Special Ductile Cast Irons with Increased Complex of Mechanical Properties

Processy litʹâ, 2019, Tom 134, №2, p.73-78

Abstract

Received 14.02.2019

UDK 669.162.275:620.17

Ductile cast iron with spheroidal graphite is acknowledged in the world as a unique multifunctional material for products of the most important purpose in many industries. It has a favorable combination of strength characteristics and high casting properties (high fluidity, low shrinkage and crack formation tendency), which allow to produce castings of any geometric complexity and weight. Therefore, research aimed at further improving of ductile cast iron technological, mechanical and operational properties and quality of cast products made of it is relevant. For increasing of strength characteristics and giving of special properties (wear resistance, impact resistance, resistance to fatigue failure, etc.) ductile cast iron is subjected for alloying. Widely used is alloying with nickel and copper which are elements that strengthen the solid solution, promote perlite formation in the metal base and at the same time do not form carbides in cast iron. Homogenizing annealing is carried out for plasticity increasing. Data about mechanical properties change of unalloyed and alloyed with nickel or copper ductile cast irons depending on castings discharge temperature from a thermal furnace for air cooling after homogenizing annealing is presented in the article. The nature of ductile irons tensile strength, yield strength and elongation changes in the castings are identified and analyzed. Higher strength values were obtained at casting discharge temperatures from 770 to 810 ⁰C. As a result of the research, the technological parameters of ductile cast iron obtaining with increased complex of mechanical properties were established.