Heat-treatable Aluminum Alloys Research Articles

Predicting Mechanical Properties and Corrosion Resistance of Heat-Treated 7N01 Aluminum Alloy by Machine Learning Methods

In this paper, mechanical properties and corrosion resistance of different heat-treated 7N01 aluminum alloys are measured. A novel approach is proposed to establish the relationship between heat-treated processing parameters and the properties using machine learning methods. With a set of trustable data, generalized regression neural network (GRNN), support vector machine (SVM) and multiple linear regression (MLR) are applied in the prediction of mechanical properties, while GRNN and SVM, two prevalent machine learning methods, are also employed to predict the corrosion resistance. By comparing coefficient of determination (R2) and mean absolute percentage error (MAPE), we demonstrate, GRNN and SVM are indeed useful machine leaning methods for both modeling and predicting. In virtue of the new approach, we can also establish other goal-oriented models for design and prediction as long as the training data set is available. Finally, it’s found that both single-stage aging and retrogression re-aging can make the alloy reach higher strength values than double-stage aging, however the corrosion resistance of double-stage aging alloy is better than that of single-stage aging.

Influence of Mx-Trivex, A-Skew, Three Flat Threaded and Concave Shouldered Mx-Triflute Tool Pin Profiles on Tensile Properties and Fractural Behaviour of AA 6082-T6 Weldments during Friction Stir Welding

Friction Stir Welding (FSW) is a topical and propitious solid-state joining process producing economical and strengthened joints of age-hardened and heat-treatable Aluminium Alloy AA 6082-T6. Mechanical and fractural behaviour of weldments were investigated in order to find crack initiation and necking on the weld zone thereby perceiving the complete behaviour of fracture occurred near the weld zone. Weldments are fabricated by employing four tool pin profiles namely MX-TRIVEX, A-SKEW, Three flat threaded and Concave shouldered MX-TRIFLUTE tools at various rotational speeds 1000 rpm, 1200 rpm and 1400 rpm at single traverse speed 25 mm/min. EXCETEX-EX-40 CNC wire cut EDM with 0.25 mm brass wire diameter has been employed to perform the extraction of tensile test specimens from the weldments according to ASTM E8M-04 standard. Tensile test was performed on elctro-mechanically servo controlled TUE-C-200 (UTM machine) according to ASTM B557-16 standards Maximum Ultimate Tensile Strength (UTS) of 172.33 MPa (55.5% of base material) and 0.2% Yield Stress (YS) of 134.10 MPa (51.5% of base material) were obtained by using A-SKEW at 1400 rpm, 25 mm/min and maximum % Elongation (%El) of 11.33 (113.3% of base material) was obtained at MX-TRIVEX at 1000 rpm, 25 mm/min. Minimum UTS of 131.16 MPa (42.30% of base material) and 0.2% YS of 105.207 MPa (40.46% of base material )were obtained by using Concave shouldered MX-TRIFLUTE at 1400 rpm, 25 mm/min. Minimum % El of 5.42 ( 54.2% of base material) was obtained by using A-SKEW at 1000 rpm, 25 mm/min.

The impact of laser surface treatment on the microstructure, wear resistance and hardness of the AlMg5 aluminum alloy

Light metal alloys due to several unique properties such as low density and high corrosion resistance are increasingly used in various technical applications, where the automotive industry is one of the most important sectors. The automotive applications use mostly aluminum alloys, where the strength to density ratio of the material plays a crucial factor. Unfortunately, relatively low mechanical properties limit their applications for parts where a high surface hardness and wear resistance is expected. The classic heat treatment of aluminum alloys can only in some limited ranges improve the bulk material properties. Despite this, surface treatment with laser processing has developed significantly over the past 20 years. The laser beam treatment allows the introduction of a wide range of alloying elements to the surface layer of an aluminum alloy and thus, as a result of the precipitation of numerous intermetallic phases, significantly increases hardness, and abrasion resistance. The purpose of this work was to modify the aluminum surface layer using high-power fiber laser (HPFL). During this process, a mixture of titanium and iron powders (90/10 wt.%) was introduced onto the surface of the AlMg5 alloy. The microhardness tests carried out by the Vickers method and tribological tests showed a significant increase in mechanical properties in the entire volume of the obtained layer. Research on light and scanning microscopy revealed fragmentation of primary precipitates and the formation of numerous intermetallic phases rich in titanium and aluminum.

