scholarly journals Role of compressive residual stresses produced by cutting and rubbing processing on fatigue strength of heat-treated SCM435 smooth specimens

2019 ◽  
Vol 85 (876) ◽  
pp. 19-00131-19-00131
Author(s):  
Terutoshi YAKUSHIJI ◽  
Tsubasa TOKUZUMI ◽  
Masahiro GOTO
Keyword(s):  
Fatigue Strength ◽  
Residual Stresses ◽  
Heat Treated ◽  
Compressive Residual Stresses

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.

Influence of Residual Stresses and of Mean Stress on the Fatigue Strength of Specimens with Longitudinal Non-Load-Carrying Fillet Welds

1970 ◽  
Vol 12 (6) ◽  
pp. 381-390
Author(s):  
T. R. Gurney
Keyword(s):  
Fatigue Strength ◽  
Residual Stresses ◽  
Stress Ratio ◽  
Fillet Welds ◽  
Direct Result ◽  
Mean Stress ◽  
Test Results ◽  
Load Carrying ◽  
Quantitative Explanation ◽  
Compressive Residual Stresses

Using results obtained in work on fatigue crack propagation in unwelded sheet specimens, an analysis has been made of fatigue test results for specimens with longitudinal non-load-carrying fillet welds tested in the as-welded and stress relieved conditions and also after treatment by local compression and by spot heating. It is shown that, by this means, it is possible to provide a quantitative explanation of the effect of residual stresses and applied stress ratio on fatigue strength, since all the results can be normalized on the basis of an effective stress range. In the course of the work it has been shown that the gross stress concentration factor for this type of joint is approximately 2·57. It has also again been demonstrated that the beneficial effect of spot heating on fatigue strength is a direct result of induced compressive residual stresses.

Effect of Deep Cryogenic Treatment on the Microstructure of an Aerospace Aluminum Alloy

2012 ◽  
Vol 445 ◽  
pp. 965-970 ◽  
Author(s):  
F. Bouzada ◽  
M. Cabeza ◽  
P. Merino ◽  
S. Trillo
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Residual Stresses ◽  
Grain Boundaries ◽  
Cryogenic Treatment ◽  
Deep Cryogenic Treatment ◽  
Heat Treated ◽  
Static Mechanical ◽  
Compressive Residual Stresses ◽  
Static Mechanical Properties

This paper describes how deep cryogenic treatment at 98K produces changes in the microstructure of a heat-treated aluminum alloy. It was observed how the sub-micrometric particles increased near and at the grain boundaries. This slight precipitation did not produce any modification in static mechanical properties. However, the compressive residual stresses of the material were higher after compared to before the treatment. Both these effects can enhance the life of this alloy through cryogenic treatment.

Characteristics of High Frequency Peening Methods and their Effects on the Fatigue Strength of Welded Details

2007 ◽  
Vol 348-349 ◽  
pp. 429-432
Author(s):  
Imke Weich ◽  
Thomas Ummenhofer
Keyword(s):  
Fatigue Strength ◽  
Residual Stresses ◽  
High Frequency ◽  
Crack Detection ◽  
Surface Hardness ◽  
Detection Methods ◽  
Laser Measurements ◽  
Mechanical Effects ◽  
Weld Toe ◽  
Compressive Residual Stresses

Research has been initiated on the effects of high frequency peening methods on the fatigue strength. These methods combine an improvement of weld toe profile with an initiation of compressive residual stresses and surface hardening. The effects of two techniques, High Frequency Impact Treatment (HiFIT) and Ultrasonic Impact Treatemnt (UIT) are compared. Laser measurements of the weld seam prove that both methods increase the overall weld toe radii. Further, residual stress measurements verify the introduction of compressive residual stresses at least up to a depth of 1 mm. The values meet the yield strength combined with an increase of the surface hardness. These material mechanical effects cause an increased crack resistance. Crack detection methods prove that the material mechanical effects yield to a retarded crack initiation. Experimental results show that these effects lead to a significant increase of the fatigue strength and reduced slopes of the SN-curves.

