Experimental and finite element analysis of hot backward extrusion process of vanadium microalloyed steel preform for determining optimum preheat temperature

Subject Areas : journal of New Materials

mohammad hoseyn Azarmi ¹ , mohammad bayat ² , majid belbasi ^{3 *}

1 - Department of mechanic engineering, Islamic Azad University, Emam khomeyni Yadegar branch, Tehran, Iran
2 - Department of mechanic engineering, Islamic Azad University, Emam khomeyni Yadegar branch, Tehran, Iran.
3 - Department of Materials,Engineering faculty, Islamic Azad University Central Tehran Branch , Tehran , Iran

Received: 2018-10-14 Accepted : 2019-06-25 Published : 2019-06-22

Keywords: Finite element method, hot compression test, hot backward extrusion, preform, preheat temperature,

Abstract :

In this research, the effect of billet preheat temperature on the forming force value in hot backward extrusion process for a preform made of vanadium micro alloyed steel is studied. The plastic deformation behavior of steel using hot compression test at temperatures of 850℃ to 1250℃ under different strain rates is obtained. Then on the basis of these data, the hot backward extrusion process for the desired vessel in the same temperature range is simulated using finite element method. The results of the hot compression test and finite element, show that with increasing the preheat temperature from 850℃ to 1250℃, the maximum stress reduced from 200 MPa to 42 MPa and the required force for hot extrusion process is reduced from 247 to 43 Ton, respectively. In addition, the microstructure of the samples was examined by optical microscopy and no defect was observed in microstructure. Finally, according to result of calculated force in hot extrusion process on billet with 1200℃ preheat temperatures was carried out in the workshop and deformation of billet to perform was carried out without dimensional distortion wrinkles and crack.