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The garlic was not broken, and the kitchen knife was broken. The news has been fermenting recently. Yesterday, our intuitive machine reader, Mr. “How Can I Eat Tutu?” suggested that the editor make another topic on kitchen knives. I re-read the comments of the readers a few days ago, and everyone’s comments are basically in place, and basically this topic is almost the same. China supplier high demand Factory price metal elbow
From the perspective of manufacturing process, materials and heat treatment, today we will re-examine the problem of kitchen knife breakage by citing the viewpoints of two professionals, one is a knife maker from the “Craftsman’s Workshop”, a knife maker who makes knives, and the other is a tooling mold. Expert Zhao Buqing senior engineer. Next, let’s focus on the “Story of Garlic and Kitchen Knife” again based on the public views of these two experts.
@Craftsman’s Workshop Little Knife Craftsman:
From a purely technical point of view, the kitchen knife is just a piece of garlic, why does it break? In physics, there is a term called toughness, which refers to the resistance of a material to breaking when it is subjected to a force that causes it to deform. A knife, the higher its toughness, the less likely it is to break or chip. Hardness and toughness are the two most important indicators of tool performance. Hardness determines the sharpness and retention of a knife. The toughness determines whether the knife is easy to break or collapse. We often use “blow hair and break hair, cut iron like mud” to describe a sword or a sword. In fact, these eight characters describe two completely different properties of swords. China supplier high demand Factory price metal elbow
Dry hair breakage mainly depends on the hardness of the knife. Cutting iron like mud depends mainly on its toughness. However, good luck, hardness and toughness are a pair of natural mutually exclusive contradictions. The higher the carbon content of the steel, the higher the hardness, but the lower the toughness. The lower the toughness, the more brittle the blade is and the easier it is to break.
In order to solve the contradiction between hardness and toughness, the ancients invented the method of clamping steel, sandwiching high-carbon steel with high hardness as a blade. At this time, the performance of the blade can fully meet the needs of cutting. Then use low-carbon steel with low hardness but good toughness on both sides to clamp the steel core in the middle to avoid breakage when the blade is stressed. This is what we often say “good steel is used on the edge of the knife”. China supplier high demand Factory price metal elbow
On the basis of the clip steel method, the ancients invented the embedded steel method. The shape of the knife is made of low carbon steel with better toughness, and then a groove is opened at the edge of the blade, and the high carbon steel is embedded in the groove. The embarrassing thing is that Zhang Xiaoquan, the protagonist of this broken knife incident, just became famous for his steel embedding technology. At the end of the Ming Dynasty, Zhang Xiaoquan’s exquisite steel-embedded scissors were already well-known both at home and abroad.
To solve the contradiction between hardness and toughness, in addition to the clamping method and the steel embedding method, there is also the famous soil-covered burning blade, also called local quenching. Coat the knife with mud first, leaving the blade part uncoated and exposed. Then put the knife on the fire to heat it up. After reaching a certain temperature, it is quickly pulled out and quenched in water. At this time, the blade without soil will cool down rapidly, while the temperature of the blade with soil will drop relatively slowly, and the final result is that the hardness of the blade is higher than that of the blade. This not only satisfies the hardness of the blade part, but also obtains the overall toughness. Since the rise of the Sui and Tang Dynasties, the technique of covering the earth and burning the blade has spread to Japan and has been used by Japanese knives to this day.
How to forge Japanese swords
Earth-covered Burning Blade
More famous than the earth-covered burning blade, there is also folding and forging patterned steel, which is what Westerners call forging-shaped Damascus knives, known as the ceiling of the knife world. The high carbon steel and low carbon steel are stacked together, heated to the point of softening but not melted, taken out from the furnace, and repeatedly forged, so that the high carbon steel and the low carbon steel are welded together. Heat again, then fold and continue forging. After many times of folding and forging, a composite steel with overlapping high carbon steel and low carbon steel is obtained. China supplier high demand Factory price metal elbow
Fold and forge
Such steel has excellent hardness and toughness, and there will be microscopic serrations on the cutting edge that are imperceptible to the naked eye. Due to the difference in reflectivity between high carbon steel and low carbon steel, the surface of this steel will show a winding pattern, so it is also called pattern steel.
The modern metallurgical industry can also solve the balance between hardness and toughness through some high-tech. For example, powder metallurgy technology, or adding specific trace elements, but these super steels are relatively expensive and are generally not used to make cheap kitchen knives.
Powder metallurgy technology process
In order to save costs, tool manufacturers rarely use the steel clipping method, the relatively complicated process of inserting steel, covering the soil and burning the blade, and folding and forging, and they are reluctant to use high-tech powder steel. In this case, you can only make the knife thicker, or sacrifice sharpness and use lower hardness steel. However, the competition in the knife industry is fierce, and sharpness is the most easily identified performance when people choose knives. How can the merchants let the sharpness be reduced? So what about increasing the thickness of the knife? On the one hand, it will increase the cost. On the other hand, customers want the tool to be lightweight, and if it is made too heavy, it will also affect the sales. China supplier high demand Factory price metal elbow
So, in order to pursue sharpness, very hard steel is used to make very light knives, and there is a joke that kitchen knives cannot shoot garlic.
