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segregation pattern
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Series: ASM Handbook
Volume: 9
Publisher: ASM International
Published: 01 December 2004
DOI: 10.31399/asm.hb.v09.a0003780
EISBN: 978-1-62708-177-1
... alloys, with the aid of black and white images. The article also provides information on the applications of etching and examination of uranium alloys, at both macro and micro scales, in characterizing the grain structures, segregation patterns, inclusions, and the metal flow geometries produced...
Abstract
This article discusses the principles of physical metallurgy and metallography of depleted uranium. It describes the techniques involved in the preparation of thin foils for transmission electron microscopy and illustrates the resulting microstructure of uranium and uranium alloys, with the aid of black and white images. The article also provides information on the applications of etching and examination of uranium alloys, at both macro and micro scales, in characterizing the grain structures, segregation patterns, inclusions, and the metal flow geometries produced by solidification and mechanical working processes.
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005210
EISBN: 978-1-62708-187-0
... zone, ℓ. The formation of a nonplanar interface causes solute segregation patterns, since the solid grows with a smaller composition than the alloy composition. The rejected solute accumulates in the intercellular/interdendritic region for alloy systems with phase diagrams in which the solute...
Abstract
Nonplanar microstructures form most frequently during the solidification of alloys, and play a crucial role in governing the properties of the solidified material. This article emphasizes the basic ideas, characteristic lengths, and the processing conditions required to control the columnar and equiaxed microstructures. The formation of cellular and dendritic structures in one- and two-phase structures is presented with emphasis on the effect of processing conditions and composition on the selection of microstructure and microstructure scales.
Series: ASM Handbook
Volume: 22B
Publisher: ASM International
Published: 01 November 2010
DOI: 10.31399/asm.hb.v22b.a0005525
EISBN: 978-1-62708-197-9
... of an array of columnar dendrites is obstructed mainly by the secondary dendrite arms, while the liquid moving perpendicular to that axis also must move around the primary arms, giving a very different flow pattern. One example of different permeability functions for flow parallel and perpendicular...
Abstract
This article presents conservation equations for heat, species, mass, and momentum to predict transport phenomena during solidification processing. It presents transport equations and several examples of their applications to illustrate the physics present in alloy solidification. The examples demonstrate the utility of scaling analysis to explain the fundamental physics in a process and to demonstrate the limitations of simplifying assumptions. The article concludes with information on the solidification behavior of alloys as predicted by full numerical solutions of the transport equations.
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005237
EISBN: 978-1-62708-187-0
... revealed no freckles and very little macrosegregation in the DS scenario. Hence, freckling in the VAR ingot must be discounted. Furthermore, a refined mesh used to simulate macrosegregation in the domain of the VAR slab ingot produces segregation patterns that are qualitatively similar to Fig. 3...
Abstract
In order to model macrosegregation, one must consider convection and the partitioning of segregating elements at the dendritic length scale. This article describes microsegregation with diffusion in the solid. It presents a continuum model of macrosegregation and illustrates the simulation of macrosegregation and microsegregation.
Book: Powder Metallurgy
Series: ASM Handbook
Volume: 7
Publisher: ASM International
Published: 30 September 2015
DOI: 10.31399/asm.hb.v07.a0006109
EISBN: 978-1-62708-175-7
... density, and compressibility of metal powders. It explains the mechanisms of powder segregation. The article provides information on green strength and springback value of rectangular test bar. It concludes with a discussion on the chemical composition of metal powders. angle of repose apparent...
Abstract
This article describes the methods for determining the flow rate of metal powders. It examines the factors affecting flow rate, apparent density, and angle of repose of metal powders. The article reviews the frictional properties, cohesive strength, frictional properties, tap density, and compressibility of metal powders. It explains the mechanisms of powder segregation. The article provides information on green strength and springback value of rectangular test bar. It concludes with a discussion on the chemical composition of metal powders.
Series: ASM Handbook
Volume: 1A
Publisher: ASM International
Published: 31 August 2017
DOI: 10.31399/asm.hb.v01a.a0006351
EISBN: 978-1-62708-179-5
... outlines the graphite nodules and reveals an absence of matrix substructure. On the other hand, color etching with aqueous 10% sodium metabisulfite can vividly reveal the dendritic segregation pattern in the austenitic matrix. (For more details on color metallography, see the article “Metallography...
