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Microstructure is formed by solid solution and number of fine intermetallic phase particles.
Grain size of both materials is nearly identical.
Closer look reveals, that the relief is created by the degradation, which is most pronounced at the grain boundaries.
Detailed micrographs clearly show corrosion at the grain boundaries, enhanced by deep etching.
More detailed observation revealed preferential degradation at the grain boundaries and in the vicinity of secondary particles.

The use of double normalization leads to the decay of austenitic grains and, upon cooling, the formation of small ferrite grains.
Thanks to repeated heating, the austenite grains are disintegrated and smaller ferrite grains are formed on cooling [5].
Chemical composition of industrial 20GL steel Melt number Weight ratio, % C Mn Si Cr Ni Cu Al P S 26257-7 0.23 1.19 0.39 0.17 0.12 0.10 0.054 0.017 0.017 67185-8 0.18 1.21 0.25 0.15 0.09 0.08 0.034 0.017 0.017 According to OST 32.183-2001 0.17-0.25 1.10-1.40 0.30-0.50 ≤0.3 ≤0.3 ≤0.6 0.02-0.06 ≤0.04 From the table, it is evident that strength-related characteristics, plasticity and impact strength of the 20GL steel at both positive and subzero temperatures meet the requirements of OST 32.183-2001.
Conclusions Thus, from the conducted studies, one may conclude that the possible causes of unstable impact strength of the 20GL steel under –60 °C are structural non-uniformity following its single normalization, liquation events along the borders of primary austenite grain, presence of areas with the dendritic structure [5].

Strength models Yield strength (σYS) of an aged Al-alloy is considered to be consisted of four strengthening mechanisms (Eq. 1): (a) solid solution, (b) grain boundary, (c) modulus and (d) precipitation
(1) where, is the yield strength of the alloy at aged condition; ΔσSSS, ΔσGBS, ΔτMS and ΔτPS are contribution of strengthening due to solid solution, grain boundary, modulus difference between the precipitate and the matrix, and precipitation, respectively.
Following Hall-Petch equation, the strengthening contribution from the grain boundary is: (3) where, σi is the intrinsic strength of the alloy and ki is the locking parameter with values of 16 MPa and 0.065 MPa m-1/2, respectively for AA6063 alloy [9] , and d is the mean grain diameter estimated as 53 µm for the investigated alloy.
Estimation of volume fraction of precipitate and their mean radii The volume fraction of precipitates can be estimated following Becker-Doring law [12]: (8) in which, A is aspect ratio, υat is molar volume of precipitates, A0 is Avogadro number, Z is Zeldovich factor = 0.5, tA is time of ageing, ΔG* is the activation barrier of nucleation of precipitates, R is the universal gas constant and TA is the temperature of ageing.
Illustration of the contributions from solid solution strengthening (SSS), grain boundary strengthening (GBS), modulus strengthening (MS) and precipitation strengthening mechanisms to the total yield strength (σYS) of AA6063 alloy aged at 473 K estimated from the DB and ZS models considering nucleation-growth -coarsening (N-G-C) as well as nucleation-growth (N-G) separately.

Quartz: as the mineral debris and lithic debris, mineral detrital quartz for edge grinding round shape, size of 0.1~ 1.5mm, part of the granular recrystallization; in the cuttings grain size of about 0.05mm of detrital quartz, muscovite, chlorite cement.
Among them, the fine-grained quartz with recrystallization, strong wavy extinction, or irregular pieces has alkali-silicate reactive ingredient, which needs to be determined by the accelerated mortar bar method.
Quartz: debris and fillings, detrital quartz for edge grinding round corners, time, particle size of 0.05mm ~0.4mm, visible wavy extinction, part of the granular recrystallization grain size of quartz; fillings for 0.002 mm ~0.03mm, main and sericite intergrowth.
The result of the petrographic method indicated that the main mineral structure of limestone samples is grain dust or block structure, which is composed of calcite, dolomite, quartz, sericite, chlorite, and opaque minerals.
Table 4 The result of the rock cylinder method specimen number Expansion rate % 11d 14d 21d 28d 56d 84d G1 0.011 0.011 0.014 0.014 0.014 0.014 G2 0.006 0.006 0.006 0.006 0.006 0.006 G3 0.008 0.008 0.008 0.015 0.015 0.015 Table 5 The result of the accelerate rock cylinder method at 80oC specimen mumber The expansion rate in 7 days% The ultimate result % x y z G1 0.037 0.060 0.014 0.060 G2 0.006 0.143 0.017 0.143 G3 0.029 0.061 0.151 0.151 The expansion rate of the specimens in 84 days which made by the limestone is less than 0.1% in the rock cylinder method means that the aggregate without potential alkali-carbonate reactive.

