Evaluation of the effect of residual stresses and surface layer hardening on the fatigue strength of components

1981 ◽  
Vol 13 (10) ◽  
pp. 1220-1226
Author(s):  
N. M. Rudnitskii
Keyword(s):  
Surface Layer ◽  
Fatigue Strength ◽  
Residual Stresses ◽  
Surface Layer Hardening

Determination of the endurance limit of the surface layer of a part after processing with a blade tool

2021 ◽  
pp. 56-61
Author(s):  
Keyword(s):  
Surface Roughness ◽  
Surface Layer ◽  
Fatigue Strength ◽  
Residual Stresses ◽  
Quality Indicators ◽  
Work Hardening ◽  
Endurance Limit ◽  
Layer Surface ◽  
Processing Mode

The dependences of the quality indicators of the surface layer of parts on the fatigue strength are analyzed. The dependences are given, taking into account both the quality indicators of the surface layer of the part after processing with the blade tool, and the parameters of the processing mode. Keywords: surface layer, surface roughness, residual stresses, work-hardening depth, endurance limit, blade tool processing. [email protected]

Laser Shock Processing of the Maraging Steel Surface

2007 ◽  
Vol 537-538 ◽  
pp. 655-662 ◽  
Author(s):  
Janez Grum ◽  
Martin Zupančič ◽  
J.L. Ocaña
Keyword(s):  
Surface Layer ◽  
Fatigue Strength ◽  
Residual Stresses ◽  
Maraging Steel ◽  
Thin Surface Layer ◽  
Beam Diameter ◽  
Laser Shock ◽  
Laser Shock Processing ◽  
Pulse Density ◽  
Shock Processing

Laser Shock Processing (LSP) is a process of laser treating of a surface with a pulsed beam of high power density. The process enables hardening of a thin surface layer; therefore, it is suitable for the improvement of fatigue strength of quality materials. Locally directed mechanical waves produce a considerably increased dislocation density in the thin surface layer, which affects the variations of microhardness and residual stresses. The magnitude and variation of the residual compressive stresses in the surface layer are favourable, which ensures higher fatigue strength. Laser shock processing (LSP) is more exacting than conventional shot peening, but it shows certain advantages such as better control of the surface state, processing of locally limited surfaces and a possibility to produce different transitions between the processed surface and the non-processed one. LSP has so far been tested and efficiently applied to various materials, including maraging steels. Relevant publications often deal with LSP mechanisms and the influence of the process on the dynamic strength of maraging steel, but less frequently the influence of individual characteristics such as the microstructure of matrix and of precipitated phases or residual stresses. The present paper deals with LSP of 12% Ni maraging steel. The material chosen is suitable for the production of complex structural parts and dies for die casting, which require high resistance of the material to thermo-mechanical loads. By means of measurement of the state before and after LSP, the value of the mean roughness Ra, surface defects and the variation of residual stresses in the thin surface layer were determined. After LSP of the surface, the influence of processing parameters such as laser-beam diameter and pulse density per unit of area was established.

FATIGUE PROPERTIES OF SUS304 STAINLESS STEEL AFTER ULTRASONIC NANOCRYSTAL SURFACE MODIFICATION (UNSM)

2012 ◽  
Vol 06 ◽  
pp. 330-335 ◽  
Author(s):  
K.Y. Zhang ◽  
Y.S. Pyoun ◽  
X.J. Cao ◽  
B. Wu ◽  
R. Murakami
Keyword(s):  
Stainless Steel ◽  
Surface Layer ◽  
Surface Modification ◽  
Fatigue Strength ◽  
Residual Stresses ◽  
Fatigue Testing ◽  
304 Stainless Steel ◽  
Test Machine ◽  
Nanostructured Surface ◽  
Surface Residual Stresses

The changing of materials surface properties method always was taken into improving the fatigue strength. In this paper, an ultrasonic nanocrystal surface modification(UNSM) technique was used on the SUS 304 stainless steel to form a nanostructured surface layer with different static load(70N, 90N, 110N, 130N) and the vibration strike number was about 20,000times/mm2. The untreated and different condition specimens fatigue strength was all tested by a dual-spindle rotating bending fatigue test machine. SPring-8(a large synchrotron radiation facility) was used to test the surface nanocrystallization components. The X-ray diffraction (XRD), the scanning electron microscopy (SEM), optical microscope and a micro-Vickers hardness tester (MVK-E3, Akashi) were separately used to get the surface residual stresses, fracture surface after fatigue testing, metallographic structure and the microhardness of the nanostructured surface layer. The result showed that martensite transformation took place on the surface of specimens, the surface residual stresses had only a small increase and some cracks occurred between the martensite layer and the austenite layer, but the fatigue strength of 90N improved 81%.

