Effect of Rare Earth Addition on Dynamic Recrystallization and Precipitation Behavior of a Niobium-Containing Microalloy Steel

2013 ◽  
Vol 762 ◽  
pp. 189-193
Author(s):  
Hai Yan Wang ◽  
Hui Ping Ren ◽  
Hui Yang ◽  
S.D. Wang ◽  
D.X. Li
Keyword(s):  
Rare Earth ◽  
Dynamic Recrystallization ◽  
Dynamic Recovery ◽  
Microalloyed Steel ◽  
Carbon Activity ◽  
Precipitation Behavior ◽  
Rare Earth Addition ◽  
Transmission Electron ◽  
Nb Microalloyed Steel ◽  
Means Of Transmission

Hot compression experiments were carried out on rare earth (RE) added and RE-free Nb-containing steels by using a Gleeble simulator. Stress-strain curves obtained at various temperatures were analyzed to investigate the dynamic recovery and dynamic recrystallization softening behaviours. Morphology, size and number of precipitates in the both steels were examined by means of transmission electron microscopy (TEM). The results showed that, for the experimental Nb-containing steel, the grain size was fined by the RE addtion. In general, dynamic recrystallization cant occur in two steel under 40% deformation rates, and the deformation resistance of RE-containing steel is higher than that of RE-free steel in both the the austenite and ferrite temperatures range.While under the higher deformation rate, the dynamic recovery starting strains of the RE addition steel are higher than that of RE-free steel.It is also shown that the number of precipitate in the RE-containing steel more than that in the RE-free steel, which is due to the RE increasing nucleation rate and promoting Nb carbonitrides precipitation growth in the austenite region. Furthermore, the carbon activity may change by the RE addition, and thereby promote the precipitation strengthening of Nb-microalloyed steel.

Carbo-Nitride Precipitation in Tempered Martensite - Computer Simulation and Experiment

2012 ◽  
Vol 706-709 ◽  
pp. 1586-1591 ◽  
Author(s):  
Sabine Zamberger ◽  
Ernst Kozeschnik
Keyword(s):  
Computer Simulation ◽  
Precipitation Behavior ◽  
Tempered Martensite ◽  
Extraction Replica ◽  
Transmission Electron ◽  
Simulation And Experiment ◽  
Precipitate Microstructure ◽  
Means Of Transmission ◽  
Quenched And Tempered Steel ◽  
Good Agreement

In the present work, the precipitation behavior of a V-microalloyed, quenched and tempered steel with 0.3wt % C is investigated experimentally and by computer simulation. The specimens are analyzed by means of transmission electron microscopy using selected area diffraction (SAD) and energy dispersive x-ray spectroscopy (EDX). The analysis is done on electropolished foils and on extraction replica. The numerical simulation is performed with the thermokinetic software package MatCalc, where the precipitation kinetics is examined for the experimentally applied thermo-mechanical cycles. Good agreement between experiment and simulation is obtained and the experimentally observed precipitate microstructure can be well explained on the basis of these simulations.

Effect of Final Rapid Cooling Temperature on Ultra-Fine Carbides of Ti-Mo Ferrite Matrix Microalloyed Steel

2018 ◽  
Vol 926 ◽  
pp. 3-10
Author(s):  
Zhi Chen Yu ◽  
Zhen Li Mi ◽  
Qing Wu Cai ◽  
Jin Guo ◽  
Na Gong
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Microalloyed Steel ◽  
Ferrite Matrix ◽  
Precipitation Behavior ◽  
Rapid Cooling ◽  
Cooling Temperature ◽  
Interphase Precipitation ◽  
Transmission Electron ◽  
Scanning Electron

The size and distribution of nanoscale precipitate particles in Ti-Mo ferrite matrix microalloyed steel under three different final rapid cooling temperatures were studied by scanning electron microscopy(SEM), transmission electron microscope(TEM) and microhardness test. The results show that the interphase precipitation could be weakened by the excessive final rapid cooling temperature. A higher supersaturated solid solubility and high-density dislocation in ferrite matrix can be obtained under a relatively lower final rapid cooling temperature, which makes it easier to precipitate in ferrite. The related thermodynamic analysis indicated that the precipitation behavior was influenced by the final rapid cooling temperature during austenite/ferrite region. It is not conducive to get a large amount of small size precipitates in Ti-Mo ferrite matrix microalloyed steel when the final rapid cooling temperature is too high or low.

Nb Microalloyed Steel of Grain Coarsening Law

2012 ◽  
Vol 174-177 ◽  
pp. 433-436
Author(s):  
Fen Liu ◽  
Jun Cai Zhang
Keyword(s):  
Experimental Research ◽  
Process Parameters ◽  
Microalloyed Steel ◽  
Processing Conditions ◽  
Precipitation Behavior ◽  
Austenite Grain ◽  
Nb Microalloyed Steel ◽  
And Performance ◽  
Austenite Grain Growth ◽  
Dissolution And Precipitation

With the process parameters and processing conditions in the mill, a systematic experimental research were conducted to Q345 steel containing niobium austenite grain growth law, and analysis the dissolution and precipitation behavior of Nb carbonitride. The results shows that Nb-microalloyed steel heated to 1180 ~ 1230 °C can significantly improve strength and toughness of steel and performance.

