Characterisation and Quantification of Complex Bainitic Microstructures in High and Ultra-High Strength Linepipe Steels

Stanislaw Zajac; Volker Schwinn; K.H. Tacke

doi:10.4028/www.scientific.net/MSF.500-501.387

Paper Titles

Factors Limiting the Achievable Ferrite Grain Refinement in Hot Worked Microalloyed Steels
p.355

Processing and Stability of Ultrafine Grained Structures in Some Microalloy Steels
p.363

Study on Ferrite Intragranular Nucleation in a V-Microalloyed Steel
p.371

In Situ X-Ray Diffraction Measurements of Deformation-Induced Austenite to Martensite Transformation in a Multiphase TRIP Steel
p.379

Characterisation and Quantification of Complex Bainitic Microstructures in High and Ultra-High Strength Linepipe Steels
p.387

Austenite Decomposition in Low Carbon Steels with Microalloy Additions
p.395

Modeling Ferrite Grain Size Distributions during the Transformation of Hot Worked Austenite
p.403

Ferrite Grain Size Refinement in Vanadium Microalloyed Structural Steels
p.411

The Kinetics of the Isothermal Bainite Formation in 1%C-1.5%Cr Steel
p.419

HomeMaterials Science ForumMaterials Science Forum Vols. 500-501Characterisation and Quantification of Complex...

Characterisation and Quantification of Complex Bainitic Microstructures in High and Ultra-High Strength Linepipe Steels

Abstract:

This paper provides a detailed description of complex bainitic microstructures obtained during the recent development of low carbon linepipe steels with strengths in the range of X100 to X120. New experimental techniques based on a high resolution FEG-SEM and EBSD have been used to characterise and quantify the mixture of ultrafine bainitic ferrite and nanosize second phases in these steels. It was found that the occurrence of incomplete transformation generates new, previously unexplored bainitic microstructures with a wealth of microstructural features that is beyond classification based on conventional concepts. Clear differences in distributions of boundary misorientations and effective grain size were noted between upper, lower and granular bainites. Based on these results a new classification scheme and definition of bainite is proposed.