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As a rule, the ferrite-bainite microstructure of steel is characterized by fine ferrite grain size (small length of bainite lath) and the increased density of dislocations.
Reduction of ferrite grain size is a well known way of simultaneous increase in strength properties of steel and improvement of its cold resistance.
Strengthening of metal at decrease of CST up to 500-550 o C takes place due to refining of grains.
Production of coiled products at HSM has the following features: only a limited number of deformation passes can be made, and final formation of microstructure of steel occurs after coiling.
The required complex of properties has been achieved due to formation of fine grained ferrite-bainite microstructure of steel and effective precipitation hardening of metal.

The results indicated that the grain size of 80SH steel was relatively uniform and the grain boundary was relatively obvious compared with N80Q steel.
Introduction With the continuous development of China's petroleum industry, the exploration and development of oil and natural gas continues to increase, and the number of wells per year is maintained at a relatively high level.
Fig. 1(a) shows a large number of tempered sorbite structures.
Compared with N80Q steel, 80SH steel has a relatively uniform grain size with obvious grain boundaries.
Fig. 5 Tensile fracture morphology of (a) N80Q steel and (b) 80SH steel at 350 °C Conclusion (1) Compared with N80Q steel, 80SH steel has a uniform grain size, obvious grain boundaries, and less black fine precipitates

The film deposited at the growth temperature of 670 K possesses the largest grain grain, the minimum dislocation density and the lowest microstrain.
The decrease of the b indicates the increase of grain size of the films.
Fig. 1 XRD patterns of the samples grown at different growth temperatures Fig. 2 The full-width at half-maximum (b) and grain size (Gs) of all the samples The lattice spacing (d) can be evaluated by means of the Bragg law [22]: , where is the wavelength of the X-ray used, m is the order number and q is the Bragg diffraction angle.
The dislocation density (d) can be estimated from the grain size Gs by the formula [22]: .
The thin film prepared at the growth temperature of 670 K has the maximum grain grain, the lowest dislocation density and the minimum microstrain.

There are increasing amounts of carbides were both at grain boundaries and inside the grains compared to in the alloys not added Cr.
After annealing at temperature of 900oC, carbides on grain boundaries are dissolved, remained a little amount of carbides within grains.
The depth of transition layer depends directly on the number of impaction load and the alloys.
When the number of impaction was a little, a few twins occurred, the depth of transition layers were so small.
When increasing the number of impact load to 1000 times, the depths of transition layer were clearly increased, as showed in fig. 4a.

In this study, 0γ� is taken as 0.001s-1 and t is 0.01 [3], and fully finite element calculations are employed to make the transition from the response of a single grain (or a region within a grain) to the response of a polycrystalline aggregate.
The accuracy of simulation can be controlled by the numbers of nodes (elements).
All the grains tend to rotate along the "soft orientations" (<110> slip directions and {111} slip plane).
Though the plastic deformation continues, the rearrangement and rotation of the grains will nearly finish, and majority of grains and texture fibers will be arranged along the certain direction.
The reason is that during the deformation, under some situations the friction force may become the restraint of the grain slips, and on the other hand, the friction force can accelerate the grains slip and rotation.

The pearlite transformation began around the grain boundary.
The finer austenite grain size can be obtained through austenite recrystallization.
It can be seen that the pearlite transformation began at the grain boundaries.
The smaller the austenite grain size, the larger fraction of the pearlite formed.
During deformation the pearlite formed firstly around the grain boundary and the deformation band (Fig.2).

Parasiz et al concluded that the grain location, size and orientation affect the deformation behavior significantly in microforming, especially when the grain size approaches the part size [4].
The results showed that the microforming ability is related to the number of involved grains in the forming [5].
Influence of Grain Size.
This mainly results from inhomogeneous deformation of surface grains.
Studies of the interactive effect of specimen and grain sizes on the plastic deformation behavior in microforming.

The fiber bundles mainly bear combined effects of shear and bending by diamond grains.
A large number of matrix fragments are left on the surface.
A large number of matrix fragments are rolled in between the fibers by diamond grains , and they are partially filled in the holes resulting from matrix spalling and fibers pulled out.
A large number of matrix fragments are left on the surface.
When grinding orientation is parallel to fiber orientation, fiber mainly bears combined effects of extrusion and stretching by diamond grains, the surface damage of QFRQC mostly involves a large number of large matrix fragments and long cracks, and a few of fiber fractures, a large number of matrix fragments are partially filled in the holes resulting from matrix spalling and fibers pulled out, the ground surface is good. when grinding is on the fiber end-faces, fiber mainly bears combined effects of shear and bending by diamond grains from different parts of grinding wheel, and a lot of fibers ends hinder matrix cracks from growing, the surface damage of QFRQC mostly involves a large number of small matrix fragments and fibers broken ends with different fracture morphologies , the ground surface is better than others.

Introduction Magnesium and its alloys often have poor formability at room temperature due to limited number of active slip systems in the hexagonal close packed structure [1].
Different colors in Fig. 2 represent various grain orientations.
Nearly identical color of the grains means that the misorientations between these grains are small.
Grain boundaries (>2°) are indicated in Fig. 2 as a black line.
Figure 3 Image quality maps of recrystallized grains together with grain boundary contours of a) crystal 1, b) of crystal 2.

The cell (i,j) under consideration is additionally represented by a random number ξ (0, 1) and it can become a nucleon only when a probability condition is fulfilled ξ < wnucl.
The grain boundary velocity is calculated as: (11) where: M – grain boundary mobility, P – driving force for grain boundary movement.
Grain boundary mobility is obtained from: (12) where: M0 – initial grain boundary mobility, Qm – activation energy for grain boundary motion.
Initial microstructure (50×50 mm) with cell number equal 100×100 (cell size 0.5mm), were used during DRX simulation.
Szyndler, Effect of number of grains and boundary conditions on digital material representation deformation under plane strain, Archives of Civil and Mechanical Engineering, In Press, Corrected Proof, Available online 29 September (2013) [13] L.