Search results

The figure also shows that the clad layer and substrate formed irregular combination, and a jagged half-melting ferrite grain was generated.
Because of the mutual crisscross between clad layer grain and Fe-substrate, a good metallurgical combination was formed.
The differences of light and shade among the bulky columnar grain are illustrated in the Fig. 2b.
Fig. 3 SEM images of outermost clad layer of samples From the above analysis, it can be seen that the organization was the same in different conditions namely it distributed as substrate-heat-affected area-fusion area-clad area, but grain sizes and shapes of different parts of the clad alloy layer were different.
These numbers also indicates that the hardness value reduce gradually from welding area, fusion area to whole matrix, which improved hardness of matrix greatly.

This can be achieved in particular by grain refinement, but without the loss of ductility which accompanies strengthening by work hardening.
Severe plastic deformation (SPD) is known to result, in a number of metals, in a greatly refined grain size.
In the last decade various SPD methods have been developed and successfully used to convert the traditional coarse grained metals and alloys into materials with ultrafine microstructures [1-3].
More recently, it was shown that HE can be viewed as an efficient SPD method which allows grain refinement down to nanometric scale to be obtained in various materials, e.g. titanium and aluminium alloys [4-6].
The friction coefficient values under lubricated conditions differ from those obtained under dry conditions in number of ways.

The processing parameters: background vacuum of sample chamber is 5×10-3Pa, accelerating voltage of electron beam is 25keV, target polar distance is 80mm, pulse numbers is 10, 15 and 20 respectively, pulse frequency is 0.1Hz and the beam spot size is 60mm.
It can be seen that the surface morphology of AZ31B magnesium alloy is the model volcano pit appearance, and pulse numbers impose obvious effects on surface morphology.
May observe, the melting layer depth in 15μm about, the melting layer crystal boundary basically vanishes, this is because the surface of AZ31B experience very fast remelting process, the crystal grain grows up without enough time. 15 times irradiated sample show that crystal grain refinement obvious nearby the remelting layer.
Therefore surface wear resistant enhance. (2) Rapid solidification make the grain of magnesium alloy surface refining, hardness and wear resistance enhance. (3)When electron beam act in material surface, the surface temperature soares.
Rapid solidification has caused the remelting area grain refining during HCPEB treatment, formed remelting layer about 15μm.

Fines are fine-grained particulates having particle grain sizes of less than 200 microns though in some cases even coarser than that are referred to as fines.
The 500µm magnification illustrates variations in fines grain sizes [5].
The optimal boundary condition set-up was found to be the 50 x 50 cell which resulted in the highest number of both type of cells penetrated liquid cells and solid fines The most important simulation results are the pressure drop profiles across the computational grid.
Below is an example of liquid flow carrying 200 µm grain size in 1000mD computational grid block.
The curves in Figs 6-8 were revealed for 200µm sensitivity of fines grain sizes through a 1000mD computational grid.

This system is characterized by a large number of binary and ternary phases, both stable and metastable.
Dimensions of individual grains are in order of tens of micrometers.
The grains got coarser (see Fig. 3) as well as the precipitates on grain boundaries (compare Fig. 2 and Fig. 4 taken with the same magnification).
The grains got coarser (see Fig. 5).
Particles inside the grains are completely dissolved.

ELID（electrolytic in-process dressing) grinding technology, which provides in-process dressing to metal-bonded fine-grain diamond wheels during ultraprecision grinding of hard and brittle materials, was pioneered firstly by H.Ohmori in 1987.
And with the aid of dynamic balance between non-liner electrolysis action and inhibiting action of passivating films, protrudent abrasive grain on the surface of diamond wheel would implement continuously [1].
For tribological action, abrasive grains will gliding and frictionizing on the parts surface, and surface material will be extruded, contact journey must be “elastic zone”.
Once cutting depth reach to a critical value, while contact stress is big enough to fracture toughness of the material, grinding chips will directly generate and flow out in front of abrasive grain.
Influential factors from workpiece include mechanical properties of material and microstructure of parts, and mechanical properties involve strength, hardness, brittleness number and fracture toughness, microstructure means content of impurities, Porosity rate, dislocation defects and crystal grain size.

That is solving the rate equation of the single grain before and after the introduction of ultrasonic vibration of the grinding process: (3) (4) Formula (3) is the equation for the speed of the single grain before the introduction of ultrasonic vibration, equation (4) is the equation for the speed of single grain after the introduction of ultrasonic vibration. 3.3 Acceleration analysis To further illustrate the introduction of polyurethane rubber grinding process of ultrasonic vibration, the acceleration of the processing similar to the analysis of the processing speed , (3) and (4 ) are taken the first derivative of time t, o get the ultrasound vibration of the introduction of a single abrasive grinding process before and after the acceleration of time variation: (5) (6) Among them, the formula (5) is the single grain before the introduction of ultrasonic
vibration acceleration equations, formulas (6) is the single grain after the introduction of ultrasonic vibration acceleration the equation.
Thus increasing the time of the single grain actually involved in the grinding, that is the effective abrasive grinding time
(3) As a result of the irregular distribution of abrasive wheel, at the same time, a large number of abrasive grain are used to grind .When multiple abrasive grains back and forth ironing pressure and intertwined in the grinding track, cutting trajectories can be formed in the surface mesh, and can get a better effect of the cutting process and higher quality of the machined surface.
Conclusions Through comparative analysis of the single grain kinematics characteristics in the machining process of the ultrasonic vibration assisted grinding of polyurethane rubber before and after the introduction of ultrasonic vibration we can draw the following conclusions: (1) In the case of ultrasonic vibration, the length of the movement path of the abrasive is longer than that of the ordinary grinding.

Sintering below the solidus temperature is inefficient and the sintered product has lower density besides containing a large number of pores.
With increasing temperature until the interval between the solidus and liquidus lines there is formation of a liquid film that penetrates the particle and grain boundaries, breaking down the structure into individual grains.
These grains rearrange themselves due to capillary phenomena favoring densification.
The carbides are located mainly at grain boundaries.
Figure 7 reveals the large carbides with higher niobium content at the grain boundary and the smaller carbides, also with higher Nb content within the grain.

The formation process of fine grains could be observed in the local deformation bands, especially near the bands of the initial grains.
The size of precipitated phases is much too small and differs a lot in contrast with surrounding grain matrix, mistaken as grain boundaries.
These precipitated phases inside grains block the grain boundaries motion of new grains by restraining growth of new grains and thus leads to refinement of grains as well as the phenomenon of inhomogeneous deformation.
Stress gathering in surrounding area of grain boundaries resulting in the bending of grain boundaries.
The research indicates that subgrains are produced around original grain boundaries and own the same orientation with original grains.

Denomination Magnetism Aided Machining (MAM) comprises a number of relatively new industrial machining processes (mainly finishing and surface improving) developed presently, too.
The parameters are described in the Mercedes-Benz standard MBN 31007-7 in 2009. [7, 8, 9] DP – period length (mm), Dγ – twist angle (° ’ ”), Dt – twist depth (μm), DG – number of threads ( ), DF – theoretical supply cross section (μm2) Fig. 1.
Process of MABB [14] As you see this equipment similar to the previously showed equipment of MAP technology, but in this case instead of the abrasive grains were applied two hard bearing balls as the burnishing tools.
The generated magnetic induction was reduced (B = 0.75 T) with polishing grain because of the applied Al2O3 shielding properties.
The average of two values (1) is the characteristic number of twist surface (am) by [15] industrial standards