Research On Influence Of Ultrasonic Impact Treatment Along Welded Joints For Titanium Alloy

As a kind of typical α titanium alloy, CP3titanium alloy has properties such as high specificstrength, resistance to corrosion. So the CP3titanium alloy is widely used in aircraft engine, heatshield et al. Recently, welded structures could be extensively found in aeronautical parts, whichcauses that more and more emphasis have been laid on the improvements of welded joints’ properties.Ultrasonic impact treatment (UIT) is an effective and convenient method to enhance the welded joints.Ultrasonic vibration was utilized to drive the device to impact the metal surface. Plastic deformationwas caused by UIT, thus strengthen the welded joints.In this paper, the mechanism of UIT was analyzed. Theoretical analysis has been done to obtainthe influence of UIT on roughness, residual stresses, fatigue performance, corrosion resistance andmicrostructure.Laser welding and UIT processes were simulated by using finite element software ABAQUS.Residual stresses distribution of welded joints after UIT were obtained. It reveals that the tensilestresses of welded joints can be transformed into compressive stresses by using UIT.Experiments were done based on the simulation results. Pneumatic slide has been designedaccording to the existing UIT device. Welded joints were impacted by different magnitude ofpre-pressure. Performance of welded joints after UIT was tested. Main results for this study are asfollows. Surface roughness reduces after UIT. The roughness firstly decreases and then comes to besteady with the increase of pre-pressure. Residual stresses of welded joints without UIT are tensilestresses. The tensile stresses can be transformed into compressive stresses by using UIT. Thecompressive stresses rise with the increase of pre-pressure, but the stresses come to be steady whenthe pre-pressure reaches60N. Micro-hardness of welded joints rises with the increase of pre-pressure.