Growth of creep life of type-347H austenitic stainless steel by micro-alloying elements

The creep life of type-347H austenitic stainless steel modified with B, Ce and N was measured, and microstructures were analyzed by optical microscope, X-ray diffraction, scanning electron microscope and transmission electron microscope equipped with energy dispersive spectroscopy. The results indicate that B, Ce and N can improve the creep life significantly at high temperature. The growth of creep life was mainly due to the precipitate of B in the elemental form at the grain boundaries and the removing O through Ce. N addition made for solid solution strengthening and effectively suppressed the precipitate of δ-ferrite at high temperature. The micro-alloying elements have a beneficial effect on creep life of type-347H austenitic stainless steel at high temperature.

Research highlights▶ B, Ce and N can improve the creep life significantly at high temperature. ▶ The precipitate of B element at the grain boundaries can improve the creep life. ▶ The removing O through Ce provided the steel with longer creep life. ▶ N increased the creep life by stabilizing austenite and solid solution strengthening.