Thermodynamic Calculation and Experimental Investigation of Second Phase Particles in Low Carbon Nb Microalloyed Steels

Luo, Yanzhao; Zhang, Jiongming; Xiao, Chao

doi:10.1002/srin.201100202

Cited by 6 publications

(6 citation statements)

References 13 publications

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“…The atom fraction of C and Nb decreases. There is ample experimental evidence18, 19 to show that Nb‐rich particles are more likely to be found with decreasing temperature and Ti‐rich particles exist at elevated temperature. The computed result presents good agreements with experimental observations.…”

Section: Resultsmentioning

confidence: 99%

Application of interactive multiple models in thermal modeling of power transformers

Akbari

Allahbakhshi

Golpari

2011

Int Trans Elec Energy Syst

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SUMMARYPower transformers are one of the most expensive equipments in power systems. The efficiency and optimal utilization of these equipments are very important issues. Some factors, like temperature, moisture and oxidation can affect the solid and liquid insulations and reduce the useful life of power transformer. Temperature of a power transformer depends on the ambient temperature, present and past loading and cooling classes. Proper thermal model is essential to predict temperature in different conditions of cooling system. Such model leads to analyze useful life and improve loading and utilization of a power transformer.In this contribution a thermal model for power transformers based on the new technique of Interactive Multiple Modeling (IMM) is suggested to predict the top-oil temperature. Practical validation is carried out with measured load and temperature data of a power transformer. Consequently the prediction error for the conventional thermal model and the new suggested model based on IMM technique are compared.

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Section: Resultsmentioning

confidence: 99%

Application of interactive multiple models in thermal modeling of power transformers

Akbari

Allahbakhshi

Golpari

2011

Int Trans Elec Energy Syst

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“…The solubility products are ${lg} K_{[{\rm M}][{\rm X}]}^{{\rm wt}\%} = A- B/T$ , where A and B are constants, [M] and [X] are the concentrations of the respective species in solution as listed in Table 2. But in the equations the concentrations and solubility products are expressed by molar fraction, thus, the following expression is used, where A and B are the tabulated parameters for each precipitate11, X % is the content of carbon or nitrogen, and M % is the content of microalloying element.…”

Section: Discussionmentioning

confidence: 99%

The Influence of Hot Charging Conditions on Microstructure and Precipitation of High Strength Nb–Ti Complex Microalloyed Steels

Luo

Zhang

Xiao

et al. 2012

steel research int.

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A comprehensive microstructure analyses were conducted for hot charging processed Nb, Ti microalloyed steel, especially focusing on the evolution of microstructure and precipitation behavior. Hot charging process was simulated in the laboratory in the current research. Precipitation and microstructure in Ti–Nb microalloyed HSLA steels were investigated in different hot charging temperature conditions using transmission electron microscope (TEM), optical microscopy, analytical transmission electron microscopy, and energy dispersive spectroscopy (EDS). The results showed that the microstructure consists of fine and homogeneous lath bainite at 1000°C, lath bainite and granular bainite at 900°C. As the hot charging temperature decreased, there appeared a small fraction of proeutectoid ferrite along grain boundary at 800°C. The grain sizes in hot charging are coarse compared with that of 700°C due to the phase transformation didn't occur. The chemical composition of complex carbonitrides changes from Ti rich to Ti–Nb uniform with decreasing temperature.

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“…It is well recognized that the composition, size, distribution, and volume fraction of the second phase particles controlled by the thermodynamic equilibrium contribute largely to controlling and improving the microstructure and mechanical properties of the steel products [13][14][15][16][17]. The thermodynamic and kinetic analysis of the solid solution and precipitation behavior of the microalloying elements in steel, as well as modeling and simulation, have been studied by researchers for many years [18][19][20]. Han et al [7] investigated the precipitation behavior of Ti in low C medium manganese steel treated by various processes and discovered that the dislocation strengthening mechanism induced by TiC precipitation is dominant for the variation of both strength and toughness.…”

Section: Introductionmentioning

confidence: 99%

"Effect of tempering process on mechanical properties of high titanium microalloyed steels containing niobium "

Guo¹,

Li²,

Zhi-qiang³

et al. 2022

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This paper focuses on the thermodynamic behavior of the precipitation of the second phase and microstructure evolution of the high titanium microalloyed steel containing niobium during tempering in the temperature range of 500-650 • C to reveal the influence of the heat treatment scheme on the toughness and microhardness. The results indicate that FCC A1#2 phase is isomorphic to FCC A1#3, which are carbonitrides of Ti or Nb, and precipitates at about 1266 • C. The Ti and Nb elements almost entirely precipitated at 800 • C, and their contents in the FCC A1#2 phase are much higher than those in FCC A1#3 in the low-temperature region. The microstructure of the tempered samples is mainly composed of granular bainite (GB), on which martensite/austenite (M/A) islands are distributed. The decomposition extent of M/A islands got higher and transformed into a large number of nano-sized cementite distributed at the grain boundaries of ferrite with the increasing tempering temperature. It is noticeable that those nanoscale spherical carbide particles provide an effective way to enhance the low temperature impact toughness of the steel significantly. The nanoparticles in the experimental steel tempered at 600 • C have an average diameter of 4.4 nm, accounting for nearly 65 % of the total number of particles. The experimental steel manifested the best low-temperature impact toughness of 361 J with a tempering temperature of 600 • C for 60 min after being quenched from 900 • C.

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Thermodynamic Calculation and Experimental Investigation of Second Phase Particles in Low Carbon Nb Microalloyed Steels

Cited by 6 publications

References 13 publications

Application of interactive multiple models in thermal modeling of power transformers

Application of interactive multiple models in thermal modeling of power transformers

The Influence of Hot Charging Conditions on Microstructure and Precipitation of High Strength Nb–Ti Complex Microalloyed Steels

"Effect of tempering process on mechanical properties of high titanium microalloyed steels containing niobium "

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