Containerless solidification of undercooled SrO–Al2O3 binary melts

2015 ◽  
Vol 17 (9) ◽  
pp. 6495-6500 ◽  
Author(s):  
Katsuyoshi Kato ◽  
Atsunobu Masuno ◽  
Hiroyuki Inoue
Keyword(s):  
Binary System ◽  
Glass Forming Ability ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Glass Forming ◽  
Aerodynamic Levitation ◽  
Cct Diagrams ◽  
Containerless Solidification

The continuous cooling transformation (CCT) diagrams of the SrO–Al2O3 binary system under containerless conditions using an aerodynamic levitation furnace provide a slight difference in glass-forming ability at the edge of the glass-forming region.

scholarly journals Optimization of the CCT Curves for Steels Containing Al, Cu and B

2021 ◽  
Author(s):  
Jyrki Miettinen ◽  
Sami Koskenniska ◽  
Mahesh Somani ◽  
Seppo Louhenkilpi ◽  
Aarne Pohjonen ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Austenite Decomposition ◽  
Final Phase ◽  
Cast Irons ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Final Optimization ◽  
Cct Diagrams

AbstractNew continuous cooling transformation (CCT) equations have been optimized to calculate the start temperatures and critical cooling rates of phase formations during austenite decomposition in low-alloyed steels. Experimental CCT data from the literature were used for applying the recently developed method of calculating the grain boundary soluble compositions of the steels for optimization. These compositions, which are influenced by solute microsegregation and precipitation depending on the heating/cooling/holding process, are expected to control the start of the austenite decomposition, if initiated at the grain boundaries. The current optimization was carried out rigorously for an extended set of steels than used previously, besides including three new solute elements, Al, Cu and B, in the CCT-equations. The validity of the equations was, therefore, boosted not only due to the inclusion of new elements, but also due to the addition of more low-alloyed steels in the optimization. The final optimization was made with a mini-tab tool, which discarded statistically insignificant parameters from the equations and made them prudently safer to use. Using a thermodynamic-kinetic software, IDS, the new equations were further validated using new experimental CCT data measured in this study. The agreement is good both for the phase transformation start temperatures as well as the final phase fractions. In addition, IDS simulations were carried out to construct the CCT diagrams and the final phase fraction diagrams for 17 steels and two cast irons, in order to outline the influence of solute elements on the calculations and their relationship with literature recommendations.

Effect of boron on the continuous cooling transformation kinetics in a low carbon advanced ultra-high strength steel (A-UHSS)

2012 ◽  
Vol 1485 ◽  
pp. 83-88 ◽  
Author(s):  
G. Altamirano ◽  
I. Mejía ◽  
A. Hernández-Expósito ◽  
J. M. Cabrera
Keyword(s):  
Research Work ◽  
High Strength Steels ◽  
High Strength ◽  
Microstructural Characterization ◽  
Low Carbon ◽  
Transformation Kinetics ◽  
Cooling Rates ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Cct Diagrams

ABSTRACTThe aim of the present research work is to investigate the influence of B addition on the phase transformation kinetics under continuous cooling conditions. In order to perform this study, the behavior of two low carbon advanced ultra-high strength steels (A-UHSS) is analyzed during dilatometry tests over the cooling rate range of 0.1-200°C/s. The start and finish points of the austenite transformation are identified from the dilatation curves and then the continuous cooling transformation (CCT) diagrams are constructed. These diagrams are verified by microstructural characterization and Vickers micro-hardness. In general, results revealed that for slower cooling rates (0.1-0.5 °C/s) the present phases are mainly ferritic-pearlitic (F+P) structures. By contrast, a mixture of bainitic-martensitic structures predominates at higher cooling rates (50-200°C/s). On the other hand, CCT diagrams show that B addition delays the decomposition kinetics of austenite to ferrite, thereby promoting the formation of bainitic-martensitic structures. In the case of B microalloyed steel, the CCT curve is displaced to the right, increasing the hardenability. These results are associated with the ability of B atoms to segregate towards austenitic grain boundaries, which reduce the preferential sites for nucleation and development of F+P structures.

scholarly journals Continuous Cooling Transformation Diagrams of 2.25Cr-1Mo-0.25V Submerged-Arc Weld Metal and Base Metal

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1055
Author(s):  
Hannah Schönmaier ◽  
Bernd Loder ◽  
Thomas Fischer ◽  
Fred Grimm ◽  
Ronny Krein ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Weld Metal ◽  
Base Metal ◽  
Lower Bainite ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Upper Bainite ◽  
Cct Diagrams ◽  
Scanning Electron

