The effect of residual stresses and cold working on fatigue strength

1976 ◽  
Vol 8 (5) ◽  
pp. 529-531 ◽  
Author(s):  
S. I. Ivanov ◽  
V. F. Pavlov
Keyword(s):  
Fatigue Strength ◽  
Residual Stresses ◽  
Cold Working

Effects of the Interference Level on the Residual Stresses in a Cold-Working Expansion Method

2013 ◽  
Vol 577-578 ◽  
pp. 329-332
Author(s):  
Marco Giglio ◽  
M. Lodi ◽  
L. Giudici
Keyword(s):  
Fatigue Strength ◽  
Residual Stresses ◽  
Fatigue Resistance ◽  
Cold Working ◽  
Expansion Method ◽  
Calculation Algorithm ◽  
Interference Level ◽  
Inner Radius ◽  
The Difference ◽  
Good Agreement

The cold-working expansion methods are extensively used in the aerospace and mechanical industry to obtain forced couplings of steel bushings into holes made on mechanical components, by means of the passage of an oversized mandrel. This work describes a calculation algorithm, able to correlate the selected interference level, as the difference between the maximum radius of the mandrel and the inner radius of the bushing, to the residual stresses expected on the hole surface. The designer, taking into account the different design choices already made, can choose the optimal interference, estimating the uncoupling resistance and the fatigue strength of forced components. Two original and different systems bushing-mandrel, in low and high interference, have been tested for determining the characteristics of fatigue resistance in the finite life part of the Wohlers diagram.The results have been compared with previously estimated data, getting a good agreement of the series. The increase of the adopted interference value determine a corresponding increase of residual stresses on the hole, both in the radial than in the circumferential direction, and an appreciable and predictable improvement of the fatigue strength of components.

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

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.

Correlation of Residual Stresses in the Fatigue Strength of Axles

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.

Effect of shot peening residual stresses and surface roughness on fretting fatigue strength of Al 7075-T651

2020 ◽  
Vol 142 ◽  
pp. 106004 ◽  
Author(s):  
Vicente Martín ◽  
Jesús Vázquez ◽  
Carlos Navarro ◽  
Jaime Domínguez
Keyword(s):  
Surface Roughness ◽  
Fatigue Strength ◽  
Residual Stresses ◽  
Shot Peening ◽  
Fretting Fatigue ◽  
Al 7075

scholarly journals Residual Stresses Induced by Surface Working and Their Improvement by Emery Paper Polishing

2020 ◽  
Vol 4 (2) ◽  
pp. 21
Author(s):  
Makoto Hayashi
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Fatigue Strength ◽  
Residual Stresses ◽  
Diffraction Method ◽  
304 Stainless Steel ◽  
Heat Treated ◽  
Emery Paper ◽  
Type 304 ◽  
Type 304 Stainless Steel

In many of machine parts and structural components, materials surface would be worked. In this study, residual stresses on the surfaces were measured by X-ray diffraction method, and effects of surface working on the residual stresses were examined. In case of lathe machining of type 304 stainless steel bar, the residual stresses in circumferential directions are tensile, and those in axial directions are almost compressive. Highly tensile residual stresses in the circumferential directions were improved by emery paper polishing. 10 to 20 times of polishing changes high tensile residual stresses to compressive residual stresses. In the case of shot peening on a type 304 stainless steel plate, the compressive residual stress inside is several hundred MPa lower than that on the surface. By applying the emery paper polishing to the shot peened surface 10 or 20 times, the residual stress on the surface is improved to −700 MPa. While fatigue strength at 288 °C in the air of the shot peened material is 30 MPa higher than solution heat treated and electro-polished material, the fatigue strength of the shot peened and followed by emery paper polished material is 60 MPa higher. Thus, the emery paper polishing is simple and a very effective process for improvement of the residual stresses.

Fatigue Strength and Wear Behavior of NCD and MLD Diamond Coatings Characterized by Different Level of Residual Stresses after Annealing

2020 ◽  
Vol 404 ◽  
pp. 39-44
Author(s):  
Georgios Skordaris ◽  
Tilemachos Kotsanis ◽  
Apostolos Boumpakis ◽  
Fani Stergioudi
Keyword(s):  
Fatigue Strength ◽  
Residual Stresses ◽  
Diamond Film ◽  
Wear Behavior ◽  
Critical Issue ◽  
Film Structure ◽  
Diamond Coatings ◽  
Coated Tool ◽  
Cutting Processes ◽  
Cemented Carbide Tools

Nano-composite (NCD) and multi-layered (MLD) diamond coatings deposited on cemented carbide tools are often applied in machining of non-ferrous materials. A critical issue for their wear behavior, especially in cutting processes in which interrupted repetitive loads are applied such as milling, is the fatigue strength. The latter parameter is significantly affected by the level of residual stresses in their diamond film structure. For investigating such an issue, untreated as well as annealed for 8h vacuum NCD and MLD coatings of the same thicknesses were produced. Inclined impact tests supported by appropriate FEA models were conducted for calculating the level of the residual stresses and for determining the critical impact force for the fatigue damage after 106 impacts. Moreover, the wear behavior of diamond coated inserts was investigating in milling aluminum foam. According to the attained results, the reduction of the residual stresses in the diamond film structure contributes to a significant increase of the fatigue strength and coated tool life for both examined cases. Moreover, due to the enhanced tribological properties of NCD films, an improved wear behavior is registered compared to the MLD ones, when both coatings possess the same level of residual stresses.

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