Search results

There have low angle grain boundaries along the cross-section of the grain microstructures.
For the multi-pass pressing, although the pressing pass numbers are same, the processing routes were of important significance on the grain sizes and grain distribution and grain boundaries (GBs) orientations of workpieces.
For the multi-pass pressing, although the pressing pass numbers are same, the processing routes were of important significance on the grain sizes and grain distribution and grain boundaries orientations of workpieces.
Most of the grain boundaries of the materials exhibit an equiaxed grain structure and the grain distribution is uniform in the view field.
The grain distribution and grain boundary grain orientations were conducted.

Grain Boundary Engineering: progress and Challenges Weiguo Wang 1, a 1 Department of metallic materials, School of mechanical engineering, Shandong university of technology, Zibo 255049, PR China a email:wang.wei.guo@163.com, Keywords: Grain boundary engineering; Grain boundary character distribution; CSL boundary; .
The resistance of grain boundary engineered materials to grain boundary degradation have been improved dramatically, and some GBE processed metals have been put into use.
Finally, the fourth, which is frequently used in GBE field [21,26], is a iterative process of low-strain low-temperature long-time anneal or intermediate-strain high-temperature short-time anneal and usually, the number of iteration is 2 -7.
These data are all given based on number or length fraction of low ∑-CSL boundaries out of the total interfaces.
Though it might be meaningful to pursuing high fraction of SBs, it must be pointed out higher number or length fraction of SBs doesn't mean the better optimization of GBCD.

When there is an additional driving force for grains to grow beyond the limit of normal grain growth or when the normal grain growth process is inhibited, an abnormal grain growth will take place.
As a result, abnormal grain growth induces a bimodal grain size distribution.
The number of large grains is very small, as clearly shown in Fig. 5d.
As the annealing time and temperature are increased, the regions with small grains decrease in size and number.
Clusters of small grains coexist with large grains.

An alternative technique, the stereological method, has been developed to obtain statistical GB orientation distributions in a sample using great number of 2D EBSD mappings containing millions of grains [5].
For a selected host grain and a neighbouring grain, the voxels that belong to the host grain with at least one adjacent voxel that belongs to the neighbouring grain are identified as host boundary voxels.
Therefore the numbers of facets that bisect host-neighbour vectors along X, -X, Y, -Y, Z and -Z are counted separately, and these numbers are denoted as Nx, N-x, Ny, N-y, Nz, and N-z.
We start the analysis by choosing a host grain (grain 105) and one of its neighbouring grains (grain 155) in the dataset.
Crystal orientations (namely {001}, {011}, and {111}) of grains 105 and 155 are represented by red (grain 105) and blue (grain 155) symbols laid to the same stereographic projection.

In general, CA-model could be defined for any number of dimensions.
The number of neighbours is equal to six.
When we divide eight by six we get, not surprisingly, the number equal to 1.3 where three is the periodic number.
Simply said, the algorithm used in this study count the number of unlike neighbours of a cell belonging to the other grain/grains.
After counting the continuous number of neighbours belonging to the other grain, it is decided whether a reorientation of the given boundary cell is performed or not.

The raw video results allow a number of qualitative statements to be made about grain growth behaviour in these systems and some simplistic quantitative statements.
Grain Tracing.
Data Analysis - Grains.
Journal Title and Volume Number (to be inserted by the publisher) 3 (especially the most active) grow beyond the field of view, or the specimen drifts to give that result.
This generated a stream of Journal Title and Volume Number (to be inserted by the publisher) 5 Fig10.

