S48 X-ray Diffraction at Constant Penetration Depth — A Viable Approach for Characterizing Steep Residual Stress Gradients

2008 ◽  
Vol 23 (2) ◽  
pp. 187-187 ◽  
Author(s):  
T. Erbacher ◽  
A. Wanner ◽  
O. Vöhringer ◽  
T. Beck
Keyword(s):  
Residual Stress ◽  
Penetration Depth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Stress Gradients ◽  
Viable Approach

Revision and extension of the standard laboratory technique for X-ray diffraction measurement of residual stress gradients

2007 ◽  
Vol 40 (4) ◽  
pp. 675-683 ◽  
Author(s):  
Cristy L. Azanza Ricardo ◽  
Mirco D'Incau ◽  
Paolo Scardi
Keyword(s):  
Residual Stress ◽  
Hole Drilling ◽  
Al Alloy ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Surface Residual Stress ◽  
X Ray ◽  
Stress Gradients ◽  
Layer Removal ◽  
Removal Technique

A new procedure is proposed to determine sub-surface residual stress gradients by laboratory X-ray diffraction measurements at different depths using a chemical layer-removal technique. The standard correction algorithm for stress relaxation due to layer removal is improved by including corrections for X-ray absorption, and by the addition of constraints imposed by the mechanical equilibrium conditions. Besides correcting the data,i.e.providing more reliable through-thickness residual stress trends, the proposed procedure also provides an elastically compatible and plausible estimate of the residual stress inside the component, well beyond the measured region. The application of the model is illustrated for a set of Al-alloy components shot-peened at different Almen intensities. Results are compared with those given by `blind hole drilling', which is an independent and partly destructive method.

X-ray diffraction at constant penetration depth – a viable approach for characterizing steep residual stress gradients

2008 ◽  
Vol 41 (2) ◽  
pp. 377-385 ◽  
Author(s):  
Thomas Erbacher ◽  
Alexander Wanner ◽  
Tilmann Beck ◽  
Otmar Vöhringer
Keyword(s):  
Residual Stress ◽  
Penetration Depth ◽  
Ground Surface ◽  
Shear Stresses ◽  
X Rays ◽  
X Ray Diffraction ◽  
Machined Surface ◽  
Near Surface ◽  
X Ray ◽  
Surface Residual Stresses

The experimental analysis of near-surface residual stresses by X-ray diffraction methods is based on measuring the spacings of lattice planes while the inclination ψ with respect to the surface plane is changed stepwise. A characteristic feature of conventional techniques is that the penetration depth of the X-rays is altered as inclination is varied. By simultaneously varying three different goniometer angles in a particular fashion, both the penetration depth and the measuring direction can be held constant while ψ is varied. Thus the normal and shear stresses can be derived from the sin2ψ plots by means of standard evaluation procedures developed for gradient-free stress states. The depth profile of residual stress is then obtainedviaLaplace transformation of the results from several stress measurements carried out at different penetration depths. In the present paper, the feasibility of this experimental approach for characterizing the strongly graded, non-equiaxed stress state existing at a machined surface is demonstrated. The results from constant-penetration-depth measurements on the ground surface of an engineering ceramic are compared with those from conventional sin2ψ measurements.

Control of Residual Stresses in As-Grown Polysilicon by Multi-Layer Deposition: The “Multipoly” Process

1999 ◽  
Vol 605 ◽  
Author(s):  
Hie Yang ◽  
H. Kahn ◽  
A.Q. He ◽  
S.M. Phillips ◽  
A.H. Heuer
Keyword(s):  
Residual Stress ◽  
X Ray Diffraction ◽  
Columnar Microstructure ◽  
X Ray ◽  
Stress Gradients ◽  
Compressive Stresses ◽  
Transmission Electron ◽  
Layer Deposition ◽  
Polysilicon Films ◽  
The Individual

