Surface stress evolution and cracks prevention of ingots during the upsetting process

Authors

  • Guofa Mi School of Material Science and Engineering; Henan Polytechnic University; 2001 Shiji Road, Jiaozuo, Henan, 454003, P. R. China
  • Junqiang Zhang School of Material Science and Engineering; Henan Polytechnic University; 2001 Shiji Road, Jiaozuo, Henan, 454003, P. R. China
  • Bin Xu Shenyang National Laboratory for Materials Science; Institute of Metal Research, Chinese Academy of Sciences; 72 Wenhua Road, Shenyang, Liaoning, 110016, P. R. China; Key Laboratory of Nuclear Materials and Safety Assessment; Institute of Metal Research; 72 Wenhua Road, Shenyang, Liaoning, 110016, P. R. China
  • Mingyue Sun Shenyang National Laboratory for Materials Science; Institute of Metal Research, Chinese Academy of Sciences; 72 Wenhua Road, Shenyang, Liaoning, 110016, P. R. China; Key Laboratory of Nuclear Materials and Safety Assessment; Institute of Metal Research; 72 Wenhua Road, Shenyang, Liaoning, 110016, P. R. China
  • Junqiang Zhang School of Material Science and Engineering; Henan Polytechnic University; 2001 Shiji Road, Jiaozuo, Henan, 454003, P. R. China Shenyang National Laboratory for Materials Science; Institute of Metal Research, Chinese Academy of Sciences; 72 Wenhua Road, Shenyang, Liaoning, 110016, P. R. China

Keywords:

surface stress, axial stress, surface cracks, bulging, upsetting

Abstract

In this research, surface axial stress and propagation of surface transverse cracks on large ingots during hot forging process was studied using finite element modeling. The simulation results show that surface axial stress changes from compressive to tensile during the upsetting process. Large ingots which need to be upset and stretched several times are easy to form cracks at anvil overlapping part during stretching process. These surface transverse cracks are crack source and mayrapidly propagate under surface axial tensile stress during the upsetting process. The effect of material, temperature, height-diameter ratio of billet, deformation speed, and friction coefficient between anvil and billet on the changing of surface axial stress was investigated. The results show that critical transformation point of surface axial stress from compressive to tensile has an obvious relationship with drum shape of the billet. In order to eliminate the surface axial tensile stress and prevent propagation of surface transverse cracks, a slim waist forging process was proposed based on the surface stress analysis. A quantitative designing method of slim waist billet was established forguiding industrial production.

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Published

2019-06-17

Issue

Engineering Review, Vol. 39, No. 3

Section

Articles

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