叶片用小规格TC4棒材的组织和织构研究

The microstructure and texture of small size TC4 bars for blades

摘要:

采用径锻加工方式制备叶片用?30mm的小规格TC4棒材，并使用金相显微镜、XRD衍射仪及电子背散射（EBSD）技术研究棒材边部到心部的显微组织、物相组成和微观织构，并分析组织和织构对棒材力学性能一致性以及超声探伤杂波水平的影响。实验结果表明，径锻棒材内部晶粒得到充分细化，从边部到心部晶粒尺寸逐渐增大，径锻棒材的β转变片层组织被破碎。棒材中含有少量等轴状β相晶粒，分布在αp的晶界和β转变组织中。棒材边部为{0001}<10-10>板织构，R/2和心部为 <10-10>//轴向的丝织构，且棒材的织构强度从边部到心部逐渐减弱。棒材抗拉和屈服强度的变异系数仅为0.24%和0.29%，具有优异的一致性。径锻加工小规格TC4棒材的超声波杂波水平为?0.8-9dB，相对于轧制棒材杂波升高，这与径锻棒材显微组织不均匀区域的晶体取向变化有关。

Abstract:

The TC4 bar with a diameter of 30mm for blades was prepared by radial forging. The microstructure, phase composition and texture of the bar from the edge to the center were tested by metallographic microscope, XRD diffractometer and electron backscatter (EBSD) technology. The effects of the microstructure and texture on the uniformity of mechanical properties and the level of ultrasonic flaw detection clutter were analyzed. The experimental results show that the internal grains of radial forging bars are fully refined, and the grain size gradually increases from the edge to the center. The transformed β lamellar structure is broken during radial forging. The bar contains a small amount of equiaxed β grains, which distribute in α_p grain boundary and transformed β structure. The texture of the edge is {0001}<10-10>. The texture of the R/2 and the center is <10-10>//axial direction. The texture strength of the bar weakens gradually from the edge to the center. The coefficient of variation of tensile and yield strength of the bar are only 0.24% and 0.29%, which means the excellent uniformity. The level of ultrasonic flaw detection clutter of small size TC4 bars is ? 0.8-9dB, the clutter level is higher than the rolling bar. That is related to the change of crystal orientation in the non-uniform area of the microstructure of the radial forging bar.