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The experimental results show that the content and grain size of the martensite in the 65Mn steel after subcritical quenched are related with pretreatment process.
Classifying number in China: TG156 Introduction 65Mn is used as the blades of straw rubbing and cutting machine, enduring great alternating stress, impact load and the acutely friction wear, such as rubbing and cutting machine blades, etc.
The smaller nucleation energy is, the greater nucleation rate is, the finer austenite grains are.
The grain fineness is 9 grade when the pre-normalizing 65Mn steel is subcritical quenched at 780℃.
From the view of nucleation, many fine spherical austenite grains formed in the austenite transformation process for the pre-quenching sample.

Based on this framework, a number of probabilistic models have been proposed in literature.
For an appropriate modeling of the RVE’s, a statistical characterization of the microstructure (grains and particles) is required.
Thus, precise information regarding the grain size distribution, the grain shape and the grain orientation (morphologic and crystallographic) were obtained.
Based on the morphologic information in the form of best-fit-ellipses, the grain size distribution, the grain shape distribution (ratio of the semi-axes) and the orientation distribution of the grains could be determined.
The particles were inserted into the grain structure at the desired location via a spherical submodel, consisting of the material of two adjacent grains and a brittle particle with user-defined size, shape and orientation at the interface of these grains.

The ferrite matrix is homogeneous with an average grain size of ~0.3 micrometers.
In principal, the plastic deformation capability of a material is direct proportion to the number of active slip systems.
The investigation shows that at least five independent slip systems must be operative simultaneously in a grain to avoid the cracking.
Thus the additional slip systems of（110）[111]and（011）[111]become active and then the cementite possesses a sufficient number of slip systems for plastic deformation.
The microstructure after three passes of ECAP is shown in figure 3(b) with clear extinction contours along grain boundaries.

Steel silos are commonly constructed by welding together a large number of curved steel panels with lap joints.Where the lap runs horizontally around the silo circumference, the lap connection causes a local eccentricity in the line of vertical thrust in the shell wall.
Steel silos are commonly constructed by welding together a large number of curved steel panels with lap joints.
By stressing loads calculated according to Chinese code for design of grain steel silos, this paper uses the finite element software to analyze the stability of lap-jointed steel silo, providing a reference for the future design of steel silos.
Chinese code for design of grain steel silos and Eurocode both consider the internal pressure to improve the stability critical stress.
Under two load cases, by formula of Chinese code for design of grain steel silos and compared it with the finite element calculation, see Fig. 7and Fig. 8.

The fig.4 also demonstrates the grain size.
Variation of grain size of Mg2Si with annealing temperature Fig.6.
Milling can induced a large number of intragranular defects.
Also Milling makes grain in high energy state, which causes grain stability decreased.
Large number of defects provided more nucleation positions for Mg2Si.

It shows that the grain size decreases with increasing Nd content.
And when Nd content increases to 1.5 wt.%, the number and size of precipitates increase and segregate as block morphology, as shown in Fig. 2 (d).
As shown in Fig. 1(a), the grains in Zn-25Al-5Mg-2.5Si alloy are coarse and adding 0.4wt%- 1.2wt% Nd, the grains become smaller(Fig. 1c-e).
According to this relationship, the smaller the grain size, the higher the strength.
When Nd content is 0.8wt.%, the grains refining effect on the alloys is optimum.

Results and discussion 3.1 Crack Fig.5 Effect of RE ferrosilicon alloy addition amount on the crack rate Addition amount of RE ferrosilicon alloy(g) Crack rate (%) Tab 4 The crack number and crack rate in samples Sample Crack number Crack rate A 21 40% B 11 30% C 9 26% D 2 6.7% E 6 20% The statistical results of crack number and crack rate in the samples are given in Table 4.
Table 5 The content of elements of samples (wt%) Sample C Si Mn P S Al Cu Ce A 0.314 0.785 1.127 0.030 0.018 0.093 0.027 0.006 B 0.323 0.821 1.053 0.022 0.016 0.095 0.059 0.023 C 0.318 0.85 1.066 0.032 0.014 0.087 0.026 0.037 D 0.287 0.699 1.080 0.035 0.012 0.102 0.028 0.057 E 0.286 0.663 1.088 0.034 0.016 0.089 0.029 0.064 3.3 Microstructure of the samples in as-cast condition 1600μm Fig.7 Grains of casting sample A (a), B (b), C (c), D (d) and E (e) 1600μm (a) (d) 1600μm (e) (b) 1600μm 1600μm (c) The grains characteristics of microstructure of the casting samples are shown in Fig.7, where sample A, B and C show coarse-grained, while sample D and E exhibit greatly refined grains.
The reason is that the RE content in Sample A, B and C was lower than that in Sample D and E, which was not sufficient to refine grains.
Therefore, grain refinement has a positive function to reduce cracks.
At the same time, it can be seen that the grain size of sample E was larger than that of sample D because the excessive RE made grains coarsened again.

The results show that the alloys with small size, uniformly distribution and moderate number of carbides present a high stress rupture performance.
The fourth group elements mainly include Mg, Zr, B, which segregate to grain boundaries, fill vacancies and reduce grain boundary elements diffusion.
The blocky and strip MC type carbides rich in Ti and Mo distribute among the grains and grain boundaries.
(5) The grain boundaries easily turn into crack propagation path, so the grain size must be controlled.
The relationship of electron vacancy number and rupture life in C1023 alloys [J].

The results show that, the number of spherical Al3Zr particles is determined by the pretreatment, and that the size is determined by the homogenization.
Introduction It has been experimentally documented [1-4] that the function of addition of Zr in aluminum alloys as a role of grain refiner and recrystallization inhibitor.
In order to provide experimentally veritable results from the TEM investigation, for each sample, at least 3 grains were investigated and at least 5 areas for each grain were imaged.
But the number of Al3Zr particles increase with the time of pretreatment prolonged and the temperature of the pretreatment rise.
According to this report, there will be form a certain number of atom cluster when the holding time is less than 24h at the temperature of 460˚C.

Rock strength and the ultrasonic velocity are related and a considerable number of empirical researches has been carried out to establish the correlation between the strength and velocity of sonic pulses.
Specimen numbers for the tests ranged from 13-25.
The very coarse-grained variety of the Jakura marble showed interpenetrating grain texture called decussate structure (Figure 2a).
The determining factor as to which mode obtains is dependent on the strength of the grain boundary relative to that of the grain interior.
Microcracking and grain size effects in Yuen.