Effects of P and Nb on mechanical properties of GH4169 alloy

GH4169 alloy has good corrosion resistance, high mechanical properties and excellent weldability. It is employed in gas turbines, turbine blades and in extrusion dies and containers. The development of advanced aero-engine design demand requires that the hot components have higher strength and longer service life. Many researches try to improve design of composition of GH4169 alloy. The effects of different P (0.006-0.019%), Nb (5.2%-5.6%) content on the alloy phase precipitation patterns and distribution state were studied systematically in this paper. Room temperature and 650 degrees C tensile, stress rupture at 650 degrees C/690 MPa were tested. The effect mechanism of Nb and P was also discussed through structure observation, fractograph analysis and thermodynamic calculation. The results show that as Nb content increases from 5.2 to 5.4%, the ultimate tensile strength (sigma(b)) and yield strength (sigma(0.2)) of direct aging (DA) samples increase at room temperature and 650 degrees C, whereas the strength decreases as Nb content from 5.4 to 5.6%. Increase rate of strength for standard heat treatment (SHT) samples is also slower than DA samples but without a descending tendency. The increase in P level (0.006-0.019%) improves the stress rupture life of both DA and SHT samples at 650 degrees C/690MPa significantly.