Research On Ultrasonic Phased Array Testing For Thin-walled Curved Surface Titanium Alloy Inertia Friction Welded

At present,the welding of compressor components is one of the important methods to reduce the weight of aero-engine and improve the thrust-weight ratio.The inertia friction welding quality is higher than the electron beam welding,witch has been widely applied in advanced aircraft engine rotor components welding manufacturing.Inertial friction welding is an advanced solid-phase connection technology.The welded interface will produce micro-cracks,“cold welding” or oxide slag of dispersive distribution defects when the welding process parameters fluctuate or the end face of the workpiece is not treated properly.The defects are distributed along the interface and have a small acoustic reflection area.In a ddition,the weld zone is curved with narrow axial space and steps,which brings more difficulties to ultrasonic detection.Ultrasonic phased array detection has high deflection-focused beam energy and higher sensitivity to micro cracks and oxide slag defects in inertial friction welds.It suitable for contact detection of curved welds of compressor components.But there is no suitable test block,coupling wedge,array probe and detection pr ocess.Therefore,ultrasonic phased array detection was studied for TA19 titanium alloy compressor assembly inertial friction weld.According to the requirements of sound velocity,wedge delay,TCG and other param eters calibration before ultrasonic phased array testing and the structural characteristics of the standard test block with workpiece to be tested design calibration block of TA19 titanium alloy with blind hole of 1mm diameter and arc groove of 20 mm and 40 mm radius.According to the structural characteristics of the inertial friction welding seam of the compressor components and the aviation industry standard design the ultrasonic test block to screen the process parameters before the actual test.The thin wall thickness,narrow space and step in the inertial friction weld zone of compressor components limit the application of conventional coupling wedge and array probe.The ideal probe placement was chosen by the structural characteristics of weld zone position.The curved surface coupled wedge and array probe was design base on probe placement outside diameter,axial length and waveform.The propagation path of the beam was simulated in the workpiece.The study shows that in 30 ° ~ 60 ° sector scanning beam angle range can completely cover the whole weld,and the echo of the structure is relatively simple.Ultrasonic phased array detection process parameters include detection frequency,sensitivity,array aperture,scanning angle range and angle step value,focusing depth and excitation pulse voltage.The optimal values of step angle,focusing depth and excitation pulse voltage are taken for improving the detection sensitivity of micro defects on inertial friction welding.The parameter variation of frequency,sensitivity,array aperture and scanning angle were studied to the impact on detection results of rectangular slot defects based on calibration block,reference blocks,curved surface coupled wedge and phased array probe.The research show process parameters of 7.5MHz frequency,33 db sensitivity,16 array aperture and fan scanning array aperture angle of 30o~54o can obtain good detection effect.The measure height of the artificial defect was 0.9mm,and the reflect wave height was 37%.