scholarly journals The interaction of fatigue cracks with a residual stress field using thermoelastic stress analysis and synchrotron X-ray diffraction experiments

2017 ◽  
Vol 4 (11) ◽  
pp. 171100 ◽  
Author(s):  
Khurram Amjad ◽  
David Asquith ◽  
Eann A. Patterson ◽  
Christopher M. Sebastian ◽  
Wei-Chung Wang
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Crack Tip ◽  
Thermoelastic Stress ◽  
Thermoelastic Stress Analysis ◽  
X Ray Diffraction ◽  
Cold Expansion ◽  
X Ray ◽  
Stress Zone ◽  
Plastic Zones

This article presents an experimental study on the fatigue behaviour of cracks emanating from cold-expanded holes utilizing thermoelastic stress analysis (TSA) and synchrotron X-ray diffraction (SXRD) techniques with the aim of resolving the long-standing ambiguity in the literature regarding potential relaxation, or modification, of beneficial compressive residual stresses as a result of fatigue crack propagation. The crack growth rates are found to be substantially lower as the crack tip moved through the residual stress zone induced by cold expansion. The TSA results demonstrated that the crack tip plastic zones were reduced in size by the presence of the residual compressive stresses induced by cold expansion. The crack tip plastic zones were found to be insignificant in size in comparison to the residual stress zone resulting from cold expansion, which implied that they were unlikely to have had a notable impact on the surrounding residual stresses induced by cold expansion. The residual stress distributions measured along the direction of crack growth, using SXRD, showed no signs of any significant stress relaxation or redistribution, which validates the conclusions drawn from the TSA data. Fractographic analysis qualitatively confirmed the influence on crack initiation of the residual stresses induced by the cold expansion. It was found that the application of single compressive overload caused a relaxation, or reduction in the residual stresses, which has wider implications for improving the fatigue life.

Influence of deposition parameters on the residual stresses of WC-Wo sputtered thin films

MRS Advances ◽  
2020 ◽  
Vol 5 (23-24) ◽  
pp. 1215-1223
Author(s):  
R.R. Phiri ◽  
O.P. Oladijo ◽  
E.T. Akinlabi
Keyword(s):  
Thin Films ◽  
Residual Stress ◽  
Residual Stresses ◽  
Substrate Surface ◽  
Tribological Performance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compressive Stresses ◽  
Deposition Parameters ◽  
Cobalt Thin Films

AbstractControl and manipulation of residual stresses in thin films is a key for attaining coatings with high mechanical and tribological performance. It is therefore imperative to have reliable residual stress measurements methods to further understand the dynamics involved. The sin2ψ method of X-ray diffraction was used to investigate the residual stresses on the tungsten carbide cobalt thin films deposited on a mild steel surface to understand the how the deposition parameters influence the generation of residual stresses within the substrate surface. X-ray spectra of the surface revealed an amorphous phase of the thin film therefore the stress measured was of the substrate surface and the effects of sputtering parameters on residual stress were analysed. Compressive stresses were identified within all samples studied. The results reveal that as the sputtering parameters are varied, the residual stresses also change. Optimum deposition parameters in terms of residual stresses were suggested.

X-Ray Diffraction Analysis of Steel with Oxidised Surface Layer

2016 ◽  
Vol 368 ◽  
pp. 99-102
Author(s):  
Lukáš Zuzánek ◽  
Ondřej Řidký ◽  
Nikolaj Ganev ◽  
Kamil Kolařík
Keyword(s):  
Residual Stress ◽  
Surface Layer ◽  
Residual Stresses ◽  
Diffraction Analysis ◽  
Oxide Surface ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electrolytic Polishing ◽  
Small Depth

The basic principle of the X-ray diffraction analysis is based on the determination of components of residual stresses. They are determined on the basis of the change in the distance between atomic planes. The method is limited by a relatively small depth in which the X-ray beam penetrates into the analysed materials. For determination of residual stresses in the surface layer the X-ray diffraction and electrolytic polishing has to be combined. The article is deals with the determination of residual stress and real material structure of a laser-welded steel sample with an oxide surface layer. This surface layer is created during the rolling and it prevents the material from its corrosion. Before the X-ray diffraction analysis can be performed, this surface layer has to be removed. This surface layer cannot be removed with the help of electrolytic polishing and, therefore, it has to be removed mechanically. This mechanical procedure creates “technological” residual stress in the surface layer. This additional residual stress is removed by the electrolytic polishing in the depth between 20 and 80 μm. Finally, the real structure and residual stresses can be determined by using the X-ray diffraction techniques.

