19 - 23 September 2023,

                                          Royal Hotel Carlton

               Bologna, Italy

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Conference Proceedings

Paper Awards Milan 2013

The Best Papers for Innovative Content

The Aluminium Two Thousand 8th World Congress officially closed on May 18th, but it’s echo is still strong. The great number of papers presented have brought to the attention of the aluminium industry very innovative technologies and some of them have already been requested to some qualified speakers and to their companies for industrial application in the near future.
technical committee formed by Prof. Lorenzo Donati and Prof. Luca Tomesani of the University of Bologna, Italy for extrusion, Dr. Walter Dalla Barba, of Interall, Italy for finishing, Dr. Rosario Squatrito of the University of Bologna, Italy for casting and Eng. Luca Magagning of AIMF, Italy for metallurgy, alloys billets & related equipment, measuring, testing & quality techniques, rolling assigned awards to the best papers for innovative content.



Characterization and modeling of the deformation and damage behavior of thick-walled aluminum profiles
Dong-Zhi Sun, Fraunhofer Institute for Mechanics of Materials Iwm
Extruded aluminum profiles show a pronounced anisotropic deformation behavior and inhomogeneous properties over thickness and for different wall thicknesses. A difficulty for modeling of thick-walled profiles is that vehicle simulations have to be performed using shell elements due to computer capacity and the applicability of shell elements for thick-walled components has not been verified. Since fracture strains of aluminum profiles are relatively low, damage modeling has to be included in component simulations. However, it is open, which model can be used in these cases and which specimen tests have to be performed to calibrate the model parameters.
In this work an extruded aluminum profile was characterized under crash relevant loading. Uniaxial and bi-axial tension, shear and bending tests were performed. The inhomogenity of local properties in the aluminum profile was quantified with specimens extracted from different positions. Component tests were performed under compression. An anisotropic material model according to Barlat and a special damage model (Bi-Failure) were used to simulate the different tests. The influence of element types (shell and solid elements) on numerical results was analyzed. The applicability of the used material models and element types was verified by comparing experimental and calculated results of the component tests.


Prediction of grain shape evolution during extrusion and annealing of 6XXX alloy
Antonio Segatori, DIN-Dept. Of Industrial Engineering, University of Bologna
Experimental and numerical analysis are used to investigate the grain shape evolution of 6082 aluminum alloy during hot forming as the extrusion process developing a prediction model. An experimental campain, by means of small scale direct extrusion, was carried out in order to investigate the texture deformation modes and retrieve the microstructure evolution model. This was coupled with the analytical recrystallization formulations available in literature for the final implementation in a FE commercial code. A unified model was therefore implemented in the Deform FE code through user-routine, thus carrying the innovation of a model able to simulate grain evolution during the entire process: deformation and following ageing with and integrated approach.
A second experimental campaign was used to validate the model. A reduced scale inverse extrusion test was performed with a wide industrial range of the Zener-Hollomon value, comparing the experimental and numerical results at the end of the dynamic evolution and at the end of the consequent static recrystallization. Attention has been given also to defective recrystallization phenomena like abnormal grain growth; while this phenomena is still to be implemented in the current model, the latter one is shown to be able to properly predict the grain evolution during the process.



Stress Accelerated Tempering of Hot Work Steels as a Failure Mechanism in Aluminum Extrusion Tooling and Die Casting Dies
Joseph C. Benedyk, Thermal Processing Technology Center
Conventional tempering curves (isothermal curves of hardness vs. time ) for steels that have been austenitized and quenched to form martensite essentially provide information on tempering behavior at tempering temperatures with zero stress applied. At the same time, in hot work tooling used in aluminum extrusion and dies used in high pressure die casting, the die steels in the quenched and tempered condition, are subjected to stress and temperature, begging the question of what is the effect of stress and temperature combined on these dies and tooling during application. A significant history of stress accelerated tempering of a variety of hot work steels has been established in various types of tests conducted under specialized thermal fatigue and creep testing conditions. The effect of stress accelerated tempering, i.e., how hardness of quenched and quenched and tempered steels changes with stress at hot working or die casting temperatures is one of the fundamental failure modes encountered in aluminum extrusion tooling and die casting dies. Previous studies of stress accelerated tempering of various hot work die steels are reviewed, and the role of high temperature austenitizing on modifying the effects of stress accelerated tempering in order to increase tooling and die life in aluminum extrusion and die casting are described.




Base metal microstructure considerations for anodizing wrought aluminum alloys
Jude M. Runge, Compcote International, Inc.
Wrought aluminum alloy components which conform to design specifications may sometimes exhibit finish deficiencies after anodizing in a well controlled process in spite of different lots of conforming material (same alloy and temper) finishing well through the same process. In many cases, the answer to the problem can be found in the overlooked characteristic of microstructure. This paper examines the relationship between extrusion parameters, temper and cold work hardening, alloy chemistry and microstructure, specifically as it pertains to the surface chemical potential and therefore the quality and appearance of the anodic oxide finish. Data will be presented for cold work hardenable and precipitation hardenable alloys. The reactions which occur during aluminum finishing will also be discussed.



