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1.
The same shot-peening treatment was applied to five steels with different mechanical properties. The induced residual stress profiles were analyzed using X-ray diffraction and incremental hole drilling (IHD). The results of both techniques showed that IHD can still be successfully used for measuring shot-peening residual stresses, even if these exceed the yield strength of the bulk material. Expected errors due to the plasticity effect are reduced by the strain hardening of the surface. For an assessment of the reliability of IHD data, strain-hardening variation was quantified by microhardness measurements to estimate the yield strength of the plastified layer. All the main calculation methods for IHD were applied. The results were compared and discussed with respect to the characteristics of each method. 相似文献
2.
J. Koutský K. plíchal P. Novosad J. Burda R. Havel 《Theoretical and Applied Fracture Mechanics》1987,8(1)
Different factors, such as irradiation, cyclic and thermal stresses, hydrogen embrittlement and static load can cause degradation of properties of reactor pressure vessel steels.The hydrogen embrittlement of low alloy ferritic steels has been investigated in dependence on the electrolytic hydrogen charging parameters. It was observed that the degradation of plastic properties appears over critical value 2.5 p.p.m. of hydrogen. In a test under constant load of notched specimens the lower threshold stress was ascertained as a function of cathodic hydrogen charging parameters. 相似文献
3.
Residual stresses and retained austenite are two important process-related parameters which need to be controlled and monitored
carefully during production and heat treatment of products. X-ray diffraction techniques are normally used in this context,
and the purpose of the present study was to investigate the reproducibility and accuracy of these methods for medium and high
carbon steels. The work was carried out as a round robin study including nine different laboratories in Sweden and Finland.
Stress measurements were carried out on three specimens etched to three different depths, 0 μm, 230 μm and 515 μm. Retained
austenite measurements were carried out on three specimens containing approximately 11, 17 and 30 vol.-% of this phase. The
stress measurements showed good reproducibility with standard deviations of typically 4% on flat and smooth surfaces and not
more than about 8% on etched surfaces. Estimations revealed that specimen misalignment and improper X-ray spot location were
the main sources behind the variation in the stress recordings. The determination of retained austenite showed a standard
deviation of typically 15% between the different contributors. However, by using identical evaluation methods for all raw
data, the data spread could be narrowed by a factor of 3 to 4 despite the fact that different experimental settings were used
in the individual laboratories. 相似文献
4.
5.
Application of X-ray diffraction, micromagnetic and hole drilling methods for residual stress determination in a ball bearing steel ring 总被引:1,自引:0,他引:1
C. O. D. Martins Ph.D. T. R. Strohaecker A. S. Rocha T. K. Hirsch 《Experimental Mechanics》2005,45(4):344-350
A basic understanding of distortion problems requires the analysis of a complete manufacturing process including an almost
complete overview of residual stress states in the component during each production step. To reduce the measurement time in
the future, three measurements methods (X-ray diffraction, micromagnetic and blind hole drilling methods) have been used to
analyze residual stress states in machined AISI 52100 ball bearing rings. X-ray diffraction was used as a state-of-the-art
method for machining induced residual stresses with pronounced gradients. The ring exhibited a complex residual stress state
with high tensile residual stresses at the surface, a strong gradient in depth, and also showed some variation along the outer
circumference due to a superimposition of machining induced residual stresses and effects from the clamping device process.
Due to this surface state, micromagnetic signals depend on the analyzing frequency. A calibration of the signals was only
possible with the X-ray diffraction data. The results of the three different measurement methods correlate reasonably well. 相似文献
6.
An X-ray diffraction technique was employed to determine the residual stresses introduced by cold working a fastener hole
in a 6-mm thick 2024-T351 aluminum plate. The radial and tangenital residual stresses were measured at both faces of the plate
and the measurements compared with the results from a two-dimensional axisymmetric finite-element model. The comparisons were
favorable, although modifying the finite-element model to simulate the X-ray process provided better agreement. Experimental
determinations of residual stresses showed differences between the two faces of the plate. This feature was attributed to
the directional nature of the cold-working process.
Paper was presented at the 1994 SEM Spring Conference on Experimental Mechanics held in Baltimore, MD on June 8–10. 相似文献
7.
The relationship between the critical shear stress for the onset of flow instabilities and the work of adhesion at the interface has been evaluated experimentally for a series of polyolefins on several steels, brasses, and coated steels. The critical shear stress was considerably affected by the chemical nature of the die. Low-surface-energy materials were found to produce smooth extrudates presumably by inducing slippage at the wall. Steel, tungsten carbide, and brass surfaces promoted sharkskin defect at shear stresses above the first critical shear stress. A linear relationship between the critical shear stress and the work of adhesion was found to be valid for values of work of adhesion smaller than approximately 30 mN/m. This indicates that slippage occurs due to a breakdown of the adhesion at the interface. For values of work of adhesion greater than approximately 30 mN/m a stronger interaction at the interface may induce a cohesive failure at the interface and subsequently, extrudate distortions. 相似文献
8.
