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China ajxu.cumt@gmail.com, bfanyu2002@hotmail.com Keywords: Fracture Toughness; Coarse-grained Heat Affected Zone (CGHAZ); X80 Pipeline Steel; Weld Thermal Simulation; Finite Element Analysis (FEA).
A large number of fracture toughness (as denoted by CTOD) tests together with 3D finite element analysis are performed using single edge notched bending (SENB) and tension (SENT) specimens at different temperatures.
Coarse-grained heat-affected zone (CGHAZ) is considered as the material microstructure in preparation of the weld thermal simulated fracture mechanics specimens.
Weld thermal simulation has been used to produce the microstructural properties of coarse-grained HAZ (CGHAZ) in X80.
A large number of CTOD (crack tip opening displacement) tests are carried out at -90℃, -60℃ and -30℃. 3D FEA are employed to model the crack tip stress fields of the tested specimens.

The effect of grain size on the semiconductor properties are in agreement with experimental and theoretical data.
The grains show complete coverage and small size as shown in Figure 2b.
The size difference of each grain is due to irregular growth rate.
The orientation of grain growth is also irregular as can be noticed from the specific decrease of grain size at different areas of the substrate.
Acknowledgments This work has been achieved using FRGS grants numbered: 9003-00249 & 9003-00255. 

For example, the grinding wheel wear is attributed to bond fracture, grain fracture, and attritional grain wear [1].
The result of grain shape measured using the SLM is shown in Fig. 2(b).
The obtained result yields a shape with clearer features of the measured grain.
The extraction method fails to approach the grain boundary in the cases that many pixels have the median value, there is a gap at the boundary between the grain and the bond, or the grain tip is far from the grain centerline.
The shape processing approach is applied for a number of grains and the obtained results are employed for measuring three angles on each prospective cutting edge of the measured grain.

Introduction The fracture of the ceramic materials was mainly due to the stress, which makes a large number of micro-cracks within the ceramic materials nucleate and expand.
Assume the ceramic material is anisotropic and the grain conical.
In addition, the research on grinding stress field is of action of grains on the surface, so the grinding stress field should be built on the contact surface between the grains and workpiece, as shown in Fig. 4.
Substituting Eq.7 into the Eq.2, we can get the grinding force of the single particle in a vibration cycle (8) Where, Fnm denotes the normal component of friction between the grains and the workpiece; Ftm denotes the tangential component of friction between the grains and the workpiece; M denotes the equivalent quality of vibration part; A and B denotes the amplitude of ultrasonic vibration in two directions respectively; Nd denotes the number of dynamic and effective grains of grinding wheel; f denotes ultrasonic vibration frequency; T denotes the vibration cycle; Δt denotes the contacted time of abrasive and workpiece.
But in other vibration time, the grains and the workpiece are separate, and the grains will not interact with the workpiece.

It also revealed that the size of austenite grain and nonmetallic inclusions on borders of grains were reduced, and sulphide inclusions were dissolved partially.
By modifying became aware obtaining ingots and castings with fine-grained structure.
The microstructure of the unmodified sample number 200 Table 3.
The structure contains minor non-metallic inclusions on the boundaries and within grains (sample number 637 in Fig. 2).
Microstructure of modified sample number 637 Table 4.

Continuity, momentum and energy equations are applied to finite number of control volumes under steady state conditions as shown in ref [8].
The unprocessed base material was assumed to have grain size of about 50 µm.
The estimated grain size distributions for the two cases are shown in Fig.4.
In both cases the finest grains are located around the pin zone on the AS.
Fig.4: Grain size distribution in processed region for (a) conventional tool vs.

A large number of investigations [1-3] show that NS metallic materials produced by severe deformation techniques exhibit a marked structure-heterogeneity effect.
Every so often bimodal grain-size distribution is observed.
The former grains account for ∼40 % of the specimen area.
Equiaxial grain structure with average grain size d ~ 1 µm is formed in the alloy subjected to ECAP [23].
Zabudtchenko in: Ultrafine Grained Materials IV, edited by Y.T.

The mechanical ball mill has a balls and vials were the powder experience high rate of strain resulting plastic deformation with dense number of dislocations.
As the process of dislocation reaches to specific point, they break to sub grains. these sub grains further deformed to fall to nanometer scale.
The particle structure and grain size of Magnesium AZ31B alloy was determined using Optical Microscope (Olympus -Gx71), SEM (Tescan-Vega 3) will be utilised for determination of grain size and Fracture morphology.
Agglomeration of nano Sic Grain Boundary Particle Boundary a Agglomeration of nano Sic Grain Boundary Particle Boundary b Agglomeration of nano Sic c Fig. 3.
Therefore, the hardness was well improved due to relative density and grain size at the sintered temperatures of 4750C.The sintered temperature has caused to increase the relative density and bonding of grains increased, causing large dislocation of particle and grain boundaries.

In reference[4], factory experiment showed that the ratio of equiaxed grain zone and the equiaxed grain density all decreased with increasing casting speed.
By this way, the propagation of grain occurs.
In this study, casting speed is the only variable, hence we assume that the number of the original separated grain is the same at different casting speeds.
As a result, the value of H (Formula 6.) is chosen as the measurement criterion of the number of the heterogeneous nucleation nucleus.
In this situation, the number of the survival separated grain which can become the heterogeneous nucleation nucleus finally is greater.

Novelty of this technique is one can build up significant amount of plastic strain by increasing the number of passes without much dimensional change.
Hence, the mechanical properties of Al-Li alloys are primarily dependent on grain size, nature, volume fraction and distribution of precipitates, both within the grains and at the grain boundaries and occurrence of precipitate free zones (PFZ).
Usually, a single grain is found to nucleate at any particle at the maximum.
These recrystallised grains were estimated to be in the size range from 20nm to about 100 nm.
It is suggested that with the assistance of non-deformable particles, it might be possible to get ultra- fine/nano-crystalline material through ECAE with relatively lesser number of passes.