Tool steel refers to a variety of carbon and alloy steels that are particularly well-suited to be made into tools. Their suitability comes from their distinctive hardness, resistance to abrasion, their ability to hold a cutting edge, and/or their resistance to deformation at elevated temperatures (red-hardness). Tool steel are generally used in a heat-treated state.
With a carbon content between 0.7% and 1.4%, tool steels are manufactured under carefully controlled conditions to produce the required quality. The manganese content is often kept low to minimize the possibility of cracking during water quenching.
*High speed steel
T-grade and M-grade tool steels are used for cutting tools where strength and hardness must be retained at temperatures up to or exceeding 760 °C (1,400 °F). M-grade tool steels were developed to reduce the amount of tungsten and chromium required.
T1 (also known as 18-4-1) is a common T-grade alloy. Its composition is 0.7% carbon, 18% tungsten, 4% chromium, and 1% vanadium. M2 is a common M-grade alloy.