Effect of Annealing Temperature on Deformed Microstructure of Low Carbon Martensite

2011 ◽  
Vol 213 ◽  
pp. 143-146
Author(s):  
Jun Zhao ◽  
Yong Ming Yang ◽  
Jiu Chuan Chen ◽  
Quan Xing Wen ◽  
Li Tao Zhang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Grain Size ◽  
Annealing Temperature ◽  
Steel Plate ◽  
Low Carbon ◽  
Average Grain Size ◽  
Long Time ◽  
New Type ◽  
Lath Structure ◽  
Carbon Martensite

In this paper, a new type steel plate with nano-layered martensite lath structure was produced by heavy cold-rolling. After rolling, subsequent annealing has great effect on the deformed martensite morphology and grain refinement. Microstructure recrystallizing course have occurred after long time annealing at 350°C. The recrystallization activation energy is 151 kJmol-1. The ultrafine ferrite grains (average grain size about 317nm), nano-carbides precipitated uniformly were seen in the specimen annealed at 500 °C. Annealing at and above 600 °C resulted in coarse ferrite grains with spheroidized coarse carbides, causing grain growth.

Thermal Stability of Ultrafine-Grained Pure Titanium Processed by High-Pressure Torsion

2021 ◽  
Vol 1016 ◽  
pp. 338-344
Author(s):  
Wan Ji Chen ◽  
Jie Xu ◽  
De Tong Liu ◽  
De Bin Shan ◽  
Bin Guo ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Grain Size ◽  
High Pressure ◽  
Annealing Temperature ◽  
High Pressure Torsion ◽  
Stored Energy ◽  
Ultrafine Grained ◽  
Average Grain Size ◽  
Thermal Stability Of

High-pressure torsion (HPT) was conducted under 6.0 GPa on commercial purity titanium up to 10 turns. An ultrafine-grained (UFG) pure Ti with an average grain size of ~96 nm was obtained. The thermal properties of these samples were studied by using differential scanning calorimeter (DSC) which allowed the quantitative determination of the evolution of stored energy, the recrystallization temperatures, the activation energy involved in the recrystallization of the material and the evolution of the recrystallized fraction with temperature. The results show that the stored energy increases, beyond which the stored energy seems to level off to a saturated value with increase of HPT up to 5 turns. An average activation energy of about 101 kJ/mol for the recrystallization of 5 turns samples was determined. Also, the thermal stability of the grains of the 5 turns samples with subsequent heat treatments were investigated by microstructural analysis and Vickers microhardness measurements. It is shown that the average grain size remains below 246 nm when the annealing temperature is below 500 °C, and the size of the grains increases significantly for samples at the annealing temperature of 600 °C.

scholarly journals The Influence of Annealing Temperature on the Structure and Magnetic Properties of Nanocrystalline BiFeO3 Prepared by Sol–Gel Method

2021 ◽  
Author(s):  
T. Pikula ◽  
T. Szumiata ◽  
K. Siedliska ◽  
V. I. Mitsiuk ◽  
R. Panek ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Annealing Temperature ◽  
Sol Gel ◽  
Weak Ferromagnetism ◽  
X Ray Diffraction ◽  
Gel Method ◽  
Sol Gel Method ◽  
Average Grain Size ◽  
Spin Cycloid

AbstractIn this work, BiFeO3 powders were synthesized by a sol–gel method. The influence of annealing temperature on the structure and magnetic properties of the samples has been discussed. X-ray diffraction studies showed that the purest phase was formed in the temperature range of 400 °C to 550 °C and the samples annealed at a temperature below 550 °C were of nanocrystalline character. Mössbauer spectroscopy and magnetization measurements were used as complementary methods to investigate the magnetic state of the samples. In particular, the appearance of weak ferromagnetic properties, significant growth of magnetization, and spin-glass-like behavior were observed along with the drop of average grain size. Mössbauer spectra were fitted by the model assuming cycloidal modulation of spins arrangement and properties of the spin cycloid were determined and analyzed. Most importantly, it was proved that the spin cycloid does not disappear even in the case of the samples with a particle size well below the cycloid modulation period λ = 62 nm. Furthermore, the cycloid becomes more anharmonic as the grain size decreases. The possible origination of weak ferromagnetism of the nanocrystalline samples has also been discussed.

