The Effect of Nb on Microstructure and Properties of GH4169 Alloy Pipe

With the manufacturing process by vacuum induction， electroslag remelting， vacuum self consumption， homogenization heat treatment， forging， hot extrusion， cold rolling， and heat treatment. we can get two types of GH4169 alloy pipes with Nb content of 4.90% and 5.30% respectively. The effect of Nb content on the microstructure and properties of GH4169 alloy pipes was studied while other components remained basically the same. The results show that under the same heat treatment process， with the increase of Nb element content， the Nb content becomes higher and the grain size becomes smaller； At 200 ℃ and room temperature with the tensile strength and yield strength both increase with the increasing of Nb content， And the content of precipitates in GH4169 alloy pipes also increases. Under different solid solution heat treatments and the same aging heat treatment process， the grain size of GH4169 alloy pipes is in the range of 4.0-7.0. The smaller the grain size， the higher the tensile strength and yield strength of the pipes； At the same grain size， the higher the Nb content， the higher the tensile strength and yield strength of the pipe.