Non-heat Treatable Alloy Research Articles

Electrical property enhancement of non-heat-treatable wrought aluminum alloys using graphene additives

With growing efforts of electrification, aluminum’s role as a light-weight conductor material has become increasingly prominent. There is a critical need to improve the electrical performance of aluminum at room temperature and high operating temperatures. In this study, the effect of graphene nanoparticle additives on the electrical performance of a non-heat treatable alloy were (AA3003) explored. Graphene’s unusual structure and electronic properties were used to improve AA3003 properties. Here, the effects of graphene on the evolution of electrical properties and microstructural features have been explored on lab scale hot extruded AA3003-graphene composites. Hot pressing schedules and extrusion temperatures were varied to investigate changes in intermetallic dispersion characteristics in the presence of dispersed graphene. We measured a reduction of 10.3 % in the temperature coefficient of resistance in the AA3003 sample with 0.05 wt% graphene extruded at 400 °C, along with a maximum increase of 1.1 % in electrical conductivity at 20 °C. Increasing the hot-pressing times up to 8 hours was also found to consistently increase the electrical conductivity, due to increased precipitation of intermetallic phases. Despite being a non-heat treatable alloy, AA3003 displays interesting precipitation dynamics and grain recrystallization trends that can be modulated with varying levels of heat treatment, graphene concentrations, and hot extrusion process parameters.

Effects of Thermal Cycling on Wire and Arc Additive Manufacturing of Al-5356 Components

Wire and arc additive manufacturing (WAAM) provides a promising alternative to conventional machining for the production of large structures with complex geometry, as well as individualized low quantity components, using cost-efficient production resources. Due to the layer-by-layer build-up approach, process conditions, such as energy input, deposition patterns and heat conduction during the additive manufacturing process result in a unique thermal history of the structure, affecting the build-up properties. This experimental study aims to describe the effects of thermal cycling on the geometrical and material properties of wire arc additive manufactured Al-5356 aluminum alloy. Under consideration, that Al-5356 is a non-heat treatable alloy, a significant effect on geometrical formation is expected. Linear wall samples were manufactured using pulsed cold metal transfer (CMT-P) under variation of wire-feed rate, travel speed and interpass temperatures. The samples were analyzed in terms of geometry; microstructural composition; hardness and residual stress. Furthermore, the mechanical properties were determined in different building directions.

Effect of sheet thickness on the FSW parameters for dissimilar aluminium grades tailor welded blanks

ABSTRACT Friction stir welding has been in use since 1991, for various applications in aerospace, automotive, shipbuilding industries, especially in fabrication with aluminium alloys for structural members. The friction generated between the rotating tool and blank material heats up the base metal, when it is deformed, stirred and mixed. As this takes place in solid state, dissimilar materials are joined with relative ease. This paper describes an attempt to create a joint between AL5083 and AL6082 with optimal friction stir welding parameters and determine the mechanical behaviour of the tailor welded blank for automotive and structural use. The former is non-heat treatable alloy and the latter is treatable aluminium alloy. Thickness of the blanks is varied between 1 and 3 mm to create dissimilar joints and its influence on the joint properties are studied. The process parameters, including tool rotation speed, traverse speed and the applied axial force, were varied to form several dissimilar joints. An empirical relation to predict the tensile strength of the joint is established along with optimal FSW process parameters to attain maximum joint strength. The relationship between optimal FSW process parameters and the sheet thickness is also found out.

Corrosion behavior of Friction stir welded aluminum alloys: A review

A review on corrosion behavior of Friction Stir Welded aluminum alloys has been presented. Objective of the work is to discuss the behavior of Friction Stir Welded aluminum alloys under chloride environment. The variation of corrosion potential and corrosion rate for the welded portion and base metal and within the welded region for various zones like weld nugget, HAZ and TMAZ has been studied. Alloys of series 2XXX, 5XXX, 6XXX & 7XXX are considered and a comparison is made in between heat treatable and non-heat treatable alloys on basis of their response to chloride atmosphere. The effect of tool rotational speed, traverse speed & tool profile on and are investigated. It is concluded that 5XXX series alloy exhibit better corrosion resistance compared to other series whereas 2XXX & 7XXX are most susceptible to corrosion. It is found that except for hexagonal tool profile corrosion rates of welded joints are higher than the parent metal for both heat treatable as well as non-heat treatable alloys.

