Research Progress on the Formation and Control of Cracks in Wrought Nickel-Based Superalloys

Abstract

With the continuous improvement of material requirements for high-performance aviation engines， the degree of alloying and the mass fraction of the γ' phase in new nickel-based superalloys for high-temperature applications continue to increase. This leads to progressively more challenging melting processes for these alloys. High-alloyed wrought nickel-based deformation superalloys are generally produced through a triple combination process of Vacuum Induction Melting （VIM） + Protective Atmosphere Electro-Slag Remelting （PESR） + Vacuum Arc Remelting （VAR）. Due to the influence of alloying degree， alloys are prone to solute segregation and elemental partitioning between liquid and solid phases during the melting process， making electrodes and ingots susceptible to cracking under the combined effects of thermal stress and phase transformation stress. This not only causes arc fluctuations during the subsequent remelting process but also adversely affects the quality of the ingots. Electrode crack formation is a complex metallurgical defect that occurs in the solidification process of superalloys and has been a common technical challenge that has long plagued the expansion of ingot sizes for high-alloy， difficult-to-deform superalloys in China. Therefore， this paper reviews the recent research progress of the author’s team and research groups at home and abroad in the crack formation mechanism， influencing factors of crack and crack control of wrought nickel-based superalloys， and looks forward to the future development direction of wrought superalloy precipitation strengthened nickel-based superalloys.

Keywords

• triple melting； highly alloyed； wrought superalloy； formation mechanism of crack； crack control