Phase transformation in Fe–Mn–C alloys by severe plastic deformation under high pressure

2016 ◽  
Vol 185 ◽  
pp. 109-111 ◽  
Author(s):  
Nozomu Adachi ◽  
Ningning Wu ◽  
Yoshikazu Todaka ◽  
Hideyuki Sato ◽  
Rintaro Ueji
2011 ◽  
Vol 239-242 ◽  
pp. 1300-1303
Author(s):  
Hong Cai Wang ◽  
Minoru Umemoto ◽  
Innocent Shuro ◽  
Yoshikazu Todaka ◽  
Ho Hung Kuo

SUS316L austenitic stainless steel was subjected to severe plastic deformation (SPD) by the method of high pressure torsion (HPT). From a fully austenitic matrix (γ), HPT resulted in phase transformation from g®a¢. The largest volume fraction of 70% a¢ was obtained at 0.2 revolutions per minute (rpm) while was limited to 3% at 5rpm. Pre-straining of g by HPT at 5rpm decreases the volume fraction of a¢ obtained by HPT at 0.2rpm. By HPT at 5rpm, a¢®g reverse transformation was observed for a¢ produced by HPT at 0.2rpm.


Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4621
Author(s):  
Carmela Gurau ◽  
Gheorghe Gurau ◽  
Felicia Tolea ◽  
Bogdan Popescu ◽  
Mihaela Banu ◽  
...  

This work focuses on the temperature evolution of the martensitic phase ε (hexagonal close packed) induced by the severe plastic deformation via High Speed High Pressure Torsion method in Fe57Mn27Si11Cr5 (at %) alloy. The iron rich alloy crystalline structure, magnetic and transport properties were investigated on samples subjected to room temperature High Speed High Pressure Torsion incorporating 1.86 degree of deformation and also hot-compression. Thermo-resistivity as well as thermomagnetic measurements indicate an antiferromagnetic behavior with the Néel temperature (TN) around 244 K, directly related to the austenitic γ-phase. The sudden increase of the resistivity on cooling below the Néel temperature can be explained by an increased phonon-electron interaction. In-situ magnetic and electric transport measurements up to 900 K are equivalent to thermal treatments and lead to the appearance of the bcc-ferrite-like type phase, to the detriment of the ε(hcp) martensite and the γ (fcc) austenite phases.


2016 ◽  
Vol 683 ◽  
pp. 174-180 ◽  
Author(s):  
Yuri P. Sharkeev ◽  
Zhanna G. Kovalevskaya ◽  
Margarita A. Khimich ◽  
Vladimir A. Bataev ◽  
Qi Fang Zhu ◽  
...  

The phase transformations of the alloy Ti-40 mas % Nb after tempering and severe plastic deformation are studied. The phase transformations of the alloy according to the type and conditions of external influences are analyzed using methods of XRD, SEM and optical metallography. It is determined that inverse phase transformation of the metastable α''-phase to equilibrium β-phase is carried out after severe plastic deformation. Complete phase transformation α'' → β is typical for the mode, which consists of three pressing operation with the change of the loading axis in cramped conditions, followed by a multi-pass rolling in grooved rolls.


2011 ◽  
Vol 487 ◽  
pp. 63-69 ◽  
Author(s):  
Xiang Ming Huang ◽  
Z.X. Zhou ◽  
W. Li

Ground white layer is caused primarily by grinding temperature induced phase transformation. So, it may form when grinding temperature exceeds the nominal phase transformation temperature. However, no attempt is made to investigate mechanical effect on formation of white layer. In this study, grinding temperature is measured by using thermocouple technique in grinding of AISI 52100 annealed steel. The specimens are investigated by using scanning electron microscope (SEM), energy disperse spectroscopy (EDS), micro hardness tester and X-ray diffraction (XRD). The microstructure and formation mechanism of white layer are analyzed. Ground whiter layer is confirmed to be composed of fine-grained cryptocrystalline martensite and retained austenite. High hardness of white layer is caused by transformation hardening through fine grain and high dislocation density due to severe deformation. White layer can form at temperatures below the nominal austenitization temperature of the material. Plastic deformation is also important in white layer formation during grinding process. High pressure on grinding surface exists under severe deformation. Phase temperature can be reduced due to high pressure; while crystal grain can be refined by plastic deformation. Oxidation and carburizing phenomenon exist during formation of white layer.


2009 ◽  
Vol 283-286 ◽  
pp. 629-638 ◽  
Author(s):  
Vladimir V. Popov ◽  
Ruslan Valiev ◽  
E.N. Popova ◽  
A.V. Sergeev ◽  
A.V. Stolbovsky ◽  
...  

Submicrocrystalline structure of W obtained by severe plastic deformation (SPD) by high pressure torsion (5 revolutions of anvils at 4000C) and its thermal stability have been examined by TEM. Grain boundaries of submicrocrystalline W have been studied by the method of the emission Mössbauer spectroscopy in the initial state and after annealing at 400-6000С.


2013 ◽  
Vol 738-739 ◽  
pp. 491-495 ◽  
Author(s):  
Igor Litovchenko ◽  
Alexander Tyumentsev ◽  
Alexander V. Korznikov

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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