Livarski vestnik 58 / 2011 Nr. 1

Zdenka Zovko Brodarac, Faruk Unkić, Katarina Terzić
INFLUENCE OF THE MELT TREATMENT ON THE MICROSTRUCTURE AND MECHANICAL PROPERTIES DEVELOPMENT OF THE ALSI10MG ALLOY

Janez Tušek
THE COMBINATION OF LASER WELDING AND TIG WELDING FOR THE REPAIR OF DAMAGED TOOLS

Lorenz Ratke, Ashok Sharma, Divya Kohli
EFFECT OF ROTATION SPEED AND HOLDING TIME ON AL-7SI ALLOY CAST BY RAPID SLURRY FORMATION (RSF) TECHNIQUE


Zdenka Zovko Brodarac, Faruk Unkić, Katarina Terzić

Influence of the melt treatment on the microstructure and mechanical properties development of the AlSi10Mg alloy
Abstract

 

An influence of the melt treatment on the microstructure development and mechanical properties of the AlSi10Mg alloy has been established. Melt of the AlSi10Mg alloy has been treated by inoculant on the basis of Al-Ti-B composition with the aim of primary αAl grains refinement, and by sodium salts to achieve modified fibrous morphology of eutectic silicon, βSi. A microstructure development of the AlSi10Mg alloy was determined on the basis of phase analysis and microstructural characteristics of the main constituents such as average surface area and the particles length in base, inoculated and modified melts related to the secondary dendrite arm spacing (SDAS). Correlated SDAS values and mechanical properties such as tensile strength and micro hardness indicate the efficiency of particular mode of melt treatment.

Key words: AlSi10Mg alloy, inoculation, modification, microstructure, mechanical properties

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Janez Tušek

The Combination of Laser Welding and TIG Welding for the Repair of Damaged Tools

Abstract


The article presens and describes the use of two welding processes for the repair of damaged tools for different purposes. The first part presents the problem, and then a brief comparison of the TIG welding and laser welding in terms of repairing is made. The macro section of welds shows the difference between the above mentioned processes and two macro sections illustrate the use of the two welding processes for the repair of damaged tools. At the end of the article the main findings are given. The most important conclusion is that, in many cases, for the repair of damaged tools it is useful to use TIG welding and laser welding in order to achieve better quality. The order, however, is dependent on the type of tools and the type of damage to the tool, which should be remedied.

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Lorenz Ratke, Ashok Sharma, Divya Kohli

 

 

Effect of Rotation Speed and Holding Time on Al-7Si Alloy Cast by Rapid Slurry Formation (RSF) Technique

Abstract

The experimental investigation consisted of casting Al-7Si alloy by rapid slurry formation (RSF) technique. The RSF process is based on the enthalpy exchange between at least two alloy systems having different enthalpies, with the aim of forming a semi-solid metal slurry. Thus, slurry with 0.3 solid fraction was made by this process. Prior to starting the experiment 0.01 % SiB (mass fraction) was also added in the melt for additional grain refinement. Stirring speed was varied from 800 to 1800 rpm and for each experiment the samples were quenched in water at different time intervals; 0 min, 5 min, 10 min and 15 min. It was observed that rapid heat extraction, nucleation and forced shearing action developed globular α-Al phase. It was also found that rotation speed, holding time and addition of Si-B grain refiner affected the average α-Al particle size. The coarsening of particles was experimentally investigated and also theoretically described by applying the LSW theory.

Keywords: rheocasting, semi-solid slurry, RSF, Al-7Si alloy, particle size, coarsening.
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