Simulation of Heat Assisted Forming of Commercial Aluminium Alloy AA5182

To improve the formability of commercial aluminium alloy AA5182, a new heat assisted forming method is used. The process sequence of this method is; cold forming (pre-forming, 90 to 95% of final shape), heat treatment and cooling it down to room temperature and final cold forming. AA5182 is a non-heat treatable alloy and hence heat treating a strain hardened non-heat treatable aluminium alloy leads to lose in strength and gain in plastic recovery. Therefore by heat treating a preformed part and then following it up by further forming stages, it not only gains the lost strength back but also shows increased formability. This behavior is particularly useful in forming more complex automotive interior body parts. To accurately simulate this method, modeling the effect of heat treatment is important. Initial investigations on tensile tests showed that the degree of pre-forming in combination with heat treatment is directly proportional to plastic recovery. Which means, the more the pre-strain is the more the recovery becomes viable. Based on this, a new algorithm has been developed and implemented in LS-DYNA to capture the effect of heat treatment. Finally experimental investigations were carried out on a cross die deep drawn cup to validate the developed simulation model.

Influence of Vacancy Formation and Mg Migration on Cracking in Spot Welding AA5754 Alloys

Al alloys with Mg as the major alloying element constitute a group of non-heat treatable alloys with medium strength, high ductility, excellent corrosion resistance and weldability. However, the segregation of Mg may adversely affect the performance of these materials if they are exposed to rapid heating and cooling environments such as resistance spot welding. The formation and migration of vacancy is an important factor affecting Mg segregation. In this paper, the amount and distribution of Mg were measured by electron probe microanalysis and the vacancy formation energy in AA5754 alloys was measured by positron annihilation lifetime spectroscopy. The results indicated that the segregation of Mg at cracks, occurring under suitable temperature and stress conditions, is related to the formation and migration of vacancies, and may promote crack initiation and propagation.

Strength of Commercial Aluminum Alloys after Equal Channel Angular Pressing and Post-ECAP Processing

The effects of equal channel angular pressing (ECAP), further heat treatment and rolling on the structure and room temperature mechanical properties of the commercial aluminum alloys 6061 (Al-0.9Mg-0.7Si) and 1560 (Al-6.5Mg-0.6Mn) were investigated. It has been shown that the strength of the alloys after ECAP is higher than that achieved after conventional processing. Prior ECAP solution treatment and post-ECAP ageing can additionally increase the strength of the 6061 alloy. Under optimal ageing conditions a yield strength (YS) of 434 MPa and am ultimate tensile strength (UTS) of 470 MPa were obtained for the alloy. Additional cold rolling leads to a YS and UTS of 475 and 500 MPa with 8% elongation. It was found that the post-ECAP isothermal rolling of the 1560 alloy resulted in the formation of a nano-fibred structure and a tensile strength (YS = 540 MPa and UTS = 635 MPa) that has never previously been observed in commercial non-heat treatable alloys.

The Effect of Dispersoids on the Recrystallization Behavior of a High-Purity Al-1.3 Mn Alloy

The effects of concurrent precipitation on recrystallization are reviewed with special emphasis on dispersoid precipitation in non-heat treatable alloys. The isothermal annealing behavior of a supersaturated and deformed Al-Mn alloy is reported and analyzed in terms of a simple model. At low annealing temperatures, precipitation on the prior boundaries prevents recrystallization whereas at high temperatures, recrystallization is complete before precipitation occurs. In the temperature range 375-500°C, recrystallization is affected by precipitation, and complex microstructures containing high fractions of low-angle boundaries are formed. It is shown that large-scale strain induced boundary migration (SIBM) is a very important recrystallization mechanism in this temperature range.

Stress Relaxation in Al Alloys of Al-Mg-Mn, Al-Mg-Sc and Al-Mg-Li-Systems

The paper deals with the investigation results of stress relaxation in deformed semiproducts from AL-alloys of AL-Mg-Mn, AL-Mg-Sc, AL-Mg-Li- systems during their heating from 70 to 210°C and exposure up to 500 hrs. It was established that on the stretcher straightening the compression (up to 180 Mpa) and on the cold rolling the tensile (up to 80 Mpa) stresses occur in specimens. In nonheat-treatable alloys of AL-Mg-Mn, AL-Mg-Sc, AL-Mg-Li- systems the resudial stresses at 70°C for 100 hrs are 60-80% whereas at 120°C - 10-30%. In heat-tretable AL-Mg-Li-alloys the higher level (50%) of residual stresses is retaind on heating at temperature above 120°C. Scandium in combination with zirconium hamper the diffusion mobility in the aluminium solid solution at 70 to 120°C to the greater degree than the manganese does and so decrease the stress relaxation rate.

The Status of the Aluminum Sheet and Plate Industries and Related Research Activities in Korea

This paper was prepared to review the status of the aluminum sheet and plate industries and related research activities in Korea. The aluminum sheets and plates which have been produced in Korea are mainly non-heat treatable alloys, so that the installations of the heat treatment facilities for producing the heat treatable sheets and plates are considered recently by aluminum industries in Korea. Concerning the research activities on the aluminum sheets and plates in Korea, the research topics and contents are mainly described on the basis of the highly advanced national projects which have been started since the middle of 1992.

