Behavior of Pearlite in ThermoMechanical Processing and Service-Historical Perspective

Abstract

After 1780, wrought iron (WI) provided a structural material and steel was cherished for its hardness and cutting qualities. When available in quantity after ~1860, steel’s structural strength and wear resistance were recognized in normalized condition in armor plates, rails and drawn wire. The responsible microstructure component was pearlite in which the lamellar spacing of ferrite and carbides could be refined by simple bulk heat treatments that are practiced with small modification until today. The strength and toughness rose as the layer thickness decreased the ferrite slip length and the carbide cracking. In hot working, the strength rises as much as 200% (while ductility falls) with fraction of pearlite; below the transus compared to austenite just above it, strengths are equal at about 0.7C (ductilities equal at 0.35C).