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Investigation of Laser Scribing Technics for Reducing Core Loss of Grain-oriented Silicon Steels Y.
Zhu 3, c 1, 2, 3 College of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China a yuhuang_hust@163.com, bliuyongable@yahoo.com.cn, cglzhu@mail.hust.edu.cn Keywords: Laser processing, Laser scribing, Core loss, Orthogonal test, Grain-oriented silicon steel, Technical parameters Abstract.
Introduction Grain-oriented silicon steels have a large market in the field of soft magnetic materials.
According to the statistics, the waste caused by core loss of the grain-oriented silicon steel reaches 4% of the whole waste of electric energy in advanced industrial countries.
Hence, one domain will become two or more, and the core loss of the grain-oriented silicon steel is reduced [2-4].

Very rarely has toughness been measured with a number of alternative quench paths sufficient to fit predictive equations.
For Alloy 7085 we did fractography on a limited number of the used R-curve specimens of Alloy 7085.
In a range of high hold temperature, precipitation is found only on grain boundaries.
At medium and low hold temperatures, precipitation on subgrain boundaries exceeds precipitation on grain boundaries.
This pattern was first recognized from early datasets with a limited number quench paths [14].

We have covered three different grain sizes of particles.
The possible solution of these problems can be the plating of the SiC grains.
A number of common reducing agents have been suggested for use in electroless copper baths, like formaldehyde, sugars, hypophosphyte.
The copper deposit is light, and there is on the dark grey grains.
If the coating time increases, the numbers of the particles and the plating rate increase, as well.

The top surface comprises equiaxed grains, and columnar grains are observed in the cross-section.
As the grains grew larger, the grain boundaries became more obvious, as shown in Figs. 4 (a) and 4(b).
The number of these structures increased with time, and their growth was intertwined and overlapping.
Additionally, the number of particles in each rod-like structure also depended on the reaction time; it was diffusely molded between the particles, and joined together.
The morphology of the cross-section comprises columnar grains and the top surface is composed of grains that are almost equiaxed grains.

Additionally to the global stress determination, we propose a local grain by grain stress study.
Micro-stresses in electrolyte grains.
Measurements have been performed in ten grains of each sample.
Unfortunately, the low number of measurements does not allow statistical analysis and highlighting a systematical relationship between heterogeneity and grain orientation could not be achieved.
Further investigations with measurements on a large number of grains would allow a statistical analysis between stress and grain orientation.

Results and Discussion The main microstructural factors closely examined here are the grain size, solid volume fraction, tungsten-tungsten interfacial fraction (contiguity) and number of solid-solid contacts per tungsten grain (Connectivity).
The mean grain size slightly increases with the effective sintering time due to ostwald ripening.
The contiguity (the fraction of internal surface area of the phase shared with grains of the same phase in two phase alloys) and connectivity (the number of solid- solid contacts per grain) are the mean values for all grains.
It can be seen that the grain size, contiguity and connectivity is decreasing with wt% oxide impurity content.
Higher contents of oxide impurity reduced the tungsten grain size at the same sintering temperature and time.

However, the hexagonal lattice of magnesium and magnesium alloys is the reason behind the small number of slip systems, which make the cold deformation difficult or even impossible.
It consists of a large number of lath shaped grains with a length of 3 μm and a thickness of 0.4 μm, as well as very fine equiaxed grains with a diameter of 0.5 μm.
The smaller grains of deformed microstructure favor more uniform distribution of the grain size.
Hence, the number of ECAP passes had an influence on refining microstructure in the semi-solid state.
The grain growth in alloys at temperatures of the semi-solid range is caused by a number of phenomena including coalescence, coagulation as well as Ostwald ripening [2, 3].

Fig. 1 - TEM micrograph PM 1000 alloy in the as-received condition showing a large number of particles (bright field).
It allowed verifying the presence of tiny elongated grains within a [100]-oriented grain after annealing (Fig. 5a).
Conventional SEM cannot resolve these tiny grains.
Fig. 3 - Details of recrystallized grains in grain boundaries in a sample 44% deformed and further annealed at 1200 o C for 2 h (SEM, BSE).
Conclusions The recrystallization of the PM 1000 alloy occurs by nucleation and growth of large grains with size varying of 10 to 20 mm at prior grain boundaries and also by nucleation of tiny elongated grains located within most of the grains.

As illustrated in Fig. 2, the microstructure of AF, QF, GB, and DP exhibited irregular-shaped grains, and the EBSD analysis was applied to estimate corresponding effective grain size.
The effective grain was mainly composed of high-angle boundary.
There are general two methods to define effective grain size of microstructure.
The other one is equivalent diameter, which can be estimated by equivalent the irregular-shaped grain to circle, and the diameter of circle is regarded as effective grain size [11, 12].
The dimples and tearing rides involved in the fracture surface were typical features of ductile fracture, implying that large number of energy was consumed during fracture.

It makes an electromagnetic vibration box to feed grains and counts grains.
The equipment could identify and segment grains with slight color difference.
Therefore the number of kernels was obtained.
Classification of cereal grains using machine vision: IV.
Hardware-based image processing for high-speed inspection of grains.