Comprehensive Utilization Status of Mine Solid Waste Solid waste contains a large number of substances, which are potential resources.
For example, massive and coarse grained tailings of iron ore are dry magnetic separation or cast out of the products in Ma anshan Gu Mountain iron ore with solid and density texture, less hazardous substances, coarse surface and well-graded, suitable for concrete aggregate.
The concrete hollow slab, made from block and coarse grain of tailings in concentrator of gu mountain iron ore was exported to other regions except for roadway support and mine construction
(2)Produce a variety of architectural products by fine-grained solid waste Fine-grained solid waste, as the main raw material, can be made into a variety of architectural products, especially the tailings with quartz as the main element, which can not only produce unburned wall tile, stick wall brick, artificial marble, terrazzo, aerated concrete and granite etc., but also can be used as the raw material of glass and ceramics production.
Under the situation of environmental management and recovery, and resources scarcity, the comprehensive utilization of long-term, large number of surface mine solid waste accumulation should be actively carried out.

Average grain size determined by linear intercept method was around 3 mm for both materials.
Data recording rate was under 0.3 ms in order to record high number of data on the hysteresis loop.
It was shown earlier [4] that the second peak changes with increasing number of loading cycles.
Markings of different slip systems were observed in grains suitably oriented to stress axis and they often run along the whole grain.
As a result slip markings, or persistent slip markings are produced on the surface of individual grains.

Regimes of used HTIP-treatment, including type of ions, charging voltage of condensers U, density of plasma flow energy Q and number of pulses N, are presented in Table 1.
Regime B differs from regime A in the significantly higher density of plasma flow energy and the greater number of pulses, so that by regime B the tube surface bears evidence of intensive everywhere melting, whereas by regime A similar traces are only local and feebly marked.
The X-ray line profile analysis was aimed to determination of the interplanar spacing dhkl in the crystalline lattice of reflecting grains and the angular half-width Вhkl, characterizing grain fragmentation and distortion of their lattice [4].
Since the HCP unit cell has the single basal plane (0001) and the BCC unit cell has 6 planes {011}, the cycle of phase transformations α→β→α results in "multiplication" of α-Zr grain orientations.
Changing of material texture signifies, that under treatment the directed rotation of grain lattice occurs due to initiation of collective dislocation processes in material and, in particular, operation of slip and twinning systems, responsible for texture changes under usual plastic deformation.

In (a), it was shown that the coarse precipitates with size from several μm to several 10 μm were formed uniformly for the whole crystal grain on the specimen surface, in furnace cooling FC material to room temperature after the solution heat treatment at 493K.
In the case of FC material, it was thought that large number of Ge atoms were carried near surface and vacancy disappeared and the coarse Ge precipitate was formed with residue Ge atom because high concentration of vacancy existed at high temperature such as 623K during furnace cooling and the diffusion rate was large.
The cause of this phenomena is thought that large number of solute atoms accumulated near surface during quench hardening and then it was grown to μm sized precipitate during subsequent aging treatment because the bond energy of Ge atom with vacancy is considerably larger than that of Si atom10).
According to the results of TEM observation14), the Ge precipitate with average size of 124 nm was uniformly formed in crystal grain, however, the precipitate‐free zone was also formed near the grain boundary and the coarse Ge precipitate with average size of 254 nm was formed.
Therefore, it can be thought that the Ge precipitate on grain boundary became starting point of break and it made breaking elongation smaller.

The structure of the FSW weld is uniform and consists mainly of big grains of structural constituents of aluminium and magnesium, as well as intermetallic compounds.
Big grains may signify fragile structure that can be verified by the shear test.
Number Marking Size a Pin diameter in the shear area [mm] Size b Shear specimen width [mm] Maximal force Fmax [N] Shear strength τm [MPa] Elonga- tion A5 [%] Remarks.
Big grains of intermetallic compounds have been accumulated in the relatively narrow zone of the weld and caused the fragile breakage of this weld.
Ding: „Ultrafine grained surface layer formation of Aluminum alloy 5083 by Friction Stir Processing„, Procedia CIRP 45 (2016), 243-246 [13] L.N.Boţilă, R.Cojocaru, C.

The results indicate that the abrasive grain size exerted the greatest effect on abrasive wear, followed by reinforcement size.
The tex number represents the kenaf yarn fiber diameter where 1400 tex number is roughly equivalent to 1.90 mm.
The tex number of the yarn will determine the number of yarns needed during the pultrusion process.
It can be seen that the counterface roughness or abrasive grain size shows highest effect on the wear rate of kenaf/polyester composites, followed by applied load, sliding speed and fiber loading.
This shows that the number of yarn reinforced into the polymer matrix is important in affecting the frictional contact between composites and the sliding counterface.