Enhancing the Tribological Properties of Talc and Boron Nitride based Composites by T6 - Heat Treatment

Aluminium matrix composites (AMC) strengthened with hard particles has given rise to a potential material particularly for wear resistant and weight basic applications. The effect of heat treatment of aluminium alloys sliding wear nature are observed under varying load and speed. Irrespective of materials heat treatment improves hardness of the material. The particulate reinforcements embedded with Al2218 Aluminium metallic element alloy with 4% constant weight proportion of Talc, Boron Nitride and a variable amount of hard reinforcement particulates. By introducing fly ash as reinforcement satisfies the structural and thermal properties. 5%, 10% & 15% of fly ash added to the composite by metal stir casting technique. The specimens are treated with ASTM T6 standard. Performance of heat-treated matrix composite was investigated with a pin on disc apparatus through a constant load 2 kg and with a desirable rpm. Hardness of the specimen at temperature were measured before and once the heat treatment. Heat treated metal exhibits high hardness and wear resistance. This investigation reveals that 2218 Aluminium matrix composites with high hardness and wear resistance will replace the material employed in Automobiles like brake drum, cylinder block, connecting rod, piston etc for higher performance and longer life.

Early Stages of Precipitation in Mould-Cast, Cold-Rolled and Heat-Treated Aluminium Alloy AA7075 with Sc,Zr-Addition

Early Stages of Precipitation in Mould-Cast, Cold-Rolled and Heat-Treated Aluminium Alloy AA7075 with Sc,Zr-Addition

Web crippling of aluminium alloy channel sections with flanges restrained

Abstract This paper describes an investigation of web crippling behaviour of aluminium alloy plain and lipped channels with flanges restrained. A total of 340 data is presented that include 52 test results and 288 numerical results. A series of tests was conducted on plain and lipped channels fabricated by extrusion using 6063-T5 and 6061-T6 heat-treated aluminium alloys under end-two-flange (ETF) and interior-two-flange (ITF) loading conditions. The concentrate loads were applied by means of bearing plates. The flanges of the channels were either bolted (fastened) to one or two bearing plates. A finite element model was developed and verified against the experimental results. Geometric and material non-linearities were included in the finite element model. It was shown that the finite element model closely predicted the web crippling strengths and failure modes of the tested specimens with flanges restrained. Hence, the finite element model was used for an extensive parametric study of cross-section geometries, and the web slenderness value ranged from 24.0 to 207.3. The test results and the web crippling strengths predicted from the finite element analyses were compared with the design strengths obtained using the American, Australian/New Zealand and European specifications for aluminium structures. A unified web crippling equation with new coefficients for aluminium alloy channels with flanges restrained under ETF and ITF loading conditions is proposed in this study. Since two failure modes of web buckling and web yielding were also observed in the aluminium plain and lipped channels with flanges restrained, design rules of web crippling strengths are also proposed by considering the lesser of the web buckling strength and web yield strength.

Microstructural Refinement and Corrosion Resistance Improvement of Heat-Treated A356 Alloy Processed by Equal Channel Angular Pressing

The microstructure refinement, hardness and corrosion resistance of heat-treated A356 aluminium alloy processed by equal-channel angular pressing (ECAP) were investigated. ECAP was carried out at room temperature using a mold, with a channel angle of 120° via route A. Results of the investigation confirm that the flaky coarse silicon particles were effectively fragmented from 4.22 to 0.761 μm and the grain size reduced from 171 to 40 μm after four passes of heat-treated as-cast using ECAP process. ECAP processing increases the hardness of heat-treated as-cast alloy from 61 Hv to 125 HV after four passes. Heat-treated A356 alloy shows enhanced corrosion resistance from 0.0424 to 0.00149 mmy-1, after four passes. In this research, ECAP processing has been shown to improve the hardness and corrosion resistance of as-cast A356 alloy.

