(中南大学 材料科学与工程学院，长沙 410083)
摘 要: 利用锻造镦粗工艺制备高横向塑性纯钼棒，检测其在退火过程中横向弯曲性能和组织结构，并利用SEM对其断口形貌进行分析。结果表明：镦态纯钼棒中形成沿纵向伸长的纤维组织，且晶粒间相互穿插，横向弯曲伸长率达到5%；在退火过程中，纯钼棒横向塑性逐渐增大，经980 ℃退火时，其横向弯曲伸长率达到最大值10%，此时开始发生再结晶。在此过程中，镦态纯钼棒中形成的位错胞亚结构逐渐合并形成许多细小亚晶；纯钼棒经锻造镦粗变形后断口以穿晶断裂为主，具有明显的河流状花样和解理台阶，解理面上出现大量塑性变形的撕裂岭，且形成鱼网状的韧窝。
关键字: 纯钼棒；镦粗；横向塑性；穿晶断裂
transverse ductility of upset pure Mo bars
（School of Materials Science and Engineering, Central South University, Changsha 410083, China）
Abstract:Pure molybdenum bars with good transverse ductility were prepared by modified forge and upset technique. The transverse elongation and structure of the bars were investigated by bending measurement, optical microscopy (OM), scanning electron microscopy (SEM) and transmitting electron microscopy (TEM) during the annealing treatment. The results show that the transverse elongation of the bars produced by the modified forge and upset technique reaches 5% because of the interpenetrate grains and the fiber structures. During the annealing process, the transverse ductility of the pure molybdenum bar is improved and reaches a maximum value 10% at 980 ℃ when recrystallization begins. Over 1 250 ℃, further recrystallization continues and results in the decrease of transverse ductility. The fracture type of the pure molybdenum bar with good transverse ductility is mainly a transgranular fracture type and net-type, which is characterized by a large amount of cleavage planes and river patterns. Tearing ridge and net-type dimples can also be seen on the fracture.
Key words: pure molybdenum bar; upset; transverse ductility; transgranular fracture
