23.1% when the angle is below 7.8°.But they are decreased quickly when the angle is above 7.8°.

Keywords

• superalloy
• low angle grain boundary
• rupture life
• tensile property