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Until now, many studies have been reported about the effects of pre-strain [2-5], carbon content [6], grain size [7] and etc. on the fatigue properties of carbon steels.
Some of the specimens were etched (5% HNO3, 95% Ethanol) to get clear surface microstructure and monitor the surface condition during the fatigue test by replica method. 0 1 2 3 4 5 6 7 8 9 10 130 140 150 160 170 180 190 200 210 220 Fatigue limit τw, [MPa] Tensile pre-strain εp, [%] S25C S35C S45C Fig. 2 S-N curves of S35C Fig. 3 The relationship of τw and εp φ φ φ Fig. 1 Shapes and dimensions of the specimen 10 5 10 6 107 108 130 140 150 160 170 180 190 200 210 220 Stress amplitude τa, [MPa] Number of cycles to failure Nf, [cycles] εεεεp=0% εεεεp=2% εεεεp=5% εεεεp=8% Experimental results and discussions Effects on the fatigue strength.
Fig. 6 The relationship of (τw / τwo) and εp Table 3 Surface hardness in ferrite grains [Hv] εp=0% εp=2% εp=5% εp=8% S25C 152 163 171 204 S35C 169 171 174 204 S45C 189 190 210 220 Crack initiation and propagation behaviors.
The observing results show that the non-propagating cracks initiated in the inner part of ferrite grains, and stopped at the grain boundaries irrespective to ferrite or pearite grains.
(c-1) N=0 (c-2)N=1×107 (a-1) N=0 (a-2) N=1×107 (b-1) N=0 (b-2)N=1×107 Axial direction (a) εp=2%, τa=145 [MPa] (b) εp =5%, τa=160 [MPa] (c) εp =8%, τa=175 [MPa] A B A A B B N, [cycles] 50µm 50µm 50µm Fig. 11 Non-propagating crack of S25C with different pre-strain ratios 2) Torsional fatigue cracks initiate in the weak part of ferrite grains in the surface.

The desired microstructure can be promoted by the addition of small amounts of boron (< 40 ppm), where boron segregates to the austenite grain boundaries.
Niobium inhibits the nucleation and growth of ferrite and helps in the homogenous distribution of boron to austenite grain boundaries.
The grain coarsening of austenite during the reheating process is influenced by the time of reheating and the reheating temperature itself.
Lowering the reheating temperature on the one hand reduces the initial grain size of austenite which positively influences the toughness properties of the product.
Between the deformation step number 21 and 22 an increase of rolling force described as range of transformation is observed.

At the same time, the value of equivalent strain is increasing with the increasing of the number of deformation pass.
Researchers gave different opinions on the effect of grain refinement with different routes for pure Al and Al alloys.
The grains become elongated in the X direction.
So Furukawa et al. [14,15] summarized the effectiveness of ECAP routes in grain refinement as BC ≥ C≥ A or BA.
(3) The value of the equivalent strain and load increase with the increasing number of passes.

When these alloys are strengthened by artificial age process (i.e.T6 or T8 type tempers), their damage tolerance capability becomes quite compromised due to severely weakened grain boundaries.
Therefore, Ω-phase nucleates more readily in the grain matrix than do the other metastable phases, θ' and S' phases.
Validity Kc at -54°C Kapp at-54°C Validity number dir.
Fig 7 shows the Bright Field image of Al3Zr particles at the grain boundary and subgrain boundaries.
This further compromises grain boundary strength in the temper and makes the alloy even more prone to intergranular fracture than alloys not containing Zr.

Introduction The nanocrystalline materials, defined as polycrystalline solids having crystallite sizes usually less than 100 nm, can exhibit unique properties due to the large fraction of grain boundaries that they possess.
Significant efforts have centred on enhancing the mechanical properties of intermetallics through grain refinement [7, 8].
The selection of the most satisfactory fitting is made on the base of the weighted residual error (Rw) defined as follows: (20) The Goodness of Fit (GOF) is established by comparing Rw with the expected error Rexp: (21) where (22) N and P are the number of experimental points and the number of fitting parameters, respectively.
The XRD patterns of the milled powders (Fig. 1) are found to contain a significant number of overlapping peaks arising from the formation of crystalline intermediate products.
With the progress of the milling process, the effective diffusivity can be increased by decreasing crystallite size, i.e. increasing the area of grain boundaries.

It is seen that Steel 1 comprises partially-recrystallized ferrite grains with streaks of fine spherical carbides in them (Fig.1(a)).
The microstructure of Steel 3 is much different from those of Steels 1 and 2 with larger grain sizes and the absence of the spherical carbide streaks.
The grain size in Steel 4 is similar to that of Steel 1, but the carbides mainly existed as Fe3C/Fe eutectoid at the ferrite grain boundaries.
Interestingly, when the samples were oxidized at 850°C and 900°C, the number of blisters increased with oxidation time, whereas the number of blisters formed at 950°C decreased with oxidation time.
Each sample has a number of aabbbccd where aa is the steel type, bbb temperature in °C, cc oxidation duration in minutes, and d repeat number.

The resistance and stability of silo vertical stiffeners under axisymmetric loads during grain storage are being studied.
Introduction Steel cylindrical silos are the primary engineering structures used for storing grain and grain products today.
Please note that the numbers in parentheses are indicated for a smaller number of ribs.
The initial data is specified as the current, , and the desirable, , number of vertical ribs.
Steel Corrugated Grain Silos Structures.

Abstract: The rural land turnover has begun since the late of 1980s with the large number of migrant workers go for works in cities.
On the other hand, in the land transfer process, will also have a number of public land conversion for non-agricultural construction USES, such as for starting companies, real estate development waiting two, three industry send.
However, in the actual rural land circulation, as grain comparative benefits low, part of the licensee in order to obtain the land benefit maximization, in circulation has tendency, the area of the land circulation for grain and proportion of the trend of further reduction.
Especially the scale of the land circulation, more for development of high quality economic crops, this increased crop, aquaculture and tourism high value-added agriculture, rarely used in grain farming.
In recent years, Chongqing up around the adjustment of industrial structure and land circulation pace, especially the abolition of agricultural tariffs, a grain subsidies, the rural land output efficiency improved obviously, therefore, more and more people to sow the land began to interested.

Observed the the process of neck formation and growth, grain growth and pore shrunk.
Model and calculation conditions Fig.1 is the initial model of simulation, in this model the number of atoms is 21028, the model size is 5.0585 nmх10.117 nmх10.117 nm, cut off is 1nm, use the periodic boundary conditions in X/Y/Z axis directions, NTP ensemble, and UFF potential function.
In Fig.6 we can clearly see the changes of volume, grain size, sintering neck and stomatal of the model before and after sintering.

Once the ceramic begins to crystallize, the long range order of atomic arrangement, the crystal nucleus number, the grain size and the crystallinity of the ceramic significantly increase in a short time.
To qualitatively compare the crystallinity and the grain growth rate of the ceramics hot pressed at 1900 oC for different times, the Scherrer equation is utilized to calculate the grain sizes.
The calculated grain sizes are listed in table 1.
When the ceramic is heated up to 1900 oC, nano crystallites appear in the amorphous matrix, but the average grain size is only 8.7 nm.
Hot pressed at 1900 oC for 0 mins or 10 mins, the prepared 2Si-B-3C-N ceramic has an average grain size of 8.7 nm and 22.3 nm, respectively.