Stress Of Aluminum Alloy Research Articles

Methods for Non-destructive Testing of Welding Residual Stresses in Aluminum Alloys

There will be large residual stress after welding, and the residual stress will affect the service life of the aluminum alloy welding structure. Therefore, aluminum alloy welding residual stress needs to be accurately detected. Compared with the lossy method, the nondestructive testing method can produce negligible damage to aluminum alloy, which will not affect the reuse of aluminum alloy and can detect the residual stress. This paper summarizes the nondestructive testing methods of welding residual stress in aluminum alloy and their advantages, disadvantages, and applicability, which lay a foundation for rapid nondestructive testing of welding residual stress in aluminum alloy.

Material removal mechanism of aluminium alloy in barrel finishing under grinding fluid

ABSTRACT In barrel finishing, the grinding fluid as a liquid processing medium has an important effect on aluminum alloy parts finishing. Therefore, the wettability of grinding fluid by contact angle and quantum chemical calculation was analyzed. Based on different grinding fluid, the experiments on barrel finishing were achieved. And, the effect of barrel finishing on plastic deformation and residual stress of aluminum alloy were discussed utilizing electron backscattered diffraction (EBSD) and X-ray diffraction (XRD). The results show that hydrogen peroxide and triethanolamine oleate can enhance the wettability of grinding fluid. The A3 grinding fluid with good wettability can obtain the best surface roughness and brightness. The main depth influence range of plastic deformation and residual stress is at 0~200 μm from the upper surface of the workpiece, which indicates that barrel finishing has the effect of low-stress plastic deformation. And the material removal mechanism of low-stress plastic deformation in barrel finishing is proposed. It shows that barrel finishing can not only meet the requirements of good surface roughness, but also restrict the formation of subsurface damage due to the low-stress plastic deformation.

Property Evaluation of FML (Glare)

Fiber metal laminate (Glare) made of 2014-T6 aerospace aluminum alloy sheets adhesively bonded with E-glass fiber based composite prepregs is investigated in the paper. The fabrication procedure of the laminate is explained. Chemical composition, macrostructure and residual stress of aluminum alloy are obtained. Mechanical properties of the laminate viz. tensile, flexural and shear strengths are measured.

50th Anniversary Article: The Origin and Management of Residual Stress in Heat‐treatable Aluminium Alloys

ABSTRACTThe presence of macroscopic residual stresses in heat‐treatable aluminium alloys can give rise to machining distortion, dimensional instability and increased susceptibility to in‐service fatigue and stress corrosion cracking. This paper presents and reviews details about the residual stress magnitudes and distributions introduced into wrought aluminium alloys by the thermal operations associated with heat treatment. Experimental measurement data and the results of finite element analysis are presented and discussed. The available technologies by which residual stresses in aluminium alloys can be relieved are reviewed. The limitations of these techniques are described, and recommendations are made as to selecting the most appropriate technique to manage residual stresses. Opportunities for the future optimisation of these techniques are also presented.

Modelling Creep Induced by Machining Residual Stresses in Aluminium Alloys

Aluminium alloy precision components such as those used in optical systems often experience distortion of their shape during service. This distortion occurs because of residual stresses that are introduced into the surface of the component during machining and lead to creeping of the material when the component is subjected to an elevated temperature for a long time. In this paper, a creep model is developed and used to describe how the residual surface stresses created by milling and by fly cutting affect the geometry of an aluminium alloy component as it creeps. The accuracy of the model is verified by comparing its predictions to measurements made on components manufactured from 4032-O and 6061-T6 aluminium alloys.

Research on the Residual Stress of Aluminum Alloy (LF6) Welding

This paper use the software ANSYS to study the aluminum alloy (LF6) welding residual stress by numerical simulation and experimental study. The result indicates that the aluminum alloy (LF6) has the same residual stress distribution with others, there is a maximum value existing at the range of 4-5mm near the welding seam.

The Effect of UIT on the Residual Stress of 7N01 Al-Alloy Welding Joints

The X-ray diffraction method (iXRD) has been applied into the measurement of residual stress ultrasonic impact ultrasound before and after the impact test process residual stress of aluminum alloy welded joints. Research different inrush current, different impact time of different ultrasonic impact of the process on the residual stress of welded joints of aluminum alloy welded joints welding residual stress distribution and its variation. We can study the distributing status and disciplinarian, and testify the step to adjust the welding residual stress by ultrasonic impact treatment. The research supplys the data supports for welding residual stress engineering disposal and weld joint assistant consolidation to improve abilities against the gatigue. The research shows appropriate welding and ultrasonic impact treatment technics can effectively adjust welding residual stress and meet the RAMS demands about the product.

