低活化钢闭塞式双通道等径角挤压变形行为及机理研究

Study on deformation behavior and mechanism of reduced activation steel in occlusive-double channel equal channel angular pressing

为探究闭塞式双通道等径角挤压变形过程中不同区域金属变形行为对应变分布及组织的影响规律,以低活化钢为材料,对闭塞式双通道等径角挤压变形过程进行了有限元模拟分析,获得了Bc路径下3个道次变形后不同区域的等效应变分布云图,对特征区域进行逆向点追踪,分析了特征区域的变形历史和变形方式对等效应变积累的作用规律,最后进行物理试验观察金相组织进行验证。结果表明:大变形区内分别受到挤压和剪切作用;小变形区内每道次平均等效应变仅为0.37;各区域不同的受力状态与变形方式是导致多道次变形后累积等效应变存在差异的主要原因。经3道次变形后,剪切变形区的最大平均等效应变为4.75,该区域第1道次变形时经历了剪切和伸长变形区,第2道次变形后为剪切变形区、剪切变形和挤压变形交叉区域,主要受到强烈的挤压变形。分别对3个道次变形后不同特征区域组织进行观察,第1和第2道次变形后不同特征位置均显示出了典型的变形特点,经过3道次变形后,应变的积累使得晶粒得到有效细化,方向性基本消失并且分布更加均匀,呈现近等轴状态。

To investigate the influence of deformation behavior of metal in different zones on strain distribution and microstructure during the occlusive-double channel equal channel angular pressing(O-DECAP)deformation process,taking the reduced activation steel as the material,the finite element simulation analysis on O-DECAP deformation process was carried out.The cloud diagram of effective strain distribution in different zones after three passes deformation under Bc path was obtained,and the inverse point tracing was carried out for characteristic zones,the effective laws of deformation history and deformation modes of characteristic zones on the effective strain accumulation were analyzed,and finally the physical tests were carried out to observe the metallographic microstructure for verification.The results show that the large deformation region is subjected to the compression and shear action respectively;the average effective strain per pass in the small deformation region is only 0.37,the different force states and deformation modes in each region are the main reason for the difference in the accumulated effective strain after multiple passes deformation.After three passes deformation,the maximum average effective strain in the shear deformation zone is 4.75,and this zone experiences shear and elongation deformation zones in the first pass deformation,and experiences shear deformation zones,shear deformation and extrusion deformation crossoverzone after the second pass deformation,which is mainly subjected to strong extrusion deformation.The microstructure of different characteristic zones after three passes deformation was observed,and the different characteristic positions after the first and the second passes deformation show typical deformation characteristics.After three passes deformation,the accumulation of strain results in the effective refinement of grain,the directionality basically disappears,the distribution is more uniform,showing a nearly isometric state.