Search results

Increasing the number of pulses from 3 to 30 at ES = 15 J/cm2 leads to the formation of a multiscale island structure (Fig. 4).
To the mesoscale there corresponds a grain structure formed in the interisland space (Fig. 4, e).
The grain size varies in the range 1–5 mm.
To the nanoscale there correspond round crystallites forming the grain structure and islands (Fig. 4, c–e).
In the interisland space (Fig. 5, regions 1 and 3) in which the grain size varies in the range 1–5 mm, the Ti concentration is 2–4 wt %.

Discussion The changes during annealing in the microstructure, texture and mechanical properties of cold - rolled commercial purity aluminium have been analyzed previously in a number of experiments.
At still higher temperature recrystallization is followed by some grain growth leading to grain sizes of 8.1µm (CR4) and 7.0µm (ARB6) after annealing at 420°C for 2h (Fig. 3).
Such variations can have their cause in the presence of grain boundaries and coarse particles.
• Annealing at 420°C for 2h leads to uniform polycrystalline structures in both samples with a grain size of 8.1µm (CR4) and 7.0µm (ARB6)
Godfrey acknowledges support from the National Natural Science Foundation of China under contract numbers 50571051 and 50371041.

Laser beam welding of light alloys has always represented a big challenge for both designers and technologists due to the large number of process parameters to take into account and the variable responses of the different materials to be welded.
Weld beads as seen in Fig. 4 show a very fine grain structure as result of high speed laser welding process.
The HAZ of both skins and stringers are very narrow: the HAZ of skins are usually few grains wide, as can be seen in Fig. 5.a, while those of stringers (Fig. 5.b) involve a greater number of grains simply due to the fact that the stringers are extruded and their grain structure is very fine.
Figure 6 - Micrographs of a single grain in the HAZ of a skin Micro-hardness measurements.
Corrosion appears confined within the above mentioned PMZ: such zone is rich in particles on grain boundaries (cathodic area), and the particles themselves are close the precipitate free zone (anodic area).

According to the applicable regulations, Minister of Energy and Mineral Resources Policy Number 1827 K 30 MEM 208 concerning Mining Slopes with unidentified geological conditions in the previous geotechnical study, the following actions are taken: 1.
Soft 16.75 17.85 1.1 Swamp Material, Grey, Sand, Clay, Very Soft 17.85 18 0.15 Sandstone, Grey, Fine Grained, Clay, Quartz Soft Fresh 18 19.4 1.4 Sandstone, Grey, Fine Grained, Clay, Quartz Soft Fresh 19.4 21 1.6 Sandstone, Grey, Fine Grained, Clay, Quartz Soft Fresh HD-21-004 0 5 5 Dumping Material.
Grey, Sand, Clay, Soft (based on cutting) 2 4 2 Swamp Material, Grey,Clay,Very Soft 4 5 1 Coal,Black,BrownisTreak, Brittle, Brigh 60-79%, Soft, Fresh 5 9 4 Sandstone, Grey, Fine Grained, Subroiunded, Quartz, Soft Fresh Standard Penetration Test (SPT) In the research area, three sample points for material were tested using the SPT method, namely: a.
SDGT-LMO-19-140 The dominant material properties are soft to very soft, with the number of SPT "N" blows being less than 4.
Geological Resources Bulletin Volume 6 Number 2, PP 105-106

The issues of increasing the efficiency of grinding tools due to their design features (composition and structure of a wheel, shape and orientation of abrasive grains, etc.) are traditionally given increased attention by researchers [1-3, 5, 8].
The influence of the grinding wheel characteristics on the thermal factor of the grinding process is determined by the number of abrasive grains involved in the work, the size of the abrasive grains and the wheel hardness.
At a shallow depth of cut, the minimum temperature is ensured by fine-grained wheels, at a large one - by a coarse grain.
With an increase in the number of the structure and porosity of the wheel, the grinding temperature decreases due to a decrease in the number of heat impulses, better self-sharpening of the wheel and a decrease in fouling of its surface.
Strelnikov, The influence of the grinding grains shape and orientation on performance of coated abrasive tools, MATEC Web of Conferences 297, 09006 (2019). https://doi.org/10.1051/matecconf/201929709006

The company was asked to supply a number of samples with the specific requirement that they must come from different production batches.
In the Al alloy 8xxx series the grain refiner agent is iron.
The grain size is reduced by increasing iron content.
In both cases, the structure was very fine and homogeneous and the average grain size was very small.
In the case of Sample 1c it was impossible to quantify the grain size, while for specimen 3c the average grain size was about 15µm.

To avoid grain coarsening of the microstructure of sintered specimen, SPS was conducted below the γ prime temperature, which is about 1140 °C (1413 K) [29].
Experimental record of a number of SPS-parameters for sintering Ni-alloys powders at 1273 and 1323 K and a hold-time 15 min: a) undoped (as-received) and b) Pt-doped.
Fig. 2 shows experimental record of a number of SPS parameters such as the densification of Ni-alloys powders as function of time.
During this period, grain boundaries were deformed and reorganized, especially due to the plastic deformation of the β phase rich in aluminum.
A short hold-time also helps to avoid grain ripening due to diffusion controlled by phase transformations.

Huadong Fu [8] et al. reported that the grain orientation and precipitation were found to be crucial parameters for obtaining significant superelasticity.
When the number of variables increases, it becomes more complex and time-consuming [12,13].
It reduces the number of experiments as well as quantifies the influence of process variables on the output.
This is due to the occurrence of recrystallization at 1150℃.New grain formation takes place,leading to grain refinement, which enhances the strength of the material and thereby developing greater resistance to deformation.
At high temperature (1200℃) and low strain rate (0.1s-1), recrystallized grain growth occurs, which decreases the strength of the material.

In order to produce the desired surface texture and remove the physisorption layer, a part of the investigated samples was mechanically processed with a coated abrasive tool (grain P320) for 30 seconds.
The number of necessary measurements in the main tests was defined on the basis of the scatter analysis and assumed materiality level [12].
“i”, y - arithmetic mean, n- total number of measurements.
Table 4 lists roughness profiles of the surface of the samples made of 316L steel before and after mechanical treatment with a coated abrasive tool (grain P320).
Notably, the level of the polar component of the SFE after mechanical treatment with a coated abrasive tool (grain P320) more than doubled in comparison to samples prior to mechanical treatment. 3.

Total number of experimental runs is 9.
Nugget region has grain structure which is randomly oriented.
The grain size is finer than base metal at nugget zone.
The grain size normally increases with higher rotational speed due to high heat input.
Observed higher strength of weld can be attributed to refined grain structure.