RESEARCH AND IMPROVEMENT OF THE MECHANICAL PROPERTIES OF SILUMIN AK7ч

Abstract

Purpose. Research and improvement of the technology of improving the quality of secondary silumins developed by Zaporizhzhya Polytechnic National University. Due to the lack of own production of primary aluminum in Ukraine, improving the mechanical and service properties of secondary aluminum alloys obtained from scrap is an urgent task.
 Research methods. The object of research was the secondary aluminum alloy AK7ч with chemical composition, %: 6.72 Si, 0.05 Cu, 0.08 Mn, 0.32 Mg, 0.02 Zn, 0.01 Ti, from 0.49 to 1 .59 Fe (5 fractions), the rest – Al. To neutralize the negative effect of iron and other impurities on the mechanical properties of the secondary alloy AK7ч, a complex technology (sorting of scrap, refining and modification of liquid metal) was used. The content of the complex modifying additive MK-1 was 0.10%; 0.12%; 0.14%; 0.16% and 0.20%, respectively, with increasing iron content. Yield strength, elongation, and hardness were determined by standard methods at room temperature. Fatigue tests were performed on a magnetostriction machine at a frequency of 18 kHz. Control of the frequency of oscillations was carried out using a frequency meter. The influence of the load frequency on the fatigue characteristics of the alloy was evaluated using the fatigue life curves with a limited endurance limit.
 Results. An increase in mechanical properties, including resistance to destruction at high load frequencies, has been achieved.
 Scientific novelty. New data were obtained on the effect of iron on the fatigue strength of aluminum alloy AK7ч.
 Practical value. The obtained results expand the possibilities of using secondary aluminum alloys. The established dependencies can be used in the optimization of the composition of secondary silumins.