Computation of parent austenite grain orientation from product grain orientations upon displacive phase transformations

2013 ◽  
Vol 21 (8) ◽  
pp. 085009 ◽  
Author(s):  
M J Holzweissig ◽  
D Canadinc ◽  
H J Maier
Keyword(s):  
Phase Transformations ◽  
Grain Orientation ◽  
Austenite Grain ◽  
Grain Orientations ◽  
Parent Austenite

Back calculation of parent austenite orientation using a clustering approach

2013 ◽  
Vol 46 (1) ◽  
pp. 210-215 ◽  
Author(s):  
V. Tari ◽  
A. D. Rollett ◽  
H. Beladi
Keyword(s):  
Face Centered Cubic ◽  
Orientation Relationships ◽  
New Approach ◽  
Austenite Grain ◽  
Parent Orientation ◽  
Back Calculation ◽  
Clustering Approach ◽  
Face Centered ◽  
Parent Austenite ◽  
Good Agreement

A new approach is presented for calculating the parent orientation from sets of variants of orientations produced by phase transformation. The parent austenite orientation is determined using the orientations of bainite variants that transformed from a single parent austenite grain. In this approach, the five known orientation relationships are used to back transform each observed bainite variant to all their potential face-centered-cubic (f.c.c.) parent orientations. A set of potential f.c.c. orientations has one representative from each bainite variant, and each set is assembled on the basis of minimum mutual misorientation. The set of back-transformed orientations with the minimum summation of mutual misorientation angle (SMMA) is selected as the most probable parent (austenite) orientation. The availability of multiple sets permits a confidence index to be calculated from the best and next best fits to a parent orientation. The results show good agreement between the measured parent austenite orientation and the calculated parent orientation having minimum SMMA.

scholarly journals Physical and Numerical Simulations of Closed Die Hot Forging and Heat Treatment of Forged Parts

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 15
Author(s):  
Łukasz Poloczek ◽  
Łukasz Rauch ◽  
Marek Wilkus ◽  
Daniel Bachniak ◽  
Władysław Zalecki ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Grain Size ◽  
Numerical Simulations ◽  
Phase Transformations ◽  
Hot Forging ◽  
Transformation Model ◽  
Controlled Cooling ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Conventional Heat Treatment

The paper describes physical and numerical simulations of a manufacturing process composed of hot forging and controlled cooling, which replace the conventional heat treatment technology. The objective was to investigate possibilities and limitations of the heat treatment with the use of the heat of forging. Three steels used to manufacture automotive parts were investigated. Experiments were composed of two sets of tests. The first were isothermal (TTT) and constant cooling rate (CCT) dilatometric tests, which supplied data for the identification of the numerical phase transformation model. The second was a physical simulation of the sequence forging-cooling on Gleeble 3800, which supplied data for the validation of the models. In the numerical part, a finite element (FE) thermal-mechanical code was combined with metallurgical models describing recrystallization and grain growth during forging and phase transformations during cooling. The FE model predicted distributions of the temperature and the austenite grain size in the forging, which were input data for further simulations of phase transformations during cooling. A modified JMAK equation was used to calculate the kinetics of transformation and volume fraction of microstructural constituents after cooling. Since the dilatometric tests were performed for various austenitization temperatures before cooling, it was possible to include austenite grain size as a variable in the model. An inverse algorithm developed by the authors was applied in the identification procedure. The model with optimal material parameters was used for simulations of hot forging and controlled cooling in one of the forging shops in Poland. Distributions of microstructural constituents in the forging after cooling were calculated. As a consequence, various cooling sequences during heat treatment could be analyzed and compared.

scholarly journals Reliability of multigrain indexing for orthorhombic polycrystals above 1 Mbar: application to MgSiO3 post-perovskite

2017 ◽  
Vol 50 (1) ◽  
pp. 120-130 ◽  
Author(s):  
Christopher Langrand ◽  
Nadège Hilairet ◽  
Carole Nisr ◽  
Mathieu Roskosz ◽  
Gábor Ribárik ◽  
...  
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Grain Orientation ◽  
Diamond Anvil Cell ◽  
Polycrystalline Material ◽  
Data Set ◽  
Grain Orientations ◽  
Diamond Anvil ◽  
Diffraction Peaks

