This is because the weld solidification crystallization

 As can be

seen from the figure, the organization of the butt weld all thick cylindrical ferrite. This is because the weld solidification crystallization is the process of nucleation and grew up, due to the

characteristics of laser welding heat fast cooling fast, bath center and the edge there is a big temperature gradient, leading to columnar grains in the weld development. The higher the temperature rise, the faster the temperature drops, which makes the heat affected zone, but the higher the

frequency the more small.
The hardness of the impact on the performance of tailor welded blanks (1) analysis can be seen from Figure 3.9, the overall hardness greater than the hardness of the base metal laser welding of

welded joints. This is because in the welding process, the melting of the weld metal carbonitride precipitates in the ferrite and cementite of punctate, in the subsequent cooling process, so the

weld hardness greater than any one of the base metal hardness. Large hardness variation the M170P side of the heat-affected zone hardness increased rapidly, there are much higher than the maximum

hardness of the weld and parent material near the weld position; downward trend in the DC06-side heat-affected zone from the weld to the parent material, and much lower than the M170P side of the

heat affected zone; DC06 side of the heat affected zone width is greater than the width of the the M170P side heat-affected zone. This kind of battery is one of the most commonly used Li batteries

among all batteries used by the electronic equipments including green laser pointer .
This is due to the in the M170P side of the heat-affected zone in the heating, the original solid solution precipitates in the ferrite C, N, Ti and other elements, in the subsequent cooling in the

carbonitride near the weld region gathered in the ferrite collective formation of organizations such as bainite and martensite, which makes the high hardness in the region. DC06-side heat-affected

zone, the organization of the base metal ferrite content of alloying elements, especially the lack of pinning the grain boundary carbides, austenite grain boundaries when the heating is growing up,

the heat diffusion in the crystal faster in the subsequent cooling process of the formation of ferrite microstructure thick, the width of the heat-affected zone than M170P side, so DC06 side of the

heat affected zone hardness than the hardness of the weld. That is the reason why this kind of battery of green laser pointer is called Li battery.