Analysis and characterisation of ultra-fine ferrite produced during a new steel strip rolling process

• Published in: Scripta materialia 1999-01, Vol.40 (4), p.433-438
• Main Authors: Hurley, P.J., Hodgson, P.D., Muddle, B.C.
• Format: Article
• Language: English
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Metals. Metallurgy; Other heat and thermomechanical treatments; Physics; Treatment of materials and its effects on microstructure and properties
• ISSN: 1359-6462; 1872-8456
• DOI: 10.1016/S1359-6462(98)00442-4

A new steel strip rolling process has been recently discovered which uses a combination of heavy shearing of the strip at the surface, resulting from friction between the strip and the rolls, and roll chill to bring about remarkable ferrite grain refinement. Intragranular ferrite nucleation occurs rapidly and extensively on the dislocation substructure within individual austenite grains. The nuclei quickly impinge, but coalscence and growth are inhibited to a large degree by the large misorientation angles between adjacent ferrite grains. EBSD indicates that the ferrite nucleated within each austenite grain is strongly textured. The microtexture observed in a given grain depends on the initial orientation of that austenite grain. The fine ferrite produced by this process has bulk texture components which are predicted by transforming the texture components commonly found in the shear layer of rolled fcc metals using the Kurdjumov-Sachs orientation relationship. Composition of the vacuum cast steel used in this work was 0.0022C, 1.66Mn, 0.22Si, 0.27Mo, 0.023P, 0.026Ni, and 0.014Al.