The Collaborative International Dictionary
Tool steel \Tool steel\ Hard steel, usually crucible steel, capable of being tempered so as to be suitable for tools.
WordNet
n. alloy steel that is suitable for making tools; is hard a tough and can retain a cutting edge
Wikipedia
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 and deformation and their ability to hold a cutting edge at elevated temperatures. As a result, tool steels are suited for their use in the shaping of other materials.
With a carbon content between 0.5% and 1.5%, tool steels are manufactured under carefully controlled conditions to produce the required quality. The presence of carbides in their matrix plays the dominant role in the qualities of tool steel. The four major alloying elements in tool steel that form carbides are: tungsten, chromium, vanadium and molybdenum. The rate of dissolution of the different carbides into the austenite form of the iron determines the high temperature performance of steel (slower is better, making for a heat resistant steel). Proper heat treatment of these steels is important for adequate performance. The manganese content is often kept low to minimize the possibility of cracking during water quenching.
There are six groups of tool steels: water-hardening, cold-work, shock-resisting, high-speed, hot-work, and special purpose. The choice of group to select depends on cost, working temperature, required surface hardness, strength, shock resistance, and toughness requirements. The more severe the service condition (higher temperature, abrasiveness, corrosiveness, loading), the higher the alloy content and consequent amount of carbides required for the tool steel.
Tool steels are used for cutting, pressing, extruding, and coining of metals and other materials. Their use, such as the production of injection molds, is essential, due to their resistance to abrasion, which is an important criterion for a mold that will be used to produce hundreds of thousands of moldings of a product or part.
The AISI- SAE grades of tool steel is the most common scale used to identify various grades of tool steel. Individual alloys within a grade are given a number; for example: A2, O1, etc.
Usage examples of "tool steel".
It's graphitic tool steel, hardened to sixty-five on the Rockwell `C' scale.
They were invisible to X-ray, having the same density as the enamel of my teeth-but were as hard as tool steel.
Three of the weakened breeches failed, flinging fragments of jagged tool steel across the corridor and shredding two of the Molts who'd been crippled by the initial blast.
What we're really short of is tool steel for drills and working edges, and stuff like Teflon lagging tape, hacksaw blades, files, sandpaper….
Zinc, tool steel for machinists, bluestone, sulfuric acid, magnet coils, brass for keys and sounders, springs, insulators, poles, creosote, and battery jars each have their own chains, or in some cases webs of need.