Abstract
This article describes two contemporary approaches for preparing cast iron specimens with a wide range of phases and constituents as well as different graphite morphologies. It introduces concepts and preparation materials that enable metallographers to shorten the process while producing better, more consistent results. Recommended procedures to prepare cast irons and examples of high-alloy cast iron microstructures revealed using a variety of etchants are presented. Several etchants are used to reveal the matrix microstructure, depending on the alloy content. The article discusses the use of black and white etchants and lists the compositions of abrasion-resistant cast irons according to ASTM A532/A532M in a table.
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005208
EISBN: 978-1-62708-187-0
... in the solid, combined with rapid transport in the liquid, leads to the Scheil equation for microsegregation. Finally, the principles of transport and scaling are applied to homogenization processes to ameliorate the undesirable segregation pattern. References References 1. Dantzig J.A...
Abstract
This article begins with balance equations for mass, momentum, energy, and solute and the necessary boundary conditions for solving problems of interest in casting and solidification. The transport phenomena cover a vast range of length and time scales, from atomic dimensions up to macroscopic casting size and from nanoseconds for interface attachment kinetics to hours for casting solidification. The article describes how to determine which phenomena are most important at the particular length and time scale for the problem. It concludes with several examples of the application of transport phenomena in solidification, focusing on microstructure formation.
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005437
EISBN: 978-1-62708-196-2
... to ameliorate the undesirable segregation pattern. Acknowledgment This article originally appeared as “Transport Phenomena During Solidification,” by J.A. Dantzitg, Casting , Vol 15, ASM Handbook , ASM International, 2008, p 288–292. References References 1. Dantzig J.A. and Tucker...
Abstract
This article presents the governing equations for moving a solidification front, based on the balance of mass, momentum, energy, and solute. It reviews how material properties and geometry can be analyzed in the context of the governing equations. The article provides several example problems that illustrate how the hierarchy of time and length scales associated with transport leads to the important features of cast microstructures. It includes equations for estimating microsegregation in cast alloys.
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005236
EISBN: 978-1-62708-187-0
... alloy, distinct by composition and atomic structure. Within one grain metallic alloys also show a microstructure caused by segregation patterns due to the dendritic growth instability of the growth front. Figure 1 presents a longitudinal cross section of a 0.17 m (7 in.) Al-7wt%Si cylindrical ingot...
Abstract
Modeling of structure formation in casting of alloys involves several length scales, ranging from the atomic level to macroscopic scale. Intermediate length scales are used to define the microstructure of the growing phases and the grain structure. This article discusses the principles and applications of the phase field method and the cellular automaton method for modeling the direct evolution of structure at the intermediate length scales, where transport phenomena govern the spatial and temporal evolution of the structure that involves nucleation and growth.
Series: ASM Handbook
Volume: 22A
Publisher: ASM International
Published: 01 December 2009
DOI: 10.31399/asm.hb.v22a.a0005406
EISBN: 978-1-62708-196-2
.... The microstructure of a casting can consist of different grains of the same thermodynamic phase, distinct by orientation, or different phases of one alloy, distinct by composition and atomic structure. Within one grain metallic alloys also show a microstructure caused by segregation patterns due to the dendritic...
Abstract
This article focuses on the intermediate length scales, where transport phenomena govern the spatial and temporal evolution of a structure. It presents the cellular automaton (CA) and phase field (PF) methods that represent the state of the art for modeling macrostructure and microstructure. The article describes the principles of the PF method and provides information on the applications of the PF method. The CA model is introduced as a computationally efficient method to predict grain structures in castings using the mesoscopic scale of individual grains. The article discusses the coupling of the CA to macroscopic calculation of heat, flow, and mass transfers in castings and applications to realistic casting conditions.
Series: ASM Handbook
Volume: 4B
Publisher: ASM International
Published: 30 September 2014
DOI: 10.31399/asm.hb.v04b.a0005940
EISBN: 978-1-62708-166-5
...) After round rolling stand. Source: Ref 26 Fig. 23 Macrostructure of the bar cross section (a) on the face of a forged disk and (b) sampling. Source: Ref 27 Fig. 24 Characteristic of fiber flow pattern of gear blanks described by (a) the distance y α and (b) its dependence...
