TC6钛合金叶片在榫头加工后发现叶背侧存在沿叶身横向分布的裂纹。采用宏观观察、断口分析、金相检验、硬度测试等方法，对叶片裂纹产生的原因进行分析。结果表明：裂纹起源于叶背侧表面，并向叶盆侧扩展；高温锻造过程中，叶片近表面发生吸氧反应，形成了富氧α层；榫头加工过程中，叶片承受一定的弯曲载荷，叶背侧厚度较大区域表面承受的应力较大。榫头加工时的弯曲载荷作用和热成型时产生的富氧α层均会促进裂纹萌生和扩展。

After machining the tenon of a TC6 titanium alloy blade, it was found that there were cracks distributed laterally along the blade body at the back side. The causes of blade cracks were analyzed using macroscopic observation, fracture analysis, metallographic examination and hardness testing. The results show that the cracks originated from the surface of the blade back side and extended toward the blade basin side. During the high-temperature forging process, oxygen absorption reaction occurred near the surface of the blade, resulting in oxygen-enriched α-case. During the tenon machining process, the blade bore a certain amount of bending load, and the surface of the area with a large thickness on the back side of the blade bore a large stress. Bending load during tenon processing and oxygen enrichment during thermal forming oxygen-enriched α-case promoted crack initiation and propagation.