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Keywords: gears, springs, grain coarsening, case-hardening, niobium, hardenability.
This level of strength has been the "new frontier" for a number of years.
C Si Mn P S Cr V 60SiCrV7 0.56-0.64 1.50-2.00 0.70-1.00 0.025 max 0.025 max 0.20-0.40 0.10-0.20 54SiCrV6 0.51-0.59 1.20-1.60 0.50-0.80 0.025 max 0.025 max 0.50-0.80 0.10-0.20 45SiCrV6 0.40-0.50 1.30-1.70 0.60-0.90 0.025 max 0.025 max 0.40-0.80 0.10-0.20 SAE 9260 0.56-0.64 1.80-2.20 0.75-1.00 0.035 max 0.040 max -- -- Grain size measurements performed according to the standard NF EN ISO 643 show that this small Nb addition is particularly effective in grain refinement (Fig.1). 5 7 9 11 13 800 850 900 950 1000 1050 Austenitizing temperature (°C) ASTM grain size number 60SiCrV7+Nb 60SiCrV7 SAE 9260 [13] Fig. 1.Austenite grain size versus austenitising temperature
This would lead to Nb segregation at the γγγγ grain boundaries and reduce the grain boundary energy available for transformation.
Austenite ASTM grain size index: 3/5 without Nb, 4/6 with 0.030 wt.% Nb.

The Research on the Adaptation of Grain Production in China to Climate Changes Based on Structural Equation Model Jiliang Xue School of Economy and Management, Inner Mongolia University, Huhhot Inner Mongolia 010021 Email: xuejiliang1981@163.com Keywords: The Structural Equation Model; Grain Production; Climate Changes; MIMIC Model Abstract: This paper uses the year data from 1998 to 2009, according to the MIMIC model in structure equation model to construct the adaptability system model of China's climate change to grain production, and makes an empirical research, found that sows area, the consumption of chemical fertilizers, agricultural water conservancy construction expenditure and the rainfall affects the maximum on grain production yield fluctuation of our country ; then according to the estimation results calculated the latent variable intensity fluctuation of grain yield, found that the grain production fluctuation of output intensity in future is further toward the positive
The advantage of structural equation model could use a number of observable variables to score the unobserved variables.
The sowing area and consumption of chemical fertilizer affect the production fluctuation of grain yield in China from two aspects of the total grain yield and the yield per unit.
From the graph 1, we see the grain yield fluctuation from year 1998 is relatively acuteness in the years 1998-2009.
With 2004 as a dividing line, after it the grain yield fluctuation intensity in China tends to decline.

Strain rate sensitivity of ultrafine grained fcc- and bcc-type metals J.
In particular, the differences between conventional grain size (CG) and ultrafine grain size (UFG) are pointed out.
The applied strain rate is always indicated by numbers, e.g. "-4" stands for a strain rate of ε& = 1×10 -4 s-1.
In Fig. 3a tensile tests for the recrystallized reference material and after different number of ECAP passes is plotted.
In (a) the curves are labelled by the number of passes and the applied route.

The average length of a crack is seen to increase at a lower boron concentration at grain boundaries, but appears less sensitive to the concentration of boron at grain boundaries as the boron concentration at grain boundaries increases(Fig. 5).
Dependence of average crack length (a) and average number of cracks (b) per weldment section on the calculated boron segregation concentration [8] Fig. 5 Variation of average length of single crack with the calculated boron content at grain boundaries with Eqs.(1) and (2) [8] .
When the solute concentration at the grain boundary induced by the diffusion of complex is higher than the equilibrium grain boundary concentration, a reverse diffusion of solute atoms from grain boundaries to the center of the grain will also occur along the gradient of solute concentration.
The experiments of P grain boundary segregation in INCONEL 718 alloy.
McLean grain boundaries in Metals, Oxford Univ.

