RESEARCH OF MELT PROCESSING IMPACT WITH ELECTROMAGNETIC PULSES UPON SILUMIN WEAR-RESISTANCE

Abstract

To improve functional properties of pre-eutectic silumins there are used many different methods having a complex effect upon processes of structure formation and physical-mechanical properties of alloys. In this paper there is offered a method for alloy operation characteristics increase by the example of wear-resistance by the impact of nanosecond electro-magnetic pulses (NEMP) upon silumin melt AK7ch (AL9). Melt illumination was carried out with the generator (NEMP) (GNI-01-1-6) submersible rod radiator. The melt was overheated to 900ºC and processed with NEMP with the length up to 25 min after that it was cooled at a rate of 20ºC/min. Slow cooling contributed to the formation of a structure close to equilibrium. Cylindrical ingots with a diameter of 0.06 m (60mm) and a height of 0.06 m (60 mm) were obtained. Wear-resistance was defined on a cross cut of ingots according to GOST 23.208-79. As a standard of comparison were used non-irradiated samples of silumin. It is defined that melt NEMP processing changes considerably parameters of crystallization, structure formation and increases silumin properties. At abrasive wear, silumin wear-resistance changes from the duration of melt electro-pulse processing according to an extreme dependence with the evident maximum at melt irradiation in the course of 15 min. At that in the edge area of the ingot wear-resistance increases by 1.54 times, and in the central one – by 1.34 times. This effect is explained by the fact that during melt NEMP processing during 15 min the characteristics of alloy micro-structure change considerably: morphology and dimensions of structural constituents. At that there is formed a qualitatively new fine structure of a non-dendritic type which ensures maximum values of alloy wear-resistance. The data obtained allow developing technology of wear-resistant silumin fusion intended for operation under abrasive wear conditions.