Effects of cross rolling on multiple twinning and martensitic transformation in an austenitic steel

To improve the shape memory effect (SME) of 304 austenitic steel effectively and efficiently, thermomechanical cycling, comprising deformation at room temperature and annealing, was applied. The influences of cycle number and annealing temperature on the SME and microstructures in 304 austenitic steel were investigated by light microscope (LM), X-ray diffraction (XRD), and transmission electron microscope (TEM). The shape recovery ratio was remarkably improved from 16% to 40% after two thermomechanical cycles. The optimum annealing temperature was 833 K in the process of thermomechanical cycling. The improved SME by thermomechanical cycling was mainly related to stress-induced ε martensite rather than stress-induced α’ martensite. The reason is that thermomechanical cycling can not only promote the occurrence of the stress-induced γ→ε martensitic transformation, but also suppress the subsequently stress-induced ε→α′ transformation.

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In Situ SEM Observation and Analysis of Martensitic Transformation During Short Fatigue Crack Propagation in Metastable Austenitic Steel

Advanced Engineering Materials ◽

10.1002/adem.200900337 ◽

2010 ◽

Vol 12 (4) ◽

pp. 255-261 ◽

Cited By ~ 15

Author(s):

Ulrich Krupp ◽

Ingmar Roth ◽

Hans-Jürgen Christ ◽

Martin Kübbeler ◽

Claus-Peter Fritzen

Keyword(s):

Fatigue Crack ◽

Martensitic Transformation ◽

Crack Propagation ◽

Austenitic Steel ◽

Fatigue Crack Propagation ◽

Sem Observation ◽

Metastable Austenitic Steel ◽

Short Fatigue Crack

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Reversible Martensitic Transformation Produced by Severe Plastic Deformation of Metastable Austenitic Steel

Materials Science Forum ◽

10.4028/www.scientific.net/msf.738-739.491 ◽

2013 ◽

Vol 738-739 ◽

pp. 491-495 ◽

Cited By ~ 4

Author(s):

Igor Litovchenko ◽

Alexander Tyumentsev ◽

Alexander V. Korznikov

Keyword(s):

Plastic Deformation ◽

High Pressure ◽

Martensitic Transformation ◽

Severe Plastic Deformation ◽

Dynamic Recrystallization ◽

Austenitic Steel ◽

High Pressure Torsion ◽

Martensitic Transformations ◽

Metastable Austenitic Steel ◽

Nanostructured States

The peculiarities of martensitic transformations and formation of nanostructured states in metastable austenitic steel (Fe-18Cr-8Ni-Ti) after severe plastic deformation by high pressure torsion are investigated. It is shown that during severe plastic deformation with increased strain rate not only direct (γ→α΄) but also reverse (α΄→γ) martensitic transformations occur, which is revealed by the changes in the volume content of α΄ - martensite during deformation. The fragments thought to be formed by direct and reverse martensitic transformations and those of dynamic recrystallization of austenite are observed.

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