Recrystallized Grain Size Distributions.
Fig. 3 clearly shows that recrystallized median grain size generally decreases with increasing flow stress and 0 5 10 15 200.0 0.1 0.2 0.3 natural strain (εεεε) flow stress [MPa] p40t109 dry all: strain rate ~5x10 -7 s -1, T=125°C calculated: p40t109 + solution-precipitation p40t114 wet p40t111 wet p40t112 wet p40t115 wet bb a Journal Title and Volume Number (to be inserted by the publisher) 5 2.0 2.1 2.2 2.3 2.4 2.5 2.60.8 0.9 1.0 1.1 1.2 1.3 1.4 log stress [MPa] log median grain size [µµµµm] 100°C 125°C 150°C 175°C 200°C 240°C -0.98 -1.71 -1.24 -1.64 -1.22 -1.99 temperature.
Typical slopes of adjacent points are indicated (numbers).
Strain rate contours for -7 < ε&log < -4 are indicated by thin solid lines (numbers).
Journal Title and Volume Number (to be inserted by the publisher) 7 [12] R.C.M.W.

The high-purity (99.99%) copper was received in a coarse-grained state with a grain size of ~1.2 mm.
It is important to note that there is a difference in the of the creep curves between the unpressed and the pressed materials and there is a difference in the fracture strain levels for the pressed material with different numbers of ECAP passes: these differences are denoted by the numbers B1 – B12 where the numeral denotes the number of ECAP passes using the route Bc [4].
Creep curves of (a) pure aluminium and (b) pure copper for unpressed (coarse-grained) state and various number of ECAP passes.
The solid regression lines correspond to the unpressed (coarse-grained) materials (N is number of ECAP passes).
Relation between mean creep rates and the minimum creep rates for (a) aluminium, and (b) copper (N is number of ECAP passes).

The focus is to model austenite grain size evolution.
Equipment Pass number T,  oC Strain Strain rate, s-1 Delay times, s Pre-heating furnace 1200 70 Rougher 1 1150 0.03 0.2 14 9 1110 1.08a) 2.0 90b) Finisher (web schedule) 1 1060 0.12 5.4 5 2 1060 0.13 10.2 16 12 810 0.08 18.4 28 13 785 0.07 15.5 6 14 720 1.57c) 14.8 Air cooled Finisher (Flange schedule) 1 1070 0.05 5.4 5 2 1060 0.17 10.2 16 12 980 0.11 18.4 28 13 950 0.10 15.5 6 14 890 1.90d) 14.8 Air cooled a) Total equivalent strain after pass number 9 in the rougher; b) Delay time after pass number 9 during transfer from the rougher to the finishing stands; c) and d) Total equivalent strains after pass number 14 for the web and flange parts, respectively.
Note in Table 2 that the fraction recrystallized after pass number 8 is 60% and that after pass 9 is 100%.
Austenite and ferrite grain sizes calculated by the model for the finisher: flange schedule Equipment Pass number Average dγ before pass, μm Delay times, s Recrystallized fraction, % Average dγ after delay, μm Finisher (flange schedule) 1 105 5 0 105 2 105 16 54 53 3 53 5 83 31 4 31 18 100 61 5 61 6 48 38 6 38 20 100 80 7 80 5 27 55 8 55 22 100 74 9 74 7 16 59 10 59 26 91 38 11 38 6 23 28 12 28 28 90 24 13 24 6 0 24 14 24 Air cooling -- 15* * Ferrite grain size after air cooling to room temperature.
Here, all numbers are given in weight percentages except for the case N, given in ppm.

To characterize the geometry of a grain boundary, we have to determine the misorientation between the neighboring grains, and the direction of the GB-plane.
Introduction Phenomena associated with grain boundaries (GB) in metals (e.g. corrosion, energy, segregation, etc) are known to be influenced by the grain boundary geometry. [1] The characterization of the geometry of a grain boundary relies on the calculation of the orientations of both neighboring grains and on the determination of the boundary-plane normal.
The symmetry-equivalent misorientation matrices (the number of them depends on the crystal structure) are determined from the orientation matrices of the corresponding grains.
Schematic figure of the projection of a grain boundary.
This can be shown by plotting the number of the GBs against the angle they extend to the sample surface.