Cause Analysis and Inspection Method of TC17 Titanium Alloy Integral Blisk Blade Defects
The morphology of the low-magnification defects of TC17 titanium alloy blisk blades was observed,the micro-zone composition,metallographic structure and hardness were analyzed,and the source of the defects and the impact on the substrate were studied.The results show that the low-magnification corrosion defects of the blisk blades are abnormal microstructure defects.Such structure defects are caused by the wrong flattening of the YG8 cutter head of the titanium alloy blisk blade during the ingot production.The sticking phenomenon causes the tungsten steel cutter head to be embedded in the flat tening head of the casting ingot,and W alloy inclusions are introduced.The presence of W alloy inclusion leads to the appearance of fine crystals and abnormal structure such as hidden needle martenite,and the hardness sharply increases,and it also has a significant transition layer with the substrate.Since such W alloy inclusions exist in the form of particles or agglomerations of tens of microns,and are dispersed along the forging streamline,they cannot be detected by non-destructive testing methods such as X-ray and ultrasonic tests,but can be detected by low magnification corrosion or metallographic method inspection for conventional titanium alloys.
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