Hot deformation behaviour and microstructure of a high-alloy gear steel

Abstract

High strain isothermal compression tests at temperatures of 700–1200°C and strain rates of 0.1–50 s−1 were performed in a Gleeble-3800 thermal simulator to investigate the hot deformation behaviour of a high-alloy Cr–Co–Mo–Ni gear steel, and the constitution equation and hot processing map were established based on these experiments. The results show that the flow stress can be described by the constitutive equation in hyperbolic sine function, and the optimum hot working regions are at the temperature of 1000–1100°C and strain rate of 0.3–1.0 s−1. Optical microscopy observations of austenite grains indicate that dynamic recrystallisation occurs when the deformation temperature is over 900°C. The forging was successfully produced on the basis of the above-described researches.

Microstructure and stability conditions for hot deformation of a modified iron-based superalloy

“…The Garofalo parameters A , Q n and α of the Garofalo equation [15] were calculated from the experimental data by means of a nonlinear method without the use of initial values involving an algorithm specifically developed for the treatment of this equation [16,17]. This is an alternative to the RCR method used elsewhere [18,19] and other methods used in the literature [20,21].…”

Thermomechanical behaviour modelling and microstructure evolution of high Cr–Co–Mo aerospace bearing steel

“…As well as the interaction influence of hot deformation parameters and carbides on dynamic recrystallisation (DRX) was analysed. Tang et al [18] have established a hot processing map based on high strain rates ranging from 0.1 to 50 s −1 . This report provides an understanding of the thermal deformation behaviour at higher deformation rates.…”

“…Tang et al. [18] have established a hot processing map based on high strain rates ranging from 0.1 to 50 s −1 . This report provides an understanding of the thermal deformation behaviour at higher deformation rates.…”