This paper describes a methodology for characterizing the orientation and position of grains of an orthorhombic polycrystalline material at high pressure in a diamond anvil cell. The applicability and resolution of the method are validated by simulations and tested on an experimental data set collected on MgSiO3 post-perovskite at 135 GPa. In the simulations, ∼95% of the grains can be indexed successfully with ∼80% of the peaks assigned. The best theoretical average resolutions in grain orientation and position are 0.02° and 1.4 µm, respectively. The indexing of experimental data leads to 159 grains of post-perovskite with 30% of the diffraction peaks assigned with a 0.2–0.4° resolution in grain orientation. The resolution in grain location is not sufficient for in situ analysis of spatial relationships at high pressure. The grain orientations are well resolved and sufficient for following processes such as plastic deformation or phase transformation. The paper also explores the effect of the indexing parameters and of experimental constraints such as rotation range and step on the validity of the results, setting a basis for optimized experiments.

Grrain Orientations and their Influence on Precipitation in Hot Compressed Columnar Grains in Electrical Steel

2011 ◽  
Vol 702-703 ◽  
pp. 738-741
Author(s):  
H. Qian ◽  
Ping Yang ◽  
G.H. Zheng ◽  
Wei Min Mao
Keyword(s):  
Hot Deformation ◽  
Grain Orientation ◽  
Electrical Steel ◽  
Compression Axis ◽  
Electrical Steels ◽  
Grain Orientations ◽  
Columnar Grains ◽  
Columnar Grain ◽  
The Relationship ◽  
Sample Axis

To identify the relationship between grain orientation and precipitation of MnS/AlN particles during hot deformation, cylinder samples containing columnar grains in electrical steels were prepared with different angles between columnar grain axis and sample axis. They were heated at 1360°C and compressed at 1100°C for 50%. Grain orientations and the precipitation states are determined using XRD, EBSD, EDS and SEM. Results indicate a general behavior of less precipitates in <100> and more precipitates in <111> grains. In addition, more precipitates were observed in samples with grain boundaries perpendicular to compression axis.

scholarly journals On the Formation of Micro-Shrinkage Porosities in Ductile Iron Cast Components

Metals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 551 ◽  
Author(s):  
Ehsan Ghassemali ◽  
Anders Jarfors ◽  
Attila Diószegi
Keyword(s):  
Ductile Iron ◽  
Electron Backscatter Diffraction ◽  
Pressure Change ◽  
Grain Structure ◽  
Absolute Pressure ◽  
Dendrite Fragmentation ◽  
Austenite Grain ◽  
Backscatter Diffraction ◽  
Parent Austenite ◽  
Ebsd Method

A combination of direct austempering after solidification (DAAS) treatment and electron backscatter diffraction (EBSD) method was used to study the formation of micro-shrinkage porosities in ductile iron. Analyzing the aus-ferritic microstructure revealed that most of micro-shrinkage porosities are formed at the retained austenite grain boundaries. There was no obvious correlation between the ferrite grains or graphite nodules and micro-shrinkage porosities. Due to the absolute pressure change at the (purely) shrinkage porosities, the dendrite fragmentation rate during the DAAS process would be altered locally, which caused a relatively finer parent-austenite grain structure near such porosities.

scholarly journals MACRO- FEATURES AND DENSITY OF VARIOUS TIMBER SPECIES FROM PAPUA

2020 ◽  
Vol 6 (2) ◽  
pp. 141-148
Author(s):  
MULIYANA ARIFUDIN ◽  
WAHYUDI
Keyword(s):  
Tropical Forest ◽  
Sample Size ◽  
Grain Orientation ◽  
Density Measurement ◽  
Pulp And Paper ◽  
Timber Species ◽  
Low Density ◽  
Dominant Color ◽  
Alstonia Scholaris ◽  
Grain Orientations

This research highlights diversity of macro-features and density of major timber species from Papua. Thirty-one species of air-dried timber with sample size of 13 cm × 6 cm × 4 cm gathered across Papua were used for density measurement and macro-features observation, cover of colors, grain orientation, and wood texture. The results showed that whitish and straw to yellow brown are dominant color of timber mostly harvested from Papua tropical forest. Their grain orientations are mostly straight, while their textures are medium. With regard to their density, Xantostemum spp is the heaviest timber having density of 1,25 g/cm3 while Alstonia scholaris is the lightest species of timber with density of 0.29 g/cm3. Therefore, majority Papua`s timber species studied are classified into light class species or low density timbers. Pulp and paper, veneer, plywood, flooring, meubels, indoor urnitures and handles or woody utensils are the potential uses of these timber species.

