热加工历史对Ti-24A1-15Nb-1.5Mo/TC11双合金盘焊接界面组织与性能的作用

采用电子束焊连接,随后近等温锻造+梯度热处理的工艺加工Ti-24Al-15Nb-1.5Mo/TC11双合金盘,通过OM、SEM、TEM、XRD等研究双合金盘的焊接界面状况.结果表明,经此工艺加工的Ti-24A1-15Nb-1.5Mo/TC11双合金盘的高温拉伸性能较优,焊缝的高温强度大于TC11钛合金,但室温拉伸性能分散度较大.采用梯度热处理不能消除经50%变形的双合金盘的焊缝到TC11侧热影响区的晶界α相.焊缝区簇状α_2相的形成与在近等温锻造、梯度热处理加热保温过程中Al、Nb元素从α_2相中分离出来有关.

Action of Hot Working History on Microstructure and Properties of Welding Interface of Ti-24Al-15Nb-1.5Mo/TCll Dual Alloy Disc

The Ti-24Al-15Nb-1.5Mo/TC11 dual alloy discs were joined by electron beam welding firstly, and then underwent near isothermal forging and gradient heat treatment. The welding interface state was investigated by OM, SEM, TEM and XRD. The results show that the elevated temperature properties of the dual alloy disc are better and the high temperature strength is larger than that of the TC11 alloy. However, the dispersion degree of tensile properties is larger at the room temperature. When the dual alloy disc is deformed by 50%, the a phase is distributed in the β phase grain boundary from welding seam to the heat-affected zone of TC11 alloy, which can not be eliminated by gradient heat treatment. The cluster α_2 phase in the welding seam area is formed, which is ascribed to the diffusion of the Al and Nb elements from the α_2 phase during near isothermal forging and gradient heat treatment.