Substantiation of rational replacement material for connecting hoses brake system of railways rolling stock

Purpose. Purpose of the work was study of structure and mechanical properties of cast irons with different shape of graphite including their thermal treatment, to support rational replacement material connecting hoses break system. Methodology. Material studies were malleable according to GOST 1215 and high strength according to DSTU 3925 irons for the manufacture of hoses brake system according to GOST 2593. Heat treatment of cast irons matrix conducted on lab equipment according to adopted in industrial practice modes of austempering. Mechanical tests on static tension conducted according to GOST 1497 on testing machine ?Instron?. Impact toughness tests were carried out in accordance with GOST 9454 on pendulum machine PSW-5. Hardness studied using testing equipment TB 5004 according to requirements of GOST 9012. Metallographic analysis was carried out on manufactured according to standard methods of GOST 3443 microscopic specimens by using of microscope ?Neophot-2?. Findings. Data analysis of microstructure research and mechanical trials demonstrated a significant dependence of the plasticity of cast iron from graphite inclusions form. This shows that elongation insignificantly varies depending on the type of metal matrix. It was discovered that, instead, the hardness is mainly determined by the matrix of iron. Comparative analysis of mechanical properties of both the investigated types of cast irons with various graphite shape and different type of metal matrix fixed during the transition from the ferrite structure to pearlite falling relative elongation in almost ten times. It was shown in the work unconditional perceptiveness of cast irons with graphite component isothermal hardening in terms of their mechanical and exploitations properties increasing. Originality. Absolute advantage of cast irons with nodular graphite iron, both in terms of plastic and strength characteristics compared with malleable irons with compact branched form of graphite has been determined. Achievement of nodular graphite iron after austempering mechanical characteristics, that prevailing relevant indicators for malleable cast irons allowed considering the thermal strengthening by isothermal quenching method as an additional argument in favor of use the high-strength cast irons in heat treated condition for metal elements manufacturing for railways rolling stock brake system. Practical value. Obtained in the work results were the basis for rational replacement of material connecting hoses brake system rolling stock of railways according to GOST 2593 by globular graphite iron according to DSTU 3925. Such a technological implementation clearly can be seen also as a preferential for use in terms of saving energy, in the first place - natural gas, taking into account the peculiarities of technological processes of industrial production of malleable and high strength cast irons.