Speaker
Description
Nanostructurization by bainitic phase transformation is a revolutionary method of improving mechanical properties of the wide range of steels. It can be applied as a single process or as a part of the innovative multistage heat treatment, named B-Q&P, which combines, in one route, two processes: Bainitization and Quenching & Partitioning. While implementing to high carbon low-alloy steels it allows obtaining a new type of complex microstructure consisting of very hard carbides in tough, nanocrystalline matrix. By changing the amount of particular components in the microstructure it is possible to change mechanical and service properties of steel.
In the present work, the kinetics of bainitic phase transformation was investigated in high carbon steel, containing enhanced concentration of silicon and carbide forming elements, by dilatometric tests. The phase composition and morphology of phase constituents were determined by observations with the scanning electron microscope (SEM) and transmission electron microscope (TEM), accompanied by the XRD and magnetic measurements. The study was completed with mechanical tests, including hardness measurements, uniaxial tensile test, impact and fracture toughness tests.
Content and distribution of precipitates in austenite influence the kinetics of bainite transformation, as well as the final microstructure morphology. It occurred that some of the particles can act as additional sites for nucleation of bainitic ferrite, which results in finer structure and larger misorientation. The investigation led to the hypothesis of the significant impact of the bainite morphology on the increase and deflection of crack propagation path.
| Speaker Country | Poland |
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