Microstructures and mechanical properties of AMed CoNi-base superalloy based on EBM

Abstract

Additive manufacturing provides a new way to develop high-performance superalloys and components. A γ′- strengthened CoNi-base superalloy suitable for additive manufacturing was developed，and a crack-free block material was prepared by optimizing the parameters of electron beam melting（EBM） technology. The experimental results show that the lowest porosity of the alloy is about 0.14% when the scanning speed is 2000 mm/s. The microstructures of the as-printed CoNi-base alloy are columnar grains growing along the direction，the average grain width is about 235 μm，and the volume fraction of γ′ phase is about 30%. After hot isostatic pressing and solution aging treatment，the porosity of the alloy is further reduced to about 0.09% with unobvious change of columnar grains. The average size of γ′ phases is about （70±18）nm with the volume fraction of about （32±3.6）%. The results of room temperature tensile tests show that the additive manufactured γʹ-strengthened CoNi-base superalloy exhibits excellent strength and ductility，showing a good potential of industrial application.

Keywords

• coni-based superalloy
• additive manufacturing
• cracking susceptibility
• microstructure
• mechanical property