Abstract
This article presents the three levels of investigations of distortion engineering. On Level 1, the parameters and variables influencing distortion in every manufacturing step must be identified. More than 200 parameters can affect distortion. The design of experiments approach allows for the investigation of larger numbers of parameters by a limited number of samples, and can be structured into system analysis, test strategy, test procedure, and test evaluation. Level 2 focuses on understanding the distortion mechanisms by using the concept of distortion potential and its carriers. Distortion engineering aims to compensate distortion using the so-called compensation potential (Level 3). Level 3 discusses the measures to improve homogeneity, and respectively the symmetry, of the carriers of the distortion potential. The article also discusses the compensation of the resulting size and shape changes of the existing asymmetries by well-directed insertions of additional inhomogeneity/asymmetries in one or more of the distributions of the carriers.
Series: ASM Handbook
Volume: 1A
Publisher: ASM International
Published: 31 August 2017
DOI: 10.31399/asm.hb.v01a.a0006342
EISBN: 978-1-62708-179-5
... automatic devices are used, a multidirectional scratch pattern is produced, and thus, specimen reorientation is not required. Automatic devices provide the best flatness and graphite retention. Grinding with worn or loaded papers, or grinding in the same direction with each paper grade, degrades...
Abstract
The metallographic specimen preparation process for microstructural investigations of cast iron specimens usually consists of five stages: sampling, cold or hot mounting, grinding, polishing, and etching with a suitable etchant to reveal the microstructure. This article describes the general preparation of metallographic specimens and the methods of macroscopic and microscopic examination. Usually, gray-scale (black-and-white) metallography is sufficient for microstructural analysis of cast irons. The article discusses the use of color metallography of gray irons and ductile irons. It also presents application examples of color metallography.
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005216
EISBN: 978-1-62708-187-0
...% for the uppermost contour at approximately midheight). (b) Macrosegregation pattern. The gray shades indicate the titanium concentration, with the darkest shade inside the open channels in the mush corresponding to the largest positive macrosegregation. Channel segregates are also observed in large steel...
Abstract
Macrosegregation refers to spatial compositional variations that occur in metal alloy castings and range in scale from several millimeters to centimeters or even meters. This article presents a derivative approach for understanding the mechanism of macrosegregation induced by flow of the liquid and movement of the solid with examples.
Series: ASM Desk Editions
Publisher: ASM International
Published: 01 December 1998
DOI: 10.31399/asm.hb.mhde2.a0003250
EISBN: 978-1-62708-199-3
.... This map provides a method for characterizing chemical inhomogeneities on a spatial resolution scale midway between the ∼1 cm range of “bulk XRF” and the ∼1 μm scale of electron probe microanalysis, for example, characterizing segregation patterns in cross-sectioned ingots. Optical emission...
Abstract
The overall chemical composition of metals and alloys is most commonly determined by X-ray fluorescence (XRF) and optical emission spectroscopy (OES), and combustion and inert gas fusion analysis. This article provides information on the capabilities, uses, detection threshold and precision methods, and sample requirements. The amount of material that needs to be sampled, operating principles, and limitations of the stated methods are also discussed.
Series: ASM Handbook
Volume: 9
Publisher: ASM International
Published: 01 December 2004
DOI: 10.31399/asm.hb.v09.a0003750
EISBN: 978-1-62708-177-1
.... 1 Center segregation in an alloy steel billet (a) Graded C-1 in the graded series ( Ref 4 ). 0.625×. (b) Graded C-5 in the graded series ( Ref 4 ). 0.5×. Both samples etched in 50% aqueous HCl. Source: Ref 7 , courtesy of Republic Steel Ingot Pattern The conditions leading...
Abstract
Macroetching is a procedure for revealing the large-scale structure of a metallic specimen, that is, the structure visible with the unaided eye, by etching an appropriately prepared surface. This article provides information on the basic procedures for macroetching as well as the apparatus used. It discusses selected etchants for efficient macroetching of various metals and their alloys, including iron, steel, high-alloy steels, stainless steels, high-temperature alloys, titanium, titanium alloys, aluminum, aluminum alloys, copper, and copper alloys. The article also describes various conditions that are revealed by the macroetching of aluminum.
Series: ASM Handbook Archive
Volume: 10
Publisher: ASM International
Published: 01 January 1986
DOI: 10.31399/asm.hb.v10.a0001766
EISBN: 978-1-62708-178-8
... be solved, at least in part, with AEM. analytical electron microscopes analytical transmission electron microscopy bright-field microscopy data analysis defect analysis deformation dislocations electron diffraction electron energy loss spectroscopy electron guns grain-boundary segregation...
