scholarly journals Structure of Retained Austenite in Plain Carbon Steels

Nature ◽  
1947 ◽  
Vol 160 (4055) ◽  
pp. 93-93 ◽  
Author(s):  
W. J. WRAZEJ
Keyword(s):  
Retained Austenite ◽  
Carbon Steels

A New Approach Using EBSD to Quantitatively Distinguish Complex Transformation Products Along the HAZ in X80 Linepipe Steel

2014 ◽  
Author(s):  
Jennifer M. Reichert ◽  
Matthias Militzer ◽  
Warren J. Poole ◽  
Laurie Collins
Keyword(s):  
Orientation Relationship ◽  
Transformation Temperature ◽  
Retained Austenite ◽  
Electron Backscatter Diffraction ◽  
High Strength ◽  
Transformation Products ◽  
Carbon Steels ◽  
Low Carbon ◽  
Structure Property ◽  
Linepipe Steel

State-of-the-art linepipe steels are microalloyed low-carbon steels that combine high strength and fracture toughness with good weldability. During welding of pipe sections the heat affected zone (HAZ) experiences rapid thermal cycles resulting in a graded microstructure that can be significantly different from that of the base metal. In particular a variety of bainitic microstructures can form in the HAZ. Depending on the type of bainite mechanical properties may be improved or may lead to poor fracture resistance and be detrimental to the overall HAZ performance. Optical microscopy is not sufficient to differentiate bainitic morphologies which vary with the transformation temperature. The investigated X80 linepipe steel also contains retained austenite at room temperature. Based on the retained austenite it is possible to characterize the orientation relationship (OR) between austenite and the transformation products. It is found that bainite shows an orientation relationship near Kurdjumov-Sachs with the prior austenite. Variant selection is related to the driving force for the bainite reaction and hence depends on the transformation temperature. In the current study Electron BackScatter Diffraction (EBSD) mapping is used to characterize transformation products based on their orientation relationship. This approach offers a quantitative way to determine volume fractions of different types of bainite in complex HAZ microstructures which is necessary to establish structure-property relationships of the HAZ.

scholarly journals The Influence of Vanadium Additions on Isothermally Formed Bainite Microstructures in Medium Carbon Steels Containing Retained Austenite

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 392 ◽  
Author(s):  
Irina Pushkareva ◽  
Babak Shalchi-Amirkhiz ◽  
Sébastien Yves Pierre Allain ◽  
Guillaume Geandier ◽  
Fateh Fazeli ◽  
...  
Keyword(s):  
Retained Austenite ◽  
Bainitic Ferrite ◽  
High Energy ◽  
Carbon Steels ◽  
Ex Situ ◽  
Transformation Rate ◽  
Medium Carbon ◽  
X Ray ◽  
Medium Carbon Steels ◽  
Carbon Mass Balance

The influence of V additions on isothermally formed bainite in medium carbon steels containing retained austenite has been investigated using in-situ high energy X-ray diffraction (HEXRD) and ex-situ electron energy loss spectroscopy (EELS) and energy dispersive X-ray analysis (EDX) techniques in the transmission electron microscope (TEM). No significant impact of V in solid solution on the bainite transformation rate, final phase fractions or on the width of bainite laths was seen for transformations in the range 375–430 °C. No strong influence on the dislocation density could be detected, although quantitative analysis was impeded by ferrite tetragonality. A reduction in the carbon content of retained austenite Cγ that is not believed to be due to competition with VC or cementite precipitation was observed. No influence of V on the carbon supersaturation in bainitic ferrite Cb could be directly measured, although carbon mass balance calculations suggest Cb slightly increases. A beneficial refinement of blocky MA and a corresponding size effect induced enhancement in austenite stability were found at the lowest transformation temperature. Overall, V additions result in a slight increase in strength levels.

scholarly journals Optimized Corrosion Performance of AISI 1345 Steel in Hydrochloric Acid Through Thermo–Mechanical Cyclic Annealing Processes

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 265 ◽  
Author(s):  
Muhammad Arslan Hafeez ◽  
Aqil Inam ◽  
Misbah Ul Hassan ◽  
Malik Adeel Umer ◽  
Muhammad Usman ◽  
...  
Keyword(s):  
Hydrochloric Acid ◽  
Hot Rolling ◽  
Retained Austenite ◽  
Carbon Steels ◽  
Coarse Grained ◽  
Corrosion Performance ◽  
Cyclic Annealing ◽  
Immersion Corrosion ◽  
Treated Sample ◽  
Hcl Solution

