Spatial Uniformity of the Rate of Grain Coarsening in a Submicron Al-Sc Alloy Produced by Severe Plastic Deformation

2006 ◽  
Vol 503-504 ◽  
pp. 251-258
Author(s):  
Michael Ferry
Keyword(s):  
Fine Particles ◽  
Grain Structure ◽  
Processing Route ◽  
Grain Coarsening ◽  
Boundary Character ◽  
Angular Pressing ◽  
Grain Boundary Character ◽  
Uniform Dispersion ◽  
Grain Orientations ◽  
The Difference

The uniformity of grain coarsening throughout the microstructure of a submicron grained particle-containing aluminium alloy has been investigated using high resolution EBSD. The alloy was processed by equal channel angular pressing (ECAP) and low temperature ageing to generate ~0.8 􀁐m diameter grain structure containing a relatively uniform dispersion of nanosized Al3Sc particles. While the initial processing route generated a uniform grain size distribution, the distribution of grain orientations was rather inhomogeneous with certain regions of microstructure containing colonies of grains consisting predominantly of either HAGBs or LAGBs. It was found that, despite the difference in grain boundary character between these regions, the fine particles produced by pre-ageing promote uniform coarsening throughout the microstructure despite the marked differences in boundary character between these regions. An analytical model is outlined which predicts the uniformity of grain coarsening in particle-containing alloys despite the presence of orientation gradients in the microstructure.

The Potential of HAZ Property Improvement through Control of Grain Boundary Character in a Wrought Ni-Based Superalloy

2010 ◽  
Vol 654-656 ◽  
pp. 488-491 ◽  
Author(s):  
Hyun Uk Hong ◽  
In Soo Kim ◽  
Baig Gyu Choi ◽  
Hi Won Jeong ◽  
Seong Moon Seo ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Solution Treatment ◽  
Crystallographic Analysis ◽  
Treatment Temperature ◽  
Solution Treatment Temperature ◽  
Slow Cooling ◽  
Grain Coarsening ◽  
Boundary Character ◽  
Grain Boundary Character

The effects of grain boundary serration on grain coarsening and liquation behavior in simulated weld heat-affected-zone (HAZ) of a wrought Ni-based superalloy Alloy 263 have been investigated. Recently, the present authors have found that grain boundary serration occurs in the absence of adjacent coarse γ' particles or M23C6 carbides when a specimen is direct-aged with a combination of slow cooling from solution treatment temperature to aging temperature. This serration leads to a change in grain boundary character as special boundary based on the crystallographic analysis demonstrating that the grain boundaries tend to serrate to have specific segments approaching to one {111} low-index plane at a boundary. The present study was initiated to investigate the interdependence of the serration and HAZ property with a consideration of this serration as a potential for the use of a damage-tolerant microstructure. It was found that the serrated grain boundaries suppress effectively grain coarsening, and are highly resistant to liquation cracking in HAZ due to their lower tendency to be wetted and penetrated by the liquid phase. These results reflect closely a significant decrease in interfacial energy as well as grain boundary configuration by the serration.

A Comparison of Grain Boundary Character Distributions between Grain Boundary Engineered Austenitic Stainless Steel and Pb-Ca Based Alloy

2013 ◽  
Vol 753 ◽  
pp. 83-86
Author(s):  
Wei Guo Wang ◽  
Xiao Ying Fang ◽  
Hong Guo
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Grain Boundary ◽  
304 Stainless Steel ◽  
Orientation Relationships ◽  
Boundary Character ◽  
Grain Boundary Character ◽  
Stainless Steel 304 ◽  
Grain Orientations ◽  
Austenitic Stainless Steel 304

Though there developed same concentrations of special grain boundaries (SBs) in grain boundary engineered (GBE) austenitic stainless steel (304 stainless steel) and a Pb-Ca based alloy, the makeup of SBs, size distribution of clusters of grains with ∑3n (n=1,2,3) orientation relationships (∑3n CG), and grain orientations (textures) are quite different between the two specimens, suggesting there have two different mechanisms separately governing the evolution of grain boundary character distributions (GBCDs) in the two types of materials during GBE processing.

Investigation of Tensile Property and Pore Closure Behavior and the Influence of Processing Route during Equal Channel Angular Pressing of Pure Aluminum Powder Compacts

2014 ◽  
Vol 592-594 ◽  
pp. 444-450 ◽  
Author(s):  
R. Venkatraman ◽  
S. Raghuraman ◽  
R. Balaji ◽  
Kumar K.S. Ajay ◽  
M. Viswanath
Keyword(s):  
Equal Channel Angular Pressing ◽  
Cell Structure ◽  
Pure Aluminum ◽  
Dislocation Cell ◽  
Grain Structure ◽  
Ultrafine Grain ◽  
Processing Route ◽  
Angular Pressing ◽  
Ecap Process ◽  
Pore Closure

