科研之友
微信
新浪微博
Facebook
分享链接
摘要
Purpose: This study describes the influence of initial austenite grain size and parameters of hot plastic deformation on the deformability and structure of high-temperature Fe每Ni austenitic alloy of A-286 type.Design/methodology/approach: The hot deformation characteristics of the alloy were investigated by hot torsion tests using torsion plastometer. The tests were executed at constant strain rates of 0.1 and 1.0 s-1, at a testing temperature in the range from 900 to 1150～C. The structural inspections were performed on microsections taken from plastometric samples after so called ※freezing§.Findings: Plastic properties of the alloy were characterized by the worked out flow curves and the temperature relationships of flow stress and the strain limit. The relationship between the peak stress (考pp) and the Zoner-Hollomon parameter (Z) were described by power function. Activation energy for hot working (Q) was assessed for the alloy after two variants of previous heating. The examinations performed, focusing on the influence of hot working parameters on the structure of austenitic alloy, revealed subsequently occurring processes of dynamic recovery, recrystallization and repolygonization.Practical implications: Characteristics of the alloy plastic properties during hot deformation depend considerably on the initial soaking temperature and hot deformation parameters. Optimum values of yield stress and strain limit were obtained for the alloy after its initial soaking at 1100～C/2h and strain rate of 0.1 s-1 in the temperature range of 1050-950～C.Originality/value: An increase of the alloy deformation temperature led to a growth of the size of subgrains with a simultaneous decrease of their internal dislocation density. The influence of the strain rate of the alloy on the size of subgrains and dislocation density is complex by nature and depends on the initial size of the austenite grains and on the mechanism of the dynamic recrystallization process.