Experimental/Modelling Study of Residual Stress in Al/SiCp Bent Bars by Synchrotron XRD and Slitting Eigenstrain Methods

2008 ◽  
Vol 571-572 ◽  
pp. 277-282 ◽  
Author(s):  
Xu Song ◽  
Solène Chardonnet ◽  
Giancarlo Savini ◽  
Shu Yan Zhang ◽  
Willem J.J. Vorster ◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Residual Strain ◽  
Numerical Models ◽  
Front Face ◽  
Stress Profile ◽  
X Ray Diffraction ◽  
Element Analysis ◽  
X Ray ◽  
Residual Stress Profile

The aim of the study presented here was to evaluate the residual stresses present in a bar of aluminium alloy 2124-T1 matrix composite (MMC) reinforced with 25vol% particulate silicon carbide (SiCp) using X-ray diffraction and 3D profilometry (curvature measurement using Mitutoyo/Renishaw coordinate measurement machine) and comparing these results with numerical models of residual strain and stress profiles obtained by a simple inelastic bending model and Finite Element Analysis (FEA). The residual strain distribution was introduced into the test piece by plastic deformation in the 4-point bending configuration. At the first stage of this study the elasticplastic behaviour of the MMC was characterized under static and cyclic loading to obtain the material parameters, hardening proprieties and cyclic hysteresis loops. Subsequently, synchrotron Xray diffraction and CMM curvature measurements were performed to deduce the residual stress profile in the central section of the bar. The experimental data obtained from these measurements were used in the inelastic bending and FEA simulations. The specimens were then subjected to incremental slitting using EDM (electric discharge machining) with continuous back and front face strain gauge monitoring. The X-ray diffraction and incremental slitting results were then analysed using direct and inverse eigenstrain methods. Residual stresses plots obtained by different methods show good agreement with each other.

Measuring residual stresses in stainless steel—recent experiences within a VAMAS exercise

2009 ◽  
Vol 24 (S1) ◽  
pp. S41-S44 ◽  
Author(s):  
A. T. Fry ◽  
J. D. Lord
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Residual Stresses ◽  
Best Practice ◽  
Test Procedure ◽  
Industrial Plant ◽  
X Ray Diffraction ◽  
X Ray ◽  
Industrial Sectors

Residual stresses impact on a wide variety of industrial sectors including the automotive, power generation, industrial plant, construction, aerospace, railway and transport industries, and a range of materials manufacturers and processing companies. The X-ray diffraction (XRD) technique is one of the most popular methods for measuring residual stress (Kandil et al., 2001) used routinely in quality control and materials characterization for validating models and design. The VAMAS TWA20 Project 3 activity on the “Measurement of Residual Stresses by X-ray Diffraction” was initiated by NPL in 2005 to examine various aspects of the XRD test procedure in support of work aimed at developing an international standard in this area. The purpose of this project was to examine and reduce some of the sources of scatter and uncertainty in the measurement of residual stress by X-ray diffraction on metallic materials, through an international intercomparison and validation exercise. One of the major issues the intercomparison highlighted was the problem associated with measuring residual stresses in austenitic stainless steel. The following paper describes this intercomparison, reviews the results of the exercise and details additional work looking at developing best practice for measuring residual stresses in austenitic stainless steel, for which X-ray measurements are somewhat unreliable and problematic.

