The Effectiveness of Cold Rolling for Residual Stress Reduction in Quenched 7050 Aluminium Alloy Forgings

2016 ◽  
Vol 716 ◽  
pp. 521-527 ◽  
Author(s):  
Ran Pan ◽  
Catrin Mair Davies ◽  
Wei Zhang ◽  
Zhusheng Shi ◽  
Thilo Pirling ◽  
...  
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Cold Rolling ◽  
Stress Reduction ◽  
Stress Distributions ◽  
Effective Technique ◽  
The Core ◽  
Cold Rolled ◽  
Neutron Diffraction Technique

Residual stresses are often introduced into aluminum alloys through quenching processes performed to generate the required microstructure. Such residual stresses are known to be deleterious to the integrity of the component. Methods to mitigate residual stresses in quenched components are therefore of great importance. Cold rolling has been proposed as an effective technique to remove residual stresses in large components. In this work, the effectiveness of cold rolling in reducing the residual stresses in quenched blocks AA7050 has been quantified using the neutron diffraction technique. Neutron diffraction measurements have been performed on two blocks one quenched and the other quenched & cold rolled block. Comparing the residual stress distributions pre and post rolling it has been found that cold rolling almost eliminates the tensile residual stresses in the core of the block, however it generates large tensile residual stresses d in a shallow region near the surface of the block.

Interpretation of residual stress distributions in previously loaded cracked beams

1992 ◽  
Vol 27 (2) ◽  
pp. 77-83 ◽  
Author(s):  
D J Smith ◽  
M A M Bourke ◽  
A P Hodgson ◽  
G A Webster ◽  
P J Webster
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Crack Tip ◽  
Stress Distributions ◽  
Element Analysis ◽  
Sampling Volume ◽  
Neutron Diffraction Technique ◽  
Good Agreement

The measurement and prediction of residual stress distributions in a fatigue pre-cracked and a plastically overloaded A533B steel beam are described. The residual stresses were obtained experimentally using the neutron diffraction technique. Finite element analysis was employed to predict the elastic-plastic response and residual stresses introduced after overloading. Comparison of the experimental results have been made with the finite element predictions (for both plane stress and strain conditions) averaged over the same sampling volume used to make the neutron diffraction measurements. It has been found that good agreement is achieved away from the near crack tip region. However, close to the crack tip the measured compressive residual stresses are significantly smaller than predicted. This difference is attributed to the A533B steel exhibiting a Bauschinger effect and yielding at a lower stress after a stress reversal.

Comparison of Neutron Diffraction Residual Stress Measurements of Steel Welded Repairs With Current Fitness-for-Purpose Assessments

2008 ◽  
Author(s):  
Anna M. Paradowska ◽  
John W. H. Price ◽  
Trevor R. Finlayson ◽  
Ronald B. Rogge ◽  
Ronald L. Donaberger ◽  
...  
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Thick Plate ◽  
Stress Distributions ◽  
Fitness For Purpose ◽  
Stress Variation ◽  
Full Penetration ◽  
Heat Treated ◽  
Strain Stress ◽  
Neutron Diffraction Technique

In this research the neutron diffraction technique was used to investigate the residual stress distributions in carbon steel components with weld repairs. Two full penetration weld repairs were studied using a) the stringer bead and b) the temper bead weld techniques in 25 mm thick plate. The welds were not post weld heat treated. The focus of the measurements is on the values of the sub-surface and through-thickness strain/stress variation near the middle of the weld and the toe. The experimental results showed that both processes had high residual stresses particularly through the thickness. The measurements were compared with current fitness-for-purpose approaches, such as BS7910 and R6 showing that these approaches underestimated and overestimated the stresses in various regions.

scholarly journals SPR Characteristics Curve and Distribution of Residual Stress in Self-Piercing Riveted Joints of Steel Sheets

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
Rezwanul Haque ◽  
Yat C. Wong ◽  
Anna Paradowska ◽  
Stuart Blacket ◽  
Yvonne Durandet
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Steel Sheet ◽  
Sheet Material ◽  
Stress Distributions ◽  
Steel Sheets ◽  
Riveted Joints ◽  
Lower Magnitude ◽  
Thick Joint ◽  
Neutron Diffraction Technique

Neutron diffraction was used to describe the residual stress distributions in self-piercing riveted (SPR) joints. The sheet material displayed a compressive residual stress near the joint, and the stress gradually became tensile in the sheet material far away from the joint. The stress in the rivet leg was lower in the thick joint of the softer steel sheet than in the thin joint of the harder steel sheet. This lower magnitude was attributed to the lower force gradient during the rivet flaring stage of the SPR process curve. This study shows how the residual stress results may be related to the physical occurrences that happened during joining, using the characteristics curve. The study also shows that neutron diffraction technique enabled a crack in the rivet tip to be detected which was not apparent from a cross-section.