Abstract
Analytical transmission electron microscopy (ATEM) is unique among materials characterization techniques as it enables essentially the simultaneous examination of microstructural features through high-resolution imaging and the acquisition of chemical and crystallographic information from small regions of the specimen. This article illustrates the effectiveness of the technique in solving materials problems. The first section of the article provides information on analytical electron microscope (AEM) and its basic operational characteristics as well as on electron optics, electron beam/specimen interactions and the generation of a signal, signal detectors, electron diffraction, imaging, x-ray microanalysis, electron energy loss spectroscopy, and sample preparation. The second section consists of 12 examples, each illustrating a specific type of materials problem that can be solved, at least in part, with AEM.
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0001808
EISBN: 978-1-62708-180-1
..., such as bursts. Internal stress concentrators can also be introduced during solidification of ingots from which forged shafts are made. Generally, these stress concentrators are internal discontinuities, such as pipe, segregation, porosity, shrinkage, and nonmetallic inclusions. Fractures also result from...
Abstract
This article discusses failures in shafts such as connecting rods, which translate rotary motion to linear motion, and in piston rods, which translate the action of fluid power to linear motion. It describes the process of examining a failed shaft to guide the direction of failure investigation and corrective action. Fatigue failures in shafts, such as bending fatigue, torsional fatigue, contact fatigue, and axial fatigue, are reviewed. The article provides information on the brittle fracture, ductile fracture, distortion, and corrosion of shafts. Abrasive wear and adhesive wear of metal parts are also discussed. The article concludes with a discussion on the influence of metallurgical factors and fabrication practices on the fatigue properties of materials, as well as the effects of surface coatings.
Book Chapter
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003507
EISBN: 978-1-62708-180-1
.... The article discusses the types of imperfections that can be traced to the original ingot product. These include chemical segregation; ingot pipe, porosity, and centerline shrinkage; high hydrogen content; nonmetallic inclusions; unmelted electrodes and shelf; and cracks, laminations, seams, pits, blisters...
Abstract
This article describes the general root causes of failure associated with wrought metals and metalworking. This includes a brief review of the discontinuities or imperfections that may be the common sources of failure-inducing defects in bulk working of wrought products. The article discusses the types of imperfections that can be traced to the original ingot product. These include chemical segregation; ingot pipe, porosity, and centerline shrinkage; high hydrogen content; nonmetallic inclusions; unmelted electrodes and shelf; and cracks, laminations, seams, pits, blisters, and scabs. The article provides a discussion on the imperfections found in steel forgings. The problems encountered in sheet metal forming are also discussed. The article concludes with information on the causes of failure in cold formed parts.
Book Chapter
Book: Casting
Series: ASM Handbook
Volume: 15
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.hb.v15.a0005202
EISBN: 978-1-62708-187-0
...: Tree ring patterns Freckles White spots Tree ring patterns can be identified in a macroetched transverse section as light-etching rings. They usually represent a negative crystal segregation. Tree ring patterns seem to have little effect on material properties. Freckles and white spots have...
Abstract
The vacuum arc remelting (VAR) process is widely used to improve the cleanliness and refine the structure of standard air melted or vacuum induction melted (VIM) ingots. It is also used in the triplex production of superalloys. This article illustrates the VAR process and the capabilities and variables of the process. It also presents a discussion on the melt solidification, resulting structure, and ingot defects. The article concludes with a discussion on the VAR process of superalloy and titanium and titanium alloy.
Series: ASM Handbook
Volume: 9
Publisher: ASM International
Published: 01 December 2004
DOI: 10.31399/asm.hb.v09.a0003768
EISBN: 978-1-62708-177-1
... the presence of deformation and annealing twins in the austenite grains. Alcohol rinsing is again recommended to minimize staining of the specimen surface. Deep immersion etching, that is, longer etching times, can be used to reveal the solute segregation pattern within the austenite grains. In addition...
Abstract
This article focuses on the specimen preparation procedures of austenitic manganese steels: sectioning, mounting, and grinding. It provides information on macroexamination and microexamination of a fracture surface, the microstructure and special features of austenitic manganese steels, and the alloying elements used.