TP347不锈钢动态再结晶行为及组织演变分析

Dynamic Recrystallization and Microstructure Change of TP347 Stainless Steel

采用Gleeble-3500热模拟试验机对TP347含铌奥氏体不锈钢进行单道次等温热压缩试验。热压缩温度为900～1150℃,应变速率为0.005～0.05 s-1。由流变应力曲线的回归分析得到TP347钢的动态再结晶激活能及有关的材料常数。通过金相检验揭示了TP347钢动态再结晶晶粒尺寸的变化。研究表明,TP347钢的动态再结晶晶粒尺寸随着应变速率的增大而减小;由于含铌,导致在相同变形条件下,与304不锈钢相比TP347钢的稳态应力更高,晶粒更加细小。这主要是由于TP347钢中高温析出碳化铌并对晶界及位错运动起钉扎作用所致。

Isothermal single-pass hot compression test for TP347 niobium-containing austenitic stainless steel was carried out at the temperature range of 900 to 1150 ℃ at the strain rate of 0. 005 to 0.05 s-l by means of a Gleeble-3500 thermal-mechanical simulator. The activation energy of dynamic recrystallization of TP347 steel and related material constants were achieved by a regression analysis of flow stress curves. The change of dynamically crystallized grain size of TP347 steel was revealed through metallographic examination. The study shows that the dynamically crystallized grain size of TP347 steel will decrease with the increase in strain rate, and that TP347 steel will possess higher steady-state stress and finer recrystallized grains due to niobium in it relative to the steel type 304 under the same hot compression condition, which is attributed to precipitation of niobium carbides at high temperature in TP347 steel and their hindering grain boundary and dislocation from movement.