Effect of Alloying with Molybdenum and Chromium on Pipe Steel of Strength Category X65 Properties

Abstract

Kinetics of austenite phase transformation in previously deformed steels of different alloy systems during continuous cooling are studied. It is shown that with a basic chemical composition of 0.06% C and 1.55% Mn–Nb–Ti alloying with chromium (0.19%) leads to the formation after cooling of an almost identical microstructure, as also with addition of molybdenum (0.14%), from the point of view of fineness and hardness. An optimum steel alloy system is suggested from an economic point of view that provides the required set of properties for rolled sheet more than 30 mm thick of strength category X65 produced under conditions of the VMZ (Vyksa) sheet rolling complex (5000 mill).