Search results

Grinding abrasives samples was executed with finesse abrasive grains increasingly smaller.
The primary grain boundaries were difficult to see.
Acknowledgments This work was supported by a grant of the Romanian National Authority for Scientific Research, CNCS-UEFISCDI project number PN-II-PT-PCCA-2013-4-1048.

Mäntyjärvie University of Oulu, Oulu Southern Institute, Pajatie 5, FIN-85500 Nivala, Finland aantti.jarvenpaa@oulu.fi, btonikiur@paju.oulu.fi, cantti.j.maatta@oulu.fi, dmatiasja@paju.oulu.fi, ekari.mantyjarvi@oulu.fi Keywords: Inverse approach, laser heat treatment, grain refinement, strength, formability.
By using LLHT, it is possible to tailor mechanical properties locally, e.g. to produce softened or hardened ultrafine grained (UFG) areas for subsequent forming [3-5].
The number of the designation indicates the average Brinell hardness value [HBW].
They indicate that the most crucial factor for good bendability of LLH-treated sheet is to obtain homogenous ultrafine-grained microstructure.

The liquid with directional covalent bond had lower coordination number and higher viscosity[5,6].
From the viewpoint of atomic movement characteristics of melts to explore possible discontinuous change in liquid structure, it has profound academic significance to realize the structure and solidification theory of liquid metal and alloy, to deepiy research the melt processing technique of crystal grain refinement.
The coordination number Ns of Sn melt at different temperatures.
Fig.4 shows the relation between the coordination number and temperature of the Sn melt.
There is an abrupt change of 9.866 in the coordination number of Sn from 673 K to 593 K.

In case of the examined heavy plate thickness range the higher strength can be effectively reached by grain refinement and the change of the second phase quality, size and distribution.
Among the fine grained high strength steels, the highest strength steels are the quenched and tempered group, followed by the thermomechanical steels.
Due to the avoidance of excessive grain coarsening microalloying elements (Al, Nb, V, Ti) are frequently used in these steels.
High cycle fatigue is considered when the loading is relatively low, and the number of cycles are relatively high, between 104 (5*104) cycles and 108 (109) cycles.
In case of the W700Q at lower number of cycles (approximately under 2*105), namely at higher load levels, the fatigue resistance of the overmatching joint is lower than the matching joint, however at higher number of cycles the overmatching joint has better fatigue characteristics.

Dynamic recrystallization during forging or subsequent heat treatment generates fine grain microstructure which exhibits as well good fatigue strength as good heat resistance.
Refinement is applied by hot extrusion with special insulation technique, so that the microstructure can recrystallize to smaller grains.
Fig. 4 Manufacturing sequence of high pressure compressor blades Due to the very slow forming, which is more a hot creep than a forging process, the number of parts per time is small.

With the same distance of tool path and grinding depth, three factors influence the speed of grinding heads consumption .They are Grinding grain (mesh),feed speed(m/min)and spindle speed(r/min),kept for A, B and C in order.
“yi” is the number of used grinding heads during “i” experiment.Rj shows the range of Ij, IIj, IIIj reflecting the influence of level’s change.
From picture 3, grinding grain plays a decisive role in consumption of grinding head.

Structure of the Polishing Machine Several principles should be noticed during the arrangement of polishing process planning [3]:1) the polishing process should start with larger grain size and gradually go down to smaller grain size.2) the polishing path should distribute evenly on the surface.
Anymore, the material removal depth is directly proportional to the relative velocity at polishing point, mean pressure and number of polishing times and inversely proportional to feed rate and workpiece hardness [4].

Giant dielectric constant has been attributed to barrier layer formation at grain boundaries or due to formation of twin boundaries[4-6].
Atomic force microscopy revealed the presence of an intrinsic electrostatic potential barrier at the grain boundaries that is considered to be responsible for the varistor properties[8].
The maximum dielectric constants is found when x=0.2 and the value of number reaches to 104.

Dynamic recrystallization is characterized by grain refinement and evolution of compact dislocation structures and differs from static recrystallization in that the kinetics are much faster and the refined grains are very small [2].
The total number of elements representing a quarter of the specimen is 35.

He claims that the main reason for the initiation of the fatigue crack are plastic slips in metal grains [4,5].
It happens so since the grains are provided with the systems of easy slip.
The integral approach can be effective under non-proportional loadings, however the range of use should be proven by comparision to wide number of experimental results..