The Experimental Study of Diffraction Angle of Aluminum Alloy 3003

The most suitable diffraction angle of aluminum alloy 3003 used for stress measuring is aimed to be determined in this paper. The experiment makes a stress measurement of a loading aluminum alloy 3003 equal strength beam with the traditional electrical measuring method and the X-ray stress measurement. With the electrical measuring method as reference, the research study the measured values that acquired from the X-ray diffraction method when the diffraction angle are 142° and 156°, and then compare them with that acquired from electrical measuring method. The measurement results demonstrate that the diffraction angle at 156 ° is better than at 142 ° based on the assessment standards of the liner slope and the distribution of data. Thus the optimum diffraction angle for X-ray to measure the macroscopic stress of aluminum alloy 3003 is 156 °. In this paper，the stress caused by the load on the equal strength beam is assumed to be "residual stress" and thus the conclusion has reference values for the standardization of residual stress measurement of aluminum alloy by XRD and has theoretical guiding significance in the production practices.

Influence of Anisotropy Generated by Rolling on the Stress Measurement by Ultrasound in 7050 T7451 Aluminum

Stress applied to a material can be evaluated using ultrasonic waves. This practice is based on acoustoelastic theory, which relates the stress to the velocity of a wave traveling through the body. How the stress affects the wave velocity is determined by the material’s acoustoelastic constant. This constant can be experimentally measured or calculated from the material’s elastic constants. However, ultrasonic techniques have yet to be adopted as an inspection tool in the field. A factor contributing to this fact is the non-uniformity of materials, mostly associated with grain alignment or texture. As researchers consider this factor, they should take into account the anisotropy generated by rolling. The common practice, however, when relating strain and wave velocity is to ignore anisotropy and to simply utilize isotropic models. No studies have been performed to evaluate the effect of anisotropy on the stress measurement by ultrasound, especially for methods using critically refracted longitudinal waves. The aim of this study is to evaluate how the anisotropy generated by rolling affects the acoustoelastic effect for 7050 T7451 aluminum alloy. We compare the value of the acoustoelastic constant obtained experimentally for rolled samples to the constant calculated with measured elastic constants when the material is assumed to be isotropic. The results show that the methods yield different results, suggesting that the simplified isotropic model should be applied with caution. Since no true known value for elastic constants exists, the results can be used to approach the uncertainty when employing the isotropic model to evaluate stresses in aluminum alloys.

Modeling and Optimal Design of Machining-Induced Residual Stresses in Aluminium Alloys Using a Fast Hierarchical Multiobjective Optimization Algorithm

The residual stresses induced during shaping and machining play an important role in determining the integrity and durability of metal components. An important issue of producing safety critical components is to find the machining parameters that create compressive surface stresses or to minimize tensile surface stresses. In this article, a systematic data-driven fuzzy modeling methodology is proposed, which allows constructing transparent fuzzy models considering both accuracy and interpretability attributes of fuzzy systems. The new method employs a hierarchical optimization structure to improve the modeling efficiency, where two learning mechanisms cooperate together: the Nondominated Sorting Genetic Algorithm II (NSGA-II) is used to improve the model's structure, while the gradient descent method is used to optimize the numerical parameters. This hybrid approach is then successfully applied to the problem that concerns the prediction of machining induced residual stresses in aerospace aluminium alloys. Based on the developed reliable prediction models, NSGA-II is further applied to the multiobjective optimal design of aluminium alloys in a “reverse-engineering” fashion. It is revealed that the optimal machining regimes to minimize the residual stress and the machining cost simultaneously can be successfully located.

Stress in Aluminium Alloys Measured Using Göbel Mirror as a Primary Beam Optics of X-Ray Diffractometer

Grazing incidence geometry, called MGID-sin2y, was applied to measure surface stresses in very thin layers (depth of a few mm) of Al-Mg alloy samples subjected to different thermal and mechanical treatments. The Göbel mirror was used to parallelize the incident X-ray beam. Perfect collimation of the beam significantly increases accuracy of determined peak position and consequently allows to measure low stresses in surface layers.

