Hot workability of nimonic 115 as a function of strain rate

Abstract

The hot workability of Nimonic 115 was studied by means of very high strain rate stress rupture tests in the temperature interval 1323 to 1473 K (1050 to 1200°C) at strain rates of 10⁻⁴ to 10 per s. Hot plasticity, measured as elongation and reduction of area at fracture, increased generally with decreasing strain rates. Maximum values of about 40 pct elongation and 70 pct reduction of area were obtained between 1398 to 1448 K (1125 to 1175°C) for strain rates below about 1 per s. For higher rates of strain than about 1 per s, ductility at fracture fell sharply. Ductility above 1448 K (1175°C) was poor at all strain rates and fell to a minimum at 1473 K (1200°C) regardness of strain rate. The highest ductility values are associated with intermediate temperatures and intermediate strain rates where conditions are optimum for significant recovery without encountering grain growth. The presence of excess phases leads to severe intergranular embrittlement at the highest temperatures and strain rates.