How did the ancients carburize when they hit iron?

Carburizing is to increase the carbon content of steel products, we now usually put the carbon content of about 0.3-0.6% called medium carbon steel, above to 2% or so are high carbon steel, and then high is pig iron, down to 0.1% is low carbon steel, and then go down to wrought iron. The higher the carbon content of steel, the harder it is. In ancient times, surface carburizing was usually used to improve the hardness of steel products. In addition to carburizing, quenching is also an important technology to improve hardness, generally after carburizing.

How was the continent carburized in ancient times?

We can know from the ancient method of smelting and forging operations passed down from ancient times and from Places such as Japan, and there are at least two main categories.

One is carburizing during smelting. For example, the ancient smelting method that Japanese swordsmiths have been using to this day is actually a more primitive technology that uses charcoal fuel to smoulder to obtain sponge iron. Since the temperature of charcoal can only reach about 1200 degrees at most, this smelting usually involves covering the charcoal on the ore and burning it continuously for several days. Combustion will make the steel lose carbon, but the means of covering charcoal for smouldering makes some unburned carbon monoxide react and eventually become a carburizing process, partially supplementing the carbon content. But also because of this smelting method, the finished composition of the 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. So blacksmiths would smash the finished sponge iron open, and then use experience to pick out the parts with similar carbon content and classify them for different purposes. This is one of the most primitive and common smelting carburizing techniques.

Another type is carburizing during the forging process after smelting the finished steel. There are more means in this process, and the very interesting things I said also appear at this stage.

One of the means is to carburize the product solidly. For example, when japanese knives are manufactured, when steel is folded and forged, paper and grass and wood ash and mud are wrapped around the workpiece for forging, which is a carburizing method. Paper grass and wood ash are all infiltration agents, and mud is a dispersant, which prevents uneven cementation of carbon infiltration and helps precipitate carbon black.

The needle making method recorded in the Mainland Ming Dynasty's "Tiangong Kaiwu" is also solid carburizing, but compared with the carburizing technology in the Japanese knife manufacturing process, this is a very (gao) high (da) end (shang) external heating box carburizing technology, and the height of the technology tree is not the same.

This technique is to shape the workpiece, put it into a crucible and other containers, and then cover it with charcoal, tempeh, and minced soil, and heat it on the outside of the container. Charcoal and tempeh are naturally carburized, 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 technology is still used in modern times, which is the so-called "stewing steel method".

In addition, there are some methods that are the same as the carburizing technology in the Japanese sword forging process, but the materials used are different. For example, in the Ming Dynasty's "Little Knowledge of Physics", it is said that the workpiece should be smeared with large sauce and nitrate, and then heat treatment should be carried out - do not underestimate this difference, just this little bit is different, and the nature of things will change.

The material of the sauce and tempeh is the same, but the nitrate is nitrogen-containing, so this carburizing technology is the carbonitriding technology, and the sauce and nitrate are the co-permeation medium - God (hu) Qi (you) bar, using charcoal tempeh mud is a technology, a change to sauce and nitrate into another principle are different technologies.

In addition, carburizing is carried out with grease, animal horns and hairy nails, as well as natural ash, which is sodium carbonate (which is a good hypnotic agent), etc. In fact, this technology is still in a large number of applications, generally with oil and carbon black and other materials made of paste to apply the workpiece, and then carburizing, called paste carburizing.

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 divine weapons, especially those famous swords, went, right? That's it.

"Wu Yue Chunqiu" records the process of making the famous sword "Gan general" in ancient times on the mainland. From this record, it can be known that because the "essence of gold and iron" cannot be "sold", he will put in hair and nails, and then let people put a lot of charcoal, and finally the "essence of gold and iron" will dissolve into a sword. This is actually a relatively primitive liquid carburizing technology.

In the era when bronze was prevalent, a steel sword appeared, of course, a sword without a doubt, and it is not a legend to cut that bronze like mud. But the problem is that steel is too easy to corrode, and if you are not careful, you will rot into slag. Judging from the records of the gan generals, I think that the vast majority of famous swords in ancient China, especially in the Spring and Autumn Warring States to the Western Han Dynasty, were only famous for a while because they were steel tools, but it was precisely because they were steel tools that they were quickly eroded by the river of time and completely disappeared - this is the fundamental reason why the famous swords such as the gan general Mo Evil Pure Jun Zhan Lu and so on have not been seen in the future generations.

Then there is the famous steel filling method. This technique is to use pig iron as a carburizing agent, carburize wrought iron, and obtain a suitable carbon content of steel. Therefore, this technology is to prepare wrought iron first, and then dissolve the pig iron and pour it onto the wrought iron workpiece for carburizing. This technique is well documented in mainland literature, such as the Tiangong Kaiwu.

