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Recently a close connection between properties of the wire and the orientation of the cementite lamellas in the grains was shown [4].
The components of the deformation tensor ijε are calculated through integration of each component of the strain rate tensor along the flow line: ∑∫ = = ∆= = τ τξττξε τ kk k kk ij ijij d 1 )()( 0 )( , (2) where: )(k τ∆ − the current time increment, )(k ijξ − the values of the components of the strain rate tensor determined according to the follow equation: ijn n n n k ij nd N ξ ξ ∑== 1 )( , (3) where: N − the finite element shape functions, ijnξ − the nodal values of the components of the strain rate tensor for the current finite element, nnd - the number of nodes in element.
This results in: ( ) ∑ = = ∆ = τ τ τµτε ξ ψ σ mm m m p m i k1 )( )( )(),( , (9) where: )(m τ∆ − the current time increment, )(m iξ − the values of the strain rate in the current time, m - is a index number of time step during numerical integration along the flow line.
Properties of phase (ferrite and cementite) are presented by the flow curves; − boundary conditions (nodes velocities on the grain boundary) for RVE are obtained from the macro-model according the equation (4); − for numerical imposition of the boundary conditions on grain boundary the penalty method is applied.
In order to obtain the solution of the boundary problem for the RVE, the modified variation principle of rigid-plastic theory is used: ( ) ( ) , J 2 2 00 2 2 1 ∫∫∫∫ + + + = F nn F V V i dFvKdFvKdVξσdVµ ξ ττ (12) where nK - a penalty coefficient on impenetrability condition of the pearlitic colony boundary, zzrrn vavav += ; τK - a penalty coefficient on sliding between the grain boundaries: ( ) ( ) ( )1 1 − − = p p p v K τ τ τ σ , (13) where p - number of iteration, τv − slip velocity of grains boundaries, τσ − friction stresses between the boundaries of the grains.

It is found that hard phases with rich vanadium are mainly distributed at grain boundaries.
The number of designed cycling was 800.
The quantity of hard phases at grain boundaries was more than that in the matrix.
At the same time, the carbides precipitated along the grain boundaries of δ phase.
A part of vanadium existed in hard phases, most of which distributed at grain boundaries.

The ultra-fine grained structures in metallic polycrystals is possible to develop by methods based on severe plastic deformation (SPD).
Mahallawy et al. investigated the effect of outer corner angle ψ and ECAP number of passes on inhomogeneity index in effective plastic strain [16].
Influence of strain rate on ultimate tensile stress of coarse-grained and ultrafine-grained copper.
On the cyclic response of ultrafine-grained copper.
Principles of equal-channel angular pressing as a processing tool for grain refinement.

Fig 1(b) shows that there are some coarse particles of second phase in the grains after solid solution.
After cold rolling, the grains are elongated along the rolling direction as shown in Fig. 1(c).
The mechanical properties are relatively unchanged because the number of dislocations is not reduced in aging initial stage.
As aging continued new small grains nucleate and growth, which means recovery and recrystallization occur.
As the grains growing the number of dislocations is greatly reduced and the microhardness of the samples reduces rapidly.

Especially the crystal nucleus can become smaller because of ultrasonic cavitation, that is to say, high-pressure caused by cavitation can create instantaneously local supercooling which reduces the critical radius of crystal nucleus, so that the crystal grain has been refined.
The grain refinement can decrease the gap and make the grains integrate very closely, thus the performance of coating has been improved.
Ultrasonic vibration can make the metal atoms deviate from its original equilibrium position, and ultrasonic cavitation can refine crystal grains, which both lead to a compact and hardened coating.
(1) So a large number of bubbles would be produced.
In order to test the adherence between the coating and the substrate, the samples were heated to 300 ℃ and kept for 2h, then immediately put into water of 16 ℃ for 5min.Through observing the number of blister on the surface of coating to evaluate the coating adhesive strength.

