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To detect the defects of cast ingots, a large number of specimens along different orientations of the ingot were prepared after grinding and polishing, and then etched with the saturated picric acid solution for recording the optical micrographs.
Coarse grains primarily consist of columnar and equiaxed grains, as shown in Fig. 1.
(a) columnar grain (b) equiaxed grains Fig. 1 Coarse Grains (a) CaO inclusion (b) FeS inclusion Fig. 2 Non-metallic Inclusions Refining Law of Coarse Grains Effects of Temperature and Deformation on Grain Refinement The average grain size in the primary deformation zone of the specimen was measured after deformation at different experimental conditions, and the grain size grade was also calculated (see Table 1).
The main reason for the tendency can be discovered from the grain growth curve of 30Cr2Ni4MoV steel in Fig. 4 which demonstrates that grain coarsening occurs at about 950˚C, and after that the grain size rises from 40um to 180um rapidly.
Table 1 Average grain size and grain size scale [T—temperature, R—reduction ratio, d—average grain size, G—grain size grade] NO.

Table 1 Chemical composition of medium-manganese Q&P steel Number C Mn Si P S N Nb Al 7Mn-Nb 0.23 6.93 1.47 0.0062 0.0053 0.0049 0.058 0.0046 The investigated steel was prepared using a laboratory vacuum induction melting process.
The austenite grain nucleation firstly appears in the scope of the original austenite grain, including the boundary of the high carbon high manganese martensite lath and the boundary of slat group and the boundary of the original austenite grain [13].
It is obvious that grains of the investigated steel annealed at 640℃ become equiaxial, and the grain size becomes bigger.
Moreover, it is more obvious that the grains of investigated steel annealed at 660℃ and 680℃ become equiaxial, and grain size becomes maximum
Austenite nucleation position, nucleation number and eventually austenite grain size all depends on the annealing temperature in cold-rolling microstructure.

Meanwhile, a large number of small scattered martensite-austenite (M-A) islands are observed in the color optical micrograph (Fig. 3).
It indicates that a large number of large angle grain boundaries exist in the investigated steel.
It is seen that a large number of sub-grains exist in the tested steel.
In this work, the microstructures predominantly consist of a large number of acicular ferrite and polygonal ferrite grains plus a small proportion of scattered M-A constituents.
In the present work, the microstructures mainly consist of a large number of acicular ferrite.

It is founded that surface roughness deteriorates with higher sand grain size and vice versa.
The grain size of the sorted sand was quantified by AFS graininess number.
The shape of the sand grains was almost sphere with sphericity index of 0.91.
Only factor A (Sand number) is significant that have positive affect on the surface roughness.
The surface roughness of the casting improves when the AFS number of the sand grains increases.

There are two (interrelated) processes leading to change of microstructure: 1) the production of a very high number of dislocations, leading to a high dislocation density, 2) the "fragmentation" of the original crystal grains into much smaller structural elements leading to what is sometimes called "nanocrystalline" material.
This is why they are often called "grains".
For these, the term "non-equilibrium grain boundaries" has sometimes been used [6] ∗ .
∗ After a mild annealing treatment one obtains small real grains surrounded by large angle grain boundaries.
It would be analogous to grain boundary sliding and superplasticity - again with the reservation that no true grain boundaries are involved.

The forces acting on individual grains, among various factors affecting wheel wear, play a very important role since they dominate grain fracture and grain pullouts from the bonding [1].
A commonly used method for estimating such forces is to divide the total tangential and normal forces by the number of active grains in the contact zone [3].
It is apparently more reasonable to use the maximum forces along the path instead of the average value for evaluating grain fracture and grain pullouts.
The maximum forces on individual grains can be calculated as the peak distribution value divided by the number of active grains in the area of grinding width by a unit arc length.
To predict force distributions, the full arc B0T0 is divided into consecutive segments or sub arcs: s1, … si, … sN, where N is the total number of segments.

Further increasing Nd content leads to the coarsening of primary α-Mg grains.
As the Nd content is further increased to 1.5wt.%, grain coarsening of primary α-Mg occurs (Fig. 1(d)).
When the content of Nd reaches 4 wt.%, a large number of polylateral phases emerge in the microstructure, as shown in Fig. 1(f) (marked by white arrows).
On the other hand, the refinement of primary α-Mg grains enlarge the grain boundary areas including secondary dendrite arms boundary, which makes the residual liquid phase decrease and dispersedly distributes.
A large number of massive Al2Nd phases emerge when Nd content reaches 4.0wt

This can produce the necessary number of slip systems to promote plastic deformation.
Second, to reduce the grain size.
(c) Grain size distribution.
The rather small grain size of the materials under investigation leads to suggest that in this temperature range, grain boundary sliding can be a major contribution to deformation.
Fracture occurs in this case producing a large number of small particles.

Processing of a large number of novel steel types, such as DP, TRIP, CP and TWIP, and high-strength low-carbon bainitic and martensitic DQ-T steels, have been developed based on physical simulation and modelling studies.
Among stainless steels, guidelines for processing of ultra-fine grained austenitic stainless steels have been created.
For past 15 years, a large number of test programs have been accomplished on a Gleeble 1500 simulator at the University of Oulu to investigate and develop thermomechanical processing of steels.
It was also realized that the Nb alloying tends to increase the ferrite fraction but refines the grain size.
Ultra-fine austenite grain size in reversion annealed 301LN and flow stress curves following different annealing treatments.

Its configuration is based on warehouse area, grain stack height, grain (grain temperature, moisture, etc), environmental conditions (temperature, relative humidity, storage temperature, power supply etc.)
The forth category is modern grain storage.
At present the storage grain of mechanical ventilation has been used gradually in national grain reservoir in large number provinces and cities of our country.
At present the gas adjusted grain storage may divide into 3 ways in our country: grain storage of nitrogen filling[4], grain storage of carbon dioxide filling[5],“double low” grain storage of natural oxygen deficit and low dose of medicament.What uses most is “double low” grain storage, the one which is studied most is grain storage of carbon dioxide, the grain storage of nitrogen filling mainly uses in the oil preserve.
It is believed that with the development of the technology and productivity some methods of grain storage which are low-carbon and effective will be widely used in grain storage and the technology of grain storage in our country will be developed constantly.