MICROSTRUCTURE EVALUATION OF Fe-BASED AMORPHOUS ALLOYS INVESTIGATED BY DOPPLER BROADENING POSITRON ANNIHILATION TECHNIQUE

2013 ◽  
Vol 27 (19) ◽  
pp. 1341014
Author(s):  
WEI LU ◽  
PING HUANG ◽  
YUXIN WANG ◽  
BIAO YAN
Keyword(s):  
Grain Size ◽  
Positron Annihilation ◽  
Amorphous Alloys ◽  
Annealing Temperature ◽  
Amorphous Matrix ◽  
Nanocrystalline Phase ◽  
Magnetic Alloy ◽  
Type I ◽  
Doppler Broadening ◽  
Average Grain Size

Microstructure of Fe -based amorphous and nanocrystalline soft magnetic alloy has been investigated by X-ray diffraction (XRD), transmission electronic microscopy (TEM) and Doppler broadening positron annihilation technique (PAT). Doppler broadening measurement reveals that amorphous alloys (Finemet, Type I) which can form a nanocrystalline phase have more defects (free volume) than alloys (Metglas, Type II) which cannot form this microstructure. XRD and TEM characterization indicates that the nanocrystallization of amorphous Finemet alloy occurs at 460°C, where nanocrystallites of α- Fe with an average grain size of a few nanometers are formed in an amorphous matrix. With increasing annealing temperature up to 500°C, the average grain size increases up to around 12 nm. During the annealing of Finemet alloy, it has been demonstrated that positron annihilates in quenched-in defect, crystalline nanophase and amorphous-nanocrystalline interfaces. The change of line shape parameter S with annealing temperature in Finemet alloy is mainly due to the structural relaxation, the pre-nucleation of Cu nucleus and the nanocrystallization of α- Fe ( Si ) phase during annealing. This study throws new insights into positron behavior in the nanocrystallization of metallic glasses, especially in the presence of single or multiple nanophases embedded in the amorphous matrix.

scholarly journals Strong Interactions between Austenite and the Matrix of Medium-Mn Steel during Intercritical Annealing

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3366 ◽  
Author(s):  
Tianpeng Zhou ◽  
Cunyu Wang ◽  
Chang Wang ◽  
Wenquan Cao ◽  
Zejun Chen
Keyword(s):  
Grain Size ◽  
Annealing Temperature ◽  
Ferrite Matrix ◽  
Strong Interactions ◽  
Recrystallization Process ◽  
Austenite Grain Size ◽  
Recrystallization Kinetics ◽  
Average Grain Size ◽  
The Matrix ◽  
Austenite Grains

The effects of heat treatment on the microstructure evolution was studied in regards to austenite nucleation and grain growth. It was found that the austenite nucleation and matrix recrystallization kinetics of samples annealed at 675 °C for different times were revealed, implying a strong interaction between the ferrite matrix and austenite. The recrystallization of the matrix during annealing provided favorable conditions for austenite nucleation and growth, and the formation of austenite during this process reduced the matrix recrystallization kinetics, thus delaying the recrystallization process of the matrix around the austenite grains. The statistical results for the austenite grain size under different annealing temperatures indicated that the average grain size of the austenite slightly increases with increasing of the annealing temperature, but the austenite with the largest grain size grows faster at the same temperature. This difference is attributed to the strict Kurdjumov Sachs (KS) orientation relationship (OR) between the austenite grains and the matrix, because the growth of austenite with a strict KS OR with the matrix is often inhibited during annealing. In contrast, the austenite maintains a non-strict KS OR with the matrix and can grow preferentially with increasing annealing temperature and time.

scholarly journals Characterization and Alumina Leachability of 12CaO·7Al2O3with Different Holding Times

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Hui-lan Sun ◽  
Bo Wang ◽  
Jian-xin Zhang ◽  
Shu-feng Zong
Keyword(s):  
Grain Size ◽  
Surface Morphology ◽  
Lattice Constant ◽  
Preferred Orientation ◽  
Holding Time ◽  
Synthesis Time ◽  
Rate Of Increase ◽  
Average Grain Size ◽  
Long Time ◽  
Scherrer Formula

The effect of synthesis time on phase compositions, lattice constant, average grain size, preferred orientation, and surface morphology of 12CaO·7Al2O3synthesized at 1500°C was analyzed by XRD and SEM. The results indicate that the main phase of samples synthesized is 12CaO·7Al2O3when holding time is over 30 min. The lattice constant increases and the preferred orientation decreases as synthesis time prolongs. The average grain size of samples is about 59 nm calculated by Scherrer formula, and it does not change with synthesis time. The synthesis time affects the micromorphology of samples greatly. There are more and bigger holes in samples synthesized for long time. The aspects mentioned above cause the alumina leaching ratio of 12CaO·7Al2O3to increase with the prolonging of synthesis time, but the rate of increase drops.

