Chinese tool steel grades are steels used to make cutting tools, gauges, molds and wear tools. Tool steels have high hardness, and high hardness and red hardness at high temperatures, as well as high wear resistance and proper toughness.
According to different chemical compositions, Chinese tool steel grades is often divided into 3 categories:
- carbon tool steel,
- alloy tool steel, and
- high speed steel (high alloy tool steel).
According to the use of steel, it can be divided into three categories:
- cutting tool steel,
- die steel
- and measuring steel.
Carbon Tool Steel (Non-alloy)
Compared with alloy tool steel, carbon tool steel 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 steel, carbon mold steel and carbon measuring steel.
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 GB/T 1298.
The carbon content of Chinese carbon tool steel ranges from 0.65% to 1.35%. There are 8 grades of carbon tool steel in China National Standard GB/T 1298-2008. Among them, T7 tool steel with low carbon content has good toughness, but its wear resistance is not high. It is suitable for cutting tools for cutting soft materials and tools for impact load, such as woodworking tools, boring tools, chisels and hammers.
T8 tool steel has good toughness and high hardness, and is suitable for making punches, scissors, and woodworking tools.
T8Mn tool steel with high manganese content has good hardenability, and is suitable for making woodworking tools with large fractures, chisel for coal mines, masonry chisel and hand saw blades with less deformation, and horizontal trowels.
T10 tool steel has good wear resistance and wide application range. It is suitable for making metal cutting tools with poor cutting conditions and high wear resistance, as well as cold stamping dies and measuring tools such as turning tools, planing knives, milling cutters and boring tools. Silk plate, wire drawing die, engraved chisel, caliper and plug gauge.
T12 tool steel has high hardness and good wear resistance, but its toughness is low. It can be used to make cutting tools and measuring tools with high hardness and good wear resistance, such as scraper, drill bit, reamer and reaming drill, taps, dies and micrometers.
T13 tool steel is the steel with the highest carbon content in carbon tool steel. Its hardness is very high, but its toughness is low. It can not withstand impact load. It is only suitable for cutting tools for cutting high hardness materials and tools for processing hard rock, such as boring tools and engraving. Knives, wire drawing dies, engraving tools, etc.
Alloy Tool Steel
Alloy tool steel is a kind of steel grade that adds alloying elements such as chromium, molybdenum, tungsten and vanadium to carbon tool steel to improve hardenability, toughness, wear resistance and heat resistance. It is widely used in cutting tools, cold and hot deformation molds and measuring tools. It can also be used to make pistons, valves, valve seats and fuel valve nozzles for diesel fuel pumps.
Alloy tool steel has higher hardenability, hardenability, wear resistance and toughness than carbon tool steel. It can be roughly classified into three types: cutting tools, molds and measuring tools. Among them, steel with high carbon content (carbon mass fraction greater than 0.80%) is mostly used in the manufacture of cutting tools, measuring tools and cold working molds. The hardness of such steels after quenching is above HRC60 and has sufficient wear resistance; steel with medium carbon content ( The carbon mass fraction of 0.35%-0.70% is mostly used to make hot working molds. The hardness of these steels after quenching is slightly lower, HRC50-55, but the toughness is good.
High Speed Tool Steel (High Alloy)
High-speed tool steel is high-carbon high-alloyed Leysite steel with tungsten, molybdenum, chromium, vanadium and sometimes cobalt as the main alloying elements. It is usually used as a high-speed cutting tool, referred to as high-speed steel.
Because of its high red hardness, good wear resistance and high strength, it is also used to manufacture molds, rolls, high temperature bearings and high temperature springs with high performance requirements. The hardness of high-speed tool steel after heat treatment can reach above HRC63, and it can maintain high hardness at working temperature of about 600 °C, and its toughness, wear resistance and heat resistance are good.
High speed steel can be divided into the following types according to the containing alloying elements:
- Tungsten high speed steel (W 9 – 18%),
- Tungsten-molybdenum high-speed steel (W 5 – 12%, Mo 2 – 6%),
- High molybdenum high speed steel ( W 0 to 2%, Mo 5 to 10%).
- Each line can be divided into general vanadium content (V 1-2%) and high vanadium content (V 2.5-5%) according to the amount of vanadium.
- Any high-speed steel such as cobalt (Co 5 to 10%) is classified as cobalt high-speed steel.