Steel

 

(57) Abstract:

The invention can be used for the manufacture of parts operating under conditions of thermal Cycling loading. The proposed steel contains components in the following ratio (wt.%): carbon 0.5 to 1.5; silicon 0,4-0,8; manganese of 0.05-0.1; titanium 2,5-7,5; iron rest. The technical result of the invention is to improve razgromliali while maintaining a high level of mechanical properties and reduce the number of alloying elements. The tensile strength of steel isIN450 - 530 MPa,T320-390 MPa, ductility 10-20%, the impact strength of an1,0-2,3 KGM/cm2the number of cycles TCN 330-440. table 2.

The invention relates to the field of metallurgy, in particular to the compounds of tool steels, which can find application in the manufacture of parts operating under conditions of thermal Cycling loading (TCN).

Known tool steels, for example, die following composition [1], wt.%:

Carbon - 0,4-0,7

Manganese - 0,4-0,9

Silicon - 0,15-0,5

Chrome - 0,7-1,0

Molybdenum - 0,2-0,45

Nickel - 1,4-1,8

Vanadium - 0,08-0,2

Titanium - 0,005-0,01

Aluminum - 0,002-0,02

Cerium - 0,005-0,05

Niobium - 0,005-0,05

Manganese - 0,4-0,9

Silicon - 0,15-0,5

Chrome - 0,5-0,8

Molybdenum - 0,15-0,3

Nickel - 1,4-1,8

Vanadium - 0,05-0,5

Titanium - 0,04-0,1

Aluminum - 0,009-0.02

Cerium - -

Niobium - 0,005-0,1

Nitrogen - 0,009-0.02

Zirconia - 0,01-0,1

Iron - Rest

These steels have relatively high level properties such as strength at 400 - 600oC, toughness, razgromliali and heat.

However, these were mnogokomponentnye contain expensive scarce metals, they are not high-tech.

Most are similar in composition and technical essence is the steel [3], which contains, wt%:

Carbon - 0,25 - 0,50

Silicon - 0,20 - 0,50

Manganese - 0,2 - 3,0

At least one component from the group of elements that increase the hardness, in particular titanium - 0,3 - 10,0

Iron - Rest

The steel according to their mechanical properties mainly satisfies the requirements of steels subjected to dynamic loads in the conditions of abrasive wear. However, it does not meet the requirements for technological properties, heat resistance, moreover, the disadvantage of this steel is low resistance to cracking termedia eliminate these drawbacks, namely, the increase of the material's resistance to cracking thermomechanical fatigue under conditions of temperature and cyclic loading while improving the workability of the steel.

This task is solved in that the proposed steel containing carbon, silicon, manganese, titanium and iron has the following ratio of components, wt.%:

Carbon - 0,50 - 1,50

Silicon - 0,40 - 0,80

Manganese - 0,05 - 0,10

Titanium - 2,50 - 7,50

Iron - Rest

The specified content of the components and their relationship proved the following.

Titanium is introduced in a quantity providing a specific structure, namely fine-grained ferritic matrix with uniformly distributed therein dispersed carbides of titanium, and at a certain excess titanium intermetallic compounds of Fe2Ti. With this structure, the material of parts operating under conditions of cyclic changes of temperature, does not undergo structural transformations, there is no work hardening phase, which reduces the tendency of the material to cracking the TMA. Titanium is introduced based Ti = 4C+0,5-1,5 C.

Introduction titanium more than 7.5% when the ratio of the elements causes technologically all of the carbon in carbides of titanium, which leads to structural transformations in steels during thermal Cycling exposure.

Manganese reduces thermal conductivity of the steel and thereby adversely affect razgromliali material. Therefore, the upper limit of the manganese content is limited to 0.10%. The lower limit of the manganese content is determined by the minimum amount necessary to bind the residual sulfur in the sulfide manganese to avoid krasnopolski steel.

The silicon content 0,40 - 0,80% was made on the basis of experience in the manufacture of steels with high heat resistant properties.

The technical effect of application of the invention is to improve razgromliali while maintaining a high level of mechanical properties and reducing the number of alloying elements. Improved razgromliali ensured homogeneity of the matrix alloy, fine grain structure, the heat resistance and wear resistance are provided by the presence of uniformly distributed in the matrix of the carbides of titanium, Titanides iron and LEGIROVANNOGO ferrite.

Experienced steel melting was performed in an induction furnace with magnesite lining. As the charge materials used low-alloy article is 2">

Table 1 shows the chemical compositions of the experimental heats.

Table 2 shows the mechanical properties of the steels in the as-cast condition, as well as the characteristic that defines razgromliali steels, namely the number of cycles TCN to cracking the TMA critical value, defined on the set-up for testing of metals fatigue [4].

The typical mode of test steels to cracking the TMA and the wear of the dies semisolid forging was the following: the maximum voltage on the engraving stampIN= 1900 MPa, the maximum temperature on the engraving stamp Tn=953 K, the temperature gradient is not the surface of the stamp grad T = 275 K/mm, the length of the stamping = 3 c.

The list of information sources

1. USSR author's certificate N 1044663, C 22 C 38/50, 1983.

2. USSR author's certificate N 931791, C 22 C 38/50, 1982.

3. French Patent N 2180192, C 22 C 38/50, 1973.

4. USSR author's certificate N 313132, 1971.

Steel containing carbon, silicon, manganese, titanium and iron, characterized in that it contains components in the following ratio, wt.%:

Carbon - 0,50 - 1,50

Silicon - 0,40 - 0,80

Manganese - 0,05 - 0,10

Titanium - 2,50 - 7,50

Iron - Rest

 

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2 tbl, 1 ex

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