Study Of Internal Friction In MR T-2.5 Tinplate And Al-Zr Alloy

The property of metallic materials depends on their composition and internal structure, and the existing state of interstitial and trace elements have an impact on the property of materials.In order to control the property of material, It is important to study the effect of the interstitial atoml and trace elements on the property of materials. Currently, there are few methods that used to test the state of interstitial and trace element in materials, but it is effective method to measure internal friction curves of metallic materials.Experiments, including low frequency internal friction inverted torsion pendulum measurement, metallographic examination and energy dispersive spectrometer detection, were carried out to study the state of free carbon atoms existing in MR T-2.5 tinplate when rolled and the state of Zirconium atoms existing in Al-Zr alloys after annealed or quenched.Carbon atoms were dissolved in the interval of ferrite lattice in the continuous hot rolling state. The increase of dislocation density in the process of cold rolling attracted the carbon atoms to form Cottrell atmosphere at lattice dislocation. The carbon atoms were dissolved to form Fe3C in the process of annealing. The precipitation of carbon was intensified when leveled.After different heat treatment conditions, six different types internal friction peak were observed in Al-0.03wt%-Zr, Al-0.05wt%-Zr and Al-0.10wt%-Zr alloys: a grain boundary internal friction peak which was caused by solid solution of Zirconium at lower temperature, a grain boundary internal friction peak was caused by special arrangement of grain and a grain boundary internal friction due to precipitate of second phase; a diffusion internal friction peak was observed, caused by the diffusion of Zirconium at high temperature side of P1 peak; between the temperature where P1 peak and P2 peak located another internal friction peak caused by phase transformation was observed; at higher temperature a bamboo grain boundary internal friction peak was observed.By comparing the effect of Zirconium content on P1 peak, an important law was found. For the grain boundary internal friction, the content of 0.06wt% is the turning point. The grain boundary internal friction is mainly due to solid solution grain boundary internal when Zr content is less than 0.06wt%, and the grain boundary internal friction may come from the precipitate grain boundary internal friction based when Zr content is more than 0.06wt%. Besides, the effect of Zr on high temperature background was studied. The result is that with annealing temperature increasing Zr addition will give rise to a decrease of background.