Microstructural evolution on continuous casting of nickel based superalloy Inconel* 713C

Abstract

In the present work, the evolution of microstructure in the nickel based superalloy Inconel 713C was investigated for the vertical continuous casting of small cross-section rods (10 mm dia.), using several microstructural characterisation techniques. Microstructural evolution was greatly affected by the mould design, average casting speed, and distance from the rod surface, but the strongest influence was from the alternating drawing mode consisting of the drawing stroke, the resting period, and the reverse stroke, which caused periodic orientation changes of columnar γ crystal grains. Combined with other casting parameters this determined the local solidification conditions, influencing the formation and growth of γ dendritic grains and primary and eutectic MC carbide, as well as the stress distribution in the solidified shell, which caused shell deformation and the appearance of the inverse segregation and, occasionally, hot tears. A physical model is presented to explain the influence of casting parameters on microstructural evolution on the continuous casting of this alloy.