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The code numbers for the variables used in the Table 4 were obtained from the following equations: （1） （2） （3） （4） Where, r is the number of replication of level (r=3), m is the number of level (m=3), n is the number of total test (n=9) and T is the sum of the testing results.
Al) is columnar grains around periphery and equiaxed grains in the center.
For 201 stainless steel, as shown in Fig.3, the typical microstructure of spot welded joint is the equiaxed grains around periphery and columnar crystals in nugget.
The HAZ has equiaxed grain structures shown in Fig.3 b.
When the welding current is over 6400A, because of the heat input increasing, larger columnar-dendritic grains can be observed.

Fatigue cracks of MB8 alloy initiate principally at surface and subsurface, and propagate along the grain boundary.
The large facets are in the order of the grain size in this alloy, whereas smaller features reveal a serrated fracture mechanism.
The fatigue crack is propagated along grain boundary as well as transgranular form.
The facet sizes are nearly the same as, or smaller than, the average grain size.
Fatigue cracks of MB8 alloy initiate principally at alloy subsurface, and propagate along the grain boundary.

The change of the number and morphology of β-Mg17Al12 phase results that the β-Mg17Al12 phase is turned from continuous network structure into intermittent-like and granular structure.
Therefore, the number of precipitation β-Mg17Al12 in No. 2 alloy after T6 heat treatment is greatly reduced than that of No.1 alloy, as shown in Fig.2(b).
The Al2Y and Al2Gd phase effectively hinder the barriers across the grain boundaries, preventing grain boundary sliding and migration.
At 200˚C, Al2Y and Al2Gd compounds can be used to stabilize the grain boundaries and prevent grain boundary sliding, which, in turn, significantly improved the thermal stability of alloys.
The tension crack tends to extend along the continuous, fragile grain boundary of the β-Mg17Al12 phase, which, in turn, results in the cracking between grains.

The size of crystalline grain was minished and elongated, equiaxial grain was elongated and staved along the rolling direction.
When the deformation exceeded 64.26%, non-equiaxed grain was more and more severity [5], the grain was stretched heavily and further refined and warping.
The grain was elongated remarkably along the rolling direction and began putting up to a trend of crack when the deformation was 43.71%, a mass of ferrite grain was distorted and refined with deformation increasing, the grain boundary was hard to discern.
Form the fig.3(c) known that cold deformation leaded to a large number of dislocation in intracrystalline, the augment of dislocation density was heavily because of dislocation multiplication with deformation increment.
The grain was elongated and refined with the deformation increasing, and to a certainly deform, the grain was warped and broken, it was formed the deformation texture

The grain size was refined from 800 µm to 15 µm.
The fatigue cracks developed on the surface of the work piece limit the number of corrugation and straightening.
Cyclic extrusion can be used to produce superfine grained metal materials, to locally strengthen a part or to locally refine the grain size in a part.
The as-received Al99.5 has elongated grains (Fig. 3).
The potential applications of cyclic extrusion include producing superfine grained metal materials and locally hardening or grain refining in a part.

From a large number electoral ward electron diffraction (SAD) analysis, BNf’s crystal structure have close relation with crystalline grain size, crystalline grain size has close relation with technology condition.
BNf’s crystalline grain size and layer interval d002 value change following a certain rule (From table 2) which is crystalline grain turning large ,d002 value turning gradually small.
In BNf, crystalline grain grows up at different level.
Crystal grain is small and even, arranging closely, only small air holes exist.
Surface crystalline grain appears long state and arranges by axle.

Authors, based on microstructural analysis observed distinct bi-modal grain structure where columnar grains were accompanied by very fine grains without preferential grain orientation.
As per these findings, the growth of epitaxial columnar grains above fine grains was due to segregation of Al3(Sc,Zr) precipitates along melt pool boundary which ultimately results in bi-modal grain structure.
The bi-modal grain structure observed by many investigations can be converted into fully equiaxed grains in the entire sample with nucleation of fine grains on the substrate of Al3(Sc,Zr) [12, 8].
Number density: Fig. 8 and 9 show the number density of Al3Sc due to IHT.
These precipitates could be acting as a substrate for the equiaxed grains and thereby resulting in the fine-grain microstructure.

Therefore, the GOS value of a recrystallized grain is expected to be small as compared to GOS value of a deformed grain.
To investigate the relation between critical strain and GOS at different deformation conditions, the number of DRX grains (in percentage form) at each condition has been plotted against the corresponding critical strain.
This is supported by the presence of several pancaked (elongated) grains surrounded by fine grains in Fig. 5a.
The increase in temperature may favour DRX kinetically, but due to insufficient thermal activation, the number of nucleating grains is limited.
This can be attributed to the greater number of nuclei available for recrystallization at these elevated temperatures.

For example, pure aluminium is known to be a soft ductile metal, but the fracture toughness is very low in absolute numbers.
Both UFG-metals show similarities such as the elongated grain structure and the inclination of the grains with respect to the shear direction, which is not noticeable in TEM-microhgraphs.
The grain sizes are around 200 nm to 300 nm in both cases.
The hardness increases linearly with the radius for different number of rotations.
High toughness cannot simply be referred to a reduction in grain size focusing on the given bcc examples.

While plastic deformation sets in within the softer austenite grains, fatigue crack initiation has been observed to occur at phase boundaries at locations where the slip bands emanating from an austenite grain impinge a neighboring ferrite grain [1].
Fatigue cracks propagate along slip bands through the ferrite grains and can be blocked by the next phase or grain boundary.
By using this geometrical information, fatigue damage can be assessed by using the approach of Tanaka and Mura [7] and Chan [8] to predict the number of cycles for fatigue crack initiation.
Crack propagation follows a relationship that was originally proposed by Chan [8] for the number of cycles to crack initiation Ni: , (2) where l refers to the cyclic irreversibility (the part of plastic deformation that contributes to fatigue damage).
By using Dgpl as a fatigue damage parameter, the interaction of fatigue cracks with the grain and phase boundaries as well as with the local stress state (e.g. superimposed residual stresses) can be predicted as a number of cycles Ni to extend the crack by a length increment a.