The Research and Science behind UIT


After putting UIT through extensive testing and verification by the most demanding research groups imaginable, APPLIED ULTRASONICS has thoroughly proven that UIT is real-world ready.

Application of operational Ultrasonic Impact Treatment (UIT) technologies in production of welded joints.

The first results of investigating the influences of ultrasound on ductility and strength properties of steel and alloys were published in the late fifties and during the sixties. At the same time the first attempt was made to control the deflected mode of a welded joint through its deformation treatment employing ultrasound............

The influence of Ultrasonic Impact Treatment of fatigue behavior of welded joints in high strenth steel.

This paper presents the results of the research aiming at the evaluation of the influence of various post-weld fatigue improvement techniques on the fatigue limit and life of welded joints in mid-and high-strength steels.

Post weld treatment of a welded bridge girder by Ultrasonic Impact Treatment.

This report is a follow up to demonstration of a new ultrasonic hammer peening technique (Ultrasonic Impact Treatment– UIT) Representatives of Fenix Technology International, Inc. post-treated some of the fillet welds on a welded plate girder in the laboratory with the ultrasonic equipment. Following treatment, fatigue test specimens were cut from the plate girder to study the fatigue behavior of both treated and untreated weldments. Results indicate that the fatigue performance of the weldments was improved following the UIT treatment.

Enhancing Fatigue Strength by Ultrasonic Impact Treatment

Enhancement in fatigue performance of welded joints by Ultrasonic Impact Treatment (UIT) was evaluated in large-scale specimens having a nominal yield strength of 345 to 690 MPa. Eighteen rolled-beam specimens having welded details at cover plates and transverse stiffeners and eight built-up specimens having only transverse stiffener details were fatigue tested after treating them by UIT

Comparison of the improvements in corrosion fatigue stength of weld repair of Bronze propellers by UIT and Heat treatments.

The paper presents the results of an investigation of the application UIT as an alternative to heat treatment based on comparative corrosion fatigue tests of plate specimens made from the same material as that used for propellers, bronze Cu 3.


It is shown that with UIT application during weld repair the corrosion fatigue strength is higher than that of heat treated propellers.

The influence of Ultrasonic Impact Treatment of fatigue behavior of welded joints in high strenth steel.

This paper presents the application of a relatively new post-weld treatment method called “Ultrasonic Impact Treatment” (UIT). The paper summarizes the results obtained on a series of experimental fatigue tests where UIT has been applied in order to extend the life time of partially damaged non load carrying filletwelded joints.

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Enhancing fatigue strength by Ultrasonic Impact Treatment for welded joints of offshore structures  

This paper summarises fatigue tests on Y-joints to estimate the influence of a post weld treat-ment method called Ultrasonic Impact Treatment. With this method the fatigue resistance could be increased significantly. Furthermore, tubular joints of tripod structures for offshore wind energy converters are analysed with numerical simulations to judge these welded joints with the hot-spot-concept. The stress concentration factor for the treated weld toe geometry was determined numerically and compared to experimental results.  

Introductory fatigue tests on welded joints in high strenth steel and aluminium improved by various methods including UIT.

This paper summarizes fatigue test on high strength steel specimens in the as-welded condition and specimens treated by ultrasonic impact treatment, TIG dressing and a combination of TIG dressing and ultrasonic impact treatment

Fatigue strength enhancement by means of weld design change and the application of the Ultrasonics Impact Treatment.

This presentation serves to report the results to date of these studies and provide some insight into the conclusions drawn in consideration of fatigue fracture details on bridge girders. Specific emphasis will be focused on weld design options and the benefits achieved by ultrasonic impact treatment. The study covered areas of new welded structures as well as repair procedures and fatigue improvement techniques

Efficiency Evaluation of Ultrasonic Impact Treatment (UIT) of Welded Joints in Weldox 420 Steel in accordance with the IIW Program

The paper presents comparative fatigue test results for specimens in the as-welded condition and specimens treated by hammer peening, shot peening, TIG dressing, ultrasonic impact treatment and a combination of TIG dressing and ultrasonic impact treatment. Welded specimens were fabricated from WELDOX 420 steel at SSAB.

Fatigue strength of longitudinal attachment improved by UIT.

It is commonly observed that complex fabricated structures subject to fatigue loading fail at the welded joints. Some problems can be corrected by proper detail design but fatigue performance can also be improved using post-weld improvement methods. In general, improvement methods can be divided into two main groups: weld geometry modification methods and residual stress modification methods. The former remove weld toe defects and/or reduce the stress concentration while the latter introduce compressive stress fields in the area where fatigue cracks are likely to initiate. The ultrasonic impact treatment method belongs to the class of residual stress improvement methods. The method makes use of an ultrasonic carrier frequency to accelerate hardened tools that, in turn, impact the weld toe. The fatigue strength of non-load carrying attachments in the as-welded condition has been experimentally compared to the fatigue strength of ultrasonic impact treated welds.

Lehigh shows improved fatigue strength of welded joints using UIT.

Enhancement in fatigue performance of welded joints by Ultrasonic Impact Treatment (UIT) wasevaluated with large-scale rolled beam and built-up specimens having yield strength of 345 to 760MPa

Effect of UIT on fatigue life in Web-gusset welded joints

Ultrasonic impact treatment (UIT), which is a peening method, is usually used as a post-weld treatment in order to improve the fatigue strength of welded joints. In this study, fatigue tests were carried out on web-gusset welded joints treated by UIT and the results were compared with the fatigue lives of as-welded joints in order to examine the effects of UIT on the fatigue lives of welded joints. The fatigue lives of web-gusset welded joints treated by UIT increased to more than ten times those of as-welded joints. The introduction of compressive residual stress, relaxation of stress concentration at a weld toe, and refinement of grains under the weld toes were considered as possible reasons for the improvement in fatigue life caused by UIT. Residual stress near weld toes was measured using the X-ray diffraction method. The stress concentration factor at the weld toes was analyzed using the finite element method (FEM). The grain size under the weld toes was measured using electron backscatter diffraction pattern (EBSD) analysis.

Fatigue strengthening of welds in light rail structures

Some of the welds connecting stiffeners to main beams, which were found to be under strength in fatigue, were strengthened by ultrasonic impact treatment (UIT). A programme of fatigue tests has been carried out to evaluate the extent of the improvement and confirm that it is adequate. The tests were on tensile test pieces having non-load-carrying fillet welded attachments relevant to the (BS5400 class F2) under strength welds. Test pieces were pre-fatigued to simulate 20 years’ service and treated by ultrasonic impact. The UIT improved the class F2 fillet welds to a performance between class D and class E. There is a 97?5% probability that performance is improved by a factor of 3 on life and the value