Abstract
20Mn5 steel is widely used in the manufacture of heavy hydro-generator shaft due to its good performance of strength, toughness and wear resistance. However, the hot deformation and recrystallization behaviors of 20Mn5 steel compressed under high temperature were not studied. In this study, the hot compression experiments under temperatures of 850–1200 °C and strain rates of 0.01/s–1/s are conducted using Gleeble thermal and mechanical simulation machine. And the flow stress curves and microstructure after hot compression are obtained. Effects of temperature and strain rate on microstructure are analyzed. Based on the classical stress-dislocation relation and the kinetics of dynamic recrystallization, a two-stage constitutive model is developed to predict the flow stress of 20Mn5 steel. Comparisons between experimental flow stress and predicted flow stress show that the predicted flow stress values are in good agreement with the experimental flow stress values, which indicates that the proposed constitutive model is reliable and can be used for numerical simulation of hot forging of 20Mn5 hollow steel ingot.
Highlights
Heavy cylinder forgings are widely used in key equipments such as nuclear pressure vessel, hydro-generator shaft and hydrogenation reactor [1].Compared with solid steel ingot which is used for manufacture of cylinder forging, the advantages of adopting hollow steel ingot are as follows: (1) avoiding punching process; (2) increasing the utilization ratio of the steel ingot significantly; (3) reducing segregation and improving the material homogeneity as a result of a small solidification section and a high solidification speed; (4) requiring lower forging force [2].20Mn5 steel has been widely used in the manufacture of hydro-generator shaft due to its good balance of strength, toughness, wear resistance and weldability
In order to carry out a successful simulation of hot forging process, a precise constitutive model which describes the effect of temperature, strain rate and strain on stress is essential
It can be seen that at high temperatures and low strain rates, the flow stress increases to a peak stress at first, 3
Summary
Heavy cylinder forgings are widely used in key equipments such as nuclear pressure vessel, hydro-generator shaft and hydrogenation reactor [1]. In order to carry out a successful simulation of hot forging process, a precise constitutive model which describes the effect of temperature, strain rate and strain on stress is essential. Flow stress curves and microstructure after hot compression on different temperatures and strain rates are obtained. The newly developed constitutive model of 20Mn5 steelafter can numerical simulation of hot forging process. The flow stress curves and microstructure be used for numerical simulation of hot forging process. The flow stress curves and hot compression can provide important reference for establishment of forging process specification of microstructure after hot compression. Can provide important reference for establishment of forging process specification of 20Mn5 heavy hydro-generator shaft
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
