Numerical simulation of dimensional change during austempering heat treatment in ductile cast iron

Abstract

Changes in the form and dimensions of ductile iron parts occur during the austempering process, and this poses a challenge whenever tight tolerances need to be satisfied. Thus, it is important to be able to predict the deformation which occur under heat treatment to evaluate the minimum and maximum stock material required to perform the final machining. Moreover, parts could be machined before heat treatment under better machinability condition. This paper presents a thermo-mechanical-metallurgical formulation to predict the dimensional changes and final microstructure of a ductile cast iron part as a consequence of the austempering heat process. A coupled thermal, mechanical and metallurgical problem is solved using a finite element method, to take into account different coupled and complex phenomena present in this process. As an illustration, the heat treatment of a specimen is considered and results are validated by comparison with experimental data