The thermo–mechanical treatments and cyclic annealing processes have the potential of optimizing the corrosion performance of carbon steels in corrosive environments. Herein, an attempt has been made to optimize the corrosion performance of AISI 1345 steel in hydrochloric acid by thermo–mechanical cyclic annealing treatments. AISI 1345 steel was produced and cast in the laboratory and subjected to three types of thermo–mechanical cyclic annealing treatments (TMCA). The first TMCA treatment comprised hot rolling at 1050 °C followed by oil quenching and single austenitizing at 900 °C followed by furnace cooling (TMSA). The second and the third TMCA treatments involved similar hot rolling processes with double austenitizing and furnace cooling (TMDA) and triple austenitizing and furnace cooling (TMTA) processes. Microstructure analysis showed that dual-phase (retained austenite + pearlite) microstructure was achieved after all TMCA treatments with an exception of secondary phase particles precipitation after TMSA treatment. Maximum fractions of retained austenite and minimum fractions of pearlite were achieved after TMTA treatment. Highly refined microstructure of size 26.7 µm was achieved after TMDA treatment whereas; TMSA treatment offered coarse grained microstructure of size 254 µm. Electrochemical analysis was performed in 5 vol% HCl solution using Tafel scan technique. Results revealed that both TMDA and TMTA treatments caused three-fold reduction in corrosion rates (3.025, 2.771 mpy) compared to non-treated steel sample. After 168 h of immersion corrosion analysis in 5 vol% HCl solution, the surface of TMTA treated sample was observed to be partially covered with a very thin, crack-free oxide layer exhibiting minimum oxygen (8.16%) percentage. These features indicated that the TMTA treated sample underwent a very low-intensity minor corrosion attack of HCl solution and exhibited the best immersion corrosion performance among all samples. Electrochemical and immersion corrosion analysis results were in good agreement.

The Effect of Isothermal Hold Temperature on Microstructure and Mechanical Properties of TRIP Steel

2017 ◽  
Vol 270 ◽  
pp. 253-257 ◽  
Author(s):  
Ludmila Kučerová ◽  
Martin Bystrianský ◽  
Josef Káňa
Keyword(s):  
Mechanical Properties ◽  
Trip Steel ◽  
Retained Austenite ◽  
Mechanical Treatment ◽  
Volume Fraction ◽  
Carbon Steels ◽  
Processing Route ◽  
Isothermal Hold ◽  
Low Carbon ◽  
Thermo Mechanical Treatment

TRIP (transformation induced plasticity) steels are low alloyed low carbon steels with complex microstructures consisting of ferrite, bainite and retained austenite. This complex microstructure provides them with excellent strength to ductility balance, making them a member of advanced high strength steels (AHSS) group. Suitable microstructure can be obtained by either heat or thermo-mechanical treatment. A hold in bainite transformation region is an integral part of any form of commercial TRIP steel processing route, as it enables formation of sufficient volume fraction of bainite and also stabilization of retained austenite in the final microstructure. Various bainitic hold temperatures ranging from 350 °C to 500 °C were tested within thermo-mechanical treatment of 0.2C-1.5Mn-0.6S-1.5Al steel and the final microstructures were evaluated with regard to the suitability to TRIP effect and achieved mechanical properties. The microstructures were analyzed by scanning electron microscopy and mechanical properties measured by tensile test.

scholarly journals Erratum: Pushkareva, I., et al. The Influence of Vanadium Additions on Isothermally Formed Bainite Microstructures in Medium Carbon Steels Containing Retained Austenite. Metals 2020, 10, 392

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 565
Author(s):  
Irina Pushkareva ◽  
Babak Shalchi-Amirkhiz ◽  
Sébastien Yves Pierre Allain ◽  
Guillaume Geandier ◽  
Fateh Fazeli ◽  
...  
Keyword(s):  
Retained Austenite ◽  
Carbon Steels ◽  
Medium Carbon ◽  
Medium Carbon Steels

The authors wish to make the following erratum to this paper [...]

Electron-Metallographic Identification of Retained Austenite in Steels

1975 ◽  
Vol 33 ◽  
pp. 30-31 ◽  
Author(s):  
B. V. Narasimha Rao ◽  
J. Y. Koo ◽  
G. Thomas
Keyword(s):  
Retained Austenite ◽  
Dark Field ◽  
Carbon Steels ◽  
Electron Microscopic ◽  
Medium Carbon ◽  
X Ray ◽  
Dark Field Imaging ◽  
Medium Carbon Steels ◽  
Field Imaging ◽  
Microscopic Techniques

Recently it has been discovered by electron microscopy that even in medium carbon steels (Mf≳200°C) small quantities of interlath retained austenite (γ) is present in as-quenched structures. It is speculated that this small quantity of retained γ can have a profound influence on the mechanical properties of steel. This austenite is severely deformed and in most cases the amount is so small that detection by x-ray analysis becomes impossible. However, sophisticated electron microscopic techniques involving careful selected area diffraction, bright field and dark field imaging can unequivocally establish the presence of such small quantities of austentite. Extremely useful morphological and microstructural information on the austenite can also be obtained from the electron metallography.

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