Abstract
The effect of a change in the morphology of the pearlite colonies on the Charpy impact energy of a fully pearlitic steel containing 0·76%C, 1·20%Mn, and 0·085% V was examined over the range of testing temperatures from −50 to 200°C. The change from a multicolony nodular pearlite structure produced from austenite of grain size 185 μm to a structure composed of individually formed colonies produced from austenite of grain size 25 μm caused a decrease in the transition temperature of 75 K and an almost 100% increase in the Charpy impact energy measured at room temperature. It is proposed that the impact toughness of pearlitic steel can be affected by pearlite morphology, at constant interlamellar spacing, only at temperatures above the ductile–brittle transition temperature of the ferrite, when local plastic deformation in the pearlitic ferrite at high angle boundaries can arrest propagating brittle cracks.
MST/730
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