Effect of Annealing Temperature on Microstructure and Properties of Surface Nanocrystalline Structure in Low Carbon Steel Specimen

2007 ◽  
Vol 353-358 ◽  
pp. 1601-1604
Author(s):  
Xin Min Fan ◽  
Yan Jiao Ji ◽  
Jie Wen Huang
Keyword(s):  
Surface Layer ◽  
Carbon Steel ◽  
Annealing Temperature ◽  
Low Carbon Steel ◽  
Nanocrystalline Structure ◽  
Low Carbon ◽  
Steel Cylinder ◽  
Surface Nanocrystallization ◽  
Microstructure And Properties ◽  
Average Grain Size

Nanostructure surface layer was fabricated on a low carbon steel cylinder specimen by means of circulation rolling plastic deformation (CRPD), and the effect of annealing temperature on microstructure and properties of surface nanocrystalline structure was studied. The microstructure of the surface layer on the samples was observed by transmission electron microscopy and the microhardness variation along the depth was measured on the cross-sectional samples by using microhardness instrument. After CRPD treatment for 250min, the average grain size was about 10nm in the top surface layer and increased with an increment of the distance from the top surface. The surface nanocrystallization samples were annealed at 200°C, 300, 400°C and 500°C for 30min respectively. The nanocrystallization grain of surface layer did not grow for samples after annealed at 200°C and 300°C. After surface nanocrystallization by CRPD treatment the microhadness of top surface obviously increase from 220HV0.1 to 520HV0.1.

Study of the Plastic Deformation in Nanocrystalline and Ultrafine Iron and Carbon Steels

2008 ◽  
Vol 584-586 ◽  
pp. 617-622 ◽  
Author(s):  
Josep Antonio Benito ◽  
Robert Tejedor ◽  
Rodriguez Rodríguez-Baracaldo ◽  
Jose María Cabrera ◽  
Jose Manuel Prado
Keyword(s):  
Grain Size ◽  
Low Carbon Steel ◽  
High Strength ◽  
Carbon Steels ◽  
Low Carbon ◽  
Compression Tests ◽  
Consolidation Process ◽  
Heat Treated ◽  
Average Grain Size ◽  
Grain Size Distributions

Samples of nanostructured and ultrafine grained steels with carbon content ranging from 0.05 to 0.55%wt. have been obtained by a warm consolidation process from mechanically milled powders and subsequent heat treatments. In general, homogeneous grain size distributions were obtained except for the low-carbon steel in which a bimodal grain size distribution was observed when it was heat treated at high temperatures. The stress-strain response has been studied by means of compression tests. Nanostructured materials showed high strength but poor results in terms of ductility. In the low-ultrafine range (mean grain size between 100-500 nm) the three materials showed an increase in the ductility with strain softening. Finally, when the average grain size was close to 1 µm samples showed larger ductility and strain hardening.

Grain Size Effects on the Oxidation of Fe-33Ni-19Cr Alloy at 700°C

2014 ◽  
Vol 699 ◽  
pp. 151-156
Author(s):  
Noraziana Parimin ◽  
Esah Hamzah ◽  
Astuty Amrin
Keyword(s):  
Grain Size ◽  
Annealing Temperature ◽  
Oxidation Kinetic ◽  
Solution Treatment ◽  
Oxidation Behaviour ◽  
Solution Annealing ◽  
X Ray ◽  
Average Grain Size ◽  
Different Temperatures ◽  
Different Grain Size

