Neutron Surface Residual Stress Scanning Using Optimisation of a Si Bent Perfect Crystal Monochromator for Minimising Spurious Strains

2011 ◽  
Vol 681 ◽  
pp. 399-404 ◽  
Author(s):  
Joana Rebelo-Kornmeier ◽  
Jens Gibmeier ◽  
Michael Hofmann ◽  
Robert C. Wimpory
Keyword(s):  
Residual Stress ◽  
Stress Analysis ◽  
Surface Effect ◽  
Stress Gradient ◽  
High Energy ◽  
Surface Strain ◽  
X Rays ◽  
Surface Residual Stress ◽  
Gauge Volume ◽  
Residual Strains

For non destructive stress analysis of surface treated steel samples the application of laboratory X rays or high energy synchrotron radiation in reflection mode covers the region from some micrometers up to a depth of about 150 - 200 µm. To access depth regions deeper than 200 µm the incremental layer removal technique in combination with the repeated application of X‑ray stress analysis for the newly generated surfaces can be used. However, this procedure is destructive, laborious and furthermore, it has to be checked whether corrections have to be applied due to stress relaxation. By using neutron radiation penetration depths generally up to several millimetres can be achieved non destructively [1]. However neutron measurements are critical at the surface. When scanning a sample surface, aberration peak shifts caused by so called spurious strains arise due to the fact that the gauge volume defined by the primary and secondary optics is partially outside of the sample. These aberration peak shifts can be of the same order of magnitude as the peak shifts related to residual strains [2-6]. In this exemplary study it will be demonstrated that, by optimising the bending radius of a Si (400) monochromator, the spurious surface strains can be strongly reduced when compared to the values obtained with a traditional Ge (311) mosaic monochromator, even when the gauge volume is mainly out of the surface. The objective of the experiments is to find the optimal monochromator settings for the Si (400) monochromator at the STRESS-SPEC instrument at the research reactor FRM II, Munich, Germany. For the parametric studies a stress free steel sample of the fine grained construction steel, S690QL was used. The optimised conditions for the Si (400) monochromator that resulted from the systematic studies were applied to a shot peened plate of steel SAE 4140. The residual stress distribution is analysed by means of through surface strain scanning. The residual stress gradient obtained is in very good agreement with the well characterised residual stress depth profile obtained within a round robin test in the scope of the BRITE-EURAM-project ENSPED (European Network of Surface and Prestress Engineering and Design) [7]. The results indicated that surface residual stress profiles can be measured with neutrons up to 200 µm underneath the surface without time consuming and laborious surface effect corrections.

Influence of Shot-Peening Parameters on the Sub-Surface Residual Stress Profiles in Al-7075 Alloy Components

2013 ◽  
Vol 768-769 ◽  
pp. 66-71 ◽  
Author(s):  
Diego Cecchin ◽  
Cristy Leonor Azanza Ricardo ◽  
Mirco D'Incau ◽  
Michele Bandini ◽  
Paolo Scardi
Keyword(s):  
Residual Stress ◽  
Stress Analysis ◽  
Shot Peening ◽  
Stress Gradient ◽  
Stress Profile ◽  
Surface Residual Stress ◽  
X Ray ◽  
Al 7075 ◽  
Stress Profiles ◽  
Residual Stress Analysis

Aluminum alloy (Al-7075-T6) samples were analyzed to determine the in-depth residual stress profile induced by a shot-peening treatment. The influence of coverage degree and Almen intensity on the surface residual stress and on the sub-surface residual stress gradient was investigated. Residual stress profiles were obtained using three different techniques: (i) standard laboratory X-ray diffraction (XRD) residual stress analysis with progressive chemical layer-removal; (ii) XRD residual stress analysis with synchrotron radiation using different X-ray energies, thus changing the penetration depths, and (iii) Blind Hole Drilling (BHD). A comprehensive comparison of the results given by the used techniques is shown.

scholarly journals Depth-Resolved Residual Stress Analysis with High-Energy Synchrotron X-Rays Using a Conical Slit Cell

