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A number of existing researches have affirmed the positive role of Si in high speed steel, such as improving the secondary hardness of high speed steel and steel toughness etc. [1-2].
While after quenching at 1200°C, the structure of W6Mo5Cr4V2Si steel is mainly composed by implicit needle or strip-typed martensite, residual austenite and carbide, with average grain size of 40 ~ 60 um.
(3)After quenching at 1200°C around, the quenching structure of W6Mo5Cr4V2Si steel is mainly composed by implicit needle or strip-typed martensite, residual austenite and carbide particles, with average grain size of 40 ~ 60 um around.

The grains are darkened with light gray, gray and dark gray to present the recrystallized, substructured and deformed grains, respectively.
By using three-dimensional calculated electronic charge density, the numbers of electrons that hold in the atomic sphere were evaluated to be 2.30 e for aluminum instead of 3 at the valence band.

Some of the grains of the needle-shaped β-AlFeSi intermetallic are shown to stem directly from layer 1 or 2 such as a peritectic reaciton.
Moreover, the layer 2 is composed of small irregular dispersed grains, which seems to be deteched from the layer 1.
For semi-quantitative analyses of each phase composing the intermetallic layers and the microstructure, the composition of them (indicated by the number in Fig. 3) was analyzed by EDS and summarized in Table 2.

The number of relatively large primary α-Mg solid solutions (bright phases) appeared in the thick specimens (6 and 10 mm) are higher than that in the 2mm thick.
Because of a rapid solidification against the die wall fine grains are formed at the surface.
The grain size and the quantities of pre-solidified α-Mg dendrite fragments are increasing towards the center.

It was found that preliminary mechanical activation (MA) of powder mixtures resulted in a substantial decrease in the ignition and combustion temperatures during SHS that allowed controlling the grain size of the products [3].
The broadening of copper and titanium lines is caused by grain refinement and accumulation of microstrain during the plastic deformation.
The completeness of the reaction in the MA-ed mixture can be attributed to the drastic increase in Ti/B interfaces during MA-processing, which provide a large number of new ignition sites in the sample.

The off-axis reduces also the number of wafers that can be sliced from a boule of given length.
However, a more growth related origin was found in the region between interacting grains, typically at boundary cusps.
This may be explained in the following way: under low supersaturation the atoms can be preferentially arranged at the grain boundary, however, at higher supersaturation there is less time for diffusion and atomic disorder is expected, with defect formation as a result.

The grain size of sample was estimated to be about 100 nm in Fig. 2(a).
The equivalent sized beta-FeSi2 grains were prepared on Si(001) substrate.
Therefore, in the process of crystallographic orientation, the number of conduction carrier will be decreased small polaron effect [12].

The selected fillers are SiO2, NaOH, grain graphite and white carbon black.
And the grains of composites obtained by cutter are molded to be standard sample for test at 220~240℃.
China Standard Number, China Standard Press (2006), in press [11] Wang Xiaodong et al: China Plastics Industry Vol.35(2007), p. 22

Symbols Property Value Units T Temperature [ oC] T0 Initial temperature 27 [ o C] Tp Peak temperature 1236 [ o C] t Time [sec] τ Thermal time [sec] A Absorptivity 80 [%] K Thermal conductivity 0.041 [Watts/mm o C] q Laser power 160 [Watts] α Thermal diffusivity 9.1 [mm 2/sec] v Velocity 5.0 [mm/sec] rB Beam radius 0.4 [mm] zo Heat diffusion distance during interaction 0.001 [mm] to=rB2/4α Time constant for heat diffusion beam radius 0.004 [sec] tc=rB/v Interaction time 0.08 [sec] c Carbon contents [%] A1 A1 temperature 723 [ o C] A3 A3 temperature (1183-416c+228c 2) [ oC] g Grain size 10-5 [m] R Gas constant 0.83 [J/(mole o C )] Q Activation energy c-diffusion in Austenite 135 [KJ/mole] D0 Pre-exponential c-diffusion in Austenite 10 -5 [m 2/s] cc Critical value of c 0.05 [%] ce Austenite carbon content 0.8 [%] When a laser beam of power q and radius rB is moved in x direction, with velocity v across
The extent of these changes depends upon the total number of diffusive jumps during the cycle and could be measured by the kinetic strength of the heat cycle.
The volume fraction occupied by pearlite or minimum subsequent volume fraction of martensite is: The volume fraction of martensite depends upon grain size, g, as described in [ 4,7,8], with The Vickers hardness Hv of the treated surface varies with depth and depends upon the volume fraction of martensite and its carbon contents.

Introduction With the number of large tunnel projects increasing, the application amount of large-scale shield machine increasing.
It is usual for the steel to be supplied in a hot-rolled condition with a pearlitic microstructure including some proeutectoid cementite at the prior austenite grain boundaries[1, 2], especially in large-scale rolled bars.
The proeutectoid cementite, when it forms networks at the austenite grain boundaries, is undesirable because it has been shown to adversely affect the rolling contact fatigue life in accelerated tests conducted with contact stresses in excess of 5 GPa[3].