Ti750s钛合金板材的微观组织、织构演变及力学性能研究

Microstructure and texture evolution of Ti 750s titanium alloy sheet

摘要:

本文选取一种近α的新型高温钛合金Ti750s合金作为实验材料，将板材从11.5 mm多火次轧至1.5 mm，研究轧制变形过程中的微观组织和织构演变过程，研究表明:11.5 mm板材轧态的显微组织保留了明显的变形特征，原始β晶粒被严重拉长，晶粒内部析出大量的片状α相，板材呈现{0001}//TD方向的T型织构，具有较多的60 °和90 °大角度晶界，内部位错密度较低。换向轧至5.2 mm后，组织中出现大量呈扭折状的条状α相，且一致向TD方向倾斜，且T织构消失，出现{0001}//ND方向的B织构，此时α晶粒的{0001}轴均匀分布在极图偏离ND约20°方向上，板材大角度晶界较少，位错密度较大。二次换向轧至1.5 mm后，显微组织主要是变形的条状α晶粒构成，晶粒尺寸较小，且B型织构消失，T型织构重新出现，板材几乎没有大角度晶界，位错密度较大。

Abstract:

In this paper, a new type of high-temperature titanium alloy Ti750s alloy with nearly α is selected as the experimental material. The plate is rolled from 11.5 mm to 1.5 mm by multi-fire rolling. The microstructure and texture evolution process during rolling deformation are studied. The results show that the microstructure of the 11.5 mm plate retains obvious deformation characteristics, the original β grains are seriously elongated, and a large number of flaky α phases are precipitated inside the grains. The plate presents a T-shaped texture in the {0001}//TD direction, with more 60 ° and 90 ° high-angle grain boundaries, and the internal dislocation density is low. After reversing rolling to 5.2 mm, a large number of twisted strip-like α phases appear in the microstructure, which are uniformly tilted to the TD direction, and the T texture disappears, and the B texture in the {0001} // ND direction appears. At this time, the {0001} axis of the α grain is evenly distributed in the pole diagram deviating from the ND about 20 ° direction, and the large angle grain boundary of the sheet is less, and the dislocation density is larger. After the second reversing rolling to 1.5 mm, the microstructure is mainly composed of deformed strip α grains, the grain size is small, and the B-type texture disappears, the T-type texture reappears, and the plate has almost no large angle grain boundary, and the dislocation density is large.