Measurement of residual stresses in T-plate weldments

2003 ◽  
Vol 38 (4) ◽  
pp. 349-365 ◽  
Author(s):  
R. C Wimpory ◽  
P. S May ◽  
N. P O'Dowd ◽  
G. A Webster ◽  
D J Smith ◽  
...  
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Plastic Zone ◽  
Residual Stresses ◽  
Plate Thickness ◽  
Welding Process ◽  
Plastic Zone Size ◽  
Hole Drilling ◽  
Stress Distributions ◽  
Premature Failure

Tensile welding residual stresses can, in combination with operating stresses, lead to premature failure of components by fatigue and/or fracture. It is therefore important that welding residual stresses are accounted for in design and assessment of engineering components and structures. In this work residual stress distributions, obtained from measurements on a number of ferritic steel T-plate weldments using the neutron diffraction technique and the deep-hole drilling method, are presented. It has been found that the residual stress distributions for three different plate sizes are of similar shape when distances are normalized by plate thickness. It has also been found that the conservatisms in residual stress profiles recommended in current fracture mechanics-based safety assessment procedures can be significant—of yield strength magnitude in certain cases. Based on the data presented here a new, less-conservative transverse residual stress upper bound distribution is proposed for the T-plate weldment geometry. The extent of the plastic zone developed during the welding process has also been estimated by use of Vickers hardness and neutron diffraction measurements. It has been found that the measured plastic zone sizes are considerably smaller than those predicted by existing methods. The implications of the use of the plastic zone size as an indicator of the residual stress distributions are discussed.

scholarly journals Influence of carbonitriding conditions on phase composition and residual stresses for 20MnCr5 low alloy steel

2021 ◽  
Vol 47 (2) ◽  
pp. 790-799
Author(s):  
Richard J Katemi ◽  
Jeremy Epp
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Alloy Steel ◽  
Retained Austenite ◽  
Case Depth ◽  
Martensite Phase ◽  
Stress Distributions ◽  
Low Alloy Steel ◽  
The Core ◽  
Core Hardness

This paper reports an investigation of the influence of carbonitriding conditions for 20MnCr5 low alloy steel. Three gaseous carbonitriding conditions were investigated based on different carbon and nitrogen potentials to attain varying levels of carbon between 0.62 and 0.93% mass, whereas for nitrogen between 0.19 and 0.26% mass at the surface. Analysis of retained austenite and residual stress distributions was conducted using X-ray diffraction technique. The effective case depth varied between 900 and 1200 µm. The case microstructures were characterized by varying proportions of retained austenite and martensite, while the core contained essentially bainitic microstructures. The maximum amount of retained austenite which occurred at a depth of 50 µm from the subsurface ranged between 30 and 70% mass and significantly influenced the level of surface micro-hardness whereas the core hardness remaining relatively constant at 450 HV1. High values of residual stresses in martensite phase were observed. The signs, magnitudes, distributions and location of maximum compressive residual stresses were highly influenced by the maximum fraction of retained austenite. Retained austenite of 30%, 50% and 70% mass at the surface lead to peak compressive residue stresses of -280, -227, and -202 MPa at depths of 555, 704, and 890 μm, respectively. Keywords: Carbonitriding, retained austenite, martensite, residual stress, XRD.

Neutron Diffraction Evaluation of Residual Stress for Several Welding Arrangements and Comparison With Fitness-for-Purpose Assessments

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Anna M. Pardowska ◽  
John W. H. Price ◽  
Raafat Ibrahim ◽  
Trevor R. Finlayson
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Assessment Procedure ◽  
Stress Distributions ◽  
Fitness For Purpose ◽  
Single Bead ◽  
Surface Measurements ◽  
Number Of Passes ◽  
Neutron Diffraction Technique ◽  
Level 2

In this research, the neutron diffraction technique was used to investigate and compare the residual stress characteristics in several weld arrangements. This research has focused on the effects on residual stress of restraint condition applied during welding, the start and end of the weld for a single bead, and increasing the number of passes. The measured residual stress distributions are normalized by the yield strength of the material and compared with distribution provided in fitness-for-purpose procedures. It is found that the current safety assessment procedure BS 7910 and R6 Level 1 significantly conservative for longitudinal stresses outside the weld and heat affected zone, and for transverse residual stress across the weldment for surface measurements. For a less conservative assessment, R6 Level 2 is recommended, however, even if this assessment is often conservative, in particular, for transverse residual stresses.

Neutron Diffraction Studies of Residual Stresses Around Gouges and Gouged Dents

2012 ◽  
Author(s):  
Lynann Clapham ◽  
Vijay Babbar ◽  
Thomas Gnaeupel-Herold ◽  
Remi Batisse ◽  
Mures Zarea
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Neutron Diffraction ◽  
Stress Field ◽  
Residual Stresses ◽  
Wall Stress ◽  
Outer Wall ◽  
Stress Distributions ◽  
Wall Surface ◽  
Residual Stress Field

