Regular Article

The research on internal crack formation and solving in billet during soft reduction

¹ National Engineering and Research Center for Continuous Casting Technology, Central Iron and Steel Research Institute, 100081 Beijing, PR China
² School of Metallurgical Engineering, Anhui University of Technology, 243002 Ma'anshan Anhui, PR China

^* Email: whjchina@yeah.net; lhtustb@163.com

Received: 18 December 2016
Received in final form: 23 February 2017
Accepted: 26 June 2017

Abstract

In order to investigate the formation of internal cracks during the billet soft reduction process, a finite element model combined with a thermo-mechanical analysis was developed using a commercial finite element software ABAQUS/Explicit. Temperature distribution, stress, and strain developed during the billet soft reduction process were calculated. Moreover, correlations between equivalent plastic strain and internal crack formation as well as von Mises stress and displacement were evaluated. The obtained results indicated that the equivalent plastic strain near zero ductility temperature increases if the amount of solid fraction is decreased. Furthermore, it was found that tensile stresses can be developed in the mushy zone during the billet soft reduction process. The internal cracks form if the accumulated strain exceeds the critical strain or if the applied tensile stress exceeds the critical fracture stress during solidification. During the billet soft reduction process, the formation of internal cracks is decreased if a chamfered billet or a convex roll is used.