D. Nelson 《Experimental Mechanics》2014,54(4):695-708
Over the years, an assortment of methods for determining residual stresses has been developed in the field of experimental mechanics. Adaptations of those methods to study residual strains and stresses in various biological structures found in humans, other mammals, viruses and an insect are reviewed. Methods considered include deflections from release of residual stresses, hole drilling and ring coring, strains upon dissection, the contour method, slitting (crack compliance), X-ray diffraction, photoelasticity, and membrane and shell displacements. Sources of residual stresses and strains are summarized and examples of their physiological role noted. 相似文献
9.
Transformation plasticity in steels (i.e., the anomalous plastic flow observed during the progress of a phase transformation) is usually attributed to two distinct physical mechanisms, which have been proposed by Greenwood and Johnson and Magee. This paper proposes a theoretical approach to the problem, in the case where the Magee mechanism is negligible and the phases are ideal-plastic. An explicit expression for the transformation plastic strain rate is obtained for a steel undergoing a transformation under a small applied stress; this expression is consistent with experiments conducted on various materials. A finite element simulation provides a confirmation of the theoretical formula and allows for a detailed examination of the validity of some physical hypotheses made in the treatment. It also allows for a study of transformation plasticity under high applied stresses. Based on these results, a general (i.e., applicable for all kinds of stresses applied) model is proposed in the case of ideal-plastic phases. 相似文献
10.
The instrumentation, technique, and procedures are described for the nondestructive measurement of residual stresses on the inside surface of pipe as small as 10 in. in diam. The instrument is based upon a unique position-sensitive scintillation X-ray detector which provides for the most compact X-ray stress-measurement instrument available since the introduction of film cameras four decades ago. This instrument is capable of applying the single-exposure technique of X-ray stress measurements which results in unprecedented rapidity of stress measurement consistent with excellent precision and accuracy. The results of testing the precision and accuracy of the instrument on a zero-stress powder and four-point-bend specimen are given. Residual stresses in four austenitic stainless-steel girth-welded pipes are presented illustrating the effects of the different welding procedures. The results from the pipes confirm the beneficial residual-stress condition of heat-sink-welding procedures. 相似文献
11.
Y. Yang H. H. Ruan J. Lu N. Yao W. L. Shan W. O. Soboyejo 《Experimental Mechanics》2009,49(5):731-742
In this paper, we propose a new experimental method to investigate the fatigue crack growth mechanisms of submicron-scale
cracks by using freestanding single edge notched micro-beams that are fabricated on the surfaces of conventional bending specimens
with the focused ion beam technique. Three dimensional FEM simulations in conjugate with LEFM fracture analysis were carried
out to correlate the applied far field stresses with the local crack-tip driving force. For the validation of the new method,
micro-beam experiments were conducted on 4340 low alloy steels and the results showed the similar findings compared to those
in the literature while revealed undiscovered fatigue damage mechanisms that took place at the submicron and nanometer scales. 相似文献
12.
The limiting stresses are determined and constant fatigue life diagrams for high-cycle torsion with repeated stress cycle
are plotted using the limiting-state models obtained based on the hypothesis of a unified constant-life diagram, which is
invariant to the number of cycles to failure. The unified constant-life diagram is given by a transcendental power function
whose exponent is an additional parameter characterizing the sensitivity of the material to the asymmetry of the stress cycle.
The calculated results and experimental data for carbon and alloyed steels and composite materials are in good agreement
__________
Translated from Prikladnaya Mekhanika, Vol. 44, No. 2, pp. 19–28, February 2008. 相似文献
13.
Wendell P. de Oliveira Marcelo A. Savi Pedro Manuel C. L. Pacheco 《Archive of Applied Mechanics (Ingenieur Archiv)》2013,83(7):1013-1037
Heat treatment processes are usually employed to control the mechanical properties of steels and quenching is one of the most common treatments. This article deals with the modeling and simulation of quenching in steel cylinders using a multi-phase constitutive model. Finite element method is employed for spatial discretization. Numerical simulations are carried out by considering an iterative process associated with the operator split technique. Initially, a verification procedure is of concern establishing a comparison between numerical and experimental data, presenting a good agreement. Afterward, notched steel cylinders are treated evaluating the influence of notches in quenched pieces. Temperature, phase transformations and stresses are monitored during the quenching in order to give a general idea of the thermomechanical behavior of the process. 相似文献
14.
