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Viewing the development of metallurgical technology in China from the zhangxiaoquan incident

Author:Luo Haiwen source:China Science Daily

A few days ago, a consumer said that when he patted garlic with a kitchen knife that he had just bought, the kitchen knife broke. Subsequently, the company made an apology and compensated for the knife.

Zhang Xiaoquan knife enterprise said in a statement:”Zhang Xiaoquan’s conventional knives can shoot garlic. At the same time, the company also kindly reminded consumers that not all knives are suitable for shooting garlic, and some knives with high hardness or special purpose are at risk of breaking if used for shooting garlic.”

Can the knife be used to pat garlic? In fact, kitchen knives with both sharpness and toughness are not uncommon in the market. Many Chinese kitchen knives can be used to shoot garlic while ensuring sharpness. This is not a difficult technology.

The reason for knife brittleness is that the toughness is low. Metal materials have a common feature – when the strength goes up, the toughness will become worse. How to improve the strength of cutting tools while ensuring that the toughness will not deteriorate has been a subject pursued by craftsmen and researchers for thousands of years.

The famous swords in ancient China – moye sword and Gan Jiang sword. It is said that the sword was sacrificed to strangers in exchange for the invincibility of the sword. Such a sad and beautiful legend obviously cannot be explained scientifically.

The high-quality knives in ancient China have been forged by craftsmen and produced tough quality. Zhejiang Longquan has retained this forging technology so far. In ancient times, artisans added hard steel and soft steel together. Hard steel was placed on the blade and soft steel was placed on the back of the knife. It was not easy to cut the knife on the battlefield, not to mention hitting garlic with a knife in the kitchen.

The swords and knives used for fighting in ancient China were spread to Japan around the Tang Dynasty. Based on this, the Japanese continuously improved and made Japanese Dao. By the Ming Dynasty, its metallurgical quality had exceeded that of Chinese Dao and Jian.

However, this ancient manual forging technology is obviously too inefficient to meet the needs of mass production. Therefore, our kitchen knives and scissors are produced by modern metallurgical industrial technology, which originated from the industrial production technology developed in the west after the European industrial revolution.

Sharpness and durability are two quantifiable test standards for knives and shears in industrial production at present. In these two indicators, the quality of knives and scissors in China still lags behind international brands whose prices are more than 10 times.

How to achieve sharpness and durability? From the principle of material science, it is necessary to improve the hardness and strength of steel for knives and shears. The higher the hardness of steel, the sharper the grinding edge is, and the wear resistance is good, so the durability is also improved. The most effective way to improve the hardness and wear resistance of steel is to increase the carbon content, which brings the negative effect that the steel is easy to become brittle and poor toughness. Enterprises that can achieve extremely high hardness to maintain sharpness and durability, while ensuring constant knife cutting in the case of similar garlic patting, are technologically advanced enterprises.

Since modern times, the early kitchen knives in China used industrial carbon steel, which was cheap and easy to obtain, but it was often blunt. It needed to be honed repeatedly on the grindstone to ensure sharpness, which also gave birth to a”knife sharpener” career walking through the streets.

However, knives made of carbon steel are easy to rust in use, resulting in food contamination, so the West has long used stainless steel as knives. Among kitchen knives of international famous brands, the higher the carbon content of stainless steel, the higher the grade of the knife. With the increase of carbon content, the difficulty of metallurgy, casting, rolling and heat treatment of this high carbon and high alloy stainless steel has increased a lot. If the relevant technology is not qualified, large-size particles such as carbides and inclusions will be formed, which will significantly deteriorate the metallurgical quality and mechanical properties of the knife. In other words, there is a certain technical threshold for the industrial production of high carbon and high alloy steel.

Then, why does our kitchen knife not reach the technical level of foreign brands? In fact, the kitchen knife industry is only a small market for the steel industry. China produces half of the world’s steel every year, with a quantity of more than 1 billion tons, but the quantity used in the kitchen knife industry is only a fraction. Therefore, large steel enterprises with strong technical force do not pay attention to this market, which is one of the important reasons why China’s kitchen knife industry cannot develop. It should be reminded that although the kitchen knife is a small market, compared with the market demand of foreign countries, China is undoubtedly a big market.

More importantly, China’s tool production is still trapped in the thinking of”winning by large quantity”. As everyone knows, the market has passed the era of emphasizing quantity and neglecting quality. One of the important reasons why it is difficult to establish the reputation of Chinese cutting tool brands is the lack of technology research and development strength, which has been imitating and not surpassing. Domestic knife and shear enterprises learn from foreign technology through various channels, improve their own technology, and then produce and sell in a short and fast way. Most of them follow the old way of occupying the market by quantity.

For example, according to media reports, the sales cost of Zhang Xiaoquan knife company involved in this case exceeded the R & D cost by as much as five times in 2021, and the OEM production output was higher than the independent production output.

It is the difficulty of tool smelting and preparation to ensure the corrosion resistance and toughness of the kitchen knife while improving the hardness and sharpness. In particular, how to avoid large-scale carbides and other inclusions during casting and how to improve the metallurgical quality of steel require relevant enterprises to transform their products from mass homogeneous products to high value-added products based on technology. A modern industrial product cannot be supported only by its origin and history.

Foreign kitchen knives have developed towards higher goals. They are not satisfied with the serviceability of kitchen knives, but also emphasize artistry and appreciation, such as carving their own names, logos or drawing patterns on the knives, which are placed in the kitchen like a pleasing art.

Customization is not a modern technology. As early as the 10th to 12th centuries A.D., the Damascus knife of the Arab Samurai fascinated the whole west because of the sharpness of cutting silk. At the same time, the surface of the steel knife was covered with patterns, which seemed to be flowing and beautiful. Modern Damascus knives are a wonderful combination of manual forging and powder metallurgy.

The truth of development is the same. The key lies in whether the knife maker is willing to change his thinking and make himself a higher level.

(the author is a professor at the school of metallurgy and ecological engineering, Beijing University of science and technology,Chinese ScienceNewspaper reporter Wen caifei interviews and collates)