2013 ◽  
Vol 768-769 ◽  
pp. 72-75 ◽  
Author(s):  
Peter Staron ◽  
Torben Fischer ◽  
Jozef Keckes ◽  
Sonja Schratter ◽  
Thomas Hatzenbichler ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Analysis ◽  
Cross Sections ◽  
Materials Science ◽  
Steel Wire ◽  
High Energy ◽  
X Rays ◽  
Energy Materials ◽  
Residual Stress Analysis ◽  
Good Agreement

A conical slit cell for depth-resolved diffraction of high-energy X-rays was used for residual stress analysis at the high-energy materials science synchrotron beamline HEMS at PETRA III. With a conical slit width of 20 µm and beam cross-sections of 50 µm, a spatial resolution in beam direction of 0.8 mm was achieved. The setup was used for residual stress analysis in a drawn steel wire with 8.3 mm diameter. The residual stress results were in very good agreement with results of a FE simulation.

Determination of Real Space Residual Stress Distributions σij(z) of Surface Treated Materials with Diffraction Methods Part II: Energy Dispersive Approach

2006 ◽  
Vol 524-525 ◽  
pp. 37-44 ◽  
Author(s):  
Ingwer A. Denks ◽  
Manuela Klaus ◽  
Christoph Genzel
Keyword(s):  
Residual Stress ◽  
Stress Gradient ◽  
Depth Resolution ◽  
Real Space ◽  
Stress Distributions ◽  
Surface Residual Stress ◽  
Multilayer Systems ◽  
Near Surface ◽  
Gauge Volume

The detection of near surface residual stress gradients in real space requires high depth resolution for any orientation of the diffraction vector with respect to the sample co-ordinate system. In order to meet this demand, the slits are no longer being fixed in the laboratory co-ordinate system as in strain scanning experiments but directly coupled with the sample. Hence, the gauge volume orientation within the sample remains constant and allows performing depth-resolved sin2ψ measurements in real space. The method’s accuracy is determined by the gauge volume definition, which is investigated in detail. Apart from the evaluation of the σ(τ) versus σ(z) relation, which is of fundamental interest in X-ray residual stress gradient analysis, the method will be shown to have a unique applicability in rather delicate sample geometries such as multilayer systems.

Sin2ψ-based residual stress gradient analysis by energy-dispersive synchrotron diffraction constrained by small gauge volumes. II. Experimental implementation

2013 ◽  
Vol 46 (3) ◽  
pp. 619-627 ◽  
Author(s):  
M. Meixner ◽  
M. Klaus ◽  
Ch. Genzel
Keyword(s):  
Residual Stress ◽  
Stress Gradient ◽  
Energy Dispersive ◽  
Narrow Slit ◽  
Surface Residual Stress ◽  
Near Surface ◽  
Experimental Implementation ◽  
Gauge Volume ◽  
Small Gauge ◽  
Residual Stress Gradient

On the basis of the theoretical concept for the use of small gauge volumes to study near-surface residual stress fields with high spatial resolution [Meixner, Klaus & Genzel (2013).J. Appl. Cryst.46, 610–618], the experimental implementation of the approach is demonstrated. It is shown that specifically designed slit systems are required to avoid effects such as diffuse scattering at the slit blades and total external reflection, both giving rise to a reduced resolution. Starting from the characterization of the small gauge volume, practical guidance on how to control the alignment of the sample relative to the gauge volume for different geometrical conditions of energy-dispersive diffraction is given. The narrow-slit configuration as well as the formalism for data evaluation introduced in the first part of this series is applied to the analysis of a very steep in-plane residual stress gradient in a shot-peened Al2O3ceramic sample. The results are compared with those obtained by means of a conventional wide-slit setup using the classical universal plot method for residual stress analysis on the one hand, and with the simulations performed in the first part on the other hand.