Effect of diamond burnishing parameters on the state of the processed surface layer of billets made of high-strength "30ХГСН2А-ВД" steel

2020 ◽  
pp. 82-86
Author(s):  
A.N. Shvetsov ◽  
D.L. Skuratov
Keyword(s):  
Surface Layer ◽  
Residual Stresses ◽  
Strain Hardening ◽  
Processing Speed ◽  
Synthetic Diamond ◽  
High Strength ◽  
The State ◽  
Diamond Burnishing

The influence of the burnishing force, tool radius, processing speed and feed on the distribution of circumferential and axial residual strses, microhardness and the depth of strain hardening in the surface layer when pr ssing of "30ХГСН2А-ВД" steel with synthetic diamond "ACB-1" is considered. Empirical dependencies determining these parameters are given. Keywords diamond burnishing, strain hardening depth, circumferential residual stresses, axial residual stresses, microhardness. [email protected], [email protected]

scholarly journals Thermal Effects on Surface and Subsurface Modifications in Laser-Combined Deep Rolling

2021 ◽  
Vol 5 (2) ◽  
pp. 55
Author(s):  
Robert Zmich ◽  
Daniel Meyer
Keyword(s):  
Surface Layer ◽  
Residual Stresses ◽  
Thermal Loads ◽  
Deep Rolling ◽  
Mechanical Loads ◽  
Thermomechanical Process ◽  
Compressive Stresses ◽  
New Process ◽  
Negative Effect ◽  
Compressive Residual Stresses

Knowledge of the relationships between thermomechanical process loads and the resulting modifications in the surface layer enables targeted adjustments of the required surface integrity independent of the manufacturing process. In various processes with thermomechanical impact, thermal and mechanical loads act simultaneously and affect each other. Thus, the effects on the modifications are interdependent. To gain a better understanding of the interactions of the two loads, it is necessary to vary thermal and mechanical loads independently. A new process of laser-combined deep rolling can fulfil exactly this requirement. The presented findings demonstrate that thermal loads can support the generation of residual compressive stresses to a certain extent. If the thermal loads are increased further, this has a negative effect on the surface layer and the residual stresses are shifted in the direction of tension. The results show the optimum range of thermal loads to further increase the compressive residual stresses in the surface layer and allow to gain a better understanding of the interactions between thermal and mechanical loads.

Reduction of Residual Stresses in Medium Density Fibreboard. Part 1. Taguchi Analysis

Holzforschung ◽  
2001 ◽  
Vol 55 (1) ◽  
pp. 67-72 ◽  
Author(s):  
J. van Houts ◽  
D. Bhattacharyya ◽  
K. Jayaraman
Keyword(s):  
Surface Layer ◽  
Residual Stresses ◽  
Internal Bond ◽  
Tensile Modulus ◽  
Thickness Swell ◽  
Subsequent Paper ◽  
Medium Density ◽  
Medium Density Fibreboard ◽  
Taguchi Analysis ◽  
Dissection Method

Summary This paper demonstrates how the Taguchi method of experimental design can be utilised to investigate methods for relieving the residual stresses present in medium density fibreboard (MDF). Panels have been subjected to heat, moisture and pressure, and after equilibration to room conditions, the changes in residual stresses through various layers have been measured using the dissection method. The application of heat and/or moisture has reduced the magnitude of residual stresses while generally the application of pressure has no effect on these stresses. The subsequent paper in this series uses Taguchi analysis to investigate how other board properties such as thickness swell, internal bond strength, surface layer tensile modulus and surface layer tensile strength are affected by the different treatment methods.

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.

Surface Modification Analysis after Shot Peening of AA 7075 in Different States

2013 ◽  
Vol 768-769 ◽  
pp. 519-525 ◽  
Author(s):  
Sebastjan Žagar ◽  
Janez Grum
Keyword(s):  
Residual Stress ◽  
Surface Layer ◽  
Residual Stresses ◽  
Aluminium Alloy ◽  
Shot Peening ◽  
Fatigue Testing ◽  
Stress Profile ◽  
Treatment Conditions ◽  
Stress Profiles ◽  
Compressive Residual Stresses

The paper deals with the effect of different shot peening (SP) treatment conditions on the ENAW 7075-T651 aluminium alloy. Suitable residual stress profile increases the applicability and life cycle of mechanical parts, treated by shot peening. The objective of the research was to establish the optimal parameters of the shot peening treatment of the aluminium alloy in different precipitation hardened states with regard to residual stress profiles in dynamic loading. Main deformations and main residual stresses were calculated on the basis of electrical resistance. The resulting residual stress profiles reveal that stresses throughout the thin surface layer of all shot peened specimens are of compressive nature. The differences can be observed in the depth of shot peening and the profile of compressive residual stresses. Under all treatment conditions, the obtained maximum value of compressive residual stress ranges between -200 MPa and -300 MPa at a depth between 250 μm and 300 μm. Comparison of different temperature-hardened aluminium alloys shows that changes in the Almen intensity values have greater effect than coverage in the depth and profile of compressive residual stresses. Positive stress ratio of R=0.1 was selected. Wöhler curves were determined in the areas of maximum bending loads between 30 - 65 % of material's tensile strength, measured at thinner cross-sections of individual specimens. The results of material fatigue testing differ from the level of shot peening on the surface layer.

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.

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