Aluminum Bright Dipping – Theory and Practice
Mary Oakley, Potashcorp
The theory of Bright Dipping aluminum will be explained in practical terms as it relates to specular reflectance, diffuse reflectance and absorbance on the surface of aluminum. The chemistry of the Bright Dip reaction will be detailed and the mass balance in the Bright Dip bath will be explained as will the maintenance of the bath. The different types of formulations currently available will be mentioned. Once grasped, the practice of Bright Dipping Aluminum will become a simpler task.


Development of an innovative "super" seal with improved acid corrosion resistance and new feature: resistance to alkali
Fabio Vincenzi, Italtecno
New requirements are being proposed in this last period by the market, requirements that could also be defined as new challenges to improve the quality of the anodic oxide besides those that are its normal prerogative. The new requirements concern the resistance to alkaline environments of the anodic oxide; to be obtained with an ecological and user-friendly product. Although the anodic oxide is quite resistant when exposed to atmospheric agents and in acid environments it does, however, suffer from quite evident problems when in an alkaline environment. There are several requests to provide the anodic oxide with a high resistance to alkalis in order to use anodized aluminum in fields in which the use of the same would not have been possible until today. Examples of resistance to alkaline detergents: the car wash in the automotive field or the dishwasher in the food industry or again, windows/doors in the architectural field. Resistance to a particular oil in the mechanical field. Resistance to sweat and fingerprints in the field of internal design.
A new sealing product has been developed to meet this type of requirements. Based on tests made this product meets the requirements according to international standards in full, especially, those of the major automotive industries; very careful to ensure a good resistance of their products in anodized aluminum. The newly developed super seal passes the test of resistance to alkaline agents as – but not only – Volkswagen TL 212, TL 182, General Motors GMW14665 and FIAT 9.57448.
While the big news of this super seal is the resistance to alkaline environments there are, however, also huge improvements as regards the resistance to acid and corrosive environments and anti-fingerprints. In fact, the new super seal guarantees significantly improved results to conventional sealing tests such as the weight loss test ISO 3210, the drop test ISO 2143 and the Anotest DIN-EN-ISO 12373-5 (ASTM457-67).
The new super seal is completely ecological, non-toxic, easy to use and to analyze and not particularly affected by pollution. The new super seal will, therefore, meet any new requirement set by the market.



Prediction of phase formation during solidification, solution heat treatment, and aging of aluminum alloys using the TCAL database
Hay-Lin Chen, Thermo-Calc Software Ab
Using the TCAL database, a multicomponent thermodynamic database for Al-based alloys, extensive calculations are performed for a wide range of aluminum cast alloys of industrial relevance. First of all, equilibrium and non-equilibrium solidification calculations are performed with the Thermo-Calc software to predict the solidification sequences and phase fractions, so as to account for experimental microstructures. Since most aluminum cast alloys are heat treatable, it is equivalently important to predict phase formation during heat treatment as that during the solidification. Equilibrium and metastable equilibrium calculations are performed for many alloys or alloy systems, in order to validate the Al database and to account for the formation of both stable and metastable phases during solution and aging treatments, as well as to determine the best heating temperatures. It is also demonstrated that the precipitation process itself can be simulated with the newly released TC-PRISMA software, by combining TCAL1 with the kinetic database MOBAL, together with property data.


Prolonged aging effects on the high-temperature behaviour of Al age-hardenable alloys
Elisabetta Gariboldi, Department of Mechanical, Politecnico di Milano
The long-term high temperature, creep, properties of age-hardenable aluminium alloys are widely affected by the heat treatment as well as by the following exposure at high temperature that leads to overaging processes. The creep behaviour of an alloy of the 2xxx series in the classical T6 temper condition was compared to that of specimens further overaged before creep tests. A simple model to predict the effect of overaging on the high temperature material behaviour was proposed based on a
time-temperature parameter, namely the temperature-normalized time, and on its correlation to creep strength and ductility. The model can also be easily implemented to describe the high-temperature mechanical behaviour of complex shaped components where stress redistribution occurs during the first stages of creep or when cracks growth in a material that progressively overages. In the form here proposed, the method can be applied to other age-hardenable Al alloys and in
principle it can be used also for other materials for which exposure at high temperature substantially causes the coarsening of strengthening particles.


Influence of process parameters in ultrasonic treatment of AlSi alloys
Annalisa Pola, University of Brescia
Nowadays ultrasound is one of the most relevant treatment in the metallurgy field able to improve microstructure and mechanical properties of aluminium alloys. This simple technique, in fact, allows the achievement of different advantages like degassing, grain refinement, non-dendritic (globular) microstructure, filtration and solubilisation via a single treatment step. On the other hand, it is influenced from the process parameters used.
The aim of this paper was to evaluate the influence the microstructure of process parameters such as the amount of treated alloy, the melt temperature and the used frequency.
FEM analysis was used to evaluate the ultrasound treatment effectiveness; a comparative analysis between finite element simulations and experimental results was performed on AlSi alloys.
It was found that, even working in a not optimized configuration, the treatment guarantees a limited but positive effect.


A special award was assigned to Dr. Arthur Brace for his 60 years of studies in anodizing and for the innovative research work presented at the Congress about “The New Model of Anodic Coating Formation”.