Investigation on the nucleation mechanism of deformation-induced martensite in an austenitic stainless steel under severe plastic deformation

2007 ◽  
Vol 22 (3) ◽  
pp. 724-729 ◽  
Author(s):  
C.X. Huang ◽  
G. Yang ◽  
Y.L. Gao ◽  
S.D. Wu ◽  
S.X. Li

The nucleation mechanism of deformation-induced martensite was investigated by x-ray diffraction and transmission electron microscope in an ultra-low carbon austenitic stainless steel deformed by equal channel angular pressing at room temperature. It was found that two types of martensite transformation mechanism, stress-assisted and strain-induced, occurred via the sequences of γ (fcc) → ɛ (hcp) → α′ (bcc) and/or γ → α′. In both cases, the crystallographic relationships among γ, ɛ, and α′ followed the Kurdjumov-Sachs orientation relationships: {111}γ //{0001}ɛ //{011}α′ and 〈110〉γ//〈1120〉ɛ//〈111〉α′.

2014 ◽  
Vol 783-786 ◽  
pp. 837-841
Author(s):  
Andrea Madeira Kliauga ◽  
V.L. Sordi ◽  
Maurizio Ferrante ◽  
C.A. Rovere ◽  
S.E. Curi

A F138 austenitic stainless steel was solution heat treated, deformed by equal-channel angular pressing (ECAP) at 25 and 300°C. The equivalent strain was ~0.7 per pass and the applied equivalent strain varied from 0.7 to 2.8. Microstructure evolution was observed by transmission electron microscopy (TEM) electron back-scattered diffraction (EBSD) and X –ray diffraction. Work hardening behavior was studied by making use of Kocks-Mecking plots and hardness measurements, the influence of deformation on corrosion resistance was evaluated recording anodic polarization curves in 0.9% NaCl solution.


2010 ◽  
Vol 650 ◽  
pp. 193-198 ◽  
Author(s):  
Yuan Yuan Song ◽  
Xiu Yan Li ◽  
Fu Xing Yin ◽  
De Hai Ping ◽  
Li Jian Rong ◽  
...  

Tempering temperature dependence of the amount of the reversed austenite in the range of 570 oC to 680 oC was investigated by means of X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM) in a low carbon Fe-13%Cr-4%Ni-Mo (wt.%) martensitic stainless steel. It was found that the reversed austenite began to form at the tempered temperature slightly above the As temperature. As the tempered temperature increased, the amount of the reversed austenite changed little in the temperature range of 580-595 oC. Then, the amount of the reversed austenite increased sharply with the increased tempered temperature. When the tempered temperature increased to about 620 oC, the amount of the reversed austenite exhibited a peak. Afterward, it decreased quickly at the elevated tempered temperature. The microstructural evolvement of the reversed austenite at different tempering temperature was also observed by TEM.


2016 ◽  
Vol 49 (6) ◽  
pp. 1967-1971 ◽  
Author(s):  
Ke Tong ◽  
Fei Ye ◽  
Honglong Che ◽  
Ming Kai Lei ◽  
Shu Miao ◽  
...  

The nitrogen-supersaturated phase produced by low-temperature plasma-assisted nitriding of austenitic stainless steel usually contains a high density of stacking faults. However, the stacking fault density observed in previous studies was considerably lower than that determined by fitting the X-ray diffraction pattern. In this work, it has been confirmed by high-resolution transmission electron microscopy that the strip-shaped regions of about 3–25 nm in width observed at relatively low magnification essentially consist of a series of stacking faults on every second {111} atomic plane. A microstructure model of the clustered stacking faults embedded in a face-centred cubic structure was built for these regions. The simulated X-ray diffraction and transmission electron microscopy results based on this model are consistent with the observations.


2010 ◽  
Vol 146-147 ◽  
pp. 26-33 ◽  
Author(s):  
Ming Zhou Xu ◽  
Jian Jun Wang ◽  
Li Jun Wang ◽  
Wen Fang Cui ◽  
Chun Ming Liu

Microstructural evolution of a metastable 18Cr12Mn0.55N austenitic stainless steel during compression deformation was investigated by transmission electron microscopy (TEM) and X-ray diffraction (XRD). TEM observation showed the occurrence of deformation-induced phase transformation and atypical deformation twin, the deformation-induced phase cannot be identified as austenite or martensite. XRD test showed that the amount of deformation-induced phase is less than the detectable limit of XRD.


2014 ◽  
Vol 775-776 ◽  
pp. 482-486 ◽  
Author(s):  
Andrea Madeira Kliauga ◽  
Vitor Luiz Sordi ◽  
Sergey V. Dobatkin

A F138 austenitic stainless steel was solution heat treated, deformed by equal-channel angular pressing (ECAP) at 25, 100, 200, and 300°C. The equivalent strain was ~0.7 per pass and the applied equivalent strain varied from 0.7 to 4.2. The same material was also deformed by high pressure torsion (HPT) at 300 and 480°C, applying 6GPa pressure and 5 turns; the equivalent strain was ~ 4.5 at r/2 and ~5.2 at the vicinity of the disk edge. Microstructure evolution was observed by transmission electron microscopy (TEM) electron back-scattered diffraction (EBSD) and X ray diffraction. The effect of severe plastic deformation was studied at 25 and 300°C: at 25°C further deformation led to the formation of grain subdivision inside deformation bands and the onset of new grains formation after 2 ECAE passes. The deformation at 300 and 400°C up to 6 passes lead to the formation of recrystallized grains of the order of 100 nm size.


1997 ◽  
Vol 12 (6) ◽  
pp. 1472-1480 ◽  
Author(s):  
Katherine C. Chen ◽  
Samuel M. Allen ◽  
James D. Livingston

Microstructures of two-phase Ti–Cr alloys (Ti-rich bcc + TiCr2 and Cr-rich bcc + TiCr2) are analyzed. A variety of TiCr2 precipitate morphologies is encountered with different nominal alloy compositions and annealing temperatures. Lattice constants and crystal structures are determined by x-ray diffraction (XRD) and transmission electron microscopy (TEM). Orientation relationships between the beta bcc solid solution and C15 TiCr2 Laves phase are understood in terms of geometrical packing, and are consistent with a Laves phase growth mechanism involving twinning.


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