Characterization of Microstructure and Mechanical Properties of a Nb-Microalloyed Steel after Quenching-Partitioning-Tempering Process

2010 ◽  
Vol 654-656 ◽  
pp. 90-93 ◽  
Author(s):  
Xiao Dong Wang ◽  
Zheng Hong Guo ◽  
Yong Hua Rong
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Heat Treatment ◽  
Treatment Process ◽  
Microalloyed Steel ◽  
Heat Treatment Process ◽  
Step Process ◽  
Transmission Electron ◽  
Nb Microalloyed Steel ◽  
Tempering Process

A novel heat treatment process, that is, quenching-partitioning-tempering (Q-P-T) process, has been developed as a new way to obtain ultrahigh strength martensitic structural steel containing retained austenite and alloying carbide. In order to display merit of the Q-P-T process, a medium carbon Nb-microalloyed steel is treated by Q-P-T 1-step process and Q-P-T 2-step process, as well as treated by the transformation induced plasticity heat treatment process and quenching and tempering process, respectively. The results show that Q-P-T samples possess better mechanical properties than those treated by other heat treatment processes. The origin of the good mechanical properties is analyzed based on the phase and microstructure characterization using X-ray diffraction, scanning electron microscopy and transmission electron microscopy.

Dynamic Recrystallization of Ferrite in a Low Carbon Nb-Microalloyed Steel

2005 ◽  
Vol 475-479 ◽  
pp. 149-152 ◽  
Author(s):  
Long Fei Li ◽  
Wang Yue Yang ◽  
Zu Qing Sun
Keyword(s):  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Microalloyed Steel ◽  
Phase Region ◽  
Ferrite Phase ◽  
Recrystallization Process ◽  
Low Carbon ◽  
Promoting Effect ◽  
Nb Microalloyed Steel ◽  
Average Size

The hot deformation behavior of a low carbon Nb-microalloyed steel is investigated by hot compression test in the ferrite phase region compared with a low carbon steel with similar compositions, and the effect of Nb on dynamic recrystallization of ferrite is analyzed. Results indicate that during hot deformation in the ferrite phase region, the effect of Nb solely depends on the size of NbC precipitates. Tiny particles which average size is about 7.5nm have a retarding effect on dynamic recrystallization process of ferrite, on the contrary, coarser particles which average size is about 30.6nm have a promoting effect and are of benefit to the refinement of recrystallized grains.

20#,60Si2Mn,9Cr18MoV Steel Ferrite Area Dynamic Recovery and Recrystallization Research

2013 ◽  
Vol 690-693 ◽  
pp. 197-201
Author(s):  
Liang Li ◽  
Wen Kai Xiao ◽  
Tao Tao Fan ◽  
Zhou Quan Zhang
Keyword(s):  
Dynamic Recrystallization ◽  
Dynamic Recovery ◽  
Strain Curve ◽  
Carbon Steels ◽  
Test Machine ◽  
Simulation Test ◽  
Microstructure Observation ◽  
Transmission Electron ◽  
Deformation Activation Energy ◽  
Strain Storage

By using the Gleeble - 1500 hot simulation test machine we studied 20#, 60Si2Mn, 9Cr18MoV the three kinds of low, medium and high carbon steels to observe the dynamic recovery and recrystallization of ferrite while in the process of thermoplastic deformation. We calculated the hot deformation activation energy of each kind of steel by combining the stress-strain curve we got in the experiment and the theoretical model of Z parameter. It turns out Q9Cr18MoV<Q20#<Q60Si2Mn. In the meanwhile, microstructure observation through transmission electron microscope shows that the dynamic recrystallization of ferrite is more likely to happen in 9Cr18MoV steel than in 20# steel and in 60Si2Mn steel. These results indicate that the dynamic recrystallization of ferrite is not only determined by stacking fault energy but also closely related with the strain storage energy release degree.

Investigation on Dissolving and Strain Induced Precipitation Behavior in Nb-Bearing Microalloyed Steel

2011 ◽  
Vol 109 ◽  
pp. 3-6
Author(s):  
Shao Qiang Yuan ◽  
Guo Li Liang ◽  
Hui Bin Wu
Keyword(s):  
Relaxation Time ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Microalloyed Steel ◽  
Thermal Simulation ◽  
Holding Time ◽  
The Other ◽  
Precipitation Behavior ◽  
Simulation Test ◽  
Transmission Electron

Thermal simulation test, TEM(Transmission Electron Microscope) and nanobeam EDS techniques were used to investigate the dissolving and precipitation behavior in Nb-bearing mciroalloyed steel. The experimental results indicate that: there are two families of precipitates in the as forged samples. The larger precipitates of Nb(C,N) disappear after being held for 2h at 1300°C,while the inclusions of MnS formed from the solidification even remain for 48h held at that temperature. After 30% of predeformtion at 850°C and 900°C, the strain-induced precipitation occurs, that is, the other tiny precipitates. Compared with the samples relaxed at 850°C, the ones that are held at 900°C show larger particles by same holding time but demonstrate the same size when the relaxation time reaches 1000s.

Sign in / Sign up

Export Citation Format

Share Document