Wheel Rim Axial Residual Stress and a Proposed Mechanism for Vertical Split Rim Formation

2011 ◽  
Author(s):  
Cameron Lonsdale ◽  
John Oliver
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Axial Stress ◽  
X Ray Diffraction ◽  
X Ray ◽  
Axial Residual Stress ◽  
Railroad Wheels ◽  
Hoop Stresses ◽  
Future Work

Railroad wheels are manufactured with beneficial residual compressive hoop stresses, which are imparted by rim quenching and tempering. Hoop and radial residual stresses for wheels have been studied in detail by various organizations over the years and are relatively well characterized. However axial residual stresses, in the orientation across the rim width from back rim face to front rim face, have not been extensively investigated. This paper describes a failure mode known as a vertical split rim (VSR) and describes efforts to measure the axial residual stresses in, 1) new wheels, 2) service worn wheels and 3) wheels that have failed from VSRs. Initial axial residual stress measurement efforts, using core drilling and x-ray diffraction from the tread surface, are briefly reviewed. Further more extensive work using x-ray diffraction to measure axial residual stress on radial wheel slices is described and data are presented, focusing on differences between the three wheel types. The concept of Axial Stress Amplification (ASA) is outlined, and the relationship of axial residual stress to VSRs is discussed. A proposed mechanism for VSR formation is described. Future work, with a goal of reducing or eliminating VSRs in service, is considered.

Non-Destructive Residual Stress Analysis of Induction Hardened Components by Neutron and X-Ray Diffraction

2013 ◽  
Vol 768-769 ◽  
pp. 420-427 ◽  
Author(s):  
Jeremy Epp ◽  
Thilo Pirling ◽  
Thomas Hirsch
Keyword(s):  
Residual Stress ◽  
Chemical Composition ◽  
Residual Stresses ◽  
Stress Analysis ◽  
Stress Gradient ◽  
X Ray Diffraction ◽  
Neutron Measurement ◽  
X Ray ◽  
Layer Removal ◽  
Residual Stress Analysis

In this paper the microstructural and residual-stress analysis of an induction hardened plate of medium carbon steel is described. The stress gradient was determined using laboratory X-ray diffraction (IWT, Bremen, Germany) and neutron strain scanning (ILL, Grenoble, France). Due to slight variations of chemical composition in the depth, matchstick like (cross section 2×2mm²) d0-reference samples were prepared from a similarly treated sample. The d0shift induced by variation of chemical composition was measured by neutron and by X-ray diffraction along the strain free direction (sin²ψ*) and used for the evaluation of the neutron stress calculation. The d0distribution obtained from the neutron measurement did not appear reliable while the method using X-ray diffraction seems to be an efficient and reliable method to determine d0profiles in small samples. The evaluation of neutron measurements was then done using the X-ray diffraction d0distribution. High compressive residual stresses were measured in the hardened layer followed by high tensile residual stresses in the core. A comparison of the neutron measurements with X-ray diffraction (XRD) depth profiles obtained after successive layer removal showed that both methods give similar results. However, these investigations opened the question about the direct comparison of the residual stresses obtained by neutron and XRD. Indeed, a correction of the neutron data regarding the residual stresses in thickness direction might be necessary as these are released in the case of X-ray diffraction measurements after layer removal.

Determination of Surface Residual Stresses in Machined Ceramics Using Indentation Fracture

1996 ◽  
Vol 118 (4) ◽  
pp. 483-489 ◽  
Author(s):  
Y. Ahn ◽  
S. Chandrasekar ◽  
T. N. Farris
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Soda Lime Glass ◽  
X Ray Diffraction ◽  
Reliable Technique ◽  
X Ray ◽  
Indentation Technique ◽  
Vickers Indenter ◽  
Surface Residual Stresses ◽  
Zn Ferrite