Research on Stress Calibration Technology on Aluminum of High-Speed Train Body Structure by Nondestructive X-Ray Method Measurement

X-ray diffraction method has been employed to calibrate the stress of 6082 aluminum alloy which has been widely used among modern industrial products. Based on elastic tensile conditions, by designing rod sample of uniform intensity calibration (RSUIC), the stress measurement by X-ray diffraction method has been verificated by using elastic tensile theory calculation method and electrometric method. The results show that the stress measured by the tensile stress theoretical calculation, electrometric method and X-ray diffraction method was in good accordance with each other. And the matching relation between the surface stress measured by X-ray diffraction and the internal stress is investigated. The research will lay a foundation for the application of iXRD stress instrument for nondestructive measuring the welding residual stress of aluminum alloy.

Prediction of Machining Induced Residual Stresses in Aluminium Alloys Using a Hierarchical Data-Driven Fuzzy Modelling Approach

The residual stresses created during shaping and machining play an important role in determining the integrity and durability of metal components. An important aspect of making safety critical components is to determine the machining parameters that create compressive surface stresses, or at least minimise tensile surface stresses. These machining parameters are usually found by trial and error experimentation backed up by limited numerical modelling using Finite Element Methods (FEM) and guided by expert knowledge. The shortcomings of FEM approaches are the length of time needed for the solution of complex models and the inability to learn from data. To solve these problems, a fuzzy modelling approach is presented in this paper and is shown to be successful in modelling machining induced residual stresses.

Correlation between corrosion pits and stresses in Al alloys

Pitting corrosion is commonly observed in a wide range of aluminum alloys that are being used for aerospace applications. There is a need to study the stress environment around pits in order to predict the nucleation of cracks. The objective of this study is to investigate the correlation between pits and stresses in aluminum alloys. Corrosion experiments were carried out on aluminum 2024-T3 alloy samples and imaged through Atomic Force Microscopy (AFM) to obtain the pit profiles. An analysis procedure was developed using CAD and finite element analysis to predict stresses resulting from corrosion pits. Based on the analysis, it was observed that the stress distribution and levels on the corroded surface varied due to irregularity in the corrosion process. The results obtained indicate that the stress initially increases and reaches a plateau with increasing corrosion time. From these stresses it is possible to estimate the initiation of cracks, from which the life can be estimated for failure in the material.

Welding and Deposition of Nickel Superalloys 718, Waspaloy and Single Crystal Alloy CMSX-10

Nickel superalloys are considered extremely difficult to weld and repair because of their susceptibility to heat-affected zone (HAZ) and weld metal cracking during fabrication, postweld heat treatment (PWHT) and subsequent operation. The weldability and repairability by TIG of annealed Alloy 718 and aged Waspaloy was investigated. Alloy 718 was investigated as this alloy provides a reference aerospace grade material. Forced cooling was applied during welding to control the temperature gradient, as this is known to be able to alleviate welding residual stress in aluminium alloys and stainless steels. The level of welding residual stress is one of the main factors controlling the weldability of nickel alloys, and minimising the amount of residual stress is beneficial to cracking resistance. An investigation into the shroud sealing of single crystal nickel superalloy CMSX-10 was also performed by TIG and electro-spark deposition (ESD) techniques with no preheat applied. Application of forced cooling aged Waspaloy resulted in the reduction or elimination of HAZ microfissures due to the reduction of thermal strain, distortion and stresses. Forced cooling during welding of Alloy 718 resulted in a substantial reduction of distortion and buckling. Weld metal and HAZ hardness were almost completely recovered after PWHT of Waspaloy deposits and SEM examination showed that γ’-phase re-formed in the HAZ during PWHT. CMSX-10 showed a high susceptibility to weld metal and HAZ cracking during standard TIG welding employing a Mar-M247 consumable. HAZ cracking was associated with recrystallisation of the parent material. No cracking or microfissures were found in the HAZ of ESD deposits on single crystal CMSX-10 alloy. No recrystallisation occurred in the parent material associated with Mar-M247 deposits produced by ESD.

Surface modification by oil jet peening in Al alloys, AA6063-T6 and AA6061-T4: Residual stress and hardness

The life of structural members that experience cyclic loading is improved by the introduction of surface compressive residual stresses. A high-pressure oil jet is used for the introduction of surface compressive residual stresses in aluminum alloys, AA6063-T6 and AA6061-T4. The peening machine designed and developed in the laboratory is capable of generating high pressures using hydraulic oil. The magnitude of residual stress developed depends upon the stand-off distance and yield strength of the material. A hardened layer up to a depth of about 350μm was developed in the materials investigated. The residual stresses and surface hardening induced are comparable to that produced by other peening processes. An analytical model is proposed to predict the impact pressure.

