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M.Qian [19,20] evaluated the effect of grain size and special grain boundaries on weldability of wrought Waspaloy and Alloy 718.
(4) where Γ is the Gibbs-Thomson coefficient, R is dendrite tip radius, G is the average temperature gradient near the tip, ζc(Pei) is a function of Peclet number, C0,i is the initial concentration of element i, ki is the partition coefficient for element i, Pei is the Peclet number for element i, mi is the slope of liquidus for element i, i=Cr or Al in Ni-Cr and Ni-Al binary linear phase diagrams, and Iv(Pei) is the Ivantsov function of the Peclet number.
The combination of centerline grain boundary, stray grain formation and coarse dendrite trunk spacing provide less resistance to solidification cracking.
The centerline grain boundary, misorientation of stray grain formation and coarse dendrite trunk spacing increase with low welding speed in [100] dendrite growth region.
Welding configuration plays a more important role than heat input (laser power and welding speed), because dendrite trunk spacing, stray grain formation and centerline grain boundary are more sensitive to it.

Out of each production batch a certain number of patterns are randomly picked for testing dimensional accuracy.
At this stage all wax patterns are numbered and documented for total process tracking.
After quality inspection each cluster becomes a production number for documentation and tracking.
Very strength quality control of raw materials (purity, grain size, grain Figure 4: a) CAD drawing of finished part; b) CAD of cast part; c) wax pattern with interfaces for gating system.
Figure 5: Control of incoming ceramic materials include grain size and distribution, chemical purity and grain geometry.

However, excessive austenitic temperature causes too much big austenitic grains and super-saturated alloy, beneficial for the formation of residual austenite, and the brittle carbides deposition on the grain boundary, resulting in the decreased hardness of die steel and much worse toughness.
It is evident that the secondary carbide grains are very fine and distributed uniformly when holding time is 20 min.
The holding time mainly influences the grain size of austenite and carbides.
Moreover, precipitated Nb(CN) particles can supply a great precipitation hardening to the yield strength and another grain refinement hardening through the inhabitation of austenite grains [3-5].
As shown in Fig. 4, the size of primary and secondary carbide decreased below 1010℃, and the martensitic matrix grains are refined too, hence a higher hardness number is obtained.

In Table 2 the numbers of specimens of each fracture type and for each material are given.
It can be seen that the number of FTB is declining with increasing Cabores® P content.
On the fracture surfaces for FTA rather large grains of residual undissolved Cabores® P can be found.
These grains break in a brittle manner, which is the reason for the sudden load drops in the load-deflection curves.
Therefrom, one can conclude that the absence of large Cabores® P grains is leading to a more continuous fracture of the specimen without the fast and large propagation of the crack inside the Cabores® P grains.

After sufficient number of pulses (typically 15 to 20) of HCPEB treatment, this hardened zone can extend over hundreds of m [6].
A more advanced dissolution process of the carbides [14] together with the ultra fine grain size of the matrix grains [14, 19] are considered to be important factors for the stabilization of the  phase in the top surface layer.
These ultra fine grains improve the wear resistance property [17].
Fig. 3 illustrates that twinning was activated in grains having the <111> direction close to the sample normal direction while high misorientation deformation gradients were created by intense crystallograplic slip in some other grains.
The number of pulses of HCPEB treatment is also shown to affect the microstructure in different manners.

The studied X-ray diffraction patterns of nanostructured Ti samples processed by HPT under 1, 3 and 5 GPa (Fig. 1) have a number of X-ray peaks typical for α- Ti with a fcc crystal lattice: (1010), (0002), (1011), (1012), (112 0), (1013), (20 2 0), (112 2), (20 2 1).
The arrangement of ω-phase atomic layers (Fig. 4) differs by their coordination numbers and distances to nearest neighbouring atoms [11].
This suggests that grain rotation may have played a significant role in randomizing the grain orientations.
According to [13], grain-boundary slip was the dominating strain mechanism, providing the highest degree of plastic deformation on the rolling of a nanocrystalline palladium sample with grain size of 33 nm.
In other words, НРТ in ED Ni results in a considerable relaxation of internal stress with an almost unchanged mean grain size, while НРТ of coarse-grained Ni is usually accompanied by intense grain refinement and a considerable increase of internal stress [18].

The high carbon steel above the figure was white reticular cementite around the lamella pearlitic grain.
The low carbon steel below the figure was ferrite grain, a small mount of pearlite and reticular tertiary cementite.
As the better C diffusivity according to the changed technological parameter, the C in the interface grain has sufficient diffusion leading more grain to transforming into pearlite and diversity growing direction of layered pearlite.
The pearlite morphology towards the ferrite grain for longitudinal growth was basically in line with the contiguous pearlite grains, which was illustrated in fig. 2 c.
The pearlite morphology towards the ferrite grain for longitudinal growth was basically in line with the contiguous pearlite grains, and the cementite interlamellar spacing in the pearlite increased gradually from the end of pearlite morphology.

This increase in grain size occurs due to the high affinity for C during sintering.
WC-Co ultrafine-grained sintered carbides with submicron or nano grain sizes have been shown to have much better mechanical properties in terms of hardness, strength and wear resistance compared to traditional coarse-grained materials.
On the other hand, sintered carbides with ultra-fine grains with an average grain size of 0.1 μm to 0.6 μm have higher hardness and wear resistance, but are characterized by a much lower fracture toughness compared to the coarse-grained structure.
It follows that the properties of sintered carbides are influenced by a number of factors [21,22].
Fig. 2 Dependence of the average hardness of sintered carbides on the size of the grains used Based on the mentioned dependences of the hardness of sintered carbides on the percentage of Co and the size of the grains used, it can be concluded that with a comparable grain size, the hardness decreases with increasing Co content.

For the experiment image, the intersection number increases as the fence rotate from X to Z direction.
With imposing the AIBE, the result shows the same increment of intersection number as that of experimental result.
It can be discerned that the rods show the feature of discontinuity, which arises from the overgrowth of old grains and appearance of new grains.
The old grain near the nucleus does not grow further and is replaced w the new grain growing from the nucleus.
As a consequence, the number of grains decreases and the lamellar spacing increases.

With the extension of holding time under tempering, the martensite structure obtains fine grain and the lath characteristic becomes obvious.
Besides, It can also be found that the lath martensite in the heat affected zone obtain more and more refined grain with the increase of the tempering time from Figs.3.
This is mainly because the weld grain grown seriously, and the welded joints content a large number of M-A constituent element, which makes the microcracks generated at the interface extended along the M-A constituent element boundary[8], also the impact toughness of the material deteriorates.
(1) According to Hall-Petch formula (1)[9], we can know that strength is inversely proportional to the radius of the grain.
(1) Where in: σs is the yield strength; σ0 is the total resistance to dislocation motion bits in the matrix metal; k is a measure to strengthen the contribution of grain boundary pinning constant; d is the average grain diameter.