Image Evaluation of Distribution of Carbide Particles in Repeatedly Quenched (Two and Three Times) JIS-SUJ2 Steels

2021 ◽  
Vol 315 ◽  
pp. 66-71
Author(s):  
Koshiro Mizobe ◽  
Takahiro Matsueda ◽  
Yoshinobu Miyabe ◽  
Katsuyuki Kida
Keyword(s):  
Prior Austenite ◽  
Optimal Distribution ◽  
Image Evaluation ◽  
Austenite Grains ◽  
Carbide Particles

In order to investigate the relation between prior austenite grains (PAG) and the carbide particles, we observed etched microstructure in JIS-SUJ2 steel. We traced and drew the outlines of carbide particles and analyzed some of their shape values. We confirmed that the repeated quenching can refine PAG size while keeping the optimal distribution of the carbide particles.

scholarly journals Exploring the Difference in Bainite Transformation with Varying the Prior Austenite Grain Size in Low Carbon Steel

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 988 ◽  
Author(s):  
Liangyun Lan ◽  
Zhiyuan Chang ◽  
Penghui Fan
Keyword(s):  
Grain Size ◽  
Prior Austenite ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Bainite Transformation ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Austenite Grains ◽  
Prior Austenite Grain Size ◽  
Prior Austenite Grain

The simulation welding thermal cycle technique was employed to generate different sizes of prior austenite grains. Dilatometry tests, in situ laser scanning confocal microscopy, and transmission electron microscopy were used to investigate the role of prior austenite grain size on bainite transformation in low carbon steel. The bainite start transformation (Bs) temperature was reduced by fine austenite grains (lowered by about 30 °C under the experimental conditions). Through careful microstructural observation, it can be found that, besides the Hall–Petch strengthening effect, the carbon segregation at the fine austenite grain boundaries is probably another factor that decreases the Bs temperature as a result of the increase in interfacial energy of nucleation. At the early stage of the transformation, the bainite laths nucleate near to the grain boundaries and grow in a “side-by-side” mode in fine austenite grains, whereas in coarse austenite grains, the sympathetic nucleation at the broad side of the pre-existing laths causes the distribution of bainitic ferrite packets to be interlocked.

scholarly journals A Review of Austenite Memory Effect in HAZ of B Containing 9% Cr Martensitic Heat Resistant Steel

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1233
Author(s):  
Li ◽  
Li ◽  
Cai ◽  
Pan
Keyword(s):  
Memory Effect ◽  
Prior Austenite ◽  
Welding Process ◽  
Peak Temperature ◽  
Reverse Transformation ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
Matrix Microstructure ◽  
Austenite Grains

During the welding process of B containing 9% Cr martensitic heat resistant steel (9Cr-B steel), austenite memory effect (referred to that the prior austenite grains in the heat affected zone (HAZ) after welding inherit the shape and size of prior austenite grains before welding) occurs in its normalized sub-zone of HAZ and the grain refinement is suppressed, which can effectively prevent type IV crack, and improve the service life of the welded joint at high temperatures. In the present article, α/γ reverse transformation behavior in the normalized sub-zone of 9Cr-B steel HAZ is reviewed. Austenite memory effect of 9Cr-B steel is derived from B addition. The main mechanisms of austenite memory effect during α/γ reverse transformation are discussed. Various models of boron causing austenite memory effect are discussed in detail. Matrix microstructure also plays an important role in austenite memory effect. Effects of heating rate, peak temperature, and holding time at peak temperature on austenite memory effect are also discussed.

Defects and Particles in Laboratory Hot Rolled Steel of C-Mn-Cr-Nb Type

2014 ◽  
Vol 782 ◽  
pp. 221-226
Author(s):  
Petr Kawulok ◽  
Ivo Schindler ◽  
Jaroslav Sojka ◽  
Stanislav Rusz ◽  
Rostislav Kawulok ◽  
...  
Keyword(s):  
Heating Temperature ◽  
Niobium Carbide ◽  
Surface Cracks ◽  
Tem Analysis ◽  
Variable Parameters ◽  
Final Microstructure ◽  
Austenite Grains ◽  
Hot Rolled ◽  
Hot Rolled Steel ◽  
Carbide Particles