The transformation behavior and microstructural evolution during continuous cooling within the heat affected zone between the weld beads of a 2.25Cr-1Mo-0.25V all-weld metal and the corresponding 2.25Cr-1Mo-0.25V base metal were investigated by means of dilatometer measurements, optical and scanning electron microscopy. Furthermore, macro-hardness measurements were conducted and the ferrite phase fraction was analyzed from optical microscopic images using an imaging processing program. Thereupon a continuous cooling transformation (CCT) diagram for the 2.25Cr-1Mo-0.25V base metal and three welding CCT diagrams with different peak temperatures were constructed to realistically simulate the temperature profile of the different regions within the heat affected zones between the weld beads of the multi-layer weld metal. The microstructural constituents which were observed depending on the peak temperature and cooling parameters are low quantities of martensite, high quantities of bainite and in particular lower bainite, coalesced bainite and upper bainite as well as ferrite for the welding CCT diagrams. Regarding the base metal CCT diagram, all dilatometer specimens exhibited a fully bainitic microstructure consisting of lower bainite, coalesced bainite and upper bainite. Only the slowest cooling rate with a cooling parameter of 50 s caused a ferritic transformation. Nevertheless, it has to be emphasized that the distinction between martensite and bainite and the various kinds of bainite was only possible at higher magnification using scanning electron microscopy.

The Role of Continuous Cooling Transformation Diagrams in Material Design for High Strength Oil and Gas Transmission Pipeline Steels

2006 ◽  
Author(s):  
Douglas G. Stalheim ◽  
Govindarajan Muralidharan
Keyword(s):  
Oil And Gas ◽  
Alloy Composition ◽  
Processing Route ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Effective Manner ◽  
Final Microstructure ◽  
Cct Diagrams ◽  
Transmission Pipelines

The economical, environmental, and safe movement of gas and oil to the marketplace requires transmission pipelines to be designed to operate at higher pressures and/or with improved toughness over a variety of temperature ranges. To meet the higher strength and toughness specification requirements of these transmission pipelines, appropriate materials and processes must be used in their design and construction. This includes selection of appropriate alloy composition, processing routes, microstructure control, and cost. A continuous cooling transformation (CCT) diagram is a tool that can be used to select alloy composition and processing route in order to obtain a specific, desirable microstructure for transmission linepipe steels in a cost-effective manner. In the past, CCT diagrams were developed experimentally under laboratory conditions, thus requiring extensive time and effort. However, with the vast data available and improved computational tools, reasonably accurate computer generated CCT diagrams can be produced quickly. These computer generated diagrams can give the materials design engineer a reasonable understanding of the effect of subjecting a given alloy to various processing routes and hence the resultant microstructures. Since final microstructure is a key variable in determining the linepipe steel material properties, the chosen alloy/processing route and its effect on the final microstructure needs to be understood. This paper will discuss the role of CCT diagrams in the design of steels (cost, alloy, processing, and microstructure) for oil and gas transmission pipelines. Examples of computer generated CCT digrams for various API alloy designs are included.

Effects of Vanadium on the Continuous Cooling Transformation of 0.7 %C Steel for Railway Wheels

2016 ◽  
Vol 367 ◽  
pp. 60-67 ◽  
Author(s):  
Solange T. Fonseca ◽  
Amilton Sinatora ◽  
Antonio J. Ramirez ◽  
Domingos J. Minicucci ◽  
Conrado R. Afonso ◽  
...  
Keyword(s):  
Room Temperature ◽  
Initial Temperature ◽  
Volume Fraction ◽  
Martensite Formation ◽  
Cooling Rates ◽  
Continuous Cooling Transformation ◽  
Continuous Cooling ◽  
Xrd Techniques ◽  
Railway Wheels ◽  
Cct Diagrams

To understand the effect of vanadium on the austenite decomposition of a 0.7 %C steel used in railway wheels the Continuous Cooling Transformation (CCT) diagrams were obtained and the microstructures analyzed with optical, SEM, TEM and XRD techniques. Vanadium refined the austenitic grain (12 and 6 μm for 7C and 7V, respectively), what can be explain by the presence of fine (10 nm in diameter) V4C3 precipitates, which restricts the austenitic grain growth. In addition, vanadium, in solid solution, reduced the pearlite interlamelar spacing (0.13 and 0.11 μm for 7C and 7V, respectively) by depressing the initial temperature pearlite formation (644 and 639 °C for 7C and 7V, respectively). He increased the ferrite volume fraction from 1 to 3 % at cooling rate of 1 oC/s, due the fact that vanadium is a ferrite stabilizer. Vanadium addition did not affect the initial temperature for martensite formation, but increased the hardenability with martensite formation at slower cooling rates (10 and 5 oC/s for 7C and 7V, respectively). For higher cooling rates (20 to 100 oC/s), the austenite transformation to martensite at room temperature was incomplete and all steels presented martensite and retained austenite, which volumetric fraction was near the same for both steels varying from 20 to 40 %.

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