Investigation on Contact Heating of Aluminum Alloy Sheets in Hot Stamping Process

Application of the hot stamping process on heat-treatable aluminum alloys effectively solves the problems of large springback and poor ductility during forming at room temperature, which expands the range of applications of aluminum alloys in the transportation industry. Sheet heating plays an important role in the hot stamping process, and increasing the heating rate can improve the hot stamping efficiency to some extent. In this paper, the feasibility of applying contact heating techniques with higher heating rates in the hot stamping process was studied. A contact heating device was designed, and the temperature distribution of the device contact surface was observed. Furthermore, the heating characteristics of 7075 aluminum alloy sheets during the contact heating process were explored by experiments and finite element simulation. Finally, the rapid solution treatment of aluminum alloy was carried out with a contact heating device, which was compared with the furnace heating solution treatment. The experimental and simulation results indicate that the device contact surface has a relatively uniform temperature distribution, and the aluminum alloy sheets can be heated to close to the set temperature in 15 s using contact heating techniques. Meanwhile, the rapid solution treatment of aluminum alloy sheets can be achieved within 15–20 s by contact heating techniques, obtaining superior mechanical properties. This suggests that the contact heating process can be used for rapid heating and rapid solution treatment of aluminum alloy sheets in hot stamping process.

Influence of Thermomechanical Treatments on the Microstructure and Mechanical Properties of Aluminium Alloy AA2219 Hand Forgings

The heat treatable aluminium alloy AA2219 is subjected to mechanical stress relieving by way of cold deformation after solution treatment to relieve the quenched in stresses as thermal stress relieving is not possible due to the requirement of higher temperature than the ageing temperature. Cold deformation prior to aging has also been found to yield improved strength. Though this phenomenon is to some extent being exploited in aluminium alloy AA2219 sheets and plates, there is no experimental data available to understand the influence of cold compression on the extent of benefits obtainable on mechanical properties in forgings. In the present study to identify a thermo-mechanical treatment that can yield the maximum tensile strength, solution treated AA2219 forgings were subjected to cold deformation ranging from 0 to 25% and then artificially aged. The results indicates that the maximum room temperature tensile strength (both UTS and 0.2% PS) can be obtained at 10% post solution treatment cold deformation. As this alloy is being used for low temperature applications, it is very essential to assess the effect of higher cold compression on the low temperature (77 K) properties and the results show that the 77 K tensile properties more or less same beyond 2% cold deformation. As the weld properties are around 50% of the parent metal properties, any increase in the mechanical properties, is considered to be very crucial and very much needed for this alloy in the absence of aluminium–lithium alloy technology. Hence this study indicate that there is a good scope to increase the amount of cold compression after Solution treatment instead of restricting the same to 2%–5% maximum.

Mechanical Behavior and Deformation Kinetics of Aluminum Alloys Processed through Cryorolling and Subsequent Annealing

The influence of cryorolling (CYR) on the microstructure, mechanical properties, and formability of heat-treatable (AA 6061) and non heat-treatable (AA 5083) aluminum alloys was investigated. Solutionized (SL) AA 5083 and AA 6061 alloy plates are cryorolled to reduce the thickness from 6.5 to 1 mm (the total true strain of 1.87). Short annealing treatment is performed on cryorolled samples at different temperatures with a fixed annealing time to improve ductility. The effect of annealing temperature on microstructure, mechanical properties, and formability was systemically studied. The results showed grain refinement after CYR with higher dislocation density when compared to the SL condition, and their effect is reflected in the mechanical properties. The limiting dome height test is used in the present work to compare the formability of cryorolled and annealed samples. The formability characteristics correlated well with the strain hardening behavior, which is modeled using the Kocks–Mecking–Estrin (KME) dislocation density model. The dislocation density evolution in the original KME model was modified to consider the contributions of grain size, solutes, and precipitates. The tensile curves predicted from the KME model correlated well with the experimental curves in all the conditions investigated. In addition to that, the predicted dislocation density using the modified KME model agreed well with the dislocation density determined experimentally.

Effect of nano-sized particles on grain structure and mechanical behavior of friction stir welded Al-nanocomposites

Weldability of heat-treatable 6061-T6 aluminum alloy results in deterioration of mechanical properties due to dissolution of strengthening precipitates in the nugget zone of friction stir welded joints. These properties were improved by addition of reinforcement particles in the weld joint line. In the present work, attempts were made to produce 6061-T6 Al-based nanocomposites using the friction stir welding process by incorporating titanium oxide nanoparticles into the aluminum matrix for microstructure refining of the nugget zone and prevent the grain growth in the heat-affected zone. The effect of addition of nanoparticles on the evolution of grains structure and mechanical behavior of friction stir welded samples based on different combinations of rotational and travel speed was studied and discussed. Results revealed that the unreinforced samples were successfully welded at both low and high heat inputs, whereas the reinforced samples are not feasible at tool rotational speed (ω) < 2000 r/min and transverse speed (v) > 70 mm/min, respectively. The significant refining of grains in the nugget zone is possible with addition of nanoparticles via the Zener-pinning effect. A more pronounced increment in tensile strength, microhardness, and wear properties was observed compared to sample without nanoparticles under the same processing parameters due to embedment of nano-sized particles in the weld nugget zone.

