Ultrasonic Impact Improves Weld Fatigue Performance Of Titanium

Ultrasonic Impact (UIT/UP) technology was proposed by the world-renowned Ukrainian Paton Welding Research Institute in 1972, and jointly developed by the Paton Welding Research Institute and the Russian "Quantum" Research Institute, and has been used in the former Soviet Union for the reduction of residual stresses in welds and the introduction of beneficial compressive stresses in naval vessels.

Ultrasonic impact technology is a highly efficient method of removing harmful residual tensile stresses and introducing beneficial compressive stresses on the surface of the component or in the weld zone. Ultrasonic impact equipment using high-power energy to drive the impact head with a frequency of about 20,000 times per second impact on the surface of the metal object, high-frequency, high-efficiency and focusing under the large energy so that the surface of the metal to produce a large compressive plastic deformation; at the same time, ultrasonic impact to change the original stress field, resulting in a beneficial compressive stress; high-energy impact of the surface temperature of the metal to rise very quickly and then quickly cooled to make the effect of the area of the surface layer of the metal organization changes, the impact site to strengthen the surface of the metal. The impact site can be strengthened.

In the field of high-energy ultrasound (HPU), ultrasonic impact technology has become a promising research direction, and the scope of application has been extended to a variety of materials, components and welding units. So far, ultrasonic impact technology in Russia, Ukraine, France, Japan, Norway, Sweden, Canada and the United States and other countries in the railroads, marine engineering, automobiles, armored vehicles, heavy construction machinery, machinery parts, aircraft, bridges, rolling stock, oil pipelines, chemical machinery and equipment, and many other fields have been applied.

Ultrasonic impact is the use of high-power ultrasound to promote the impact tool to more than 20,000 times per second frequency impact on the surface of metal objects, due to the ultrasonic high-frequency, high-efficiency and focusing under the large energy, so that the surface of the metal to produce a large pressure-plastic deformation; at the same time, ultrasonic shock waves to change the original stress field, resulting in a certain number of compressive stress; so that the ultrasonic impact parts to be strengthened. Ultrasonic drive power supply through the cable and set in the shell of the ultrasonic transducer connected to the vibration output end of the transducer and amplitude rod connected to the amplitude rod end equipped with impact needle. The ultrasonic driving power supply converts the utility power into a high-frequency, high-voltage alternating current, which is transmitted to the ultrasonic transducer. Then the ultrasonic transducer will input electrical energy into mechanical energy, that is, ultrasonic waves, which is expressed in the form of transducer in the longitudinal direction for the reciprocating telescopic movement; telescopic movement of the frequency equivalent to the drive power supply AC current frequency, telescopic displacement in more than a dozen microns or so. The role of the amplitude rod is to amplify the output amplitude of the transducer, reaching more than 100 microns, on the other hand, the impact of the impact needle to apply the impact force to promote the impact of the needle high-speed forward. Impact needle impact on the workpiece, the energy to the weld seam transfer, in order to eliminate the role of internal stress. Impact head by the reaction of the workpiece after the rebound, meet the high-frequency vibration of the amplitude lever, again by the excitation, and once again at high speed to the weld, and so on for many times, to complete the impact of the operation. Features: high power, good impact effect, high reliability, long service life, light weight, portable, very easy to operate well-designed, wide use of significant energy saving, reduce costs.
Efficacy:

1,so that the residual tensile stress within the surface layer of the metal weld is changed to compressive stress, thereby significantly increasing the fatigue life of the metal structure. 

2,change the surface layer of the metal grain structure, so that the plastic deformation layer, so that the strength and hardness of the surface layer of the metal are significantly improved. 

3,Improve the geometry of the weld toe and reduce the stress concentration. 

4,change the welding stress field, significantly reduce welding deformation, improve the dimensional stability of the workpiece.