Chemical composition improvement of aluminum-iron bronze industrial casting

Interstate standard GOST 493 provides for the maximum allowable zinc content in bronze BrA9Zh3L not more than 1 (wt.) %. Zinc in aluminum-iron bronze composition has controversial influence on casting technological and mechanical properties. The specified element improves material castability, but, in certain amount, leads to product embrittlement. Problem statement. In the present work the problem of effective amount of zinc determination for casting bronze BrA9Zh3L properties improving without negative affecting the plastic and impact characteristics of foundry products has been solved. Purpose. The purpose of this study was an evaluation of Zn content influence on BrА9Zh3L bronze structure and mechanical properties and determination of its rational doping. Materials and Methods. Aluminum-iron bronze BrА9Ж3Л according to GOST 493, alloyed with zinc in an amount 0…4 (wt.) %. Fractography of destroyed impact samples surfaces and the products microstructure have been studied according to ASTM E3 − 11 (2017) requirements. Mechanical static tensile tests were carried out according to GOST 1497, impact toughness according to GOST 9454. Results. It has been established that the zinc content increasing over then 0,2 % by weight in bronze BrA9Zh3L composition effects not only on significant strength decreasing, but also on sharp ductility dropping. The reason for such regularity is the number of eutectoid component in BrA9Zh3L structure increasing. Conclusions. Active loosing of BrA9Zh3L bronze plasticity and ductility, associated with alloy structural state changing, has been recorded in the range of 0,2...0,6 (wt.) % Zn. For industrial cast products maximum Zn content in bronze BrA9Zh3L has been recommended to limit by 0,2 (wt.) % against normatively stipulated 1,0 (wt.) % as per GOST 493.