The stress relaxation behavior of GH4738 superalloy

Abstract:

The research of the stress relaxation behavior in superalloys provides the reference of selecting the appropriate working conditions for fasteners and experimental basis for relaxation laws . The effects of the temperature,the initial stress and various heat treatment regime on the stress relaxation in the superalloy GH4738 were investigated. The results indicated that: a threshold stress was found between two stages. Below the threshold stress, the plastic strain rate fell fast. The relaxation stability of the alloy decreased with the increase of temperature, meanwhile, the stress relaxation rate rised and the relaxation limit declined. The stress relaxation rate of the first stage speeded up and the relaxation limit increased when the initial stress was improved. Different heat treatment systems mainly affected the second stage of the stress relaxtion, whereas, no obvious influence was observed on the threshold stress and the relaxation stability.

Key words:GH4738; stress relaxation; temperature; initial stress; heat treatment systems