AbstractLPCVD polysilicon thin films deposited between ∼550 and ∼600 °C have an equiaxed microstructure (resulting from crystallization of an initially amorphous deposit) and contain ∼200 MPa residual tensile stresses after deposition, whereas polysilicon films deposited above ∼600 °C have a columnar microstructure and contain ∼300 MPa residual compressive stresses after deposition. Both types of films also contain stress gradients.We have grown films containing multiple layers of polysilicon ("MultiPoly") by cycling the growth temperature between 570 and 615 °C. The multilayer films thus formed are comprised of alternating tensile and compressive layers, and by control of the thickness of the individual layers, the overall stress of the polysilicon can display any value between that of the tensile layer and that of the compressive layer. We have focussed on producing films with zero overall residual stress, as measured by wafer curvature, and have characterized the microstructures by transmission electron microscopy (TEM) and X-ray diffraction (XRD).Because of the stress gradients present in both layers, devices made from films with zero overall residual stress may show distortions after release. We have measured the stress gradients in each type of layer and can design films with zero overall stress and zero overall stress gradients. It is also possible to design films with any level of overall (tensile or compressive) stress but with controlled displacements upon release.

scholarly journals Evaluation of extremely steep residual stress gradients based on a combined approach using laboratory-scale equipment

2021 ◽  
Vol 54 (6) ◽  
Author(s):  
Andreas Fischer ◽  
Sebastian Degener ◽  
Alexander Liehr ◽  
Thomas Niendorf
Keyword(s):  
Residual Stress ◽  
Material Removal ◽  
Rapid Heating ◽  
Sufficient Accuracy ◽  
Combined Approach ◽  
X Ray Diffraction ◽  
X Ray ◽  
Stress Gradients ◽  
Stress Equilibrium ◽  
Heating And Cooling

Surface treatments characterized by rapid heating and cooling (e.g. laser hardening) can induce very steep residual stress gradients in the direct vicinity of the area being treated. These gradients cannot be characterized with sufficient accuracy by means of the classical sin2Ψ approach applying angle-dispersive X-ray diffraction. This can be mainly attributed to limitations of the material removal method. In order to resolve residual stress gradients in these regions without affecting the residual stress equilibrium, another angle-dispersive approach, i.e. the universal plot method, can be used. A novel combination of the two approaches (sin2Ψ and universal plot) is introduced in the present work. Prevailing limits with respect to profiles as a function of depth can be overcome and, thus, high-resolution surface layer characterization is enabled. The data obtained are discussed comprehensively in comparison with results elaborated by energy-dispersive X-ray diffraction measurements.

scholarly journals X‐ray diffraction analysis of concentration and residual stress gradients in nitrogen‐implanted niobium and molybdenum

1991 ◽  
Vol 69 (12) ◽  
pp. 8111-8118 ◽  
Author(s):  
Satish I. Rao ◽  
Baoping He ◽  
C. R. Houska ◽  
K. Grabowski
Keyword(s):  
Residual Stress ◽  
Diffraction Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Stress Gradients

scholarly journals Statistical analysis of the reproducibility of residual stress measurements in cold extruded parts

2021 ◽  
Author(s):  
Fabian Jaeger ◽  
Alessandro Franceschi ◽  
Holger Hoche ◽  
Peter Groche ◽  
Matthias Oechsner
Keyword(s):  
Residual Stress ◽  
Statistical Analysis ◽  
Stress Measurement ◽  
Industrial Applications ◽  
Cold Extrusion ◽  
X Ray Diffraction ◽  
Forming Process ◽  
X Ray ◽  
Stress States ◽  
Key Aspects

AbstractCold extruded components are characterized by residual stresses, which originate from the experienced manufacturing process. For industrial applications, reproducibility and homogeneity of the final components are key aspects for an optimized quality control. Although striving to obtain identical deformation and surface conditions, fluctuation in the manufacturing parameters and contact shear conditions during the forming process may lead to variations of the spatial residual stress distribution in the final product. This could lead to a dependency of the residual stress measurement results on the relative axial and circumferential position on the sample. An attempt to examine this problem is made by the employment of design of experiments (DoE) methods. A statistical analysis of the residual stress results generated through X-Ray diffraction is performed. Additionally, the ability of cold extrusion processes to generate uniform stress states is analyzed on specimens of austenitic stainless steel 1.4404 and possible correlations with the pre-deformed condition are statistically examined. Moreover, the influence of the coating, consisting of oxalate and a MoS2 based lubricant, on the X-Ray diffraction measurements of the surface is investigated.

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