A. kalaki¹, M. ketabchi^1,

Determining tool steels properties, especially deformation and flow behavior in the semi-solid zone, is an essential parameter for thixoforming process. The main objective of this work is an analysis microstructure and flow behavior determining of AISI D2 tool steel in the combined uniaxial constant load compression and electrical resistance heating in the semi-solid state. The as-received material used for experiments, were in the hot rolled-annealed condition. The globular solid particles suspended in liquid phase, were obtained by the joule heating of samples. The experiments were carried out for 0.2 to 0.3 liquid phase fraction under 160N uniaxial constant load in the specimens with 10 mm height and the same Diameter value. Microstructural evaluation before and after heating has also been presented. Structural and elemental analysis was performed with the help of optical microscopy and scanning electron microscopy. The microhardness test has been carried out on the solid particles of quenched samples. The hardness values were changed from 317HV0.1 to 463HV0.1 by increasing the liquid phase. Finally, a new approach based on plastic instability and power law equation was used for flow behavior detection. The results showed that combination joule heating and plastic instability approach is compatible for flow behavior detection of AISI D2 steels in the semi-solid state.

rheological behavior, plastic instability, tool steel, semi-solid state, joule heating