When the tool is working, it has to withstand a lot of pressure and impact. At the same time, due to the plastic deformation of the metal during cutting and the strong friction between the contact surfaces of the tool, chip, and workpiece, the cutting edge of the tool generates high temperature and is subject to great stress. Therefore, as tool material, it should have the following characteristics:
1. High hardness. The tool material must have a hardness higher than that of the material to be processed. The normal temperature hardness of the tool material is generally above 62HRC.
2. High wear resistance is the ability of the tool to resist wear. It is a comprehensive reflection of the mechanical properties, organizational structure and chemical properties of tool materials.
3. Sufficient strength and toughness In order to withstand great pressure, as well as shock and vibration, the tool material should have sufficient strength and toughness. General strength is expressed by bending strength, and toughness is expressed by impact value.
4. High heat resistance refers to the performance of tool materials to maintain hardness, wear resistance, strength, and toughness at high temperatures.
5. Good thermal physical properties and thermal shock resistance The ability of the tool material to resist thermal shock can be expressed by the thermal shock coefficient.
6. Good manufacturability This refers to forging performance, heat treatment performance, high-temperature plastic deformation performance, and grinding performance.
7. Economy Economy is one of the important indicators of tool materials.
According to GB/T13304.1-2008 "Steel Classification Part 1: Classification by Chemical Composition". High-speed tool steel belongs to alloy steel. According to GB/T13304.2-2008 "Steel Classification Part 2: Classification by Main Quality Grade and Main Performance of Service Characteristics", high-speed tool steel belongs to special quality alloy steel.
High-speed tool steel is high-carbon alloy steel, the main alloying elements are tungsten, chromium, molybdenum, vanadium, etc., containing a large number of carbides. These carbides make high-speed tool steels have high thermal hardness and wear resistance. High-speed tool steels can maintain good cutting performance at higher temperatures (not greater than 600°C) and are used to manufacture high-efficiency cutting tools, such as milling cutters, Reamers, broaches, gear shapers, and drills are also used in iron-cooled molds, high-temperature springs, and high-temperature bearings, etc., and are a kind of tool material that is widely used.