Measurement of Residual Stresses in the Cold-Rolled Fe-Ni-Mn/Invar Thermo-Bimetallic Plate

2013 ◽  
Vol 768-769 ◽  
pp. 101-106
Author(s):  
Harri Lille ◽  
Jakub Kõo ◽  
Jaak Valgur ◽  
Alexander Ryabchikov ◽  
Renno Reitsnik ◽  
...  

The paper presents a method for measuring residual stresses in normal thermo-bimetal Fe-Ni-Mn/Invar strips with a thickness of 0.76 mm. For this purpose, a setup was designed which permits to remove layers from a strip substrate by electrochemical etching. Residual stresses in the directions that are longitudinal and transversal to rolling are determined by the curvature method based on the layer growing/removing techniques. As a reference, residual stresses were also determined by hole-drilling technique. Tensile and compressive residual stresses arose both in active and in passive layers and were considerably higher when determined by the hole-drilling technique.

2019 ◽  
Vol 54 (7-8) ◽  
pp. 424-430
Author(s):  
Jesus Manuel Alegre ◽  
Andrés Díaz ◽  
Isidoro Ivan Cuesta ◽  
Juan Manuel Manso

The experimental measurement of residual stresses by the hole-drilling method is a versatile technique due to its great simplicity. The technique consists of drilling on a material surface and measuring the relieved deformation on the surface by means of strain gauge rosettes. The most widespread method to obtain residual stresses from relieved deformation is the integral method and is found in the ASTM E837-13a standard. The procedure is standardised for very specific conditions, which are based on the application of the technique on a large flat-plate. To apply this technique to situations outside the standard scope, it is necessary to perform studies that validate its applicability. One of these situations is to evaluate the stresses introduced in hot- or cold-rolled profiles, where the residual stresses are concentrated on the rounded corners generated by rolling operations. In this study, a numerical simulation by finite elements has been carried out to obtain the relieved deformations for the case of drilling near rounded ends. The results show that the hole-drilling technique is applicable for the case of rounded ends; however, there is a significant deviation from the flat-plate condition which can be minimised by considering new matrices for the specific rounding radius and thickness of the analysed workpiece.


Author(s):  
X. Ficquet ◽  
C. E. Truman ◽  
D. J. Smith ◽  
T. B. Brown ◽  
T. A. Dauda

“ELIXIR – Extending Plant Life Through Improved Fabrication and Advanced Repair Methodology” was a European Union FP5 sponsored project. During the duration of the Elixir project, much work was directed at providing the necessary data for the validation of numerical modelling techniques applied to residual stress generation and hydrogen diffusion arising from the welding process. The project focussed around four industrial applications, namely petrochemical, boiler, offshore and submarine. This paper presents through-thickness residual stress measurements obtained by the University of Bristol on two of the large industrial components. The results were obtained using the deep hole drilling technique and compared to Finite Element predictions provided by other partners. The components considered are a large P275 steel set-in nozzle, typical of a boiler application and a large S690 steel set-on nozzle, typical of an offshore application. The boiler application consisted of a nozzle of diameter 600mm and thickness 50mm, on a pipe of diameter 1100mm and 100mm thickness. The offshore application was a nozzle of diameter 900mm and thickness 50mm, on a pipe of diameter 1050mm and 50mm thickness. Both the longitudinal and transverse stresses measured using deep hole drilling showed excellent agreement with Finite Element predictions through the thickness of the boiler sample. On the top surface, a zone of tensile residual stresses, over a distance of approximately 40mm, was revealed, which was equilibrated by a zone of compressive residual stresses over the final 50mm of thickness. Results for the offshore application demonstrated that at the front surface, both of the stress components were essentially zero, but both the longitudinal and transverse components rose rapidly to maxima of approximately 500MPa and 220MPa, respectively. Tensile residual stresses were supported over a distance of approximately 30mm. Over the final 20mm of thickness, compressive residual stresses existed, which again fell to approximately zero on the back face. There is excellent agreement between measurements and the Finite Element predictions for the transverse stress component, but less good agreement between measurements and predictions of the longitudinal stress component.


2013 ◽  
Vol 53 (7) ◽  
pp. 1223-1231 ◽  
Author(s):  
A. H. Mahmoudi ◽  
G. Zheng ◽  
D. J. Smith ◽  
C. E. Truman ◽  
M. J. Pavier

Author(s):  
Wim Nagy ◽  
Philippe Van Bogaert ◽  
Hans De Backer

Manufacturing processes such as welding operations cause residual stresses that are present in most civil structures. They cause plastic deformations without any external loads and are therefore often overlooked during design. Nevertheless, residual stresses can have profound influences on material strength and fatigue life. This is also true for orthotropic steel bridge decks, which have many complex welding details. Because little is known about the distribution of residual stresses due to welding, a semi-destructive experimental test setup is developed for a stiffener-to-deck plate connection on an orthotropic steel bridge deck. In particular, the hole-drilling technique is used. With this experimental test setup, a clear distribution of the residuals stresses becomes visible. Residual stresses up to the yield strength can be found near the weld and up to 50% of the yield strength elsewhere. However, more research is needed to verify why the sign of the stresses is opposite to the expected stresses in the literature.


