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Fig.1 shows that the microstructure of low Nb steel is granular bainite and lath bainite, but the microstructure of high niobium steel is mainly acicular ferrite, grain is very small, the grain size at level 13 or above.
In addition the acicular ferrite can hold back the grain coarsening of HAZ.
There is a small angle grain boundary between lath bainites.
There are the high density dislocation and a large number of carbides on the lath bainite and ferrite microstructure ( Fig. 2a and b ).
The size of M-A constituent is about 1mm, and distributes usually in the grain boundaries of triangle grain boundary of the ferrite substructure.

According to classical Hall-Petch equation, the yield stress of materials increases significantly with decreasing the grain size.
Unlike other strengthening methods, grain refinement strengthening leads to higher tensile strength without reducing the toughness [2].
Hence sufficient plastic strain will be gradually accumulated to refine original coarse-grained structure.
As a result, satisfactory grain refinement and property enhancement can not be achieved in practical application.
The effectiveness for grain refinement is significantly improved.

In particular, the frost resistance of binding materials is determined by the number of cycles of alternating freezing/thawing [1].
Mechanism action of these chains is to provide deflocculation of cement particles at the initial time, it slows down the cement grains hydration [8].
As a result, denser contact of cement grains with water is ensured.
In this case, the process of destruction is inevitable after a certain number of cycles [10, 11].
In the presence of slag, the density change curve from the number of cycles looks different (Fig.2).

Since the grains are newly formed at this time, the grain number and size are relatively small.
With the extension of annealing duration, the number of MgB2 island-crystal increases, the grain size is also enlarged.
This enhances the connection between the adjacent MgB2 grains, the film surface becomes more dense, as shown in Fig. 4 (d).
When the annealing duration extend sequentially and more than a certain value, such as 0.2332 s in this paper, the annealing temperature becomes increasingly high, part of formed MgB2 grains begins to decompose, part of Mg atoms volatiles from the film, the number and size of MgB2 grains decreases, the densely connected adjacent MgB2 grains may become isolated, the film surface becomes sparse and coarse, as shown in Fig. 4 (e).
Since there are many grain gaps in the film, the best measuring circuit can not be formed for electrical measurement.

Introduction Magnesium, being a hexagonal close-packed metal has a poor formability at room temperature due to a limited number of operative slip systems.
The as-rolled sheet had an average grain size of 35 µm.
The idea behind LSHR was to use a simple severe plastic deformation method to produce the largest amount of deformation through the smallest number of rolling passes without causing material fracture [2].
In this case grains are unfavorably oriented to tension twinning.
However, grains and grain boundaries can still be recognized.

The domain-wall motion may be affected by the grain size and porosity [2].
Hence, any alteration in grain structure and porosity would affect the loss factor.
Meanwhile, grain size is increased when the CuO content is increased [6].
When the porosity increases, the number of pores, vacancies and scattering centers for the electric charge carriers increase, as a result a marked increase in the values of the resitivity will be produced.
At higher MgO content, big pores are generated which are not located inside the grains but outside the grains.

The average grain size and root mean square roughness were 250 and 7.04 nm, respectively.
The circular-like grains with 20 nm width were observed with scanning electron microscopy (SEM) for as-deposited KNN thin films in fig. 2.
However, the grain size of thin films decreased for high oxygen concentration of 40% since many small grains forming at grain boundaries.
We found the change of grain size corresponded to the root mean square roughness.
This result reveals that the number of oxygen vacancies of as-deposited KNN thin films at 25 and 40% oxygen concentration decreases.

The average grain size and root mean square roughness were 250 and 7.04 nm, respectively.
Figure 2 shows the average grain size and root mean square roughness value of the KNN thin films surface observed from AFM morphology.
We found the change of grain size corresponded to the root mean square roughness.
However, the grain size of thin films decreased for high oxygen concentration of 40% since many small grains forming at grain boundaries.
This result reveals that the number of oxygen vacancies of as-deposited KNN thin films at 25 and 40% oxygen concentration decreases.

A large number of dawsonite-bearing sandstones has been found in Dongying Sag of Bohai Bay basin.
The three compositions of sandstones in research area are quartz, feldspar and lithic fragment(the volume fractions are 28%-70%, 23%-58%, 1%-26% respectively).The clastic rock types of these samples are feldspathic sandstone and debris-feldspar sandstone (according to Folk).They are fine-grained and fine-medium-grained(the particle size are mainly range from 0.05mm to 0.4mm), poorly to mediocre sorted, poorly rounded and dot-line contact is the major form.
Therefore, sandstones in research area are named as fine-medium-grained dawsonite-bearing feldspathic sandstone and fine-medium-grained dawsonite-bearing debris-feldspar sandstone.
There are two main types of its occurrence observed under a polarized microscope. (1) Replacing feldspar, quartz and lithic grains partly or completely with radial, bunchy and platy aggregations, or replacing the edges of feldspar, quartz and lithic grains.
Its growth is generally affected by the restriction of other minerals, sometimes replacing grains around the pores.

Average grain size = 38.1 microns.
(a) Al2198-T8 Yield Stress = 503 MPa (b) AISI304 steel Yield Stress = 207 MPa Fig. 3, ESE(T) specimen type FCGR data for (a) Al 2198-T8 in lab air with L-T grain orientation and (b) AISI304 stainless steel in lab air with T-L grain orientation Crack Closure From Internal Particles and Debris in Cracks.
Wasén [10] also notes this phenomenon and discusses the large number of experimental results that have indicated the effect on crack closure due to fracture surface roughness, debris, and oxide formation.
Also, Hertzberg [7] discusses the transition point proposed by Yoder et al [11] where the striated region changes to the faceted region when the cyclic plastic yield zone at the crack tip becomes smaller than the material’s grain size which means the slip band cannot cross the adjacent grain boundary.
Observations on the generality of the grain-size effect on fatigue crack growth in α+β titanium alloys in: H.