Powder metallurgical nanostructured bainitic steel

I. Lonardelli, M. Bortolotti, W. van Beek, L. Girardini, M. Zadra and H. K. D. H. Bhadeshia


It has been possible to produce incredibly fine plates of bainitic ferrite separated by a percolating network of retained austenite in a medium carbon steel produced by mechanical alloying followed by spark plasma sintering and isothermal heat treatment. This is because the sintering process limits the growth of the austenite grains to such an extent that the martensite-start temperature is suppressed in spite of the medium carbon concentration. Furthermore, the fine austenite grain size accelerates the bainite transformation, which can therefore be suppressed to low temperatures to obtain a nanostructure. Microscopy and in situ synchrotron X-ray diffraction were used to investigate the morphology and the thermal stability of the retained austenite during continuous heating. These latter experiments revealed a gradient of carbon concentration in the retained austenite and a reduced thermal stability in high carbon film-austenite. It was also possible to correlate the evolution of defect density and carbon depletion in both retained austenite and bainitic ferrite during tempering.

Materials Science and Engineering A, 555 (2012) 139-147

Download paper

Dowload data

Related papers

powder metallurgy

Envelope Superbainite tempering Filling welds Hot Delta
Superbainite toughness Fields Piping Hydrogen TRIP Fine pearlite
Divorced Creep Low density X80 Mechanical stabilisation

PT Group Home Materials Algorithms