中文摘要：

在拉拔速度O．6—0．9mm．s^-1、变形温度750-900℃条件下，对具有连续柱状晶组织的BFe10-1—1合金管材进行了无模拉拔成形，研究了变形后的微观组织，探讨了其组织演变规律及机理．在本文工艺参数范围内，晶界平直的连续柱状晶组织BFe10—1—1合金管材在无模拉拔成形后微观组织演变为锯齿形晶界的连续柱状晶组织．随拉拔速度和变形温度的增加，锯齿的齿深不断加大．位错易在接近晶界的区域塞积并跃出晶界，导致在晶界处出现滑移台阶，形成锯齿形晶界；在滑移变形的同时，粗大的连续柱状晶开始转动，加剧了锯齿化的程度．高的热激活能和变形储存能未能及时释放是BFe10—1—1合金保持连续柱状晶组织的根本原因．

英文摘要：

The dieless drawing forming of BFel0-1-1 alloy tubes with continuous columnar grains was performed in a temperature range of 750-900 ℃ at a drawing speed of 0.6-0.9 mm·s-1. The mierostructural evolution and mechanism of the tubes after the deformation was studied by optical microscopy, transmission electron microscopy, and X-ray diffraction analysis. It is found that the straight grain boundaries of colmnnar grains in the tubes become zigzag after dieless drawing within the process parameters of this paper. The sawtooth depth increases both with increasing drawing speed and temperature. Dislocations tend to pile up adjacent to grain boundaries and then travel over the grain boundaries, leading to gliding steps at the grain boundaries and consequently zigzag grain boundaries. Accompanied with the gliding deformation, thick continuous columnar grains start to rotate, increasing the zigzag degree. The high thermal activation energy and deformation-stored energy failed to release in time are the cause of maintaining continuous columnar grains in BFe10-1-1 alloy.