• EFFECT OF ANTIMONY ON AUSTENITE TRANSFORMATION AND THE METALLIC MATRIX STRUCTURE IN DIFFERENT WALL THICKNESSES OF DUCTILE IRON CASTINGS

    Materials Science. Non-Equilibrium Phase Transformations., Vol. 4 (2018), Issue 1, pg(s) 12-14

    Effects of additions of 0.0039, 0.01, 0.019 and 0.029 wt.% Sb on austenite transformation and the metallic matrix structure in the wall thicknesses of 3, 12, 25, 38, 50, 75 and 100 mm of ductile iron casting containing 2.11 wt.% Si and a low amount of Cu, Sn and Mn were analyzed in this paper. In the examined ductile iron casting without the addition of Sb, the share of pearlite in the metal matrix was decreased and the share of ferrite was increased with increasing wall thickness. The share of pearlite was low. Additions of Sb were increased the share of pearlite in all the walls. Increase of Sb content resulted in increasing the share of pearlite. Almost the same high share of pearlite in the wall thicknesses of 12, 25, 38, 50, 75 and 100 mm was obtained by addition of 0.029 wt. % Sb (varied from 96.00 to 97.61 %). The additions of 0.01, 0.019 and 0.029 wt.% Sb were resulted in a fully pearlitic metallic matrix in the wall thickness of 3 mm. Iron carbides were found in the wall thickness of 3 mm when Sb was added.

  • MATERIALS

    APPLICATION OF NONLINEAR CONTROLLED COOLING REGIMES FOR STRUCTURE FORMATION MANAGEMENT IN EUTECTOID STEEL

    Machines. Technologies. Materials., Vol. 12 (2018), Issue 2, pg(s) 80-81

    Using computer modelling with originally developed semi empirical physical grounded models study of structure formation when austenite transformation during cooling by certain regime in eutectoid steel was carried out. The model allowed us to predict final structure. Cooling curves leading to fine pearlite (almost without bainite) and lower bainite (with a small part of fine pearlite) structures were find out. The results obtained could be useful for high carbon ordinary instrumental and constructional steels with higher manganese production and processing (rails, cord and rope wire, springs, low stressed instruments). Realization of the fine pearlite obtaining regime needs equipment that could provide cooling rates from 0.04 deg./sec. to 6.6 deg./sec. with average value of 1.1 deg./sec.. For bainitic structure obtaining the range of cooling rates provided shoud be from 0.14 deg./sec. to 14.0 deg./sec. with average value of 2.2 deg./sec. The cooling intensivity must have an ability to arbitrary and controlled changing during process.