Joining of AA2014 and AA5059 dissimilar aluminium alloys by Friction Stir Welding

Purpose: This work aims to investigate the microstructure and mechanical properties achieved by FSW of butt joints, namely of dissimilar sheets namely of 2014-T3 to 5059-H11 Al alloys by bonding the two materials perpendicular to their rolling directions. Design/methodology/approach: AA 2014T3 and AA 5059H11 were two dissimilar aluminium alloys friction stir welded. The joint has been examined in terms of hardness, microstructure, and mechanical properties. The microstructure of the weld area was characterized by using optical microscopy. Seven diverse regions of the microstructure in the joint can be illustrious. Findings: It has been noticed that a structure of fine grain is formed in the nugget region as a consequence of recrystallization. The thermos mechanically affected and heat affected zones of aluminium alloy 2014 are characterized by the lowest hardness values in spite of there are a general hardness decrease through the weld zone compared to both base metals. The ultimate tensile strength values of the dissimilar joint were found to be varying between 54% to 66% those of the base metal. Research limitations/implications: The t joining in FSW takes place with the base materials remnant in the solid state, which gives a considerable possibility to produce joints between the alleged difficult-to-weld heat treatable aluminium alloys. Originality/value: The outcomes display that friction stir welding can be effectively applied for the joining of dissimilar aluminium alloys.

Effect of Solution Heat Treatment of Aluminum Alloy 4032 on the Structure and Corrosion Resistance in 3,5% and 10,5% NaCl Solution

Aluminum Alloy 4032 is usually used as a material for making engine pistons, which has a composition of Aluminum (Al), 21%wt Silicon (Si), 0.82%wt Nickel (Ni) and 0.67%wt Copper (Cu). The alloy is known to have mild properties and should have good corrosion resistance. Heat treatment was carried out with the aim of the enhancement of the corrosion resistance. The solution heat treatment process was performed at 510°C for 2 hours and then quenching to room temperature in water media. Some of the material were also performed an aging process at 171°C with varying duration of time and then cooling to room temperature. Corrosion resistance testing was carried out by electrochemical testing using 3.5% wt and 10.5% wt NaCl solution. The structure before and after heat treatment were characterized by using X-Ray Diffraction (XRD) were analyzed. The results of the characterization indicate that the heat treatment on the Alloy is affected by solution heat treatment and the aging process.

Evaluation of the stress vs strain curve using a high temperature bulge test device

The increasing amount of hot and warm stamping parts in the automotive industry shows that high temperature forming is critical to reach the emission goal fixed by regulation authorities, due to its contribution in reducing the vehicle’s weight. Hot stamping and warm forming take advantage of the material softening with temperature to reduce the forming forces and springback. The use of different temperature conditions also enables exploring the phase transformation occurring with in-tool quenching in hot stamping boron steels or artificial aging in heat treatable lightweight aluminum alloys. These new forming conditions require either new material characterization methods or the current methods need to be adapted to high temperature conditions. The equibiaxial expansion test allows the evaluation of the mechanical behavior of materials on a large strain range. However, the use of high temperature conditions gives rise to difficulties when using Digital Image Correlation (DIC) systems. This study analyses the possibility of using a scanner laser to obtain the stress vs. strain curve from an equibiaxial test performed with an aluminum alloy of the 6xxx series, at 150°C. The aim is to validate an experimental procedure that can be used to evaluate the stress vs. strain curve from high temperature bulge tests performed with other metallic sheets, including quenchable boron steel.

A study of microstructure and mechanical properties of friction stir welding aluminium alloy AA6082 with Zn interlayer

In the present study, the effect of Zn interlayer is analysed on friction stir welding of heat-treated AA6082 aluminium alloy. Friction stir welding joints are produced by preplacing the Zn particles interlayer into a gap of 0.7 mm between the abutting plates. Rotational speed is selected as process parameter to perform the welding. Thereafter welded joints are evaluated for microstructural aspects, microhardness and tensile properties. The microstructure analysis reveals that interlayer particles are evenly distributed in the nugget zone of joints. FSW joints produced with interlayer possess higher microhardness than the joints without interlayer. However, equivalent tensile strength is reported in both the cases. The fracture analysis revealed joint with interlayer possesses ductile failure under tensile loading.

