Study On Optimization Of Welding Processing Property Of Pressure Vessel

Ultrasonic Impact Treatment(UIT)technology has become one of the most common methods to strengthen the surface of welded joints because of its high flexibility,convenience and safety.However,the equipment of Ultrasonic Impact Treatment has its own shortcoming and limitations,such as,the impact is not smooth,the needle moving rate is low,much noise is generated during impacting and has many artificial factors etc.In this paper,UIT equipment has been optimized and improved.A kind of bracket for ultrasonic impact gun and impact roll needle have been designed.The microstructure,hardness,roughness,wear resistance,residual stress and electrochemical properties of the industrial pure titanium joint were investigated by UIT and UI&R treatment.It is found that the grain size of the surface of the material is obviously refined and the maximum thickness of the deformation layer is about 300 ?m.The impact of 1.5A-6min and 2A-6min parameters on the surface roughness was improved obviously by UI&R treatment,and the roughness was improved by changing the friction mode..The roughness decrease is obviously after UI&R 1.5A-6min and 2A-6min treated;Wear test results show that the treatment of low strength,abrasion resistance of welded joints has been greatly improved,and the wear resistance improved about 70.9 % after UI&R 1.5A-3min treated.UI&R treated overall wear resistance is better than the UIT treated;The maximum residual compressive stress of the surface layer is achieved by UI&R 2A-6min and 2A-9min treated,is about 530 MPa.Although the residual compressive stress of UIT treated is much bigger than the UI&R treated,the distribution of residual stress is much more uniformed by UI&R treated.The electrochemical corrosion behavior of 10 % HCl shows that the UI&R treatment can effectively improve the corrosion resistance of the material,and the corrosion resistance in 2A-6min is the best.As for UIT treated.only in 1.5A-9min the corrosion performance is better than that of primary sample,the other process parameters have a certain degree of decline.