The number of element divisions is 17120 and the number of the nodes is 10123.
The abrasive grain size used in theoretical analysis is 70# and material of the abrasive is carborundum, its mechanics properties can be obtained in the material manual: density 3020kg/m3, Poisson's ratio 0.3, modulus of elasticity 330GPa.
The Effect of the Machining Parameters on the Rate of the Material Removal Based on the simulation result obtained by the computer, the effects of machining parameters such as abrasive grain size and constant load on the rate of material removal are researched experimentally.
Fig. 6 The relationship between constant load and rate of material removal From Fig. 6 some results may be obtained as follow: 1) The rate of material removal by the three abrasive grain sizes increases with the constant load increasing; 2) Under every constant load the abrasive with grain size 120# has the most rate of material removal, and when the constant load is lower than 35 N, the material removal rate of abrasive with 70# is close to one of 500#, when the constant load is higher than 35N, the material removal rate of 70# is higher than 500# obviously; 3) The highest material removal rate for abrasives with 120#, 70# and 500# are obtained at the loads of 45N, 50N and 40N respectively.
The efficiency of material removal of the abrasive with grain size 120# is the best in the experiment.

Theoretically speaking, the formation of α-SiAlON is a process of cleaning the grain boundary of material thus reducing the liquid phase remaining at the grain boundary, because the most of sintering additives, such as Y2O3 (Ln2O3), CaO and MgO, can be incorporated by α-Si3N4 structure.
Because the contrast on the mean atomic number, micrographs very clearly distinguish between various phases: α-SiAlON grains (which contain a small amount of sintering additive cations) are grey, β-SiAlON grains (which contain no sintering additive cation) are black and needlelike and JEM phase (which contains high amount of additive cation) is white.
Elongated α-SiAlON grains were also observed in the sample that contained Mg-Ce.
MCA5 sample was analysed by EDX in point mode to observe whether Ce- and Mg- atoms have been incorporated into the α-SiAlON grains.
The analysis of α-SiAlON grains in different parts of the sample showed very similar results and indicates that Mg +2 and Ce +3 cations can be accommodated into α-SiAlON grains without quenching.

In present day, ECAP[1] is always adopted to refine grains by way of repeated extrusions which lead to a large number of dislocations and high internal stress in microstructure.
The other one of them is high strength of as-rolled GW123K which results from its strengthening mechanisms of grain refinement, solutiong strengthening and precipitation strengthening.
It can be seen from Fig. 5(a) that a lot of second phase partilces are dispersly distributed in grain boundary and in the interior of grains.
The second phase particles can effectively constraint grain boundary sliding which results in its high tensile strength at elevated temperatures.
Yttrium in microstructure of GW123K as an rare earth element addition plays a important role in grain refinement which results in improvement on strength and plasticity, and Gd-riched phases resulting from Gadolinium addition can effectively improve strength of GW123K by means of impeding grain boundary sliding[10].

Both the grain size and microstructure are all varied by melt treatment obviously [5].
Without melt treatment, the grain structure is almost equiaxed and fine, and most of the MC carbide particles have a blocky morphology and mainly distribute at grain boundaries (GBs) and interdendritic region.
Grain structures of M963 superalloy.
It is well known that the grain size is related to heterogeneous nucleation and the undercooling of the melt.
Generally, a large number of fine carbide particles are beneficial for GB strengthening and for inhibiting GB migration.

Thus, Nb has strong contribution in the ferrite grain refinement and in precipitation strengthening.
In this case, fine TiN particles avoid recrystallized austenite grain to grow between rolling passes, achieving in this way, a final equiaxed finer austenite grain size compared to the case of plain C-Mn steels.
Thus, Nb has strong contribution in the ferrite grain refinement and in precipitation strengthening.
Very fine austenite grain size is obtained, especially when Nb is added.
Suitable precipitates formed prior to rolling can, simultaneously, avoid excessive grain growth in the first stages of the rolling (similar to recrystallization controlled rolling) and in the case of a high number of passes, favor a fine final grain through the activation of dynamic recrystallization.