Author(s):  
Gang Zheng ◽  
Sayeed Hossain ◽  
Feng Shen ◽  
Chris Truman

The aim of the present study was to utilize a complex residual stress generated within a welded circular disc to further investigate the standard deep-hole drilling (DHD) technique and the newly developed over-coring deep-hole drilling (oDHD) technique in accurately measuring residual stresses well over yield stress. Finite Element Analysis (FEA) was used to optimize and extend the deep-hole drilling technique and improve its accuracy. The standard DHD procedure involves 4 steps. (1) A reference hole is gun-drilled through the component. (2) The internal diameter of the reference hole is measured at different angular positions through the depth of the component. (3) A cylindrical section with the reference hole as its longitudinal axis is trepanned free from the component. (4) Finally, the relaxed internal diameter is re-measured at the same angular positions and the same depths. The drilling, trepanning procedures and the parameters of the deep-hole drilling technique were all studied in detail to optimize the technique. Comparison is made between the FEA predicted residual stress in the weld, the measurements and the reconstructed residual stresses of the measurements. The close correlations confirmed the suitability of new modifications made in the deep-hole drilling technique to account for plasticity when measuring near yield residual stresses present in a component.


2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Yeong-Seok Lim ◽  
Sang-Hyuk Kim ◽  
Kwang-Jin Lee

This study was performed to investigate both the residual stress distribution and the effect of the residual stress formed at the welding region on the mechanical properties of the friction stir welded joints with 409L stainless steel sheets. Residual stress measurement with hole-drilling method; mechanical property evaluation including tensile test, Charpy impact test, and fatigue test; and microstructure observation were conducted. It has got no residual stresses to speak of at the center region of the stir zone because the stored stresses are released in the process of the dynamic recrystallization, while a small quantity of compressive residual stresses is formed at the surface region of the stir zone because of strong compression reaction by the tool shoulder. A considerable amount of compressive residual stresses is formed at the thermomechanical affected zone because of the synergy between the thermal expansion due to the heat conduction from the stir zone and mechanical compression by the tool. The formation of residual stresses shows a similar tendency between the advancing side and the retreating side. Both the mitigation of residual stress in the stir zone and the formation of compressive residual stress in the thermomechanical affected zone contribute to the improvement of the mechanical properties of the friction stir welded joints.


Author(s):  
S. Hossain ◽  
C. E. Truman ◽  
D. J. Smith ◽  
M. R. Daymond

This paper presents results from an experimental and numerical study examining the creation of highly triaxial residual stresses in stainless steel. This was motivated by a need to model and understand creep in aged power plant. The residual stresses were introduced by rapid spray water quenching of heated solid stainless steel spheres and cylinders. Finite element (FE) simulations predicted high compressive residual stresses around the surface of the specimens and tensile residual stresses near the centre. Surface residual stresses were measured using the incremental centre-hole drilling (ICHD) technique. Neutron diffraction (ND) was used to measure the interior residual stresses. The measurements were in good agreement with FE predictions. The ND measurements confirmed that a highly triaxial residual stress state existed in the core of the specimens.


Author(s):  
Evy Van Puymbroeck ◽  
Wim Nagy ◽  
Hans De Backer

Complex welding operations in orthotropic steel bridge decks introduce residual stresses near the weld region. To estimate fatigue failure of this type of bridge deck, tensile residual yield stresses are usually assumed around the weld region. However, to estimate the residual stress distribution near a weld connection more precisely, a test setup is developed. The weld connection of a closed longitudinal trapezoidal stiffener with the deck plate of an orthotropic bridge deck is investigated. The incremental hole-drilling technique is used to measure the residual stresses with strain gauge rosettes. Strain gauge rosettes are positioned on the deck plate and on a longitudinal stiffener of the orthotropic steel deck. A small hole is drilled through the center of the strain gauge rosettes and strains are measured at incremental depths. The residual stresses are calculated and based on these experimental measurements a distribution of the residual stresses is obtained. Compressive residual stresses exist near the longitudinal stiffener-to-deck plate weld. On the deck plate, the compressive residual stresses are equal to 60% of the yield strength while the compressive residual stresses on the stiffener are 42% of the yield strength. There are tensile residual stresses on both sides of the weld region. However, more research is necessary to confirm this distribution since it is contradictory to expected stresses in literature.


Author(s):  
Farid Belahcene ◽  
Jian Lu ◽  
Fabien Thomas ◽  
Xiaolai Zhou

Surface treatment methods are widely used in the aerospace industry to increase the metal parts damage tolerance by producing a thin surface layer of compressive residual stresses that prevents crack initiation and retards crack growth during service. Nondestructive evaluation of the prevailing compressive residual stresses in the shallow subsurface layer is realized by the ultrasonic technique. The method is based on the measurement of ultrasonic wave velocity variation versus the stress state variation. The application of the Lcr technique (using longitudinal critically refracted wave) has been performed on the SMAT (surface mechanical attrition treatment) steel sample, for which the residual stresses are determined in different zones and depths. The results show that the ultrasonic technique is rather efficient for the evaluation of residual stresses and control of the state of the material after mechanical treatment. The experimental results are successfully compared with the hole drilling method.


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