The technique of the famous knife maker Qi Wuhuaiwen during the Southern and Northern Dynasties was also a carburizing technique. The "History of the North" records this: "He also made an iron knife, and his method of burning pig iron essence was heavy and soft, and the number of su was chenggang." With soft iron as the ridge of the knife, bathing with the drowning of the five animals, quenching with the fat of the five animals, and cutting the armor for thirty years. Judging from the sentence "Burning pig iron is refined with heavy soft hammer, and counting is just", this is still the use of pig iron as a carburizing agent, and it is likely that he finally created some kind of patterned steel product.

In addition to carburizing technology, it is the continuous understanding and innovation of catalytic media by the ancients.

For example, the dry general uses hair nails, and the Ming Dynasty literature records use a large number of cattle and sheep horns and their ashes, grease, natural ash, as well as skin ash, green salt, sand and so on, are all of this kind. These things, animal hair and the like are nitrogen-containing, nitrogen can reduce the critical temperature of steel, increase hardenability, and improve the carburizing speed and surface hardness of the workpiece, which is a very important carburizing medium. These evolutions are all a branch of carburizing technology, that is, carbonitriding technology.

Here I would like to remind everyone that the "2022 National Nitriding and Carburizing Heat Treatment Symposium" co-sponsored by the China Heat Treatment Industry Association and the Machinery Industry Information Research Institute will be held in Jiaxing, Zhejiang In July, in order to more fully promote technical exchanges and enrich the content of the activities, the conference collects relevant papers from the whole industry, and produces the collection of papers as conference materials, and at the same time holds the "Husen Cup" excellent paper evaluation activity, welcome all engineering and technical personnel, teachers and students of universities and research institutes to actively submit papers.

01

Thesis content

The content of the paper should pay attention to practicality and innovation, strengthen the exploration, use and promotion of new technologies and new processes, and can combine the research direction to express the research results and experimental process; it can also be combined with the actual application and example of production to explain the situation of its service production. The content of this call for papers is based on chemical heat treatment, which involves high-temperature chemical heat treatment (carburizing, carbonitriding, boronizing, metal seeping, etc.), low-temperature chemical heat treatment (nitriding, nitrocarburizing, sulfur permeation, zinc permeation, etc.), multi-co-osmosis and composite treatment processes.

Specific essay topics (including but not limited to):

New technology and new process of chemical heat treatment

Application examples of chemical heat treatment techniques in various industries

Gas carburizing process

Solids, liquids and other carburizing processes

Gas nitriding process

Ion nitriding process

Vacuum nitriding process, etc

Carbonitriding process and its application

Nitrocarburizing process and its application

Seepage metal and other chemical heat treatment processes

Study of multiple co-osmosis

Quality control of carburizing or nitriding

Comparison of chemical heat treatment technology with other surface technologies

Research, design, use and maintenance of chemical heat treatment equipment

02

Dissertation requirements

Send a word attachment to your email address ([email protected]) and leave your phone and other contact information. The author should keep the manuscript of the paper, the review experts and editors have the right to text process the paper and make necessary deletions and corrections, and the paper will not be returned to the manuscript whether it is selected or not. The paper submission deadline is June 15, 2022.

Paper Format:

1. Thesis requirements: Chinese topic, author, work unit, Chinese abstract (about 200 words), keywords (3-5 quotations), the article includes the body and references.

The arguments of the candidate papers are clear, the arguments are reliable, the text is fluent, and the diagrams are clear, generally about 3,000 words.

2. Reference format: arranged in the order in which it appears in the text, the document serial number is represented in the text by the number in square brackets in the upper right corner, and the writing format is as follows:

numbering. Author (first name listed). Thesis Title[J]. Title, Year of Publication, Volume Number (Issue Number): Start-End Page Number

numbering. Author (first name listed). Book Title[M]. Edition, place of publication: publishing unit, year of publication: start-end page number

3. Figure (table): The picture (table) in the text is arranged in the body, the picture must be clear, can not be compressed, the original picture needs to be packaged and submitted together, and the table should not be truncated into a picture.

03

Publication methods and awards

(1) Conduct excellent paper selection, select several excellent papers, and issue certificates to the award-winning authors at the "2022 National Nitriding and Carburizing Heat Treatment Forum".

(2) Excellent papers can be presented at the "2022 National Nitriding and Carburizing Heat Treatment Forum".

(3) Particularly excellent papers, published in the journal Metalworking (Thermal Processing).

For details of the paper submission, please contact:

Source: New Materials Think Tank, China Metallurgical Finishing

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