Effects of Cooling Rate after Homogenizing on the Microstructure and Tensile Properties of a New Generation Cobalt Base Superalloy

Varmazyar, Sadegh; Abbasi, Seyed Mahdi; Seifollahi, Masumeh

doi:10.22034/frj.2024.426116.1188

Effects of Cooling Rate after Homogenizing on the Microstructure and Tensile Properties of a New Generation Cobalt Base Superalloy

Document Type : Original Research Article

Authors

Sadegh Varmazyar ¹

Seyed Mahdi Abbasi ²

Masumeh Seifollahi ³

¹ M.Sc. Student, Faculty of Materials and Manufacturing Technologies, Malek Ashtar University of Technology, Tehran, Iran.

² Professor, Faculty of Materials and Manufacturing Technologies, Malek Ashtar University of Technology, Tehran, Iran.

³ Assistant Professor, Faculty of Materials and Manufacturing Technologies, Malek Ashtar University of Technology, Tehran, Iran.

10.22034/frj.2024.426116.1188

Abstract

New cobalt-nickel base superalloys containing γ´ precipitates designed in order to achieve better high temperature properties than Ni base superalloys. In this article, the alloy with chemical composition of Co-28.7Ni-4.26Al-8.2Cr-17.4W-1.51Ti-2.85Ta-0.02C-0.01B (%W) casted and homogenized at 1300°C for 8hr. one sample quenched in air (1300-Air) and the other cold in furnace till 900°C and after that quenched in air (1300-900-Air). Microstructural investigation carried out using optical and electron scanning microscopy. Hardness and room and high temperatures of homogenized samples is also compared. The results showed that cast sample containing dendritic structure with primitive and secondary arms which eliminated after homogenizing. 1300-Air sample have finer grains and more scattered precipitates while 1300-900-Air sample have coarse grains and continuous precipitates at the grain boundaries. Room and high temperature ultimate tensile strength of 1300-900-Air are 775 and 232 MPa, respectively. These are 1027 and 282 MPa, respectively for 1300-Air sample which are more than ones for 1300-900-Air and related to finer grains and scattering the precipitates.

Keywords

New Generation Cobalt Base Superalloy

Homogenizing

Cooling rate

Tensile properties

Subjects