scholarly journals Microstructural differences between naturally-deposited and laboratory beach sands

2021 ◽  
Vol 24 (1) ◽  
Author(s):  
Amy Ferrick ◽  
Vanshan Wright ◽  
Michael Manga ◽  
Nicholas Sitar
Keyword(s):  
Mechanical Properties ◽  
Coordination Number ◽  
Grain Orientation ◽  
Flowing Water ◽  
X Ray ◽  
Depositional Processes ◽  
Grain Orientations ◽  
Computed Microtomography ◽  
X Ray Computed ◽  
Beach Sands

AbstractThe orientation of, and contacts between, grains of sand reflect the processes that deposit the sands. Grain orientation and contact geometry also influence mechanical properties. Quantifying and understanding sand microstructure thus provide an opportunity to understand depositional processes better and connect microstructure and macroscopic properties. Using x-ray computed microtomography, we compare the microstructure of naturally-deposited beach sands and laboratory sands created by air pluviation in which samples are formed by raining sand grains into a container. We find that naturally-deposited sands have a narrower distribution of coordination number (i.e., the number of grains in contact) and a broader distribution of grain orientations than pluviated sands. The naturally-deposited sand grains orient inclined to the horizontal, and the pluviated sand grains orient horizontally. We explain the microstructural differences between the two different depositional methods by flowing water at beaches that re-positions and reorients grains initially deposited in unstable grain configurations.

scholarly journals Nanoscale investigation of deformation characteristics in a polycrystalline silicon carbide

2019 ◽  
Vol 56 (3) ◽  
pp. 951-967 ◽  
Author(s):  
D. Zhang ◽  
L. G. Zhao ◽  
A. Roy ◽  
Y.-L. Chiu
Keyword(s):  
Electron Microscopy ◽  
Fracture Toughness ◽  
Silicon Carbide ◽  
Grain Orientation ◽  
Indentation Depth ◽  
Mechanical Response ◽  
Electron Backscatter Diffraction ◽  
High Dose ◽  
Grain Orientations ◽  
Dislocation Movement

AbstractIn this paper, we study the mechanical behaviour of silicon carbide at the nanoscale, with a focus on the effects of grain orientation and high-dose irradiation. Grain orientation effect was studied through nanoindentation with the aid of scanning electron microscopy (SEM) and EBSD (electron backscatter diffraction) analyses. Mechanical properties such as hardness, elastic modulus and fracture toughness were assessed for different grain orientations. Increased plasticity and fracture toughness were observed during indentations on crystallographic planes which favour dislocation movement. In addition, for SiC subjected to irradiation, increases in hardness and embrittlement were observed in nanoindentations at lower imposed loads, whereas a decrease in hardness and an increase in toughness were obtained in nanoindentations at higher loads. Transmission electron microscopy (TEM) analyses revealed that the mechanical response observed at a shallow indentation depth was due to Ga ion implantation, which hardened and embrittled the surface layer of the material. With an increased indentation depth, irradiation-induced amorphization led to a decrease in hardness and an increase in fracture toughness of the material.

Micromechanical Modelling of Microtexture Formation in Low Alloy Steel Bainite

2011 ◽  
Vol 172-174 ◽  
pp. 1228-1233
Author(s):  
Sophie Lubin ◽  
Anne Francoise Gourgues-Lorenzon ◽  
Brigitte Bacroix ◽  
Hélène Réglé
Keyword(s):  
Micromechanical Model ◽  
Model Parameters ◽  
Low Alloy Steels ◽  
Obvious Effect ◽  
Austenite Grain ◽  
Shape Strain ◽  
Model Predictions ◽  
Alloy Steels ◽  
Upper Bainite ◽  
Parent Austenite

A micromechanical model was developed to account for the particular microtexture of upper bainite in low alloy steels, i.e. the non-random spatial distribution of variants within a given former austenite grain. A self-consistent scheme and an Eshelby approach, considering both transformation shape strain and viscoplastic strain as eigenstrains, was applied to estimate coupling between parent austenite and two or more bainite variants without any applied stress. Model predictions concerning self-accommodation between variants are sensitive to the plane of the first “lattice invariant shear” in the crystallographic model used to determine the shape strain. No obvious effect of the constitutive equations of phases and of the other model parameters was found.

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