Manufacturer of precision lathe in Xiamen, China
Carburizing is to increase the carbon content of steel products. Now we usually call medium carbon steel with a carbon content of about 0.3-0.6%. The top to 2% is high carbon steel, and the higher is pig iron, and the bottom is 0.1% It’s low carbon steel, and then it’s wrought iron. The higher the carbon content of the steel, the harder it is. In ancient times, surface carburizing was usually adopted to improve the hardness of steel products. In addition to carburizing, quenching is also an important technique to improve hardness, which is generally carried out after carburizing. Manufacturer of precision lathe in Xiamen, China
How was carburizing in ancient my country?
We can know at least two categories from the ancient smelting and forging operations passed down from ancient times and from Japan and other places.
One is carburizing during smelting. For example, the ancient smelting method that Japanese swordsmiths have been using to this day is actually a relatively primitive technology of using charcoal fuel to smolder to obtain sponge iron. Since the temperature of charcoal can only reach about 1200 degrees at most, this kind of smelting usually involves covering the ore with charcoal and burning it for several days. Combustion will decarbonize the steel, but the method of covering with charcoal for smoldering makes some unburned carbon monoxide react and eventually become a carburizing process, partially supplementing the carbon content. However, due to this smelting method, the composition of the finished sponge iron obtained is very complex, and there are many harmful impurities, and the carbon content of each part is of course even more different. Therefore, the blacksmiths will smash the finished sponge iron apart, and then pick out the parts with similar carbon content by experience and classify them for different purposes. This is one of the most primitive and common smelting carburizing techniques. Manufacturer of precision lathe in Xiamen, China
Another type is carburizing during the forging process after the finished steel is obtained by smelting. There are more means in this process, and the very interesting things I mentioned also appear at this stage.
One of the means is to perform solid carburizing on the product. For example, when Japanese knives are manufactured, when folding and forging steel, the workpiece will be wrapped with paper, plant ash and mud for forging, which is a carburizing method. Paper, grass and wood ash are both infiltrators, and mud is a dispersant, which can prevent the carbon infiltrate from sticking unevenly and help the precipitation of carbon black. Manufacturer of precision lathe in Xiamen, China
The needle making method recorded in the “Tian Gong Kai Wu” in the Ming Dynasty in my country is also solid carburizing, but compared with the carburizing technology in the manufacturing process of Japanese knives, this is a very (gao) high (da) end (shang) outside. Thermal box carburizing technology, the height of the technology tree is incomparable.
This technique is to shape the workpiece, put it into a container such as a crucible, and then cover it with charcoal, tempeh, and soil, and heat it outside the container. Charcoal and tempeh are naturally used for carburizing, and the soil is still a dispersant. The advantage of this carburizing technology is that the carburizing of the workpiece is very uniform and stable, and the carbon potential is very high, and the efficiency and effect are quite good. In fact, this technique is still used in modern times, which is the so-called “steel stew method”. Manufacturer of precision lathe in Xiamen, China
In addition, there are some practices that are the same as the carburizing technology in the forging process of Japanese knives, but the materials used are different. For example, in the “Little Knowledge of Physics” in the Ming Dynasty, it was said that the workpiece should be smeared with miso and nitrile, and then heat-treated – don’t underestimate this difference, the nature of the matter has changed with this little difference.
Doenjang and tempeh are made of the same material, but nitrate contains nitrogen, so this carburizing technology is carbonitriding technology. Doenjang and nitric acid are co-infiltration media – God (hu) odd (you), Using charcoal fermented fermented soybean paste is a technique, but once it is replaced with miso and salt, it becomes another technique with different principles. Manufacturer of precision lathe in Xiamen, China
In addition, carburizing is carried out with grease, animal horns and hair nails, and natural ash, that is, sodium carbonate (which is a good infiltration agent). In fact, this technology is still widely used now. Generally, the workpiece is smeared with a paste made of materials such as engine oil and carbon black, and then carburized, which is called paste carburization.
One of the means is solid carburizing, then the second is naturally liquid carburizing.
I think there must be a lot of people who want to know where those ancient magic weapons, especially those famous swords, have gone? That’s to say. Manufacturer of precision lathe in Xiamen, China
“Wuyue Spring and Autumn” records the process of making the famous ancient Chinese sword “goer”. From this record, it can be known that because the “Essence of Gold and Iron” could not be “sold”, the cadres put in hair and nails, and then people put in a lot of charcoal, and finally the “Essence of Gold and Iron” melted into a sword. This is actually a relatively primitive liquid carburizing technology.
In the age of bronze wares, a steel sword appeared. Of course, it was a precious sword. It is not a legend to cut the bronze like mud. But the problem is that the steel is too easy to corrode, and it will rot into slag if you are not careful. Judging from the records of the cadres, I think most of the famous swords in ancient China, especially the Spring and Autumn Period and the Warring States Period to the Western Han Dynasty, were the most famous swords because they were steel tools. The erosion of the river has completely disappeared – this is the fundamental reason why the masters such as Mo Xie Chunjun Zhanlu and other peerless famous swords have disappeared. Manufacturer of precision lathe in Xiamen, China
Then there is the famous steel pouring method. This technology uses pig iron as a carburizing agent to carburize wrought iron to obtain steel with a suitable carbon content. Therefore, in this technology, wrought iron is prepared first, and then the pig iron is melted and poured onto the wrought iron workpiece for carburizing. This kind of technology is well documented in Chinese literature, such as “Heavenly Creation”.
Qi Wuhuai, a famous swordsman in the Northern and Southern Dynasties, used the technique of making Su iron swords as a carburizing technique. The record in the “Northern History” is as follows: “Another iron sword was built, and the method of burning pig iron to make a soft collar, and a few nights made it rigid. Using soft iron as the ridge of the knife, bathed with five animals, quenched with five animals. The fat is more than 30 pieces of armor.” Judging from the sentence “burning pig iron to make a soft collar, a few nights will become rigid”, this is still using pig iron as a carburizing agent, and it is very likely that what he finally created is Some kind of patterned steel product. Manufacturer of precision lathe in Xiamen, China
In addition to carburizing technology, it is the ancients’ continuous understanding and innovation of catalytic media.
For example, the hair and nails used by generals, and the extensive use of cattle and sheep horns and their ashes, grease, natural ash, as well as ash, green salt, sand, etc. These things, such as animal hair, all contain nitrogen. Nitrogen can reduce the critical temperature of steel, increase the hardenability, and increase the carburizing speed and surface hardness of the workpiece. It is a very important carburizing medium. These evolutions are a branch of carburizing technology, that is, carbonitriding technology. Manufacturer of precision lathe in Xiamen, China