Ya. S. Semenov S. K. Popova M. P. Lebedev 《Journal of Applied Mechanics and Technical Physics》2009,50(6):1089-1094
X-ray spectral and x-ray structural analyses and optical microscopy were used to study the chemical and phase compositions
and the structure and morphology of alloying elements of the transition layer produced by gas-flame and plasma spraying on
St. 3sp steels. It is shown that the structure and chemical and phase compositions of the transition layer depend significantly on
the technological parameters, processing methods, and the chemical composition of the coating. 相似文献
15.
Righetti V. A. N. Campos T. M. B. Robatto L. B. Rego R. R. Thim G. P. 《Experimental Mechanics》2020,60(4):475-480
Experimental Mechanics - The multireflection grazing incidence X-ray diffraction method (MGIXD) was used to analyze the surface residual stresses in 7050 Al alloy samples. This technique can... 相似文献
16.
V. P. Ermakov A. I. Ravikovich 《Journal of Applied Mechanics and Technical Physics》1971,12(2):241-243
The article gives the results of experimental investigations of the creep of heat-resistant aluminum alloy AK4-1 with constant and variable loads, at a temperature of 175 °C and a duration of the tests equal to 100 h. Based on the experimental data, a verification of the theory of creep is adduced, based on the following hypotheses: 1) the change in the volume is elastic; 2) the deviator of the creep rates is proportional to the deviator of the stresses; 3) the intensities of the stresses, of the creep deformations, and their rates are connected by a relationship which does not depend on the type of the state of stress. It should be pointed out that the results of investigation of creep, under a complex state of stress, in carbon, low-alloy, austenitic steels, copper, and certain light alloys, are given in [1–6].Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 2, pp. 83–86, March–April, 1971. 相似文献
17.
P. Pagliaro M. B. Prime J.S. Robinson B. Clausen H. Swenson M. Steinzig B. Zuccarello 《Experimental Mechanics》2011,51(7):1123-1134
The traditional contour method maps a single component of residual stress by cutting a body carefully in two and measuring
the contour of the cut surface. The cut also exposes previously inaccessible regions of the body to residual stress measurement
using a variety of other techniques, but the stresses have been changed by the relaxation after cutting. In this paper, it
is shown that superposition of stresses measured post-cutting with results from the contour method analysis can determine
the original (pre-cut) residual stresses. The general superposition theory using Bueckner’s principle is developed and limitations
are discussed. The procedure is experimentally demonstrated by determining the triaxial residual stress state on a cross section
plane. The 2024-T351 aluminum alloy test specimen was a disk plastically indented to produce multiaxial residual stresses.
After cutting the disk in half, the stresses on the cut surface of one half were determined with X-ray diffraction and with
hole drilling on the other half. To determine the original residual stresses, the measured surface stresses were superimposed
with the change stress calculated by the contour method. Within uncertainty, the results agreed with neutron diffraction measurements
taken on an uncut disk. 相似文献
18.
A study was conducted to develop a methodology to obtain near-surface residual stresses for laser-peened aluminium alloy samples using the contour method. After cutting trials to determine the optimal cut parameters, surface contours were obtained and a new data analysis method based on spline smoothing was applied. A new criterion for determining the optimal smoothing parameters is introduced. Near-surface residual stresses obtained from the contour method were compared with X-ray diffraction and incremental hole drilling results. It is concluded that with optimal cutting parameters and data analysis, reliable near-surface residual stresses can be obtained by the contour method. 相似文献
19.
In this paper several materials have been evaluated in order to select the best suitable alloy for the production of a gas
turbine transition piece. These components are exposed to complex thermal stresses and different damages, each of them requiring
particular characteristics of the material. The procedure described takes into account the variability of requirements with
some parameters, in particular temperature and service time. Due to the high value of temperature and the constraint of ductility,
the choice of material has been limited to superalloys and stainless steels. A comparison between several alloys has been
carried out on the basis of constraints and requirements previously determined. Using a suitable objective function, the method
allows ranking materials in order to find the alloy which maximize component’s performance. 相似文献
20.
Machining induced residual stress states have been identified to affect the distortion of parts during following heat treatments.
Thus, ideally a complete characterization of the components residual stress state is required. Magnetic and micromagnetic
analysis of residual stresses can represent an important gain of time compared to X-ray diffraction. Investigations with these
two methods were performed on different components with various and inhomogeneous residual stress states: cylindrical and
tapered ball bearing rings made from AISI52100 steel and a disc made from AISI5210 steel. Reliable results and good agreement
between X-ray diffraction data and residual stresses obtained from the magnetic and micromagnetic analysis can be obtained
with the use of a calibration for each single component. An important gain of time can be achieved with the combined use of
X-ray diffraction analysis for the calibration and the micromagnetic technique. However, local residual stress variations
in zones smaller than the sensor size may not be detected. A global calibration of the micromagnetic equipment with one calibration
file for several parts still needs optimization. 相似文献