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Discussion on the Methodology and Apparatus for Hot Distortion Studies

Ignaszak Z.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 2

141--145

EN

The paper refers to earlier publications of the author, on identification of properties of thermomechanical, chemically hardened core/mold sands. In that earlier period, first version of the original DMA apparatus, produced by a Polish company Multiserw-Morek, was used. The Hot Distortion (HD) study results, published by the author in 2008, referred to phenomena accompanying a thermal shock in real conditions of thermal interaction of a liquid alloy on a mold, in reference to a shock possible to obtain in laboratory conditions, without use of liquid alloy as a heat source, with analysis of solutions applied in the DMA apparatus. This paper presents author’s observations on testing a new, innovative version of the LRu-DMA apparatus, containing a module allowing the Hot Distortion (HD) study. Temperature of specimens achieved in the case of the gas burner heating reaches values definitely above 800°C on the heated side and 610°C on the other side. Using an electric radiator, with maximal temperature of 900°C allows obtaining temperatures in between 225-300°C.

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The analysis of thermo-mechanical and diffusion phenomena in the process of ceramic-metal friction welding.

Włosiński W., Zimmerman J.

Archives of Materials Science

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2006

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Vol. 27, nr 1

5-27

EN

In this paper a physical model of friction welding of elastic materials and plastic metals is presented. The model has been practically verified in the process of friction welding of corundum ceramics, containing 97.5% of Al2O3, and Al as well as in the process of friction welding of the same ceramics and Cu. In the process of Al2O3-Al welding the following conditions, i.e. values of the process parameters were applied: diameter of cylindrical bonded elements - 10 mm, pressure in the stage of friction heating - 18 MPa, rotational speed of the ceramic element - 14500 r.p.m., heating time - 0.85 s. pressure in the stage of forging - 46 MPa, time of Al forging - 3.5 s. Mechanical strength of the acquired welded joints was sufficient. Also, diffusion of Al into Al2O3 was observed in the bonding zone. The mathematical modelling of the friction welding process is also demonstrated. Simulation of the process was performed by means of finite element (FEM) method using two FEM systems, namely ADINA-T and ADINA. The process conditions in the numerical simulation were the same as those in the technological process. In ADINA-T the temperature field, which changed with time, was determined. The field was then superimposed onto the mechanical one (ADINA). The simulations made it possible to observe the thermo-mechanical phenomena that take place during the process. The obtained results show that the pressure and temperature distribution on the contact surfaces of the bonded elements is non-homogeneous. This fact has a significant influence on the quality of the welded joint. The performed calculations and studies on the influence of the diffusion phenomena on the welding process showed that the diffusion depth is approx. 4 micrometres and the calculated diffusion coefficient of Al into Al2O3 is 1.8x10 to the -13 square metres/s. Diffusion of Al into Al2O3 generates also internal stresses in the intermediate layer between the welded elements.

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Zjawiska termo-mechaniczne w procesie zgrzewania tarciowego ceramiki Al2O3 i aluminium

Zimmerman J.

Przegląd Spawalnictwa

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2005

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R. 77, nr 9-10

32-34