Influence of residual stresses on fatigue strength of large-scale welded assembly joints

The ultrasonic impact treatment (UIT) is relatively new and promising process for fatigue life improvement of welded elements and structures. In most industrial applications this process is known as ultrasonic peening (UP). The beneficial effect of UIT/UP is achieved mainly by relieving of tensile residual stresses and introducing of compressive residual stresses into surface layers of a material. The secondary factors in fatigue improvement by UIT/UP are decreasing of stress concentration in weld toe zones and enhancement of mechanical properties of the surface layers of the material. Fatigue testing of welded specimens showed that UIT/UP is the most efficient improvement treatment as compared with traditional techniques such as grinding, TIG-dressing, heat treatment, hammer peening and application of LTT electrodes. The developed computerized complex for UIT/UP was successfully applied for increasing the fatigue life and corrosion resistance of welded elements, elimination of distortions caused by welding and other technological processes, residual stress relieving, increasing of the hardness of the surface of materials. The results of fatigue testing of large-scale welded specimens in as-welded condition and after application of UIT/UP are considered in this paper. It is shown that UIT/UP is the most effective and economic technique for increasing of fatigue strength of welded elements in materials of different strength. These results also show a strong tendency of increasing of fatigue strength of welded elements after application of UP with the increase in mechanical properties of the material used.

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Correction to: Effects of residual stresses and compressive mean stresses on the fatigue strength of longitudinal fillet-welded gussets

Welding in the World ◽

10.1007/s40194-021-01139-7 ◽

2021 ◽

Author(s):

Jonas Hensel ◽

Thomas Nitschke-Pagel ◽

Klaus Dilger

Keyword(s):

Fatigue Strength ◽

Residual Stresses ◽

Mean Stresses

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Fatigue Life Improvement of Welded Elements and Structures by Ultrasonic Impact Treatment

Volume 3: Materials Technology; Jan Vugts Symposium on Design Methodology of Offshore Structures; Jo Pinkster Symposium on Second Order Wave Drift Forces on Floating Structures; Johan Wichers Symposium on Mooring of Floating Structures in Waves ◽

10.1115/omae2011-50310 ◽

2011 ◽

Author(s):

Yuriy Kudryavtsev ◽

Jacob Kleiman

Keyword(s):

Mechanical Properties ◽

Fatigue Life ◽

Fatigue Strength ◽

Residual Stresses ◽

Fatigue Testing ◽

Highway Bridges ◽

Surface Layers ◽

Ultrasonic Impact Treatment ◽

Stress Relieving ◽

Life Improvement

The ultrasonic impact treatment (UIT) is relatively new and promising process for fatigue life improvement of welded elements and structures. In most industrial applications this process is known as ultrasonic peening (UP). The beneficial effect of UIT/UP is achieved mainly by relieving of harmful tensile residual stresses and introducing of compressive residual stresses into surface layers of a material, decreasing of stress concentration in weld toe zones and enhancement of mechanical properties of the surface layers of the material. The UP technique is based on the combined effect of high frequency impacts of special strikers and ultrasonic oscillations in treated material. Fatigue testing of welded specimens showed that UP is the most efficient improvement treatment as compared with traditional techniques such as grinding, TIG-dressing, heat treatment, hammer peening and application of LTT electrodes. The developed computerized complex for UP was successfully applied for increasing the fatigue life and corrosion resistance of welded elements, elimination of distortions caused by welding and other technological processes, residual stress relieving, increasing of the hardness of the surface of materials. The UP could be effectively applied for fatigue life improvement during manufacturing, rehabilitation and repair of welded elements and structures. The areas/industries where the UP process was applied successfully include: Shipbuilding, Railway and Highway Bridges, Construction Equipment, Mining, Automotive, Aerospace. The results of fatigue testing of welded elements in as-welded condition and after application of UP are considered in this paper. It is shown that UP is the most effective and economic technique for increasing of fatigue strength of welded elements in materials of different strength. These results also show a strong tendency of increasing of fatigue strength of welded elements after application of UP with the increase in mechanical properties of the material used.

