TA19钛合金中未完全转变组织特征与拉伸性能

Semi-equiaxed Structure and Tensile Properties of TA19 Titanium Alloy

采用TA19合金加热到β相变点以上短时保温25～90s,得到了介于等轴组织与片层组织间的一种未完全转变的特殊的过渡组织,研究了随保温时间的变化对未完全转变组织演变规律及对力学性能的影响。结果表明半等轴组织主要是在β相变点以上短时保温时,β基体中的合金元素Mo向原等轴α相中扩散不均匀,冷却转变过程中初生等轴α相局部被β转变组织分割所形成。随保温时间的延长,未完全转变组织逐渐被β转变组织所取代。在保温温度为1015℃,保温时间为45 s时,抗拉强度为1219 MPa,断面收缩率为29%,伸长率为14%,具有较好的强塑性。

By heating up the Tβ temperature and then holding 25~90 s, the semi-equiaxed structure, which is a transition structure between the equiaxed structure and the lamellar structure, was shaped. The influence of the change of heat holding time on the semi-equiaxed structure evolution law and mechanical properties was studied. Experimental results indicate that the formation of the semi-equiaxed structure is mainly because the element Mo in the β matrix diffuses inhomogeneously into primary equiaxed α phase when the specimens are kept above the Tβ temperature for a short time, and in the cooling process, the β transformed structure grows through the primary equiaxed α phase. With the prolongation of holding time, the semi-equiaxed structure are gradually replaced by lamellar structure. When heated to 1015 °C and hold for 45 s, the alloy has a better strength and plasticity of tensile strength 1219 MPa, reduction of area 29%, and elongation 14%.