The effect of different grain size on the oxidation of Fe-33Ni-19Cr alloy was discussed. The present paper focuses on the oxidation behaviour in dry air at temperature of 700oC with respect to oxidation kinetics. Solution treatment was applied to Fe-33Ni-19Cr alloy by means of different solution annealing temperature to alter the average grain size of the specimens. Solution heat treatments were carried out on Fe-Ni-Cr alloys at three different temperatures, namely, 1000oC, 1100oC and 1200oC. The results showed that the average grain size increased with increase in solution annealing temperature that was significantly affecting the oxidation kinetic of the materials. Optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) were employed in this study to analyse the oxidation behaviour of solution-annealed samples. Smaller grain size improves the protective oxidation behaviour by enhancing spallation resistance and reducing oxidation rate. Spallation resistance correlates with a reduction in texture of the oxide layers.

scholarly journals Effect of Initial Microstructure on Soft Annealing of a Low-Carbon Bainitic Steel

2021 ◽  
Vol 3 (1) ◽  
pp. 6
Author(s):  
Lei Zhu ◽  
Ying Yang ◽  
Yuyang Li ◽  
Huanhuan Xuan ◽  
Hongtao Chen ◽  
...  
Keyword(s):  
Activation Energy ◽  
Annealing Temperature ◽  
High Hardness ◽  
Air Cooling ◽  
Low Carbon ◽  
Initial Microstructure ◽  
Annealing Step ◽  
Activation Energy For Diffusion ◽  
Bainitic Structure ◽  
Carbide Content

A low-carbon bainitic tool steel exhibiting high hardness after hot rolling typically has poor machinability. To soften this type of steel and to accelerate the soft annealing process, an austenitizing step was designed based on thermodynamic calculations of phase stability and introduced prior to the annealing step. Different initial microstructures were prepared by three austenitizing temperatures (680 °C, 850 °C, 1000 °C) and three cooling methods (water quenching, oil quenching, and air cooling). The effect of initial microstructure on microstructures and hardness was studied. Softening equations, a function of annealing temperature and time, were established for different initial microstructures, and the relationships between annealing temperature, annealing time, activation energy, and hardness were explored. The predicted hardness was consistent with the measured values. Martensitic structure has a low activation energy for diffusion and a higher softening rate compared to that of the bainitic structure. In addition, the higher the carbide content in the bainitic structure, the smaller the activation energy tended to be.

scholarly journals Features of the formation of structure and mechanical properties in rolled products of various thicknesses from low-carbon microalloyed steel produced by casting and rolling complex

2021 ◽  
Vol 64 (9) ◽  
pp. 669-678
Author(s):  
V. V. Naumenko ◽  
K. S. Smetanin ◽  
А. V. Muntin ◽  
O. А. Baranova ◽  
S. V. Kovtunov
Keyword(s):  
Grain Size ◽  
Stress Concentrator ◽  
Microalloyed Steel ◽  
Rolling Direction ◽  
Large Angle ◽  
Low Carbon ◽  
Rolled Metal ◽  
Average Grain Size ◽  
Carbon Microalloyed ◽  
The Impact

The article considers results of the study of microstructure parameters effect on the impact strength in temperature range from 0 to –80  °C in 20  °C increments of Charpy samples with a sharp stress concentrator and Mesnager test pieces with a circular stress concentrator from rolled coils of low-carbon microalloyed steel with various thicknesses. The used roll products were produced in conditions of JSC “Vyksa Metallurgical Plant”. The tests were performed using optical and scanning electron microscopy. It is shown that with the same chemical composition and thermomechanical treatment modes, the metal of smaller thickness (6, 8 mm) is characterized by higher strength properties (on average, by 10 MPa for temporary resistance, by 30 MPa for yield strength) and a margin for viscous properties at negative temperatures at close values of grain score and average grain size corresponding to 10 – 11 numbers according to the State standard GOST 5639. The metal with a thickness of 12 mm has the lowest level of cold resistance, and the temperature of brittle transition is minus 50 °C. Structure of rolled products of various thicknesses has a variation in grain size. Rolled metal of smaller thicknesses have a smaller grains corresponding to number 14, rolled metal of larger thicknesses has a larger grains corresponding to number 8. By conducting electron microscopic studies using the backscattered electron method, it was found that a greater number of large-angle boundaries, which are barriers for brittle cracks propagation, are observed in the 6, 8 mm thick rolled products. The constructed orientation maps of the microstructure showed the presence of pronounced deformation texture corresponding to the orientations <110>||RD (rolling direction) and (<113>...<112>)||RD for rolled products with a thickness of 6 mm.

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