Hydrogen desorption change after deformation of a bainitic steel with unstable retained austenite

2019 ◽  
Vol 170 ◽  
pp. 38-42 ◽  
Author(s):  
S.D. Pu ◽  
A. Turk ◽  
S. Lenka ◽  
S.W. Ooi
Keyword(s):  
Retained Austenite ◽  
Hydrogen Desorption ◽  
Bainitic Steel

Isothermal Transformation, Microstructure and Mechanical Properties of Ausformed Low-Carbon Carbide-Free Bainitic Steel

2018 ◽  
Vol 941 ◽  
pp. 329-333 ◽  
Author(s):  
Jiang Ying Meng ◽  
Lei Jie Zhao ◽  
Fan Huang ◽  
Fu Cheng Zhang ◽  
Li He Qian
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Volume Fraction ◽  
Bainitic Ferrite ◽  
Isothermal Transformation ◽  
Bainitic Transformation ◽  
Isothermal Treatment ◽  
Bainitic Steel ◽  
Low Carbon ◽  
Microstructure And Mechanical Properties

In the present study, the effects of ausforming on the bainitic transformation, microstructure and mechanical properties of a low-carbon rich-silicon carbide-free bainitic steel have been investigated. Results show that prior ausforming shortens both the incubation period and finishing time of bainitic transformation during isothermal treatment at a temperature slightly above the Mspoint. The thicknesses of bainitic ferrite laths are reduced appreciably by ausforming; however, ausforming increases the amount of large blocks of retained austenite/martenisite and decreases the volume fraction of retained austenite. And accordingly, ausforming gives rise to significant increases in both yield and tensile strengths, but causes noticeable decreases in ductility and impact toughness.

scholarly journals Influence of Prior Martensite on Bainite Transformation, Microstructures, and Mechanical Properties in Ultra-Fine Bainitic Steel

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 527 ◽  
Author(s):  
Hui Guo ◽  
Xianying Feng ◽  
Aimin Zhao ◽  
Qiang Li ◽  
Jun Ma
Keyword(s):  
Mechanical Properties ◽  
Retained Austenite ◽  
Bainitic Ferrite ◽  
Growth Direction ◽  
Bainitic Transformation ◽  
Bainitic Steel ◽  
Bainite Transformation ◽  
Multiphase Microstructure ◽  
Microstructures And Mechanical Properties ◽  
The Impact

A multiphase microstructure comprising of different volume fractions of prior martensite and ultra-fine bainite (bainitic ferrite and retained austenite) was obtained by quenching to certain temperatures, followed by isothermal bainitic transformation. The effect of the prior martensite transformation on the bainitic transformation behavior, microstructures, and mechanical properties were discussed. The results showed that the prior martensite accelerated the subsequent low-temperature bainite transformation, and the incubation period and completion time of the bainite reaction were significantly shortened. This phenomenon was attributed to the enhanced nucleation ratio caused by the introduced strain in austenite, due to the formation of prior martensite and a carbon partitioning between the prior martensite and retained austenite. Moreover, the prior martensite could influence the crystal growth direction of bainite ferrite, refine bainitic ferrite plates, and reduce the dimension of blocky retained austenite, all of which were responsible for improving the mechanical properties of the ultra-fine bainitic steel. When the content of the prior martensite reached 15%, the investigated steels had the best performance, which were 1800 MPa and 21% for the tensile strength and elongation, respectively. Unfortunately, the increased content of the prior martensite could lead to a worsening of the impact toughness.

scholarly journals Through Process Modelling of Rolling and Controlled Cooling of TRIP Assisted Bainitic Steel Rods and Prediction of the Retained Austenite in Products

2017 ◽  
Vol 892 ◽  
pp. 23-33
Author(s):  
Roman Kuziak ◽  
Zofia Kania ◽  
Valeriy Pidvysots'kyy ◽  
Hans Roelofs ◽  
Monika Pernach ◽  
...  
Keyword(s):  
Retained Austenite ◽  
Volume Fraction ◽  
Rolling Process ◽  
Industrial Processes ◽  
Bainitic Steel ◽  
Controlled Cooling ◽  
Hot Rolling Process ◽  
Bainitic Steels ◽  
Discrete Phase ◽  
Physical Simulations

Simulation of the rolling and controlled cooling sequence for bainitic steel rods was the general objective of the paper. The main focus was put on exploring possibility of prediction of the retained austenite occurrence in TRIP assisted bainitic steels. Existing discrete phase transformation models require long computing times and their application to optimization of industrial processes is limited. Therefore, a model based on the modified JMAK equation was proposed. The occurrence of the retained austenite was predicted by carbon distribution calculations in the austenite during bainite transformation. This model was implemented into the FE software for simulation of cooling of rods. The model was verified by comparison of results with the physical simulations during rolling in the pilot mill and during cooling. The first part of the paper contains thermal-mechanical-microstructural simulations of rod hot rolling process. The objective of this part was to determine temperature and grain size distribution at the rod cross section at the beginning of phase transformations. FE simulations of the cooling were performed next. Correlation between cooling parameters and the volume fraction of the retained austenite in rod was determined.

scholarly journals Retained Austenite Decomposition and Carbide Precipitation during Isothermal Tempering of a Medium-Carbon Low-Alloy Bainitic Steel

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1441 ◽  
Author(s):  
Seyyed Talebi ◽  
Mohammad Jahazi ◽  
Haikouhi Melkonyan
Keyword(s):  
Electron Microscopy ◽  
Retained Austenite ◽  
Carbide Precipitation ◽  
Austenite Decomposition ◽  
Bainitic Steel ◽  
Tempering Temperature ◽  
Medium Carbon ◽  
Transmission Electron ◽  
Decomposition Behavior ◽  
Isothermal Tempering

The effect of isothermal tempering on retained austenite decomposition and carbide precipitation were investigated in a medium-carbon low-alloy bainitic steel. High-resolution dilatometry was used to perform isothermal tempering at 350 °C, 550 °C and 600 °C for different holding times up to 16 h. The decomposition of retained austenite, morphology and composition of carbides were investigated by analyzing the dilatometric curves and were confirmed through scanning and transmission electron microscopy observations. The decomposition behavior of retained austenite varied significantly as a function of the tempering temperature with a full decomposition observed at 600 °C. It was also found that by increasing the tempering temperature from 550 °C to 600 °C, carbides precipitate approximately twice as fast, and evolve from M3C type to Cr7C3 and Cr23C6 after 16 h of tempering at 600 °C.

Effects of retained austenite and hydrogen on the rolling contact fatigue behaviours of carbide-free bainitic steel

2014 ◽  
Vol 594 ◽  
pp. 364-371 ◽  
Author(s):  
Chunlei Zheng ◽  
Rui Dan ◽  
Fucheng Zhang ◽  
Bo Lv ◽  
Zhigang Yan ◽  
...  
Keyword(s):  
Retained Austenite ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Bainitic Steel

scholarly journals Retained austenite thermal stability in a nanostructured bainitic steel

2013 ◽  
Vol 81 ◽  
pp. 105-110 ◽  
Author(s):  
Behzad Avishan ◽  
Carlos Garcia-Mateo ◽  
Sasan Yazdani ◽  
Francisca G. Caballero
Keyword(s):  
Thermal Stability ◽  
Retained Austenite ◽  
Bainitic Steel
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