The residual stress pattern surrounding gouges is complex and, to date, has not been accurately modeled using stress modeling software. Thus measurement of these stress distributions is necessary. Neutron diffraction is the only experimental method with the capability of directly evaluating residual strain throughout the entire thickness of a pipe wall, in and around dent or gouged regions. Neutron diffraction measurements were conducted at the NIST reactor on three gouged dents in X52 pipeline sections. These were part of a larger sample set examined as part of the comprehensive MD4-1 PRCI/DOT PHMSA project. Gouges contained in pipeline sections were termed BEA161 (primarily a gouge with little denting), and BEA178 (mild gouging, very large dent). Measurements were also conducted on a coupon sample – P22, that was created as part of an earlier study. For the moderate gouges with little or no associated denting (BEA161 and P22) the residual stress field was highly localized around the immediate gouge vicinity (except where there was some denting present). The through wall stress distributions were similar at most locations — characterized by neutral or moderate hoop and axial stresses (50–100MPa) at the outer wall surface (i.e. at the gouge itself) gradually becoming highly compressive (up to −600MPa) at the inner wall surface. The other sample (BEA178) exhibited a very mild gouge with significant denting, and the results were very different. The denting process associated with this kind of gouge+dent dominated the residual stresses, making the residual stress distribution very complex. In addition, rather than having a residual stress field that is localized in the immediate gouge vicinity, the varying stress distribution extends to the edge of the dented region..

scholarly journals Advances in Neutron Diffraction for Engineering Residual Stress Measurements

1999 ◽  
Vol 33 (1-4) ◽  
pp. 151-171 ◽  
Author(s):  
A. N. Ezeilo ◽  
G. A. Webster
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Measuring Method ◽  
Manufacturing Processes ◽  
Stress Measurements ◽  
Code Of Practice ◽  
Numerical Predictions ◽  
Engineering Materials ◽  
Neutron Diffraction Technique

The increasing awareness amongst engineers and designers, of the significance of residual stresses in influencing the useful lifetimes of engineering components, has resulted in more demanding expectations being placed on the methods used to obtain these stresses. The neutron diffraction technique is emerging as the most attractive measuring method as the residual stresses can usually be obtained non-destructively to depths of up to 40 mm in some common engineering materials. Although it is a relatively new technique it has been used to measure the residual stresses in a range of engineering materials introduced by a wide variety of manufacturing processes such as welding, quenching, machining, shot peening, cold hole expansion and autofrettage.In this paper the neutron diffraction technique for non-destructive residual stress measurements will be described including methods used to validate the measurements. Precautions that should be taken in order to obtain reliable measurements are outlined. Procedures being investigated in order to produce a code of practice will be presented. A representative selection of stress distributions developed by a range of manufacturing processes is examined. Some comparisons are made with strain gauge, X-ray and numerical predictions. It is shown how the results can be of benefit in engineering stress analysis.

Comparison of Neutron Diffraction Measurements of Residual Stress of Steel Butt Welds With Current Fitness-for-Purpose Assessments

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
Anna M. Paradowska ◽  
John W. H. Price ◽  
Trevor R. Finlayson ◽  
Ronald B. Rogge ◽  
Ronald L. Donaberger ◽  
...  
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Stress Distributions ◽  
Fitness For Purpose ◽  
Full Penetration ◽  
Heat Treated ◽  
Strain Stress ◽  
Steel Welds ◽  
Neutron Diffraction Technique ◽  
Weld Heat

In this research, the neutron diffraction technique was used to investigate the residual stress distributions in constrained carbon steel welds. Two full penetration welds were studied using (a) the stringer bead and (b) the temper bead weld techniques in 25 mm thick plate. The welds were not post-weld heat treated. The focus of the measurements is on the values of the subsurface and through-thickness strain/stress variation near the middle of the weld and the toe. The experimental results showed that both processes had high residual stresses particularly through the thickness. The measurements were compared with current fitness-for-purpose approaches, such as BS7910 and R6. It was found that the residual stress distribution in the temper bead welded specimen was not as favorable as suspected and post-weld heat treatment should be recommended to reduce residual tensile stresses in this type of steel welds.

Neutron diffraction analysis of the residual stress distribution in a bent bar

2000 ◽  
Vol 35 (4) ◽  
pp. 235-246 ◽  
Author(s):  
A. N Ezeilo ◽  
G. A Webster
Keyword(s):  
Residual Stress ◽  
Stress Distribution ◽  
Neutron Diffraction ◽  
Residual Stresses ◽  
Residual Stress Distribution ◽  
Four Point Bending ◽  
Refinement Method ◽  
Nickel Based Alloy ◽  
Neutron Diffraction Technique ◽  
Profile Refinement

A well-characterized residual stress distribution resulting from four-point bending has been analysed using the neutron diffraction technique. Residual stresses were obtained from the strains measured at discrete positions through the bent bar on the (111) and (311) crystal planes of a nickel-based alloy using the appropriate diffraction elastic constants. In addition a profile refinement method was used to determine the residual stresses from average strains from all the diffraction peaks in the spectrum. The measured residual stress profiles have also been compared with strain gauge data and with analytical and finite element predictions. It has been established that the profile refinement approach gives stresses which most closely match those obtained by the non-diffraction techniques.

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