Fatigue Life Improvement Using Mechanical Post Treatment for Weldment

2008 ◽  
Vol 580-582 ◽  
pp. 97-100
Author(s):  
Seung Ho Han ◽  
Jeong Woo Han ◽  
Yong Yun Nam
Keyword(s):  
Fatigue Life ◽  
Fatigue Strength ◽  
Residual Stresses ◽  
Quantitative Measure ◽  
Fatigue Strength Improvement ◽  
Weld Profile ◽  
Weld Toe ◽  
Life Improvement ◽  
Hammer Peening ◽  
Compressive Residual Stresses

Mechanical post treatments for welded structures have been applied in various industrial fields and, in most cases, have been found to cause substantial increase in their fatigue strength. These methods, generally, consist of the modification of weld toe geometry and the introduction of compressive residual stresses. In hammer peening, the weld profile is modified due to removal or reduction of minute crack-like flaws; compressive residual stresses are also induced by repeated hammering of the weld toe region with blunt-nosed chisel. In this study, a hammer peening procedure, using commercial pneumatic chipping hammer, was developed; a quantitative measure of fatigue strength improvement was performed. The fatigue life of hammer-peened specimen was prolonged by approximately 10 times in S=240MPa, and was doubled for the as-welded specimen.

Evaluation of Fatigue Strength of Heat Treated and Laser Hardened 42CrMo4 Steel Considering Localized Initiation Mechanisms

2014 ◽  
Vol 606 ◽  
pp. 31-34
Author(s):  
Ivo Černý ◽  
Jiří Sís ◽  
Dagmar Mikulová
Keyword(s):  
Fatigue Strength ◽  
Residual Stresses ◽  
Fatigue Resistance ◽  
Fatigue Crack Initiation ◽  
Industrial Applications ◽  
Fatigue Tests ◽  
Laser Hardening ◽  
Basic Material ◽  
Heat Treated ◽  
42Crmo4 Steel

Laser surface hardening is an advanced method of surface treatment of structural steels with a great potential for wide industrial applications. According to the recent literature results and knowledge about laser hardening, fatigue resistance can be either reduced or increased, even considerably, depending on numerous parameters of basic material, the technology parameters etc. This contribution contains results of a partial study of effect of laser hardening of relatively small specimens on fatigue resistance of 42CrMo4 steel. Two different parameters of laser hardening were used, one of them resulted in considerable longitudinal residual stresses surface speed of laser beam 4 mm/s. Results of fatigue tests of basic reference material had a surprisingly high, atypical scatter, particularly in the region near fatigue limit. Fractographical analyses indicated that this scatter was connected with presence of single inclusions, even quite large, which in some cases caused fatigue crack initiation. Compressive residual stresses after the laser treatment improved fatigue strength and reduced the scatter, likely due to short crack retardation in the compressive residuals tress field. Further analyses and discussion are provided using Murakami method of fatigue life evaluation of materials containing defects.

Influence of the Abrasive on Fatigue in Precision Grinding

1987 ◽  
Vol 109 (3) ◽  
pp. 203-205 ◽  
Author(s):  
H. K. To¨nshoff ◽  
F. Hetz
Keyword(s):  
Fatigue Strength ◽  
Residual Stresses ◽  
Strong Influence ◽  
Cubic Boron Nitride ◽  
Fatigue Tests ◽  
Machining Parameters ◽  
Precision Grinding ◽  
Surface Residual Stresses ◽  
Alternating Bending ◽  
Compressive Residual Stresses

The surface residual stresses produced by grinding may have a strong influence on the life of highly stressed components. Different abrasives such as aluminum oxide (Al2O3) and cubic boron nitride (CBN) may lead to very different results. While CBN produces compressive residual stresses in nearly all combinations of machining parameters, the use of Al2O3 normally leads to tensile residual stresses. Fatigue tests carried out in alternating bending showed a remarkable increase in fatigue strength for CBN ground specimens compared with Al2O3 ground ones.

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