Research And System Development Of Ultrasonic Imaging Detection Method For Bimetal Turbine Bonding Layer Defects

As a key component of the aero-engine combustion chamber,the turbine disk is subjected to the superposition of high temperature,high pressure and high stress,and the working environment is extremely bad.The powder superalloy turbine disk produced by the new bimetallic diffusion bonding process is widely used in the aviation industry due to its good integration,stable fatigue performance and no macrosegregation.Debonding defects are likely to occur at the bimetal diffusion bonding layer due to process problems,which will seriously affect the turbine performance.Therefore,it is very important to effectively detect and evaluate the combined quality of the turbine disk bonding layer.The irregular blade distributed on the outside of a certain type of turbine studied in this subject cannot be circumferentially scanned,and the center plunger hole is far away from the bonding layer.The existing ultrasonic testing equipment cannot effectively detect the bonding layer.In this case,the defect detection research work of the diffusion bonding layer of the turbine disk is carried out.Firstly,the structural characteristics of the bimetal turbine disk are studied,and the relevant acoustic parameters are measured and calculated.From the principle of ultrasonic detection,it is determined that the amplitude of the boundary wave of the bonding layer is used to characterize the defect.Analyze the detection difficulties,and propose two detection schemes,ultrasonic phased array detection and mirror-type ultrasonic feature imaging detection,to produce relevant test blocks.Ultrasonic phased array dedicated transducers are designed for ultrasonic phased array detection scheme,including shape design,frequency selection,number of array elements,array element spacing,wedge fabrication,and commissioned by relevant enterprises to complete the production according to design parameters.The ultrasonic phased array sound field is analyzed,and the acoustic propagation path and energy loss of the turbine disk during the finite element simulation plane wafer plus curved wedge excitation are provided to provide guidance for ultrasonic phased array transducer detection.The existing ultrasonic phased array transducer detection platform designed and manufactured by the existing ultrasonic phased array transducer matching platform is used for actual detection,and the detection results are analyzed and discussed.Then,based on the mirror-type ultrasonic feature imaging detection scheme,an automatic scanning system was designed based on the full use of the existing ultrasonic feature imaging detection technology.The main work includes overall design,system hardware and software construction,and mirror transducer design.After the design and production is completed,the automatic inspection system is used to perform actual inspection on the test block and the workpiece,verifying the performance reliability of the system,and analyzing the imaging test results.Finally,compare the detection results of the two detection schemes,discuss the advantages and disadvantages of the respective detection methods,summarize the problems that the detection system still needs to be solved,and lay the foundation for the follow-up research.The results show that both the ultrasonic phased array and the mirror-type ultrasonic imaging method can effectively detect the defects with a minimum equivalent of 2 mm for the small-diameter thick-wall turbine disk bonding layer.Among them,the mirror-type ultrasonic feature imaging detection system has high reliability and high repeatability,and can be used for standardized detection of turbine disks,and has significant industrial benefits.