RU1788074C - High-speed steel - Google Patents

Abstract

The invention relates to metallurgy, in particular to cast high speed steel. In order to increase the impact strength, durability and heat resistance, the steel additionally contains barium, magnesium, calcium in the following ratio of components, wt.%: Carbon 0.81-0.89; chrome 3.7-4.3; tungsten 5.1-6.2; molybdenum 4.7-5.6; vanadium diy 1.72-2.05; silicon 0.3-6.7; manganese 0.1-0.4; nickel 0.1-0.4; titanium 0.02-0.08; barium 0.002-0.08; calcium 0.004-0.06; magnesium 0.003-0.04; iron is the rest. 3 tab.

Description

The invention relates to tool production and can be used in machine shops of industrial enterprises.

Known steel R6M5K5 (GOST 19265-73), the following composition, wt.%:

Carbon 0.80-0.88 Chromium 3.8-4.3 Tungsten 6.0-7.0. Molybdenum 4.8-5.8 Vanadium 1.7-2.2 Silicon 0.4. Manganese 0.4 Cobalt 4.8-5.3 Nickel 0.4 Iron Else This steel belongs to the group of steels with increased heat resistance. Due to the presence of such an element as cobalt in its composition, it has high hardness and heat resistance, which makes it possible to use it for processing high-strength steels and alloys. However, due to the increased brittleness, the use of

P6M5K5 steel is limited, especially for the manufacture of cast tools.

Known high-speed steel P6M5 (GOST 19265-73), containing the following elements, wt.%:

Carbon. 0.80-0.88 Chromium 3.8-4.4 Tungsten 5.5-6.5 Molybdenum 5.0-5.5 Vanadium 1.7-2.1 Silicon 0.4 Manganese 0.4 Nickel 0, 4 Iron Else This steel does not contain cobalt, which contributes to embrittlement, and is most widely used in the deformed state for the manufacture of cutting tools for various purposes. However, in the cast state, even this steel, due to its poor impact strength, can only be used to make tools that are operated under conditions of minimal dynamic impacts.

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Also known is high-speed steel, having a higher impact strength in the viscosity and containing the following elements, as%:.

Carbon 0.85-0.88 Chromium 3.5-4.2 Tungsten 5.0-6.0 Molybdenum. 5.0-5.3 Vanadium 1.6-2.0 Silicon. . 0.2-0.3 Manganese:, /:: 0.3-0.4 Nickel: - 0.2-0.4 Titanium. . 0.05-0.15 Bismuth.-..- 0.002-0.005. ; Iron The rest of this steel, due to the presence of titanium and bismuth in its core, has relatively high values of impact strength. The disadvantage of this steel is reduced heat resistance and low cutting properties. which does not make it possible to use it for that tool that processes high-strength steels and alloys. ; ..

. The aim of the invention is to increase the heat resistance and cutting properties of cast high speed steel while maintaining a high level of toughness to increase the operational reliability of the cast metal cutting tool and expand the scope of its application.

This goal is achieved in that the steel containing carbon, chromium, tungsten, molybdenum, vanadium, silicon, manganese, nickel, phosphorus, sulfur, iron, titanium, additionally contains barium, calcium, magnesium rfpvi in the wake (total ratio of components, wt.% : Carbon 0.81-0.89 Chromium 3.7-4.3 Tungsten 5.1-6.2 Molybdenum 4.7-5.6 Vanadium. 1.72-2.05 Silicon 0.3-0.7 Manganese 0.1-0.4 Nickel 0.1-0.4 Titanium 0.02-0.08 Barium 0.002-0.08 Calcium 0.004-0.06 Magnesium 0.003-0.04 Iron Else Titanium present in the article contributes grinding of grains of a solid raster due to the formation of refractory carb rows and titanium carbonitrides, which are separated from the first liquid in the process of crystallization centers and provide additional crystals formed. The barium and magnesium are strong surface-active elements are arranged on

the crystal-liquid boundary formed and interfere with the growth of solid solution crystals and primary carbides. Calcium is a universal modifying element, i.e. exerts both inoculant and surface-active effects on the crystallization process. Magnesium is distributed over the grain boundaries in the structure of cast steel.

0 Calcium is present both on the grain boundaries and inside them, Barium, calcium and magnesium have a strong refining effect on steel, reducing the number of non-metallic inclusions and their

5 transfer to a stable globular form. The presence of titanium carbides (carbonitrides) helps to increase the wear resistance of steel. The same effect, but due to the lubricating effects, have a combination of

0. Barium, calcium and magnesium. With the combined introduction of barium, calcium, magnesium, and titanium, the alloying of the solid solution of steel increases (Table 1), which contributes to a significant improvement in the heat resistance and

5 cutting properties of the tool.

  h L r and me r. . Steel was smelted in an acid-lined induction electric furnace. Deoxidation was carried out with ferromanganese, ferrosilicon, and aluminum. The necessary alloying elements were introduced into the furnace before casting in the form of ferroalloys, barium in the form of ferrobary, magnesium and calcium in the form of ligatures ZhKMK-5 were introduced directly. Into the ladle under

5 stream of metal. Steel was poured into sandy liquid glass forms. After knocking out, the castings were subjected to isothermal annealing and then samples were cut from them to study properties. Data samples

0 heat treatment was carried out according to the following regime: quenching heating temperature of 1220 ° С, cooling in a salt bath at 600 ° С, then in air. Vacation at a temperature of 560 ° C three times in one hour. 065 sorts of base steel (P6M5) and prototype steel were subjected to similar heat treatment.

The chemical composition and research results of samples of the proposed and known steels are presented in Table 2.3.

Heat resistance was determined by measuring hardness (HRC) after additional heating at 620 ° C for 4 hours.

Impact toughness was determined on samples without an incision of 10x10x55 mm in size on a die head with an impact energy of 50 kJ.

Durable tests of the tool from the known and proposed steels were carried out during milling (oncoming) the ledge under the following processing conditions: cutting speed 50 m / min; feed 0.21 mm / tooth.

Studies have shown that the proposed steel surpasses the known steel (prototype) in resistance by 1.3-1.6 times, heat resistance with almost equal impact strength.

Claims (1)

The claims High speed steel containing carbon, chromium, tungsten, molybdenum, vanadium, silicon, manganese, nickel, titanium, iron, characterized in that, in order to increase the toughness, durability and heat resistance, it additionally contains barium, magnesium and calcium with the following ratio of components, wt.%: 0 5 Carbon Chromium Tungsten Molybdenum Vanadium Silicon Manganese Nickel Titanium Barium Calcium Magnesium Iron 0.81-0.89 3.7-4.3 5.1-6.2 4.7-5.6 1.72-2.05 0.3-0.7 0.1-0.4 0.1-0.4 0.02-0.08 0.002-0.08 0.004-0.06 0.003-0.04 Rest Table 1 The chemical composition of the solid solution of the studied steels Steel , and the proposed steel The content of alloying Elentoent, md T a b l Part 2 ---. - .- .. JriEIDZin Proposed - --- --- J ---- L- --J ---- ---- I L. T a b l Part 2 0.002 0.0040.003 0.010 01ost O, 0.020.009; 0.02 O. oiost 0.08 0.060.04 0.030 03ost 0.001 0.0020.001 0.010 01ost 0.11 0.090.08 0.03 O. ozost 0.02 - 0.02 ost. 0.03 0.02 ost. . Properties of famous and proposed steels Table 3