Structural and acoustic anisotropy of turbocompressor blade material

The investigation is concerned with working compressor blades of the sixth and eighth stages of the turbo-compressor rotor of the ДЖ59Л engine made of stainless ЭИ961 (13Х12Н2В2МФ) heat-resistant steel in a post-operation state and the same blades after tempering. The objects of research are the parameter of intrinsic acoustic anisotropy and the structural anisotropy factor of the carbide phase of material of turbo-compressor blades in post-operation state and subsequent tempering. The aim of the study is to show that the ultrasonic echo technique holds promise as a method of nondestructive control of the material structure directly on the product both at the stage of output control in the production and repair of blades, and in the post-operation state. The analysis of the blade material structure is carried out using the methods of optical metallography with the use of the “GoodGrains” software and ultrasonic echo technique of nondestructive control. Using the method of optical metallography it was established that a carbide phase of acicular shape is present in the material of blade airfoil with a high degree of anisotropy, which indicates the degradation of microstructure in the post-operation state. Positive influence of tempering on the uniformity of carbide phase distribution in the material of rotor blades is noted. Correlation between the parameter of acoustic anisotropy and the metallographic anisotropy factor of inclusions of a carbide phase in the blade material is revealed. The echo technique of nondestructive control of structure shows great promise for application at any stage of output control directly on a product.