Effect of Precipitates on Impact Property of Alloy Inconel 625 After Aging at 760

The effect of aging process at 760 ℃ on microstructure evolution and room-temperature impact properties of alloy Inconel 625 was investigated,while the microstructure and impact fratographs analyzed by means of optical,scanning electron and transmission electron microscopy for alloy samples both before and after aging test.Results show that the precipitates formed during aging are mainly M_(23)C_6,γ′ and γ″.Most M_(23)C_6 forms at grain boundaries,whereas γ″ precipitates in a direction normal to the grain boundary,and γ′ particles disperse within the matrix.During aging,M_(23)C_6 and γ′ inside grains remain basically stable,while intergranular carbides M_(23)C_6 agglomerates and grows with rising aging time,and simultaneously the γ″ on grain boundary grows both in size and quantity along the length direction.After aging,the impact energy reduces obviously,and the fracture mode changes from ductile to brittle type.