Today, high speed steel continues to be the leading material for the production of a variety of metalworking nozzles and cutting tools. Such alloys are often used in the manufacture of machine saws, drills and drill bits. Despite the large variety of various carbide composite and ceramic materials that have now appeared, providing even greater processing performance, high-speed tool steels firmly hold their positions.
The wide use of such alloys for the production of complex-profile cutting tools is due to the combination of high strength (up to 68 HRC) and heat resistance (they do not lose their working properties even at a temperature of 650 ° C) with a high viscosity value, significantly exceeding the similar indicator forcarbide composite materials. In addition, high speed steel has an extremely high workability, which means good workability in the way of pressure and cutting.
What properties such an alloy will have depends on alloying additions. Usually high speed steel is a multi-component system containing chromium, molybdenum, tungsten, cob alt and vanadium. The presence of various components, as well as their percentage content, is indicated when labeling. The letter P here means that the steel is high-speed, the subsequent figure indicates the percentage of tungsten. Further letters indicate the presence of other alloying elements, and the numbers following the letters indicate their percentage mass fraction in the alloy. So, the letter M means the presence of molybdenum in the system, F - vanadium, K - cob alt, A - nitrogen.
According to the content of alloying additives, high speed steel can be classified into tungsten, molybdenum, tungsten-molybdenum. Metals alloyed with cob alt stand out in a special group. Such alloys, as a rule, are used in the manufacture of tools for machining hard-to-machine parts from heat-resistant alloys. High-speed steel alloyed with vanadium is mainly intended for the production of so-called "finishing" tools - broaches, reamers and others.
The most common and, perhaps, the oldest brand of high-speed steel P18 is used for the manufacture of complex and shaped thread-cutting tools. Means of a standard form for high-quality metal processing are made mainly of an alloy of grade P9. Milling cutters, cutters and the like are made from it.
According to the operating temperature regime, high-speed steels are divided into three categories: alloys with normal, high and high heat resistance. The first group includes tungsten (P18, P9) and tungsten-molybdenum (P6M5). Such grades are used in the processing of non-ferrous metals, structural steels and cast iron.
The materials of the second category are characterized by an extremely high content of cob alt, carbon and vanadium. The most popular brand in this group is R6M5F3. Vanadium steels are characterized by increased wear resistance. Their only serious drawback is their poor grindability, since the hardness of vanadium carbides is not inferior to that of an electrocorundum grinding wheel.
And finally, steels of the third category are characterized by a low percentage of carbon content, which makes them suitable for processing heat-resistant, stainless and titanium alloys. Another characteristic distinguishing feature is a large number of alloying elements. This group includes such brands as 3V20K20Kh4F, V11M7K23 and others.
