. FORMATION OF LAMELIAR PEARLITE IN HOT WORKED STEEL 
D. Kmetic, F. Vodopivec, Slovenske zelezarne, Metalurski institut, 
Ljubljana, lepi pot 11, YU 
Pearlite is the main constituent of the microstructure of many 
steels. The inter-lamellar spacing which has a significant influence 
on the properties of a steel depends on the conditions of austenite 
transformation. Controlled cooling after hot work assures constant 
conditions of transformation and therefore better and more uniform 
mechanical properties and better results of subsequent cold working. 
The aim of this work was to determine the influence of the final 
temperature of deformation and that of subsequent isothermal trans- 
formation on the inter-lamellar spacing and morphology of pearlite. 
Microstructural peculiarities were examined by SEM and optical 
microscopy. 
EXPERIMENTAL 
Two different carbon steels, a manganese steel and a chromium/ 
silicon spring steel were investigated (Table 1). 
cc Si Mn S Cr Al 
C. 1531 0, Ul 0,15 0,82 0,027 0,020 -- 0,026 
C1731 0,62 0,22 0,76 0,016 0,026 -— 0,025 
¢.3134 0,45 - 0,33 1,66 0,017 0,029 oe 0,040 
€., 4230 0,62 1,28 0,47 0,016 0,012 0,68 0,033 
Table 1: Chemical composition, wt. % 
After austenitization at 1150 °c specimens were deformed between 
1000-750 26 the last reduction being carried out by hot rolling. 
25 % deformation, which represents the last partial reduction, was 
performed by drop hammer. Isothermal transformation was carried out 
using a lead bath at temperatures selected from corresponding TTT 
diagrams. 
Isothermal transformation of hypo-eutectoid steel begins with the 
formation of ferrite, the remaining austenite is enriched in carbon 
until saturation when it transforms into pearlite. The saturation 
of austenite depends on the temperature of austenite as given by 
201. 
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