Diamond is called alloy steel with a high carbon content, which is particularly hard. Comparing it to a gem is simply a beautiful expression. In terms of hardness, this steel is significantly inferior to diamond. It has not only a figurative poetic name, but also a technical one. The most common brand is designated by the abbreviation XB5, which stands for chrome-tungsten. In some ways, diamond steel is superior to any other grades. It is widely used in industry for cutting softer metals. Because of the scope of its most frequent use, this steel is called tool steel. It was invented many centuries ago, but the modern process of obtaining it is different from the old one.
General characteristics
The properties of diamond steel are due to its chemical composition. The combination of iron and carbon creates exceptional hardness. Chromium and tungsten are also added to popular modern brands to give added resistance to corrosion and high temperatures. The optimal content is 1% carbon in the alloy. An increase in its share in the composition of steel negatively affects the quality of products, since the viscosity and ductility of the material decrease with increasing hardness. A metal with a relatively high carbon content becomes brittle. Diamond steel blades and tools have excellent cutting properties, but can easily break. The hardness of the XB5 alloy blades is 60-65 HRC on the Rockwell scale, which is the maximum indicator. The limit value of this parameter for any blades in this measurement system does not exceed 65 units.
Additional items
A modern alloy contains about 1% chromium, which makes it unaffected by rust. But the amount of this component is limited because it reduces the strength of the material. For comparison: the alloy is considered completely stainless with a content of at least 18% chromium. The composition of diamond steel XB5 also includes tungsten. This is an exceptionally refractory and dense metal with unique properties. In addition to heat resistance, tungsten is resistant to acids and other aggressive substances. It improves the cutting properties of steel and protects it from wear. The XB5 alloy contains 4-5% tungsten.
Tamahagane
The history of the invention of diamond steel is rooted in medieval Japan. In the era of samurai, this metal was known as tamahagane. Translated from Japanese, this means "precious steel." It was from her that the legendary samurai swords were forged . Many myths about ancient Japanese edged weapons have survived, testifying to their belonging to the military estate. One of the legends tells that to check the quality of the sword, it was vertically thrust into the bottom of the stream and a sheet of paper was let down. The blade was supposed to cut it in half.
Ore mining
The process of obtaining and processing tamahagane was surrounded by mystery. Only the blacksmiths knew all the secrets of steelmaking and passed on their art to the heirs. The ore from which tamahagane was mined was found next to river beds in the form of black iron sand. It was a decay product of natural deposits. A laborious sand enrichment process was required since it contained only about 1% iron. The rock was washed with water in the channels. Iron particles settled at the bottom and were held up by special barriers.
Smelting process
For the production of steel , a large number of workers were needed. The process of obtaining tamahagane occurred in traditional Japanese melting furnaces. A feature of the technology was that they were built of clay and were intended for single use. After the smelting was completed, the walls had to be destroyed to extract the finished metal. Several blacksmith's assistants, by burning charcoal and fanning the flame, brought the temperature in the furnace to 1200-1500 o C. After this, a phased loading of enriched iron sand began. The entire smelting process took three days. To get the right amount of carbon, the weight of charcoal burned had to be almost twice the weight of iron sand.
Sorting
As a result of one smelting, usually received about two tons of steel. An impressive block of metal was formed in the furnace, and the clay walls were destroyed to extract it. But the ingot was heterogeneous in carbon content. It was necessary to break it into pieces and choose the most suitable for quality. About a third of the material received usually went into marriage. In Japan, there are still a number of overly massive steel blocks that could not be broken up for sorting. They serve as original monuments to the traditional art of smelting metals.
Modern methods
In today's Japan, tamahagane steel production continues. The modern production process differs from the old one in that at the stage of ore dressing, iron particles are separated from the rock using a magnet. This method is used instead of the time-consuming washing of sand with water in the channels. The era of samurai swords is long over, but kitchen knives made of diamond steel made in Japan are in demand in the world market.
Features of the XB5 alloy
Modern smelting technologies are significantly superior in efficiency to the old methods. Enriched ore is cleaned of slag using lime. The molten iron is removed from the furnace and placed in a centrifuge to improve its structure. The characteristics of XB5 diamond steel are improved by adding other metals, mainly tungsten, to it. Its exceptional refractoriness requires heating the furnace to a temperature of 3000 ° C. The addition of this component increases the wear resistance of the XB5 alloy.
Operational advantages
The main characteristic of diamond steel is its hardness. Blades and other products from this alloy can do without sharpening for a long time. They have excellent cutting properties and are able to not only process softer metals, but also remove fine chips from them. Chrome in the composition of the XB5 alloy protects it from corrosion. But products from this grade of steel are not completely stainless and can only withstand a small amount of exposure to a humid environment.
disadvantages
The high hardness of the material makes it brittle. For example, a diamond cannot be scratched, but easily cracked. The disadvantages of diamond steel XB5 are a consequence of its hardness. Blades made of this alloy require careful handling, as nicks may appear on the cutting edge. This problem is typical for any grade of high-carbon tool steel. Sometimes products from a similar material break when falling to the floor. Attempts to find the optimum ratio of hardness and brittleness led to the invention of alloys with a low carbon content. An example is the Japanese-made steel grade H1. Only 0.15% carbon is present in its composition. The disadvantages of XB5 diamond steel also include its high cost.
Souvenir knives
Blades and tools from this alloy have many fields of application. Often there are souvenir and collection knives made of diamond steel XB5. Such products are usually decorated with engraving of the author's work, and their handles are made of precious wood. Sometimes on the surface of the blade in a natural way, fancy patterns form, which increase the aesthetic value of the product. The reason for this phenomenon is the uneven distribution of carbon in steel.
Camping knives
XB5 alloy blades are used in hunting and fishing. Thanks to their excellent cutting qualities, they allow quick butchering of prey. But reviews of diamond steel from hunters and fishers do not inspire much optimism. Fragile blades require extremely careful handling. They can easily get damaged and become unusable. In marching conditions, unreliable knives pose serious problems if they fail their owners at the wrong time. In addition, rust resistance of chromium tungsten steel leaves much to be desired. Blades made of this material are more suitable for use at home.
Handling and storage
If a knife made of chrome-tungsten steel is not used for a long time, its blade should be lubricated with animal fat. It is not recommended to store the product in a sheath. In case of rust, it is necessary to process the blade with sandpaper. After use, it is advisable to wipe the knife dry and grease it with grease. Caution should be exercised when the blade contacts hard surfaces such as bone, stone, and metal. The blade may crumble from strong pressure or impact. Fragility is an inevitable disadvantage of tungsten steel. But it is worth taking into account that the technology of hardening the blade varies among different manufacturers, so the quality of the products is not the same.