Original scientific paper
https://doi.org/10.30765/er.39.3.10
Surface stress evolution and cracks prevention of ingots during the upsetting process
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;
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;
Junqiang Zhang
; School of Material Science and Engineering; Henan Polytechnic University; 2001 Shiji Road, Jiaozuo, Henan, 454003,P. R. ChinaShenyang National Laboratory for Materials Science; Institute of Metal Research, Chinese Academy of Sciences; 72 Wenhua Road,
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 may rapidly 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 for guiding industrial production.
Keywords
surface stress; axial stress; surface cracks; bulging; upsetting
Hrčak ID:
221124
URI
Publication date:
17.6.2019.
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