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The increasing versatility of testing machines, like dilatometry with easily variable temperatures, in addition to the growing expenses that go along with increasing the number of experiments for high cost materials, leads to the question whether performing all those experiments is really justified.
Reducing the number of experiments by 50 % during materials characterization therefore appears feasible.
The grain sizes after cooling are measured metallographically.
Similar spacing is used for the matrices covering grain growth, srx kinetics, grain size after drx and srx respectively.
While in classical models grain growth can only start after full srx, Fig. 8 shows that grain growth starts while srx is still in progress.

In the Mg-1Zn-1Nd alloy, grain coarsening is accompanied by a bimodal grain size distribution, whereas in the Mg-4Zn-1Nd alloy, the grain coarsening leads to a uniform grain size distribution.
However, magnesium has limited formability at room temperature due to the insufficient number of slip systems, and thus a strong basal texture after rolling.
The Mg-4Zn-1Nd alloy shows a uniform grain size distribution with an average grain size of ~50 μm, while the Mg-1Zn-1Nd alloy shows a bimodal grain distribution and the average grain size is an order of magnitude smaller, i.e. only ~5 μm.
Precipitates can be found inside the recrystallized grains and also close to the grain boundaries.
It is well-known that solute segregation can decrease the grain boundary mobility and slow down the grain growth rate.

However, there are few reports [12] concerning about the fatigue property of ultrafine-grained steel.
Fig.5 shows relationship between the load ratio of (applied stress)/(tensile strength) on fatigue tests and number of cycles.
It is found that the stronger filamentary microstructures of the ferrite phase and the pearlite phase are developed with increasing number of passes of the pure shear deformation.
From the results of TEM observation, the ferrite phase with a grain size of 1µm is observed in the microstructure of all carbon steels after heat treatment and the grain size becomes larger with decreasing Vickers hardness.
A grain size of the ferrite of the pearlite phase is sub-micrometer due to the presence of the ultrafine spherulitic cementite.

Samples were deformed for several numbers of revolutions up to N=75 and then aged at 200 °C in air for up to 96 h followed by quenching in ice water.
The grain size of the Al matrix was measured using TEM.
The equivalent strain introduced by HPT processing is a function of the number of revolutions N, the distance from the disk center r, and the thickness during HPT processing t [7]: ε = 2πNr / √3t
This grain size was rather stable up to subsequent aging at 200 °C such that the grain size was ~140 nm for aging up to 0.25 h and ~180 nm for 24 h.
The sample exhibits a recrystallized structure with the grain size increased to ~400 nm and grain boundaries well-defined as shown by the image in Fig. 6(a).

Most grains became much finer and coarse grains were broken into fine grains.
In addition, by increasing the number of PITS-ECAPT passes, micro-hardness of the sample was slightly increased and almost remained the same.
Most particles were contacted with each other, both the number and the size of pores were reduced, thus the compact density was slightly improved.
By increasing the number of ECAPT passes, as the powder compact was almost approached to the theoretical compacted density, the mechanical properties were increased slightly.
As the number of passes increased, larger accumulated strains were sufficient to reduce dislocations by annihilation and rearrangement within grains, so the dislocation density was nearly constant, i.e., a dynamic balance between working hardening and grain recovery was occurred.

The grain size distributions after the tests are plotted in Fig. 1.
For the ultimate grain size distribution, D is always around 2.5 [6-10].
Therefore, in this condition, the Bpi is defined as the area between initial grain size distribution and ultimate grain size distribution up to 0.5 mm particle size and the Bt is defined as the area between initial grain size distribution and current grain size distribution up to 0.5 mm particle size, as shown in Fig. 3.
The conclusion further verifies that the number of broken particles increases with the increasing confining pressure during compression.
The number of the largest particles decreases with the increase in confining pressures, and the number of smaller particles increases with the increase in confining pressures.

Nevertheless, the fabrication of such ultrafine cemented carbides presents a number of issues related to manipulation and pressing of finer powder mixtures and control of faster WC grain growth kinetics [4].
SEM images were used to measure WC grain size distributions.
In the absence of VC and Cr3C2 (mixture hm3), the Vickers hardness decreases continuously as the HIP temperature increases, in accordance with the expected grain growth of WC grains.
It is worth noting that, in any case, WC grain inhibition is not complete since WC-Co alloys containing up to 1 wt. % of VC show grain growth after prolonged treatments at high temperatures [20].
The fact that the lower hardness at 1200 ºC is more clearly appreciated in the material with the finest WC grain size after vacuum sintering (i.e., hm1) is also compatible with the activation of mechanisms based on coalescence since this material presents higher WC-Co surface area and a lower Co mean free path, which implies a higher number of potential WC-WC contacts.

Finally, the original coarse equiaxed grains were replaced by new recrystallized grains and the average grain size is smaller than the original grains.
Fig. 6 Grains size and number variation: (a) one pass; (b) two pass The grain size and number variation are shown in Fig. 6 after pressing one (Fig. 6(a)) and two (Fig. 6(b)) pass.
Fig. 6(a) shows, after one pass, the microstructure was coarse equiaxed grain, average size of the grains is 2.9 and the number of grain is 84.
Fig. 6(b) shows that after pressing two pass, the grain size reduced drastically; the average size of the grains is 2.7 and the number of grain is 94, which is small equiaxed grains and distributed randomly.
Under all conditions except the involving grain refinement by ECAP, the increased number of grains was determined mainly by the recrystallization nucleation process.

The classification of grits can be further specified in terms of the total number of grits per unit area GSTAT or the total number of grits actually engaged in cutting referred to as GDYN or dynamic grits.
If a small sample spacing is employed for measuring the wheel surface then information such as cutting edges and grains will be obtained however, the former can be considered high unstable as the number of cutting edges can quickly change to grain wear or fracturing.
A more stable feature to measure is the number of grains and their overall sharpness.
Selecting the appropriate sample spacing to distinguish the grains from the cutting edges can be achieved using a number of approaches proposed by various authors.
Characterisation Strategy For a grinding wheel to efficiently remove material from a workpiece, a number of criteria need to be met; there should be sufficient grains present, they should be sharp, and ideally should be exposed.

With the cooling rate decreasing, when t8/5 = 60s, the original high angle austenite grain boundaries gradually disappeared, eutectoid ferrite grains occured at the original austenite grain boundaries, lath bainite, granular bainite and granular ferrite are generated in the original austenite grain.
As can be seen that when t8/5 = 30s, due to rapid cooling rate, the number of M-A constituent is little, and strip M-A constituent distributed in ferrite matrix directively (Figure.2a).
With the cooling rate decreasing, when t8/5 =60s (Figure.2b) , M-A constituent changes significantly, gradually change from strip to block, the number and density increased.
STE355 Steel Microstructure after Welding in the Grain Shell and its Effect on Toughness.
Zr microalloyed HSLA steel coarse grain heat affected zone microstructure and properties.