scholarly journals Thermodynamic, Kinetic, and Microstructure Data for Modeling Solidification of Fe-Al-Mn-Si-C Alloys

2020 ◽  
Vol 51 (6) ◽  
pp. 2946-2962
Author(s):  
Jyrki Miettinen ◽  
Sami Koskenniska ◽  
Ville-Valtteri Visuri ◽  
Mahesh Somani ◽  
Timo Fabritius ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Cooling Rate ◽  
Electron Probe ◽  
Shell Growth ◽  
Carbon Steels ◽  
Experimental Measurements ◽  
Solidification Behavior ◽  
Delta Ferrite ◽  
Equilibrium Solidification ◽  
Cracking Tendency

AbstractIn this study, a set of thermodynamic, kinetic, and microstructure data is presented to simulate the non-equilibrium solidification of Fe-Al-Mn-Si-C alloys. The data were further validated with the experimental measurements and then used in a thermodynamic–kinetic software, IDS, to establish the effect of the alloying and cooling rate on the solidification behavior of high-AlMnSi (Al ≥ 0.5 wt pct, Mn ≥ 2 wt pct, Si ≥ 1 wt pct) steels. The modeling results were additionally validated by conducting electron probe microanalysis (EPMA) measurements. The results reveal that (1) solidification in high-AlMnSi steels occurs at much lower temperatures than in carbon steels; (2) increasing the cooling rate marginally lowers the solidus; (3) the microsegregation of Mn in austenite is much stronger than that of Si and Al due to the tendency of Al and Si to deplete from the liquid phase; (4) the residual delta ferrite content may be influenced by a proper heat treatment but not to the extent that could be expected solely from thermodynamic calculations; (5) in high-AlMnSi steels containing less than 0.2 wt pct carbon, the cracking tendency related to the strengthening above the solidus and the shell growth below the solidus may be much lower than in carbon steels.

Back Diffusion of Manganese during Solidification of Carbon Steels

2006 ◽  
Vol 508 ◽  
pp. 443-448 ◽  
Author(s):  
Altan Turkeli ◽  
David H. Kirkwood
Keyword(s):  
Carbon Content ◽  
Cooling Rate ◽  
Solid Phase ◽  
Carbon Steels ◽  
Experimental Measurements ◽  
Back Diffusion ◽  
Delta Ferrite ◽  
Delta Phase ◽  
Small Rise ◽  
Good Agreement

In this study, back diffusion of manganese in solid between secondary arms in the ternary Fe – 1.6 wt % Mn – 0.1, 0.21, 0.4 and 0.75 wt % C alloys was investigated in unidirectionally solidified quenched specimens which solidified in the range of 0.25 K/s to 4.15 K/s cooling rates. Manganese back diffusion in the solid phase during the growth has a large influence on microsegregation when the first solid formed is delta-ferrite. A decrease in Cmin after 0.1 wt % C has been observed because the fraction of delta phase decreases with increasing carbon content. Only a small rise during the growth was found in both 0.4 and 0.8 wt % C steels but there was no difference between them indicating that both solidify as austenite. Secondary dendrite arms grown at the lowest cooling rate (around 0.3 K/s) always disappeared at the end of solidification for all steels. These high increases in Cmin were attributed to the high coarsening, back diffusion and TGZM processes. The Cmin calculations obtained from the secondary dendrite arm coarsening model are in a good agreement with the experimental measurements.

scholarly journals Nucleation Behavior of a Single Al-20Si Particle Rapidly Solidified in a Fast Scanning Calorimeter

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2920
Author(s):  
Qin Peng ◽  
Bin Yang ◽  
Benjamin Milkereit ◽  
Dongmei Liu ◽  
Armin Springer ◽  
...  
Keyword(s):  
Cooling Rate ◽  
Rapid Solidification ◽  
Heterogeneous Nucleation ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Solidification Behavior ◽  
Nucleation Kinetics ◽  
Nucleation Behavior ◽  
Nucleation Undercooling ◽  
Primary Si

