Tool steels are similar carbon and alloy steels withdifferent properties such as hardness, abrasion resistance, toughness andresistance to softening at high temperatures. Tin steels contain carbideforming elements such as chromium, molybdenum and tungsten in different combinations.
They also containcobalt or nickel, which improves high temperature performance. They are usually heat-treated to improve the hardness and usedfor stamping, forming, shearing and cutting metals and forming of plastics. Water-hardening, cold-work tool steels, shock-resisting, high-speed,hot-work, and special purpose/plastic mold tools steel are catagories of toolsteels.1.
Water-hardening groupW-group steel is actually high-carbon flat carbonsteel. This set of steel is the most used tool steel due to its low costcompared to other steel steels.2.
Cold-work groupCold-work group has three groups: oil-hardening,air-hardening, and high carbon-chromium. This steels group have highhardenability and wear resistance, with average toughness. Characteristicalthey are in the production of larger parts or parts that have a minimum flectionrequirement when being hardened.2.1. Oil-hardeningA very useful oil hardening steel is O1 steel. It is avery good cold work steel.Making very good knives and forks via oil hardeningsteel.
2.2. Air-hardeningAir hardening steels are qualified by low deformation during heat treatment thanks to their high chromium content. They have good machinability so wear resistance and stiffness balance. 3. Shock-resisting groupShock-resisting group has high shock resistance and good hardenability.
This groupdesigned to resist shock at both low and high temperatures. AlsoShock-resisting group has a very high impact toughness and relatively lowabrasion resistance.4. High speed groupT-type and M-type tool steels are used to cut tools in situations wherestrength and hardness must be maintained at high temperatures. Highspeed steel is a subset of tool steel and is often used on tool tips andcutting tools. It is usually used in electric saw blades and drill bits.
It canwithstand higher temperatures without losing its hardness. This feature allowsthe HSS to cut faster than the high carbon steel, so it is called high speedsteel. HSS grades have high hardness and abrasion resistance compared to carbonand tool alloys in general. 5. Hot-working groupHot working steels are a group of steels used to cut or shape the material at high temperatures.
H-group tool steels were developed for strength and stiffness during prolonged exposure to high temperatures. These tool steels are low carbon and medium to high alloyed and provide good hot stiffness and toughness and fair wear resistance due to the significant amount of carbide.6. Special purpose group /Plastic Mold Steel(P)Moldsteels are used to make molds for molding plastics and rubber.
(L)Low-alloy type toolsteels are usually reserved for Machine parts – Arbors, chucks, cams, andcollets and Special applications needing dependable strength and toughness. 1.8.SpecialtySteelsSpecial steels include a wide range of ferrous alloys with special handling properties that stand out in terms of corrosion resistance, abrasion resistance and toughness, high strength or magnetic properties. Maraging SteelsMaraging steels are low carbonalloys containing high amounts of nickel (15% to 25%) and lesser proportions ofcobalt, molybdenum, and titanium.
Chromium is also sometimes added forcorrosion resistance. They suitable heat treatment. Heat treatment results invery high strength together with good toughness. Tensile strengths of 2000 MPa and 10% elongation are not unusual.Applications include parts for missiles, machinery, dies, and other situationswhere these properties are required andjustify the high cost of the alloy.
Free-machining steelsThese steels have extremely low carbon levels (0.005% C),which result from the use of alloying elements such as niobium and titaniumthat combine with C and leave the steel virtually free of interstitial atoms.The result is excellent ductility, even greater than low-C steels. Applicationsinclude deep-drawing operations in the automotive industry.