(中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083)
摘 要: 利用鍛造鐓粗工藝制備高橫向塑性純鉬棒，檢測其在退火過程中橫向彎曲性能和組織結(jié)構(gòu)，并利用SEM對其斷口形貌進行分析。結(jié)果表明：鐓態(tài)純鉬棒中形成沿縱向伸長的纖維組織，且晶粒間相互穿插，橫向彎曲伸長率達到5%；在退火過程中，純鉬棒橫向塑性逐漸增大，經(jīng)980 ℃退火時，其橫向彎曲伸長率達到最大值10%，此時開始發(fā)生再結(jié)晶。在此過程中，鐓態(tài)純鉬棒中形成的位錯胞亞結(jié)構(gòu)逐漸合并形成許多細小亞晶；純鉬棒經(jīng)鍛造鐓粗變形后斷口以穿晶斷裂為主，具有明顯的河流狀花樣和解理臺階，解理面上出現(xiàn)大量塑性變形的撕裂嶺，且形成魚網(wǎng)狀的韌窩。
關(guān)鍵字: 純鉬棒；鐓粗；橫向塑性；穿晶斷裂
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
