Effect of Ultrasonic Impact Treatment on Corrosion Resistance of Welded Joints of 16MnR Steel

Abstract

The weld seam and weld toe surface were treated by ultrasonic impact method. The contrast corrosion tests were performed in 3.5% NaCl aqueous solution both for the un-treated and treated joint. The experimental results indicate that the severe plastic deformation on the surface of weld seam and weld toe were formed by ultrasonic impact for different time, the maximum depth of the plastic deformation layer is about 300μm. Residual tensile stress in the surface of weld seam and weld toe can be changed to residual compressive stress by impact treatment, and the grain in the surface of welded joint could be refined. Compared to the un-treated joint, when the impact current is 1.2A and 1.5A, respectively, the corrosion rate of treated joint was reduced by 22.67%, 54.59%, 43.99% and 33.92%, 56.54%, 49.29%, respectively for 10, 20 and 30 min. treating. The corrosion resistance of welded joint has a certain relationship with the residual stress on the surface of welded joint. The ultrasonic impact treatment has distinct effect on the corrosion resistance of 16MnR welded joint.