Flow Behavior and Hot Processing Map of GH4698 for Isothermal Compression Process

Abstract

An in-depth understanding of the flow behaviors of materials deformed at high temperatures is of paramount significance. However, insufficient research on the nickel-based GH4698 alloy has resulted in inaccurate material flow prediction or even cracking in the practical billet opening of GH4698 large forgings. In this study, hot compressions were performed at 950–1150 °C and 0.001–3 s−1. Single-peaked strain-stress curves were obtained under various conditions, owing to dislocation motions in dynamic recrystallizations. The Arrhenius model was formulated to accurately describe the flow stress evolutions and the mean prediction error of the flow stress was 5.90%. Processing maps were constructed at various hot working conditions. It was found that the hot working ability of GH4698 markedly decreased under lower temperatures (950–1080 °C) and higher strain rates (0.1–3 s−1). Optimal thermal processing parameters were suggested. In sum, this study systematically investigated the flow behaviors and hot working ability of GH4698 in isothermal compressions.

A Flow Stress Model of 300M Steel for Isothermal Tension

“…Under a high temperature and a low strain rate, the true stress was low due to a low dislocation motion barrier. This phenomenon was also found in the compression of 300M steel [ 11 ], GH4169 alloy [ 17 ], GH4698 alloy [ 18 ], etc. The previous result in Figure 3 , that the ultimate elongation was greater under a higher strain rate and a lower temperature, could be interpreted by the flow stress curves in Figure 5 .…”

Special Issue on “Process Modeling in Pyrometallurgical Engineering”

“…Chen et al [39] found that the hot working ability of a nickel-based GH4698 alloy markedly decreased under lower temperatures and higher strain rates in isothermal compressions: this alloy is extremely sensitive to thermal processing parameters and cracking may easily occur. An Arrhenius model was used to estimate the flow stresses and profiles for processing under various thermal conditions.…”

The hot deformation behaviors and constitutive modeling of Hastelloy C276

“…Yao et al [42] created the processing maps of the GH909 superalloy. Chen et al [43] constructed a processing map of GH4698 alloy at high-temperature deformation conditions. Jaladurgam and Kanjarla [44] developed a processing map to predict the safe hot workability window of Hastelloy C-276 alloy.…”