This paper revolves around the idea of finding the strength enhancement of pure ‘Al’ compacts processed through Equal-Channel Angular Pressing (ECAP) process which ultimately results in fine grain structure of the material processed. The material initially prepared through conventional powder metallurgical route is processed in an ECAP die with a channel angle of 1100. The tensile test and micro-structural evaluation is done following the ECAP process and it is found that there was a substantial enhancement in the tensile properties and Ultrafine Grain (UFG) structure is obtained due to the Severe Plastic Deformation (SPD) phenomenon taking place during the process. The pore closure behavior is also analyzed using the TEM micrographs after each pass in ECAP die and promising results are obtained when the material is processed through different routes. The dislocation cell structure is also found to get refined after each pass through the die. The pore closure behavior is also confirmed using the DEFORM 3D software when the aluminum is simulated under similar conditions.

scholarly journals Precipitation Criterion for Inhibiting Austenite Grain Coarsening during Carburization of Al-Containing 20Cr Gear Steels

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 504
Author(s):  
Huasong Liu ◽  
Yannan Dong ◽  
Hongguang Zheng ◽  
Xiangchun Liu ◽  
Peng Lan ◽  
...  
Keyword(s):  
Grain Growth ◽  
Abnormal Grain Growth ◽  
Grain Structure ◽  
Pinning Force ◽  
Grain Coarsening ◽  
Zener Pinning ◽  
Austenite Grain ◽  
Composition Optimization ◽  
Gear Steels ◽  
Grain Growth Behavior

AlN precipitates are frequently adopted to pin the austenite grain boundaries for the high-temperature carburization of special gear steels. For these steels, the grain coarsening criterion in the carburizing process is required when encountering the composition optimization for the crack-sensitive steels. In this work, the quantitative influence of the Al and N content on the grain size after carburization is studied through pseudocarburizing experiments based on 20Cr steel. According to the grain structure feature and the kinetic theory, the abnormal grain growth is demonstrated as the mode of austenite grain coarsening in carburization. The AlN precipitate, which provides the dominant pinning force, is ripened in this process and the particle size can be estimated by the Lifshitz−Slyosov−Wagner theory. Both the mass fraction and the pinning strength of AlN precipitate show significant influence on the grain growth behavior with the critical values indicating the grain coarsening. These criteria correspond to the conditions of abnormal grain growth when bearing the Zener pinning, which has been analyzed by the multiple phase-field simulation. Accordingly, the models to predict the austenite grain coarsening in carburization were constructed. The prediction is validated by the additional experiments, resulting in accuracies of 92% and 75% for the two models, respectively. Finally, one of the models is applied to optimize the Al and N contents of commercial steel.

scholarly journals Influence of Grain Boundary Character on Creep Void Formation in Alloy 617

2009 ◽  
Vol 40 (12) ◽  
pp. 2803-2811 ◽  
Author(s):  
Thomas Lillo ◽  
James Cole ◽  
Megan Frary ◽  
Scott Schlegel
Keyword(s):  
Grain Boundary ◽  
Void Formation ◽  
Alloy 617 ◽  
Boundary Character ◽  
Grain Boundary Character

Impact of grain boundary character on grain rotation

2014 ◽  
Vol 80 ◽  
pp. 141-148 ◽  
Author(s):  
Luis A. Barrales-Mora ◽  
Jann-Erik Brandenburg ◽  
Dmitri A. Molodov
Keyword(s):  
Grain Boundary ◽  
Grain Rotation ◽  
Boundary Character ◽  
Grain Boundary Character

Affected Characteristics Analysis of the Pulsed Laser Forming of Metal Sheet

2008 ◽  
Vol 375-376 ◽  
pp. 333-337
Author(s):  
Li Jun Yang ◽  
Yang Wang
Keyword(s):  
Laser Beam ◽  
Pulsed Laser ◽  
Metal Sheet ◽  
Grain Structure ◽  
Experimental Result ◽  
Laser Forming ◽  
Forming Process ◽  
Grain Orientations ◽  
Characteristics Analysis ◽  
Relationship Of

Laser forming of metal sheet is a forming technology of sheet without a die that the sheet is deformed by internal thermal stress induced by partially irradiation of a laser beam. In this paper, the bending behavior of common stainless steel 1Cr18Ni9 sheet is studied after being irradiated by straight line with a Nd:YAG pulsed laser beam. The aim of the investigation is to find out the relationship of the physical behaviors of heat affected zone (HAZ) with the pulse parameters of the laser. Through the analysis of the fundamental theory of pulsed laser affected, this paper shows the affected characteristics of metal sheet with pulsed laser forming. The results show that the microstructure of HAZ of pulsed laser scanned is layered, and the micro-hardness is improved than that in matrix. The microstructures show that the deformed grain structure is inhomogeneous, that caused the grain sizes and grain orientations in HAZ to become different. By qualitative analysis of experimental result, the conclusion obtained may provide basis for theoretical investigation and possible industrial application of laser forming process in the future.

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