What is going on with the polycrystals of the metal plate of the lock forming machine?


The polycrystalline of the metal plate of the lock forming machine means that the whole metal material contains many small crystals, each of which has a basically consistent lattic position, and each small crystal has different positions from one another. This crystal structure, consisting of many small crystals, is called a multicrystal structure, in which each small crystal with an irregular shape is called a grain, and the interface between the grain and the grain is the crystal boundary. Because the crystal boundary is the transition layer of different lattic bits between two adjacent grains, the arrangement of atoms on the crystal boundary is always irregular.

Multicrystalline structures can’t measure an anthogonal heteroglycity like single crystals because a large number of tiny fine particles have different orientations and can only show the average performance of these grains in each direction.

In multicrystal structure, the general grain size is small, such as steel material grain size is generally 10 negative three square to 10 negative square millimeters, must be magnified through a microscope dozens or even hundreds of times more to observe. The stereomorphism of these small crystals cannot be directly observed under a microscope, but only the flat shape of the grain intercepted on the surface of the metal sample to be studied. By looking at the fine grinding and polishing of the surface of the sample, a smooth and clean surface with no abrasive marks is obtained, and then the surface side of the sample is corroded with a corrosion agent. Because the crystal boundary of grain is easily corroded into a groove, it shows a dark crystal boundary under the microscope, and the grain interior is relatively bright, the metal material organization determines the performance of the metal material. Experiments and theories have confirmed that the thinner the grain of the metal, the higher the strength and hardness of the metal material at room temperature. The better the plastic parts and toughness.