Machining produces surface residual stresses which significantly influence the strength and wear resistance of ceramic components. As new methods are developed for machining ceramics, a quick and reliable technique for measurement of residual stresses would be valuable in assessing the viability of these methods from a residual stress perspective. The residual stresses on ground and polished (i.e. machined) surfaces of soda-lime glass, Ni-Zn ferrite, and silicon nitride have been measured using an indentation technique with a Vickers indenter. In this technique, the surface extent of the median/radial cracks produced by the Vickers indenter in machined and in annealed ceramics are measured. These are then combined with a fracture mechanics analysis to estimate the surface residual stresses produced by machining. In order to determine the validity of the indentation technique for estimating machining residual stresses, these stresses were also measured using an X-ray diffraction and a deflection method. The residual stress values determined using the indentation technique in the machined ceramics were found to be reasonably close to those obtained from the X-ray diffraction and deflection methods. Since the indentation technique is relatively simple and easily applied, it offers a promising method for evaluating surface residual stresses in machined ceramics.

X-Ray Diffraction Measurements of Residual Stress Induced by Surface Compressing Methods

2012 ◽  
Vol 729 ◽  
pp. 199-204 ◽  
Author(s):  
Dávid Cseh ◽  
Valéria Mertinger
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Surface Region ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hardened Alloy ◽  
Compressive Stresses ◽  
Machine Parts ◽  
Stress States ◽  
Operational Behaviour

Residual stresses have a fundamental effect on the operational behaviour and lifetime of industrial products. The fatigue resistance of machine parts can be increased by introducing residual compressive stresses into the surface region. For certain machine parts especially in the vehicle industry the residual stress is strongly demanded by the quality control. For this reason, measuring the stress accurately is becoming increasingly important. The Almen test, which only gives a qualitative result, is widely used in the industry. Shot peening and rolling are methods which are suitable for creating elastic residual stresses. This paper examines the technologies used by Rába Futómű Nyrt. to increase the lifetime by means of residual stress. We performed analysis of the residual stress of samples shot peened the same way but under different heat treatment states. We compared the residual stress values of burnished and hardened shaft joints, and the residual stress states of gear made of hardened alloy, comparing the carbonized ones to ones which were shot peened under small intensity.

scholarly journals Evaluation of Weld Filler Alloying Concepts for Residual Stress Engineering by Means of Neutron and X-Ray Diffraction

2014 ◽  
Vol 996 ◽  
pp. 469-474 ◽  
Author(s):  
Arne Kromm
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Reduction ◽  
Maximum Stress ◽  
Lattice Parameter ◽  
Filler Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Stress Control ◽  
Surface Areas

Novel Low Transformation Temperature (LTT-) filler materials are specially designed for controlling residual stresses by means of adjusted martensite formation already during welding. Different alloying concepts compete for maximum stress reduction. Two newly developed LTT-alloys were evaluated concerning their potential for residual stress control. For this purpose residual stresses were determined in the surface and also in sub-surface areas of welded joints using X-ray diffraction and Neutron diffraction taking into account local variations of the unstrained lattice parameter.

Experimental Comparison of In-Depth Residual Stresses Measured with Neutron and X-Ray Diffraction with a Numerical Stress Relaxation Correction Method

2017 ◽  
Vol 905 ◽  
pp. 131-136
Author(s):  
Bruno Levieil ◽  
Florent Bridier ◽  
Cédric Doudard ◽  
Vincent Klosek ◽  
David Thévenet ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Relaxation ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Correction Method ◽  
Experimental Comparison ◽  
X Ray Diffraction ◽  
Element Analysis ◽  
Notched Specimen ◽  
X Ray

This study is an experimental comparison of in-depth X-ray diffraction residual stress measurements with neutron diffraction measurements. The goal is to evaluate the relevance of the Savaria-Bridier-Bocher [1] stress relaxation correction method. Neutron diffraction are performed on a bent notched specimen. Destructive X-ray diffraction is performed until 5.25mm below the surface by polishing the material. This polishing induces stress relaxation and X-ray diffraction results have to be corrected. For that purpose, a finite element analysis is realised and show good correlation with neutron measurements results. The application of the stress correction method improves the X-ray measurements especially after 2 mm below the surface. The differences between measured and corrected residual stresses from both diffraction techniques are analyzed and discussed.

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