Use of Neutron and Synchrotron X-ray Diffraction for Non-destructive Evaluation of Weld Residual Stresses in Aluminium Alloys

A full three-dimensional residual stress tensor was determined through a combination of neutron and synchrotron X-ray diffraction in a MIG welded Al2024 plate. The plate was first measured by synchrotron X-rays to determine the strain in the longitudinal (LD) and transverse directions (TD). Then the same plate was measured by pulsed neutrons for the transverse and normal strain directions. The stress-free lattice reference (d 0) across the weld was obtained by measuring a comb sample of insufficient constraint to hold an internal residual stress field. The point-to-point corrected strain data of the three principal directions obtained was then combined to calculate the full three-dimensional residual stress tensor. The comparability of the processes was confirmed by comparing the strain observed in the transverse direction. The combination of these two different experiments enabled determination of a full through-thickness stress map across the weld.

Mechanical Properties Of Quasicrystal Dispersed Al-Li-Cu Alloy

AbstractTo apply the ductile structural materials, the quasicrystal dispersion in aluminum alloys is one of effective methods. We have investigated mechanical properties of quasicrystal dispersed Al- Li-Cu alloy prepared by the twin-type piston anvil apparatus. The slow cooled samples are hard and ductile. The evaluated values of brittleness are from 6.0 to 14 erg for Ef, from 0.52 to 0.73MNm−3/2 for K1c and from 5.5 to 7.7 Nm−1 for Gic for the fastest and slowest cooled samples, respectively. The hardness of the quasicrystal dispersed Al-Li-Cu alloy is higher than that of the other commercial aluminum alloys. Based on the relationship between Vickers hardness and proof stress of aluminum alloys, we estimate the specific strength of Al-Li-Cu quasicrystal alloy. The maximum value is the higher than that of Ti alloys.

The X-Ray Diffraction Measurement of Residual Stresses in Aluminum Alloys

AbstractThis paper presents the theoretical and practical aspects of measuring residual stresses by X-ray diffraction with emphasis on the analysis of aluminum alloys. The theoretical considerations of radiation) beam geometry, and peak location will be discussed in regard to establishing optimum analysis techniques. The precision and reproducibility of this technique have been investigated so that results can be applied accurately. The approach, however, is basically a practical one, with the intent of studying residual stress systems as they affect engineering applications. Residual stress systems produced by thermal and mechanical treatments have been determined and the effect of treatment modifications and variations on the resultant stress system have been analyzed. The effect of operational variables such as time and temperature on the developed stress system are shown. From this, the merits of a particular treatment can be determined with respect to its intended application.Analysis of solution heat-treated and quenched 2014 aluminum has shown a significant effect of the quench temperature on the resultant residual stress system. The results obtained from shot-peening this alloy are presented, as well as the effect of time and temperature on the shot-peened stress gradient.

Al合金の加工と内部歪及び内部歪檢出液

It is well known that the internal stress in aluminium alloys is due to cold working. From the inference that the weakening of grain boundaries of the alloy in which remains the internal stress, causes cracking just in the same way as the season-cracking of copper-alloy, the author performed this research. In detecting grain boundaries of aluminium-alloys, the salts of mercury seem suitable and as mercurous nitrates do not act to aluminium-alloy, a saturated solution of mercuric chloride was tested. But by another experiment it is found that the addition of 1/15 N HO to that solution gives still more satisfactory result. By this solution, some of the cold drawn duralumin, super duralumin and aluminium-alloy containing Zn 8%, Mg 1.5% and Cu 2% cracked in a few seconds. The internal stress in these alloys caused by a working ratio was studied and it was found that a stress of 10kg/mm2 or more in hollow sunk duralumin tubes could be easily detected by this solution. By annealing the duralumin tubes having 20kg/mm2 stress at various temperatures and durations, it was found that at an annealing temperature of 275_??_300° the solution indicated the removal of stress to a great extent. Drawn super duralumin and aluminium-alloy bar containing Zn did not also show cracks by annealing at 275° and 250° respectively. According to Rosenhain the season crack in an E-alloy containing Zn could be prevented by adding 0.5% of Mn to it. In order to prevent the season crack of an alloy containing Zn 8%, Mg 1.5% and Cu 2% the author added to it a small quantity of Mn, Mo and Cr, but made little s_??_ccess.