SU1186689A1 - Steel - Google Patents

Abstract

STEEL containing carbon, manganese, silicon, chromium, vanadium, iron, characterized in that, in order to increase hardenability and heat resistance, it additionally contains niobium, aluminum, calcium in the following ratio of components,% by mass: 0.46-0 59 Carbon 0.82-1.20 Manganese 0.42-0.90 Silicon 1.20-1.80 Chromium 0.22-0.60 Vanadium 0.03-0.10 Niobium 0.005-0.01 Aluminum 0.005 -0.01 Calcium (L Rest Iron

Description

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o The invention relates to metal, in particular steel for the manufacture of a tool for hot deformation (blades for cutting steel, punches), which should have a sufficiently high level of hardness at a predetermined depth from the working surface, which is maintained during operation during periodic heating, what is provided by the properties of the steel; high hardenability and heat resistance (resistance to softening during heating). The purpose of the invention is to increase the hardenability and heat resistance of steel. The carbon content of the proposed steel increases its manufacturability during hot deformation (high ductility characteristics in the forging process, reducing the tendency to hot cracks) Lower limit carbon content (0.46%) provides the necessary level of hardenability, top (0559%) - satisfactory workability with hot deformation. It also improves the processability of steel under hot deformation. The lower limit of silicon content (0.42%) is associated with the achievement of the required resistance of softening (heat resistance) with an average tempering. The upper limit (0.90%) is determined by a decrease in the processability of steel under hot conditions. pressure treatment, the proposed content of manganese and chromium makes it possible to increase the hardenability of steel. The lower limit of the concentration range for manganese (0.8%) and chromium (1.2%) is due to the effectiveness of their effect on the hardenability. x n boundary concentration interval of manganese (1.20%) allows to achieve the optimum amount of residual austenite at Kalka and reduce Flakes. The upper limit of the concentration range for chromium (1.8%) is also associated with a possible increase in flotation sensitivity, in addition, an important factor is the difficulty in smelting steel with an increased content of chromium in open-hearth furnaces. 92 Complex doping with vanadium in an amount of 0.22-0.60% in combination with niobium microadditives with selected carbon content gives steel a fundamentally new property — the ability to disperse hardening, as a result of which the heat resistance of steel is significantly increased. In addition, the complex doping with vanadium and niobium, on the one hand, and aluminum and calcium, on the other, has a modifying effect, contributing to the grinding of grain. This leads to an increase in the ductility and toughness of the steel and, consequently, in its operating characteristics. In addition, the addition of niobium, which is an active hydride forming element, helps to reduce the flocation sensitivity of steel. The lower concentration limits for vanadium (0.22%) and niobium (0.03%) provide the necessary degree of manifestation of the effect of dispersion hardening, as well as the modifying effect (in combination with other modifiers - aluminum and calcium). Upper bounds (respectively, 0.60% and 0.10%) prevent the reduction of processability in the forging process, as well as the plastic and viscous characteristics of the steel in the finished product due to the heterogeneity of the distribution of carbides in the structure, as well as due to the decrease in the dispersity of carbide particles and the difficulty of their dissolution in austenite when heated for quenching. The lower limit of niobium content (0.03%) is due to the manifestation of its inhibitory effect on austenitic grain growth upon heating after dissolving most of the vanadium in austenite, and the upper need to retain the ability of NbC carbide particles to effectively inhibit grain growth. The lower (0.05%) and upper (0.01%) limits of the concentration range of aluminum are determined by the effectiveness of its modifying effect. Chemical compositions of known and proposed steels are given in table. 1 Ingots weighing 30 kg are forged on blanks from which they are made

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specimens for determination of heat resistance and hardenability by the Nemchinsky method (face hardening). The heating temperature for quenching for the proposed steel, treated for secondary hardness, is 1025 ° C, and for known, treated for primary hardness, 860 ° C. The duration of hardening at austenitization temperature is 1 hour.

In determining the hardenability, the cooling of the samples was carried out in a stream of air. Heat resistance esca66894

after vacationing for 6 hours on the same samples.

The results of the comparative tests on hardenability 5 and resistance to softening during tempering of the investigated steels are given in table. 2, from which it follows that the proposed steel has advantages in comparison with the known.

The economic effect is achieved by increasing the durability of the tool made from the steel offered.

Table 1

Melting 1 and 5 - steel with the content of the proposed composition. components beyond

table 2

Claims (1)

STEEL containing carbon, manganese, silicon, chromium, vanadium, iron, characterized in that, in order to increase hardenability and heat resistance, it additionally contains niobium, aluminum, calcium in the following ratio, wt.%: Carbon 0.46-0.59 Manganese 0.32-1.20 Silicon 0.42-0.90 Chromium 1.20-1.80 Vanadium 0.22-0.60 Niobium 0.03-0.10 Aluminum 0.005-0.01 Calcium 0.005-0.01 Iron Rest 1 1186689