含Nb低碳钢的热变形行为和金属塑性形变中流变应力的预测

HOT DEFORMATION BEHAVIOUR OF Nb-BEARING LOW CARBON STEEL AND PREDICTION OF FLOW STRESS FOR METALS DURING PLASTIC DEFORMATION

利用Gleeble 1500模拟试验机对含Nb低碳钢的热变形行为进行了实验研究,对热变形稳态流变应力和发生动态再结晶时的峰值流变应力与变形条件的关系进行了回归分析,阐述了由于形变诱发Nb(C,N)化合物沉淀对形变激活能的影响,在对金属塑性变形过程中位错增值,螺型位错交滑移回复和刃型位错攀移回复过程分析的基础上,建立了可预测动态回复和动态再结晶同时发生情况下的流变应力理论模型,并对不同变形条件下的流变应力进行了预测,预测结果与实验结果相当吻合。

Experimental investigation was carried out of hot deformation behaviour of Nb-bearing low carbon steel 14MnNb by Gleeble 1500 simulator. Regressive analysis was made of the relationship between deformation conditions and steady flow stress during hot deformation and peak flow stress correponding to dynamic recrystallization. Clarification was also described for the influence of strain-induced Nb (C, N) precipitation on the activation energy of formation. On the basis of analyzing the processes of dislocation multiplication and recoveries from cross-slip of screw dislocation and from climb of edge dislocation during plastic deformation of metals, the theoretical model to predict flow stress under the conditions of dynamic recovery and recrystallization occurred simultaneously was developed. The prediction about flow stress, in practice, under various deformation comditions by the model seems in fair agreement with the experimantal results.