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Investigation of Residual Stress/Strain and Texture in a Large Dissimilar Metal Weld Using Synchrotron Radiation and Neutrons

Materials Science Forum ◽

10.4028/www.scientific.net/msf.772.193 ◽

2013 ◽

Vol 772 ◽

pp. 193-199 ◽

Cited By ~ 1

Author(s):

Carsten Ohms ◽

Rene V. Martins

Keyword(s):

Synchrotron Radiation ◽

Neutron Diffraction ◽

Residual Stresses ◽

Large Scale ◽

High Energy ◽

X Ray Diffraction ◽

Butt Weld ◽

X Ray ◽

Component Size ◽

Thin Slice

Bi-metallic piping welds are frequently used in light water nuclear reactors to connect ferritic steel pressure vessel nozzles to austenitic stainless steel primary cooling piping systems. An important aspect for the integrity of such welds is the presence of residual stresses. Measurement of these residual stresses presents a considerable challenge because of the component size and because of the material heterogeneity in the weld regions. The specimen investigated here was a thin slice cut from a full-scale bi-metallic piping weld mock-up. A similar mock-up had previously been investigated by neutron diffraction within a European research project called ADIMEW. However, at that time, due to the wall thickness of the pipe, stress and spatial resolution of the measurements were severely restricted. One aim of the present investigations by high energy synchrotron radiation and neutrons used on this thin slice was to determine whether such measurements would render a valid representation of the axial strains and stresses in the uncut large-scale structure. The advantage of the small specimen was, apart from the easier manipulation, the fact that measurement times facilitated a high density of measurements across large parts of the test piece in a reasonable time. Furthermore, the recording of complete diffraction patterns within the accessible diffraction angle range by synchrotron X-ray diffraction permitted mapping the texture variations. The strain and stress results obtained are presented and compared for the neutron and synchrotron X-ray diffraction measurements. A strong variation of the texture pole orientations is observed in the weld regions which could be attributed to individual weld torch passes. The effect of specimen rocking on the scatter of the diffraction data in the butt weld region is assessed during the neutron diffraction measurements.

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Correlation of Residual Stresses in the Fatigue Strength of Axles

Journal of Applied Mechanics ◽

10.1115/1.4009189 ◽

1942 ◽

Vol 9 (2) ◽

pp. A85-A90

Author(s):

O. J. Horger ◽

H. R. Neifert

Keyword(s):

Heat Treatment ◽

Fatigue Strength ◽

Residual Stresses ◽

High Surface ◽

Full Size ◽

Tensile Stresses ◽

Compressive Stresses ◽

Actual Service

Abstract The object of this paper is to present a correlation between residual stresses, obtained by heat-treatment, with fatigue values, determined from an investigation of full-size railroad axles. The axles tested were of both solid and tubular design and represent members which could be used under a car in actual service. It was found from these tests that high axle fatigue strength is associated with high surface residual compressive stresses, and lowest axle strength values with surface residual tensile stresses.

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Prediction of Residual Stresses in a Multipass Pipe Weld by a Novel 3D Finite Element Approach

Volume 6B: Materials and Fabrication ◽

10.1115/pvp2018-85044 ◽

2018 ◽

Cited By ~ 1

Author(s):

Hui Huang ◽

Jian Chen ◽

Blair Carlson ◽

Hui-Ping Wang ◽

Paul Crooker ◽

...

Keyword(s):

Finite Element ◽

Residual Stresses ◽

High Performance ◽

Large Scale ◽

Graphics Processing Unit ◽

Computational Cost ◽

Three Dimensional ◽

Processing Unit ◽

Girth Welds ◽

Welding Processes

Due to enormous computation cost, current residual stress simulation of multipass girth welds are mostly performed using two-dimensional (2D) axisymmetric models. The 2D model can only provide limited estimation on the residual stresses by assuming its axisymmetric distribution. In this study, a highly efficient thermal-mechanical finite element code for three dimensional (3D) model has been developed based on high performance Graphics Processing Unit (GPU) computers. Our code is further accelerated by considering the unique physics associated with welding processes that are characterized by steep temperature gradient and a moving arc heat source. It is capable of modeling large-scale welding problems that cannot be easily handled by the existing commercial simulation tools. To demonstrate the accuracy and efficiency, our code was compared with a commercial software by simulating a 3D multi-pass girth weld model with over 1 million elements. Our code achieved comparable solution accuracy with respect to the commercial one but with over 100 times saving on computational cost. Moreover, the three-dimensional analysis demonstrated more realistic stress distribution that is not axisymmetric in hoop direction.

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