RU2406779C1 - Carbonic silicon containing laminated spring steel for railroad fasteners - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: steel contains carbon, silicon, manganese, sulphur, phosphorus, chromium, nickel, copper, aluminium, calcium and iron at following ratio of components, wt %: carbon 0.37 - to less, than 0.4, manganese 0.50-0.80, silicon 1.50-1.80, phosphorus not more, than 0.030, sulphur not more, than 0.030, chromium not more, than 0.30, nickel not more, than 0.30, copper not more, than 0.30, aluminium 0.005-0.05, calcium 0.0001-0.005, iron - the rest. Size of actual grain in microstructure of steel is 6-8 number.

EFFECT: steel possesses required levels of hardness, plasticity and structure.

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Description

The invention relates to the metallurgy of steel, namely to spring-spring steel, and can be used in the manufacture of rolled products for the manufacture of railway fasteners.

Steels with a high silicon content have increased strength characteristics and elastic limit, are quite stable against grain growth, which allows them to be used under high loads (for example, for the manufacture of springs and washers of machines and mechanisms used in the hardened and tempered state). Features of steels are described, for example, in the reference book of V.N. Zhuravlev and O.N. Nikolayeva "Engineering Steel", ed. 3rd, M .: Mechanical Engineering, 1981, p. 153-155.

Steel is known (see SU No. 2203341, class C22C 38/42, publ. 04/27/2003), which contains carbon, silicon, manganese, sulfur, phosphorus, chromium, nickel, copper, aluminum, iron and is characterized by the content of these components in ratio, wt.%:

Carbon 0.35 ... 0.45 Manganese 0.65 ... 0.90 Silicon 1.50 ... 1.70 Phosphorus No more than 0,030 Sulfur No more than 0,030 Chromium No more than 0.30 Nickel No more than 0.30 Copper No more than 0.30 Aluminum No more than 0,030 Iron Rest

Known steel does not guarantee the required ductility while maintaining hardness, which affects the consumer properties of the steel.

The prior art (see JP 2003-105485 A, C22C 38/58, 04/09/2003, abstract, formula) is known carbon-silicon steel containing carbon, manganese, silicon, phosphorus, sulfur, chromium, nickel, copper, aluminum, calcium and iron in the following ratio of components, wt.%:

Carbon 0.4 ... 0.9 Manganese 0,1 ... 2,0 Silicon 0.5 ... 3.0 Phosphorus ≤0.02 Sulfur ≤0.02 Chromium 0.05 ... 3.0 Nickel 0.05 ... 5.0 Copper 0.05 ... 2.0 Aluminum 0.005 ... 0.1 Calcium 0.0001 ... 0.01 Iron Rest

The disadvantage of this steel is a significant chemical heterogeneity in the content of carbon, manganese and silicon due to segregation, which necessitates an increase in hardening temperatures and leads to significant fluctuations in hardenability.

The expected technical result is the production of round rolled products for the manufacture of railroad fasteners, corresponding to the required level of hardness, ductility, structure.

To solve this problem, carbon silicon-containing spring-spring steel for railway fasteners, containing carbon, manganese, silicon, phosphorus, sulfur, chromium, nickel, copper, aluminum, calcium and iron, differs in that it contains components in the following ratio, wt. %:

Carbon 0.37 to less than 0.4 Manganese 0.50 ... 0.80 Silicon 1.50 ... 1.80 Phosphorus No more than 0,030 Sulfur No more than 0,030 Chromium No more than 0.30 Nickel No more than 0.30 Copper No more than 0.30 Aluminum 0.005 ... 0.05 Calcium 0.0001 ... 0.005 Iron Rest

and has in the microstructure the actual grain size is 6-8 numbers

All of the above limits for the content of components in the proposed steel were obtained as a result of processing experimental data.

The essence of the proposed technical solution is to optimize the content in steel with a high silicon content of its individual components. As a result of this, the plastic properties of steel increase while maintaining the required hardness, which is especially important during its subsequent processing.

The calcium content in the metal in a given range allows you to significantly increase the number of crystallization centers, which in the manufacture of railway fasteners allows you to get the actual grain size of 6-8 numbers in the microstructure and to provide the required plastic properties of the finished product.

An experimental verification of the proposed technical solution was carried out in the production of 40C2A steel in the electric steel-smelting shop of OJSC Magnitogorsk Iron and Steel Works with its subsequent rolling at 170 mill. The results of the experiments were evaluated by the results of mechanical tests of round steel.

The best results (yield of rolled products in the range of 97.5-99.8) for a given value of hardness were obtained using the proposed steel. Deviations from the required chemical composition and failure to obtain the optimal microstructure led to the marriage of mechanical properties.

So, when the content in steel (wt.%) Al <0.005 (but with the recommended content of the remaining elements), C <0.37, Mn <0.50, Si <1.50 and Ca <0.0001 (with the same condition) it was not possible to obtain the required ductility in 2.5-7.5% of round steel. When the content in steel (wt.%) Al> 0.05 (but with the recommended content of the remaining elements), C> 0.45, Mn> 0.80, Si> 1.80 and Ca> 0.005, as well as an increased content of S , P, Cr, Ni, and Cu (respectively, greater than 0.030, 0.030, 0.30, 0.30, and 0.30) insufficient plastic properties did not allow to obtain round steel with desired properties due to contamination of the steel with non-metallic inclusions.

Upon receipt of rolled steel, the chemical composition of which had at least one component with a different (from the declared) value, the sorting of finished rolled products by unacceptable deviations from the set hardenability norm was at least 0.2-2.5%, and in some cases ductility was unsatisfactory.

Comparative tests of steel 40S2A, selected as the closest analogue, led to sorting for the above reason from 4-8% of finished steel. Thus, an experimental verification confirmed the acceptability of the technical solution found to fulfill the goal and its advantage over a known object.

The implementation of the invention in the production of silicon containing steel will increase profits from the sale of rolled products with improved consumer properties by at least 2.5%.

An example of a specific implementation.

Round, diameter 11 mm, carbon-silicon-containing spring-spring steel for railway fasteners contains, wt.%:

C = 0.39; Si = 1.62; Mn = 0.71; S = 0.006; P = 0.009; Cr = 0.05; Ni = 0.064; Cu = 0.12; Al = 0.006; Ca = 0.0021, the rest is iron; in the microstructure, the actual grain size is 6 numbers.

Claims (1)

Carbon silicon-containing spring-spring steel for railway fasteners containing carbon, manganese, silicon, phosphorus, sulfur, chromium, nickel, copper, aluminum, calcium and iron, characterized in that it contains components in the following ratio, wt.%:
carbon from 0.37 to less than 0.4 manganese 0.50-0.80 silicon 1.50-1.80 phosphorus no more than 0,030 sulfur no more than 0,030 chromium no more than 0.30 nickel no more than 0.30 copper no more than 0.30 aluminum 0.005-0.05 calcium 0.0001-0.005 iron rest,
and has in the microstructure the value of the actual grain 6-8 numbers.