Local Residual Stress Depth Distribution in the Inner Gearing of a Case Hardened Sliding Collar

2016 ◽  
Vol 879 ◽  
pp. 601-606 ◽  
Author(s):  
Jens Gibmeier ◽  
Joana Rebelo-Kornmeier ◽  
Tobias Strauss
Keyword(s):  
Residual Stress ◽  
Stress Analysis ◽  
Complex Geometry ◽  
Surface Effect ◽  
Local Variation ◽  
Surface Strain ◽  
Hole Drilling ◽  
Case Hardening ◽  
Tooth Root ◽  
Residual Stress Analysis

With respect to residual stress analysis the inner gearing of an automotive sliding collar is a component with a challenging, complex geometry. The accessibility of the tooth root does not exist for conventional measuring approaches. However, the process steps like e.g. broaching and case hardening induce characteristic residual stress distributions, which must be known for the valuation of the mechanical integrity of the parts. For lab X-ray stress analysis approaches according to the sin2ψ-method [1] the ring like structure must be sectioned, which affects the process induced residual stress state. The tooth root is rather small, which further leads to shadowing effects during tilting of the sample. Standard mechanical approaches like incremental hole drilling can be excluded due to the narrow tooth root. Local neutron diffraction residual stress analysis in the tooth root by means of neutron through surface strain scanning at the STRESS-SPEC instrument at the research reactor FRM II, Garching (Germany) was successfully carried out for the inner gearing. A measuring and evaluation strategy is proposed, where special attention is paid to the compensation of the surface effect due to the incomplete immersion of the nominal gauge volume during through surface scanning and to the local variation of the D0-value as a consequence of the case hardening process.

Analytical model for neutron diffraction peak shifts due to the surface effect

2013 ◽  
Vol 46 (3) ◽  
pp. 628-638 ◽  
Author(s):  
Jan Šaroun ◽  
Joana Rebelo Kornmeier ◽  
Michael Hofmann ◽  
Pavol Mikula ◽  
Miroslav Vrána
Keyword(s):  
Neutron Diffraction ◽  
Analytical Model ◽  
Surface Effect ◽  
Perfect Crystal ◽  
Optimum Configuration ◽  
Gauge Volume ◽  
Spurious Peak ◽  
Incomplete Filling ◽  
Broad Variety ◽  
Residual Strains

Residual strains measured by neutron diffraction near sample boundaries can be biased by the surface effect as a result of incomplete filling of the instrumental gauge volume. This effect is manifested as anomalous shifts of diffraction lines, which can be falsely interpreted as a lattice strain unless appropriate data corrections are made. A new analytical model for the surface effect has been developed, which covers a broad variety of instrumental arrangements, including flat mosaic and bent perfect crystal monochromators, narrow slits, and Soller and radial collimators. This model permits the spurious peak shifts to be predicted quantitatively, and also allows the optimum configuration parameters, such as curvature of a focusing monochromator, which lead to suppression of the surface effect, to be calculated. The model has been thoroughly validated by comparisons with Monte Carlo simulations and experiments on a stress-free calibration sample. Predictions of the model proved to be very accurate, often within the interval of experimental errors, which makes it suitable for use in data analysis.

scholarly journals Residual Stress Evolution during Decomposition of Ti(1-x)Al(x)N Coatings Using High-Energy X-Rays

2006 ◽  
Vol 524-525 ◽  
pp. 619-624 ◽  
Author(s):  
Mark R. Terner ◽  
Peter Hedström ◽  
Jonathan Almer ◽  
J. Ilavsky ◽  
Magnus Odén
Keyword(s):  
Residual Stress ◽  
Phase Separation ◽  
Elevated Temperatures ◽  
High Energy ◽  
Film Plane ◽  
X Rays ◽  
X Ray Diffraction ◽  
Synchrotron Source ◽  
Simultaneous Acquisition ◽  
Initial Stage

Residual stresses and microstructural changes during phase separation in Ti33Al67N coatings were examined using microfocused high energy x-rays from a synchrotron source. The transmission geometry allowed simultaneous acquisition of x-ray diffraction data over 360° and revealed that the decomposition at elevated temperatures occurred anisotropically, initiating preferentially along the film plane. The as-deposited compressive residual stress in the film plane first relaxed with annealing, before dramatically increasing concurrently with the initial stage of phase separation where metastable, nm-scale c-AlN platelets precipitated along the film direction. These findings were further supported from SAXS analyses.

Sign in / Sign up

Export Citation Format

Share Document