What are the advantages and disadvantages of Japanese knife clamping steel covering soil and burning edge?

The advantages and disadvantages of these two processes are as follows:

Japanese knives pay attention to the high hardness of the blade, which is beneficial to cutting. The hardness of the knife body needs to be slightly lower to ensure a certain toughness, avoid breaking and absorb the stress after cutting. Therefore, Japanese knives burn their blades with soil, and the blade body except the blade is coated with special soil, and only the blade is quenched to achieve the balance between hard blade and soft blade.

Burning edge refers to quenching in metal heat treatment. The arbor is heated to a certain temperature at a high temperature and cooled rapidly in water or oil, which makes the iron molecules in the metal rearrange more closely and increases the hardness of the metal.

Several kinds of raw materials needed in the process of covering soil and burning edge;

Formula: clay+borax+iron powder+carbon powder (the ratio is 1: 1), and charcoal with the same carbon powder content.

It is recommended to use rusty iron for iron powder, which can be ground by a grinder and then sucked by a magnet; Native soil; Borax is a kind of sodium borate sandstone and mudstone powder, which is not the leading role in blade firing, and its proportion should be appropriately reduced.

In fact, borax is also very useful in modern gas welding.

Simply put, it is to wrap the knife tire with soil to expose the blade, and then start the quenching process. Only Japanese knives can cover the soil and burn the blade. But it also depends on the way the knife is made. Japanese knives with steel clips don't need to be covered with soil to burn. The ultimate goal of burning the blade by covering the soil is to make the hardness of the blade different from that of the body. Because the process of clamping steel has made the hardness of the blade and the blade body different, there is no need to cover the soil and burn the blade.

Gu Jian, which can be seen frequently in China, is hardened because it is mostly steel clips, so it does not need to be covered with soil, just like Japanese steel clips.

Changing the hardness of the burning edge is useful for steel, but not for iron, so there is no good knife maker to make all-iron burning edge knives.

Quenching: steel will change its crystallization mode due to the increase of temperature. When the temperature reaches 727 ~ 9 1 1 degree (depending on the carbon content), it will become a martensite crystal. At this time, the hot red steel will be put into water or oil, and the crystal will be fixed due to instantaneous cooling, which is called quenching. Martensite crystal is hard and brittle, and its volume is larger than before.

The water quenching speed is the fastest and the hardness is higher.

The oil quenching speed is slow and the hardness is low.

The speed of air quenching is relatively slow and the hardness obtained is relatively low.

Each has its own advantages and disadvantages, and the most suitable heat treatment method is selected according to different steels and different expected results.