Understanding the rapid solidification behavior characteristics, nucleation undercooling, and nucleation mechanism is important for modifying the microstructures and properties of metal alloys. In order to investigate the rapid solidification behavior in-situ, accurate measurements of nucleation undercooling and cooling rate are required in most rapid solidification processes, e.g., in additive manufacturing (AM). In this study, differential fast scanning calorimetry (DFSC) was applied to investigate the nucleation kinetics in a single micro-sized Al-20Si (mass%) particle under a controlled cooling rate of 5000 K/s. The nucleation rates of primary Si and secondary α-Al phases were calculated by a statistical analysis of 300 identical melting/solidification experiments. Applying a model based on the classical nucleation theory (CNT) together with available thermodynamic data, two different heterogeneous nucleation mechanisms of primary Si and secondary α-Al were proposed, i.e., surface heterogeneous nucleation for primary Si and interface heterogenous nucleation for secondary α-Al. The present study introduces a practical method for a detailed investigation of rapid solidification behavior of metal particles to distinguish surface and interface nucleation.

Effect of Cooling Rate on Microstructure and Properties of Heat-Treated Fe3Al Intermetallics

2011 ◽  
Vol 189-193 ◽  
pp. 3891-3894
Author(s):  
Ya Min Li ◽  
Hong Jun Liu ◽  
Yuan Hao
Keyword(s):  
Heat Treatment ◽  
Cooling Rate ◽  
Lattice Distortion ◽  
Annealing Furnace ◽  
Microstructure And Properties ◽  
Homogenizing Annealing ◽  
Heat Treated ◽  
Mixed Fracture ◽  
Sand Mould ◽  
The Impact

The casting Fe3Al intermetallics were solidified in sodium silicate sand mould and permanent mould respectively to get different cooling rates. After heat treatment (1000°С/15 h homogenizing annealing + furnace cooling followed by 600°С/1 h tempering + oil quenching), the microstructure and properties of Fe3Al intermetallics were investigated. The results show that the heat-treated Fe3Al intermetallics at higher cooling rate has finer grained microstructure than lower cooling rate, and the lattice distortion increases due to the higher solid solubility of the elements Cr and B at higher cooling rate. The tensile strength and hardness of the Fe3Al intermetallics at higher cooling rate are slightly higher also. However, the impact power of intermetallics at higher cooling rate is 67.5% higher than that at lower cooling rate, and the impact fracture mode is also transformed from intercrystalline fracture at lower cooling rate to intercrystallin+transcrystalline mixed fracture at higher cooling rate.

Microstructural evolution of delta ferrite in SAVE12 steel under heat treatment and short-term creep

2012 ◽  
Vol 73 ◽  
pp. 144-152 ◽  
Author(s):  
Shengzhi Li ◽  
Zumrat Eliniyaz ◽  
Lanting Zhang ◽  
Feng Sun ◽  
Yinzhong Shen ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Microstructural Evolution ◽  
Short Term ◽  
Delta Ferrite ◽  
Term Creep ◽  
Short Term Creep

scholarly journals The electrical conductivity of thin films of mercury

1939 ◽  
Vol 172 (951) ◽  
pp. 530-539 ◽  
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Electrical Conductivity ◽  
Alkali Metals ◽  
High Vacuum ◽  
Experimental Measurements ◽  
Preliminary Note ◽  
Extended Study ◽  
Temperature Coefficients ◽  
Conductivity Of Thin Films

In the present paper an account is given of experimental measurements on the electrical conductivity of thin films of mercury prepared by evaporative deposition in a high vacuum according to the technique described in previous papers (Lovell 1936; Appleyard and Lovell 1937). In a brief preliminary note (Appleyard 1937) we have pointed out that the results for mercury are very different from those for the alkali metals, and that in particular a considerable thickness of mercury must be deposited on the pyrex surface before conductivity begins. We have since confirmed and extended these observations, obtained accurate absolute values for the thickness of the films, investigated their stability, and made an extended study of their temperature coefficients after heat treatment. A comparison with the results of previous workers is given later.

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