High Temperature Ductility Loss of 16MnCr5 Pinion Steels  

作　　者：Haiwen Luo Pei Zhao Zijiu Dang(Metallurgy School, University of Science and Technology Beijing, Beijing 100083, China) 

出　　处：《International Journal of Minerals,Metallurgy and Materials》1998年第3期123-128,共6页矿物冶金与材料学报（英文版）

摘　　要：A wide ductility trough covering from 700 to 1100 is observed in the curve of Reduction of Area (RA) vs.tempetature for 16MnCr5 pinion steel. At 750℃, corresponding to the minimum of RA, it is grain boundary slidingthat controls its hot ductility rather than usual Deforming Induced Ferrite (DIF), which can only appear just below750℃ and slightly improve hot ductility. The volume fraction of ferrite is dependent on the strain and strain rate.Firstly a critical strain must be necessary for formation of DIF then with strain rate increasing, the volume fractionof DIF decreases but RA is elevated. In the γ phase region, hot ductility is seriously deteriorated because of grainboundary sliding promoted by oxidcs and sulfides at the grain boundary and recovered because of dynamic recrystal-lization at higher temperature; when strain rate increases, ductility is improved as there is insufficient time for cracksto propagate along the γ grain boundary as well as dynamically precipitating, and ductility trough becomes narrowerbecause the temperature for onset of dynamic recrystallization decreases. In addition, γ→α phase transformationintroduced by temperature drop before the tensile test encourages precipitation of AlN and impairs ductility.A wide ductility trough covering from 700 to 1100 is observed in the curve of Reduction of Area (RA) vs.tempetature for 16MnCr5 pinion steel. At 750℃, corresponding to the minimum of RA, it is grain boundary slidingthat controls its hot ductility rather than usual Deforming Induced Ferrite (DIF), which can only appear just below750℃ and slightly improve hot ductility. The volume fraction of ferrite is dependent on the strain and strain rate.Firstly a critical strain must be necessary for formation of DIF then with strain rate increasing, the volume fractionof DIF decreases but RA is elevated. In the γ phase region, hot ductility is seriously deteriorated because of grainboundary sliding promoted by oxidcs and sulfides at the grain boundary and recovered because of dynamic recrystal-lization at higher temperature; when strain rate increases, ductility is improved as there is insufficient time for cracksto propagate along the γ grain boundary as well as dynamically precipitating, and ductility trough becomes narrowerbecause the temperature for onset of dynamic recrystallization decreases. In addition, γ→α phase transformationintroduced by temperature drop before the tensile test encourages precipitation of AlN and impairs ductility.

关 键 词：hot ductility deforming induced ferrite grain boundary sliding PRECIPITATES 

分 类 号：TG14[一般工业技术—材料科学与工程]