Susceptibility to cracking of the as-cast C-Mn-Cr-Nb steel was studied by laboratory rolling. The variable parameters were the heating temperature (1150 - 1340 °C) as well as the rolling temperature (950 - 1150 °C). Final microstructure of the free-cooled samples was constituted by bainite, pearlite and ferrite with different morphology and various contribution. Deformation temperature below 1000 °C yielded in the incomplete recrystallization of austenite. Surface cracks originated preferentially on the austenite grains boundaries. Size of the present particles (inclusions and precipitates) varied from 101 nm to 101 μm. SEM and EDS analysis revealed that the inclusions ware mostly of the MnS type. TEM analysis confirmed that the grain boundaries were not enriched by any particles. In addition to the Fe3C particles, the discoid niobium carbide particles with approximately 40 nm diameter and 10 nm thickness were detected. These small particles were not connected by any notable pinning of dislocations.

scholarly journals IMPACT OF USE ON RELEASE PROCESSES IN AUSTENITIC STEEL TP347HFG

2021 ◽  
Vol 72 (4) ◽  
pp. 22-26
Author(s):  
Hanna Purzyńska ◽  
Grzegorz Golański ◽  
Michał Kwiecień ◽  
Dariusz Paryż
Keyword(s):  
Grain Boundaries ◽  
Austenitic Steel ◽  
M23c6 Carbide ◽  
Σ Phase ◽  
Precipitation Processes ◽  
Austenite Grains ◽  
Carbide Particles ◽  
M23c6 Carbides ◽  
Large Primary ◽  
Release Processes

The article presents an analysis of precipitation processes in heat-resistant TP347HFG steel after 41,000 h of operation at 585°C. Microstructure investigation showed that the use of the tested steel resulted mainly in the precipitation processes occurring at grain boundaries. Identification of the precipitates showed the presence of M23C6 carbides and σ phase particles along boundaries. Single M23C6 carbide particles were revealed also at twin boundaries. Inside austenite grains, apart from large, primary precipitates, finely-dispersed secondary NbX particles (X = C,N) were also observed.

scholarly journals Investigation of Size Effects Due to Different Cooling Rates of As-Quenched Martensite Microstructures in a Low-Alloy Steel

2020 ◽  
Vol 10 (15) ◽  
pp. 5395
Author(s):  
Marius Graf ◽  
Matthias Kuntz ◽  
Hermann Autenrieth ◽  
Ralf Müller
Keyword(s):  
Heat Treatment ◽  
Prior Austenite ◽  
Electron Backscatter Diffraction ◽  
Heat Treatments ◽  
Orientation Relationships ◽  
Quenching Rate ◽  
Physical Mechanisms ◽  
Suitable Heat Treatment ◽  
Austenite Grains ◽  
Backscatter Diffraction

Martensite transformation is a complex mechanism in materials that is classically initiated by a suitable heat treatment. This heat treatment process can be optimized based on a better understanding of the physical mechanisms on the length scale of several prior austenite grains. It is therefore appropriate to consider individual process steps of heat treatment in isolation. The aim of this study is to characterize the microstructural size changes caused by a variation of the cooling rate applied during the quenching process. For this purpose, individual martensitic microstructures from different heat treatments are analyzed using the electron backscatter diffraction (EBSD) method. With special orientation relationships between the parent austenite and martensite, the structure of the prior austenite grains and the close packet plane packets can then be reconstructed. The influence of the heat treatments on these characteristics as well as on the martensite blocks is thus quantified. No significant influence of the quenching rate on the sizes of martensite blocks and packets could be found.

Influence of Austenite Grain Size on the Crystallography of Allotriomorphic Ferrite in a Low Carbon Steel

2012 ◽  
Vol 535-537 ◽  
pp. 605-610 ◽  
Author(s):  
Yin Bai ◽  
Hui Guo ◽  
Shan Wu Yang ◽  
Xin Lai He
Keyword(s):  
Grain Size ◽  
Prior Austenite ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Allotriomorphic Ferrite ◽  
Austenite Grains ◽  
Prior Austenite Grain Size ◽  
Prior Austenite Grain

The influence of prior austenite grain size on the crystallography of allotriomorphic ferrite is investigated in a low carbon steel. The results show that as the prior austenite grain size decreasing, the fraction of allotriomorphic ferrites that do not keep K-S orientation relationship with any surrounding prior austenite grains is increased. It is observed that such ferrites usually form at the grain edges or grain corners. It is known that with the grain size decreasing, the fraction of grain edges and corners increases. It is suggested that the free energy of the defects at such nucleation sites is higher than that at grain faces, and the nucleation barrier of ferrite is lower. As a result, the possibility for the ferrite to form that does not have orientation relationship with all surrounding austenite grains is increased at such sites.

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