Structure and properties of ultra-fine grained aluminium alloys produced by severe plastic deformation

Methods of imparting ultra-fine grained (UFG) structure to conventional aluminium alloys by thermomechanical treatment, including severe plastic deformation, are analysed. The effect of initial structure parameters, such as grain size and precipitates of secondary phases, on UFG structure formation is discussed in terms of physical mechanisms. Ambient temperature mechanical behavior of UFG alloys produced by several methods is reported. The effect of grain refinement on static strength and toughness is more pronounced in non-heat treatable alloys. Evolution of UFG structure during post-deformation heat treatment and superplastic behavior of UFG alloys is shown.

Directional pressure quench casting of aluminium alloys

AbstractA novel method of casting is described in which liquid metal in permeable moulds is subjected to high ambient pressure and quenching simultaneously. A small pressure quenching chamber was used and shapes of two different geometries cast into sand moulds. Two non-heat treatable alloys, LM6M and LM21M, comprised the raw material. The results show that increasing ambient pressure alone up to a value of 2 MPa (20 bar) can reduce porosity of castings, has a limited effect on tensile strength, and little effect on dendrite arm spacing. Casting under pressure with quenching increased tensile strength by up to 30% compared with conventional castings and virtually eliminated porosity. The dendrite arm spacing is also considerably reduced. Pressure quench casting is a potentially inexpensive means of improving the mechanical and microstructural properties and integrity of a wide range of aluminium alloys made by existing sand casting methods. For heat treatable alloys it offers the possibility of solution t...

Mechanical Properties of 5083 SPF After Superplastic Deformation

ABSTRACTSuperplastic aluminium alloys may be divided into two categories: those which recrystallise dynamically during superplastic deformation, such as the Supral alloys (2004 SPF) and 8090 SPF and, secondly those in which the fine grain necessary for superplasticity is produced by static recrystallisation during thermo-mechanical processing.Both 7475 SPF and 5083 SPF belong to the second category.This paper describes the superplastic forming characteristics of 5083 SPF and its post-formed mechanical properties.Some typical applications will be shown to demonstrate the degree of complexity which is possible with this non-heat treatable alloy.

Properties of Particles Produced by Different Rapid Solidification Techniques

Two methods of producing PM rapidly solidified 7XXX series aluminium alloy are described: melt spinning (ribbons → flakes) and air atomization (powders). The microstructure and properties of particles (shape, size distribution, alloying concentration profiles) are discussed with regard to cooling rate. The reseach also emphasizes the importance of particle oxidation and its influence on their behaviour during subsequent processing. The trade-offs required between the various particle properties that are considered suggest that melt spun material should be recommended for heat treatable aluminium alloys, while powders should be used for non-heat treatable alloys. PM/0372

Production of High Strength Aluminium Alloys by Extrusion of Atomized Powders

The mechanism of powder consolidation in the extrusion chamber is analysed and it is shown that theoretically the specific pressures required to extrude initial powder compacts will be lower than an equivalent cast billet. The hot working range of metals is thus enlarged and inherently stiffer materials may be extruded. The extrusion of Al alloys from air atomized powders is described and the conditions required for meaningful increases in properties elaborated. The production of Al alloys reinforced by glass is also described and it is shown that although strength levels may be enhanced this type of reinforcement does not lead to a product having a combination of properties significantly more attractive than the cast and wrought product. Consideration is given to other forms of reinforcement. The extrusion of rapidly solidified AI10Mg powder shows that this non-heat treatable alloy has properties comparable with the strongest heat treatable Al alloy. PMj0257

ALUMINUM 214

Abstract Aluminum 214 is a non-heat treatable alloy containing 4% magnesium and characterized by excellent corrosion resistance and excellent weldability. It is recommended for marine applications and food processing equipment. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive and shear strength as well as fatigue. It also includes information on high temperature performance and corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Al-141. Producer or source: Aluminum Company of America.

ALCAN 236

Abstract ALCAN 236 is a general purpose aluminum casting alloy possessing moderate strength. It is recommended for medium-stressed castings requiring good machinability. It is a non-heat treatable alloy. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive and shear strength as well as fatigue. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Al-106. Producer or source: Aluminum Company of Canada Ltd.

5005 Aluminum alloy cables for overhead lines

THE WIDESPREAD ADOPTION of aluminum conductors for urban overhead power systems during the last 10 years has created a demand for a homogeneous aluminum-alloy cable having better sag characteristics than one made of EC (electrical grade) aluminum. With 5005 aluminum alloy, cables have been developed which meet this demand. In addition, since 5005 is a nonheat-treatable alloy, wires can be produced on conventional equipment and manufacturing costs are low.

ALUMINUM 5154

Abstract ALUMINUM 5154, formerly known as Aluminum A54S, is a strong, nonheat-treatable alloy recommended for use in unfired pressure vessels. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength as well as fatigue. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Al-64. Producer or source: Aluminum Company of America.