Ultrasonic Impact Treatment Process

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Ultrasonic Impact Treatment Process

Ultrasonic impact treatment for peening welds – HFMI / UIT

Improved fatigue resistance

HFMI (High Frequency Mechanical Impact), also known as UIT (Ultrasonic Impact Treatment) or UPT (ultrasonic peening treament), is a high-frequency weld impact treatment designed to improve the fatigue resistance of welded structures.

It is a cold mechanical treatment that involves striking the weld toe with a needle (or striker) to create an enlargement of its radius and to introduce residual compressive stresses for stress relieving weldments.

The new recommendation published by the IIW proposes a gain of 4 to 8 fatigue classes depending on the yield strength of the treated steels. The improvements actually noted in the study with our equipment show even more significant improvements.

EMPOWERING - Ultrasonic Impact Traetment - Bridge Weld Enhancement

To know more about our ultrasonic impact treatment (or hfmi), download our flyer.

Principle-of-ultrasonic-impact-treatment-UIT-HFMI or ultrasonic peening | SONATS

Principle of ultrasonic weld impact treatment

Crack growth with and without ultrasonic peening | SONATS

Improvement of the lifespan of weldments after ultrasonic weld impact treatment

Increase in stress corrosion cracking (SCC) resistance

The creation of superficial compression, by peening welds, due to the impact of the needles on the material also makes it possible to improve the resistance for stress corrosion cracking.

As this phenomenon occurs on structures and assemblies exposed to corrosive environments, the HFMI/UIT process helps to delay or even eliminate the appearance of cracks.

Correction of distorsions due to welding

The stresses created by welding processes cause distortions in the welds between the panels.

These well-known distortions occur during the cooling phase of the weld, when the molten metal shrinks, resulting in plastic deformation of the welded metals.

In order to eliminate tensile stress, conventional stress relieving processes are currently applied locally (heating, TIG dressing, etc.). These processes restore a stress level close to 0 MPa at the surface and at a depth but do not correct the defect created by the weld.

The ultrasonic impact treatment (HFMI / UIT) process not only allows to create residual compressive stresses, which are much more beneficial than stress relief but also allows to straighten the deformations caused by welding. The 2 in 1 effect of ultrasonic impact treatment (HFMI / UIT) is particularly valuable when the aim is to improve the fatigue strength of steels, aluminium and other metal alloys while correcting weldments geometrical defects.

Correction of distorsions due to welding

Correction of distortions due to welding

For both curative and preventive treatment

When producing a part or making and assembling a structure, the first step in controlling fatigue resistance is to assess the most critical areas where cracks may appear. Then the best process to apply must be determined. The key to this choice is to assess whether a method of improving fatigue resistance is needed before the onset of major damage. A preventative rather than a corrective approach is much better in order to minimise costs and maximise profits.

Ultrasonic impact treatment is one of the best preventive treatments to improve the fatigue resistance of welded structures and stress relieving weldments.

Fatigue resistance technologies, such as NOMAD (ultrasonic weld impact treatment equipment), are regularly and successfully used in many sectors: aerospace, energy, automotive, defence, transportation and infrastructure.

Extending-the-fatigue-life-of-bridges-using-STRESSONIC(r)-needle-peening | SONATS

Discover the article about application of ultrasonic impact treatment process on bridge

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Ultrasonic impact treatment for peening welds – HFMI / UIT

Improved fatigue resistance

Increase in stress corrosion cracking (SCC) resistance

Correction of distorsions due to welding

For both curative and preventive treatment

SCIENTIFIC PUBLICATIONS

Performance of high-frequency mechanical impact (HFMI) treatment for bridge application

Fatigue Life Enhancement of Welded Structures using Ultrasonic Needle Peening

Effect of high frequency mechanical impact treatment on fatigue strength of welded 1300 MPa yield strength steel

Fatigue behaviour of arc welded assemblies: paths of improvment

Experimental study of transverse attachment joints [...], improved by high-frequency mechanical impact treatment

High cycle fatigue behaviour of impact treated welds under variable amplitude loading conditions

Effect of HFMI treatment procedure on weld toe geometry [...]

Fatigue strength improvement of hifh strength welded structures by hammer peening treatment

Fatigue life improvment of welded structures by ultrasonic needle peening compared to TIG Dressing

Testing and fracture mechanics analysis of strength effects on the fatigue behavior of HFMI-treated welds

Understanding the mechanisms for fatigue life improvement and repair of welded structures

Fatigue life calculation of high frequency mechanical impact (HFMI) treated welded [...]

Residual stress state induced by high frequency mechanical impact treatment in different steel grades

Effects of ultrasonic peening on fatigue strength of out-of-plane gusset joints

Strain-based critical plane approach to predict the fatigue life of high frequency mechanical impact [...]