Maybe one day, we will get used to special knives, and we will gradually accept that kitchen knives cannot shoot garlic. I am even surprised that people in the past can use the same kitchen knife to cut vegetables and chop garlic. It is incredible…
This may sound like a joke, but in fact, it is a very serious and even a bit sad topic. In the era of industrial civilization we live in, companies pursue short-term, fast-paced, low-cost, high-profit, and mass-produced products. The craftsman spirit of doing things well in the past is farther and farther away from our lives. Things like the fact that kitchen knives can’t shoot garlic has been or is happening in many industries and fields, which deserves our deep consideration.
@Zhao Buqing, a tooling and mould expert:
From the perspective of fracture shape, it belongs to brittle cracking, overall quenching, and all-steel. To comprehensively analyze the cause of cracking, material testing and metallographic analysis of steel should be done. China supplier high demand Factory price metal elbow
- Kitchen knife material
Most domestic knives are made of high carbon steel such as 60 steel and 65 steel. The hardness requires 55~61HRC. If the hardness is low, it is easy to roll the knife. If the hardness is high, it is easy to break the knife and drop the block, but it will not be split in half. The metallographic structure is tempered martensite, and the level of martensite is less than or equal to 3 is qualified. The world famous brand of kitchen knives – Japan’s Guanzhen kitchen knife is made of 7Cr15 steel with a hardness of 56~61HRC. The kitchen knife is beautiful, corrosion-resistant, sharp and durable.
There are also domestic manufacturers using 4Cr13 steel. Although the hardness is as high as 60HRC, although the hardness is as high as 60HRC, the user’s response is not sharp.
Some people also use 50BA steel knives with a hardness of 56~60HRC, which are very easy to use.
- Analysis of the reasons for the breakage of kitchen knives
1) Poor raw materials: The raw materials of kitchen knives should be strictly inspected when they enter the factory, and they can only be put into storage if they meet the national standards. China supplier high demand Factory price metal elbow
2) The materials used are particular: from the point of view of use, it is hoped to use composite steel, that is, high carbon steel for the blade, and ordinary steel for the back of the knife body (that is, good steel is used on the knife). Although this manufacturing process is complicated, the kitchen knife is durable.
3) The manufacturing process, especially the heat treatment process, is the key: from the surface of the broken kitchen knife, it is an all-steel knife, that is, the whole is of the same material, and should be partially quenched or quenched by induction heating. 40~45mm is enough.
If the whole is quenched, the hardness of the parts that do not need to be hardened should be reduced to below 30HRC.
4) Negligible heat treatment: Is the heating temperature too high, whether the martensite is coarse, whether the hardness exceeds the standard, and whether tempering is forgotten? Has the heat treatment process been pickled? These are all unknowns, and cracking is inevitable. China supplier high demand Factory price metal elbow
5) The problem of people: People are the first element of productivity. The good miracles in the world are created by people, and all the bad things are also done by people. The kitchen knife is cracked. On the surface, it is a problem with the knife. In essence, it is a human fault. It reflects the technical level, management level, and personnel quality of the enterprise. As long as people use it well, all other problems will be solved easily.
- Some suggestions
1) A kitchen knife has aroused heated discussion among Chinese people, which shows that everyone cares about and loves famous brands, and sincerely hopes that the factory will think deeply. Creating a brand is not easy, but maintaining a brand is even more difficult. We must continue to reform and innovate to make the road of branding wider and wider.
2) Quality is the life of an enterprise. An enterprise that does not pay attention to quality will withdraw from the market sooner or later. If it wants to gain a share in the competition, it must aim at the international advanced level and move forward step by step towards the goal.
3) Pay attention to people’s livelihood and benefit the people. In addition to kitchen knives, there are also scissors, sickles, axes, screwdrivers, hammers, etc. Although they are all small workpieces, they are related to thousands of households and must be done carefully. China supplier high demand Factory price metal elbow
At this point, the public views of the two industry professionals have been shared. @Craftsman’s Workshop 小刀smith shared the traditional craftsmanship of making knives and how to solve the contradiction between hardness and toughness, and called for the quality of products to not be ignored because of reducing manufacturing costs, and the spirit of craftsmanship should be paid attention to. Zhao Buqing, an expert in tooling and moulding, shared the heat treatment technology and material selection of kitchen knives, and analyzed several factors that may cause kitchen knives to break. Because there is no material composition and metallographic phase, Zhao Gong can only make judgments based on experience, but Zhao Gong The workers called on enterprises to pay attention to product quality and brand, and make products from the needs of users. China supplier high demand Factory price metal elbow