Uphill quenching to reduce residual stress in a heat treatable aluminium alloy

ABSTRACTThree rectilinear blocks of the aluminium alloy 7449 were characterised using neutron and X-ray diffraction. One block was heat treated normally and two blocks were subject to uphill quenching from −196°C to 100°C. Boiling water and steam were used to rapidly increase the temperature of the blocks to reverse the thermal gradients introduced by cold water quenching. It was possible to detect the beneficial influence of uphill quenching on residual stress using either fluid. The influence of steam was very effective but localised and limited to the surface in close proximity to the steam jet. For more uniform stress relief, multiple steam jets will be required to ensure the entire surface receives a significant thermal input.

Friction Stir Welding of Thick AA2519 Alloy: Defect Elimination, Mechanical and Micro-Structural Characterization

Friction stir welding (FSW) of thick aluminium sections will pave way for remarkable new defence applications, provided the accompanying challenges are successfully addressed. These challenges include elimination of tunnel defects, loss of strength in heat-treatable aluminium alloys, tool design and excessive process forces. Accounts of defect elimination, detailed micro-structural and mechanical characterization for thick section FSW are scarce in the published literature. Further, special strategies such as bobbin tool, pre-drilled hole for plunging and inverted double pass are generally deployed to overcome these challenges. This makes the process less productive and complex. In the present work, armor grade aluminum alloy AA2519-T87 plates having a thickness of 15.4 mm have been successfully joined with a joint efficiency of greater than 75% without supplementary strategies. The disparity in the effects of tool rotational speed and welding speed in the formation of a sound weld has been addressed in detail to enhance the understanding of FSW of thick sections. Micro-hardness measurements have been carried out throughout the transverse cross-section of the welds and correlated with different zones and their corresponding microstructures. Scanning electron microscopy and X-ray energy dispersive spectroscopy have been used to characterize the coarse phase particles present in the weld zones.

INDENTATION SIZE EFFECT OF HEAT TREATED ALUMINUM ALLOY

The aim of the submitted work is to study the influence of applied loads ranging from 0.09807 N to 0.9807 N on measured values of micro-hardness of heat treated aluminum alloy 6082. The influence of applied load on a measured value of micro-hardness was evaluated by Meyer’s index n, PSR method and by Analysis of Variance (ANOVA). The influence of the load on the measured value of micro-hardness is statistically significant and the relationship between the applied load and micro-hardness manifests the moderate reverse ISE. As the temperature of the solution treatment rises, the YS/UTS ratio and also Meyer’s index n, measured and “true hardness“ increase. On the other hand, its effect on the plastic properties of the alloy is ambiguous.

Electro chemical response of stir zone in friction stir welded AA7075-T651 joint in sodium chloride solution

Abstract High strength heat treatable aluminium alloy AA7075T-651 is widely used in aircraft industries. It is very difficult to weld in fusion technique due to poor solidification and microstructure in weld region. Friction Stir Welding is reliable technique to joining aluminium alloys in solid state condition with sound weld ability. In this work, rolled aluminium plate with thickness of 10 mm were square butt welded by Friction Stir Welding (FSW) process. The electrochemical corrosion behavior of FSW joints were investigated in 3.5% wt NaCl solution. The corrosion morphology of friction stir zone has been compared with parent metal. It is observed that, stir zone prone more corrosion potential than parent metal.

Correlating Tensile Properties with Microstructures of Various Regions in Gas Tungsten Arc Welded AA2014 Alloy

AA2014 is a heat treatable aluminium alloy found its application in light weight structures owing to its superior strength to weight ratio. The alloy was welded with automatic gas tungsten arc welding. The microstructure and mechanical properties of each zone such as parent metal (PM), heat affected zone (HAZ) and fusion zone (FZ) of the weldment were studied using optical microscopy, microhardness survey and micro-tensile testing. The PM with elongated grains with evenly distributed Al2Cu phases showed a tensile strength of 456 MPa and 24% elongation; the HAZ and FZ offered a reduction in strength and ductility. The grain coarsening with segregation of continuous string of Al2Cu along grain boundaries in HAZ and the formation of coarse dendritic grains with continuous network of brittle Al2Cu and a minor fraction of porosity at interdendrite in FZ were attribured to the observed strength reduction in these regions. Keywords: AA2014 alloy; gas tungsten arc welding; optical microscopy; microhardness; micro-tensile testing.