【摘要】 通过弯曲性能测量、金相、SEM以及TEM观察对不同工艺锻造的纯Mo棒横向弯曲性能及组织进行了研究。结果表明:纯Mo棒直接拔长时,随着变形量的增加,其横向塑性变化不大,纵向晶粒逐渐被拉长,当变形量达到96%时,出现明显的纤维组织,断口呈冰糖状。若纯Mo棒在1100℃镦粗50%再拔长到Φ45mm,这样反复进行三次,随后在此温度下从Φ45mm直接拔长到Φ18mm,其横向组织与直接拔长后的相比变化不大,纵向晶粒虽有拉长,但较直接拔长的晶粒长宽比要小,且晶粒不规则程度增加,此锻造工艺仍然不能有效改善其横向塑性。若纯Mo棒在1100℃先镦粗50%再拔长到Φ45mm,反复进行三次后,再将在此温度下从Φ45mm直接拔长到Φ18mm的纯Mo棒镦粗50%后,其横向塑性可得到大幅度提高,弯曲变形量>5%;金相观察表明,其横向晶粒边界变得不很明晰,扭曲程度加重;而纵向晶粒之间晶界相互穿插程度较为严重;其弯曲断口以穿晶断裂为主,断口上有大量的解理面,具有明显的河流状花样和解理台阶;TEM观察表明,其大部分区域以亚晶组织为主,部分区域存在位错胞组织且缠结有大量位错线。更多还原

【Abstract】 The transverse bending property and microstructure of pure molybdenum bar forged by different ways were investigated by bending test,optical microscope(OM),scanning electron microscope(SEM) and transmission electron microscope(TEM).The results indicate that with increasing deformation amount,transverse bending property of pure molybdenum bar forged by conventional way changes little,and its grains are gradually elongated in longitudinal direction,and fibre structure is formed after forging to deformation amount of 96%.Compared with the conventional forging process,transverse bending property of the bar forged at 1100℃ by repeated forging and upsetting(deformation amount is 50%) followed by directly drawn Φ45mm to Φ18mm is not greatly improved,and no significant change of transverse microstructure with little elongation of grains in longitudinal direction is observed.However,after re-upsetting to deformation amount of 50% for the deformed bar,its transverse bending property is improved greatly,bending deformation amount reaches 5%.The unclear and heavily warped grain boundary are formed in transverse direction,and the adjacent grains in longitudinal direction interpentrate each other seriously.Transcrystalline fracture is the main mode of fracture,and a large number of cleavage planes with obvious river pattern and steps appear on the bending frcture.In addition, subgrain is the main structure in most area,only part of it contains dislocation cells and tangled dislocation lines.更多还原