Possibilities of influencing the γ‐α‐transformation products of hot‐rolled pearlitic steels

Abstract

Controlled alloying, optimum configuration of the rolling schedules, and a suitable cooling strategy make it possible to broadly influence the microstructure and mechanical properties of higher‐carbon steels. Increasing the manganese content and microalloying with vanadium delay the diffusion‐controlled γ‐α‐transformation, and the increase in the amount of pearlite improves strength properties. Lowering of the finishing temperature refines the austenite microstructure, and increases the level of residual strengthening that remains in the austenite. This changes the amount of ferrite and improves the resistance to brittle fracture. Applying a cooling interruption step in the ferrite formation temperature range also permits an additional variation of the amount of ferrite. The extent to which recalescence develops during the formation of pearlite can bring about significant changes in the pearlite morphology and hence influence strength and toughness properties. Accelerated cooling to a low coiling temperature, as a further process‐related modification, promotes the formation of bainite, obtaining high strength properties without any mentionable loss of toughness.