Carbon steel for cutting tools, molds and gauges. Compared with alloy tool steel, it has good processability, low price and wide application range, so it is used in the production of tools. Carbon tool steel is divided into carbon cutting tool steel, carbon mold steel and carbon measuring steel. Carbon cutting tool steel refers to carbon tool steel used for making cutting tools, carbon mold steel refers to carbon tool steel used for making cold and hot working molds, and carbon measuring steel refers to carbon tool steel used for making measuring tools. . Such steels are generally delivered in an annealed condition and may be delivered without annealing according to the requirements of the purchaser. The hardness, fracture structure, reticulated carbide, pearlite structure, sample quenching hardness, hardenability depth and decarburization depth of the steel surface of the annealed steel shall comply with the Chinese national standard GB1298. When there are reticulated carbides and lamellar pearlites in such steels, quenching deformation, cracking and uneven hardness are likely to occur, and the wear resistance of the cutting tools is lowered, which is liable to cause edge cutting of the cutting tools and reduce the life of the cutting tools. In order to prevent the formation of reticulated carbides, the steel is repeatedly forged and cooled quickly after forging. The cementite in the lamellar pearlite can be spheroidized by spheroidizing annealing. Such steel quenching heating generally uses a salt bath furnace to prevent or reduce the decarburization of the surface of the tool. At the time of quenching and cooling, care should be taken to prevent deformation and cracking. For this purpose, graded quenching or austempering is generally used, and some are subjected to induction hardening. After quenching, it should be tempered in time to prevent deformation or cracking during parking.

Carbon tool steel has low production cost and convenient raw material source; it is easy to be cold and hot processed, and can obtain relatively high hardness after heat treatment; it has good wear resistance even when work is not heated, so it is widely used. Among them, the high-quality carbon tool steel has high toughness and can obtain a high degree of smoothness during grinding, and is suitable for manufacturing tools with complicated shapes and high precision. However, such steels have poor red hardness, and the hardness and wear resistance rapidly decrease after the operating temperature exceeds 250 °C. This kind of steel has low hardenability, and when the tool section size is larger than 15 mm, only the surface layer has high hardness after water quenching, so it is impossible to make a large-sized tool. This kind of steel has a narrow quenching temperature range, is easy to overheat, has a large distortion during quenching, a tendency to crack, and is easy to produce soft spots. Compared to alloy tool steels, such steels have low hardenability, a diameter of 15 mm in water hardening, and a diameter of only 5 mm in oil. In addition, the steel has low heat hardness, and the hardness and wear resistance of the steel drop sharply when the working temperature is higher than 250 ° C, so that the cutting ability of the steel is remarkably lowered, so the steel is only suitable for making small size, simple shape, and cutting. A tool with low speed, small feed, and low operating temperature.