Deformation behavior of hot-rolled IN718 superalloy under plane strain compression at elevated temperature

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2014-06, Vol.606, p.24-30
• Main Authors: Cheng, Liang, Xue, Xiangyi, Tang, Bin, Liu, Degui, Li, Jizhen, Kou, Hongchao, Li, Jinshan
• Format: Article
• Language: English
• Subjects: Applied sciences; Cold working, work hardening; annealing, quenching, tempering, recovery, and recrystallization; textures; Compressing; Cross-disciplinary physics: materials science; rheology; Deformation; Deformation mechanisms; Elasticity. Plasticity; Exact sciences and technology; Flow behavior; Hot rolling; Materials science; Mathematical models; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Ni-based superalloy; Nickel base alloys; Physics; Plane strain; Plane strain compression; Processing map; Shear band; Softening; Strain rate; Superalloys; Treatment of materials and its effects on microstructure and properties
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2014.03.075

The hot deformation behavior of hot-rolled IN718 superalloy was studied by plane strain compression in the temperature range of 900–1050°C and strain rate range of 10−3–10s−1. The results showed that the flow curves exhibit weak softening at most deformation conditions. However, intense softening caused by adiabatic heating was observed in the flow curves when the alloy was deformed at high strain rate (10s−1), and these curves are characterized by unique “double-peak” which cannot be observed in those under uniaxial compression. Intensive strain localization and dynamic recrystallization occurred in the deformed specimens. Constitutive model based on the hyperbolic-sine equation was established to characterize the dependence of flow stress on strain, strain rate and temperature, and the activation energy was estimated to be 429kJ/mol. The processing maps were constructed to evaluate the power dissipation efficiency (η) and recognize the instability regimes. Optimum parameters were obtained in the temperature range of 1030–1050°C at strain rates of 0.02–0.1s−1 for plane strain compression.