Introduction Grain-oriented silicon steel is a soft magnetic material that is used as the core material in electrical transformers.
The global movement in energy saving and environmental protection has aroused deep interest in the properties and total transformer performance of grain-oriented silicon steel [1-3].When grain-oriented silicon steel is produced using CSP technology, the sufficient solution and refining precipitation of inhibitors during rolling, cooling and heat-treating, are conducive to the formation and development of grain-oriented texture of secondary recrystallization grains, conducive to the improvement of magnetic properties, but also conducive to the improvement of surface quality and dimensional accuracy.
Experimental procedure The starting material was grain oriented silicon steel, whose chemical composition was illustrated in Table 1.
The designed idea was to make experimental steel dynamic recrystallization, which made grains refined.
A large number of AlN inhibitors whose sizes were effective separated out by controlling the cooling after normalizing and AlN in normalized plate was separated out in the light of certain habit plane, which tended to be separated out in the form of bundle parallel to each other.

Effect of Aging on Microstructure and Performance after superplastic deformation of fine grained 1420 Al-Li alloy Yanling Zhanga, Hongliang Houb *, Yaoqi Wangc Beijing Aeronautical Manufacturing Technology Research Institute, Beijing, P.R.China a zhangyanling205@163.com, b hou_hl@163.com, c xiaoqigh@sina.com Keywords：Fine grained 1420 Al-Li alloy, Superplastic forming, aging, strengthening mechanism Abstract: Superplastic forming (SPF) is an important process for forming fine grained 1420 Al-Li alloy.
The microstructure of the plates is shown in Fig 1 and the average grain size is about 12μm.
It is found that a large number of cavities are existed in post-SPF materials.
A large number of δ’ phase (Fig.8(a)) which is the major strengthening phase are existed and distributed homogeneously in material after two-step aging.
A large number of δ’ phase are precipitated and distributed homogeneously in material after two-step aging for post-SPF. β（Mg2Al3）and S（Al2MgLi）phases are also exsited, and S phase can improve coplanar slipping which is created by δ’.

Disks of an AZ31 magnesium alloy were processed by High-Pressure Torsion (HPT) at 463 K to different numbers of rotations.
Most researchers estimate the amount of strain (ε) imposed to the material as a function of the thickness of the sample (t), distance to the center of the disk (r) and number of rotations (N): .
Different disks were processed to different numbers of turns.
This multimodal grain size distribution is attributted to the mechanism of grain refinement of magnesium alloys processed in the temperature range of ~400 – 600 K [2-4] which is characterized by slow consumption of coarse grains by the nucleation of fine grains along the grain boundaries.
This mechanism leads to multi-modal grain size distributions in the intermediate stages of grain refinement when the original coarse grains have not been completely consumed.

The increase in the number of passes could promote the growth of dynamic recrystallization grains under the same amount of deformation.
The DRV grains were continuously deformed, and the number of DRX grains was gradually increased.
A large number of fine DRX grains appeared in the grains, which much of them were existed along the grain boundaries.
The increase in the number of passes can increase the relative density at the same amount of deformation.
The increase in the number of passes can promote the growth of DRX grains under the same amount of deformation.

Fig.1 Grain cumulative grading curve of different coarse-grained contents Test Result and Analysis Stress-strain relationship of materials with different coarse grain contents.
between coarse grain content and shear modulus G.
Shear planes of the specimen with a coarse grain content of 80% and 100% have no visible scratches, their compactness are poor , and a large number of rock block distribute on shear planes dispersedly.
Material with a coarse grain content of 70% means its framework is excellent, and fine grains fill in the coarse grain adequately, that let the compactness increase accordingly.
It is because that coarse grain cannot contact with each other perfectly and internal friction angles will become small when fine grains increase, while coarse grains will contact with each other perfectly and internal friction angles increase with the increase of coarse grain content.

Coarse-grained Parallel Genetic Algorithm To try to avoid the “precocity” and “deceit” phenomenon, we put forward a coarse-grained parallel genetic algorithm.
Use to express the path information from the -th node to the j-th node, and , (both “i” and “j” are integer values, and “n” is the number of network nodes).
Initial population. 1) First, find the connection between every node, and save the number of connected nodes into an array together with relevant path information. 2) Then initialize each individual as the zero individual, which means that the assembly information about the individual nodes are: (), =N.
（2） Fig. 2 The shortest path of the experiment simulation Conclusion The coarse-grained parallel genetic algorithm segments those randomly generated initial populations into several major sub-populations by the number of processors [5].
After the contrastive analysis of the calculation results of classic examples, we get some relevant conclusions on coarse-grained parallel genetic algorithm’s performance feature and optimal parameter setting.