SU1101467A1 - Steel - Google Patents

Abstract

STEEL, containing carbon, manganese, chromium, nitrogen, boron, silicon, calcium, and iron, is distinguished by 200 J400 1450 15001550 T, ° C / ra for 8, and additionally contains cerium, b, titanium, zirconium at the following ratio of components, wt.%: 0.02-0.15 Carbon 19-25 Manganese 12-15 0.05-0.30 0.005-0.01 0.2-0.8 Silicon. 0,005-0,01 Calcium. 0.05-0.2 0.4-4 0.005-0.2 Zirconium 0.55-1.5 Remaining Iron.

Description

The invention relates to metal rot, namely to cold-resistant cast steels, with increased viscosity, fluidity and operational reliability at sufficiently high strength for loaded parts and stop valves operating at low temperatures down to -196 ° C.

Known stainless steel l, designed to operate at cryogenic temperatures, containing, in May.%:

Carbon .To 0.03

Manganese8,5-10,5

Nickel7-8

Chrome 18,5-20,5

Molybdenum2-2,5

Nitro 0.31-0.4

Kremniydo O, 8

IronErest

The disadvantage of the steel is the poor fluidity characteristics.

Closest to the invention to the technical essence and achieved the 4th effect is steel C2 containing, in May.%:

Carbon0.01-0.1

Chrome 12-15

Manganese 16-22

Silicon0,2-0,8

Az.ot0.03-0.23

Bor0.006-0.01

Calcium0.001-0.1

; Sulfur0,01-0,04

Phosph € 0.01-0.04

Iron - The Rest

The goal of the invention is to increase the fluidity and mechanical properties at low temperatures up to.

The goal is achieved by the fact that steel containing carbon, manganese, ofom, nitrogen, bar, silicon, calcium, iron additionally contains cerium, honey, titanium, zirconium at the following ratio of components,% by weight:

Carbon0.02-0.15

Manganese19-25

Chrome 12-15

Nitro0.05-0.30

Boron. 0,005-0,01

Silicon0,2-0,8

Calcium 0.005-0.01 Cerium 0.05-0.2

Copper-0.4-4.0

Zirconium 0.005-0.2 Titanium0.55-1.5

IronErest

Steel may contain impurities, wt.%:

Sulfur0,001-0,04

Phosphorus 0.001-0.04

The combined effect of titanium and zirconium within the specified limits

beneficial effect on structure, mechanical and casting properties

Owing to the increased affinity of zirconium to nitrogen, its introduction into steel ensures the absorption of nitrogen from the atmosphere, which prevents the formation of fistulas, pores and microplate in the ingot. Zirconium helps to increase the total nitrogen content of the metal, thereby contributing to the stability of austenite at low temperatures. Doping steel zirconium leads to grinding austenitic grain.

The introduction of titanium in the amount of 0.55-1.5 wt.% Leads to the formation of low-melting Mie and Ti n compounds in chromo-manganese steels and Ti and improves the processability of steel during smelting. The resulting titanium carbides TiC significantly strengthen the austenitic matrix, which leads to an increase in the temporal resistance and yield strength of the steel to be distinguished over the entire temperature range, in comparison with the known steel. However, T1 C, being the phase of incorporation, has a limited austenite solubility, and a further increase in the titanium content in steel is impractical.

When steel containing Ti and Zf is heated, the austenitic grain grows more slowly than without them. In addition, these alloying elements reduce the sensitivity of steel to overheating. Zirconium in the selected alloying range contributes both to an increase in the density of the cast material and to an improvement in the fluidity of steel by 55-60% compared with the known

1 wherein the increase in fluidity increases significantly at low casting temperatures (see drawing).

The drawing shows the dependence of the fluidity of the casting temperature.

The mechanical properties of the steel were investigated on a metal of five experimental heats produced in an open induction furnace with a capacity of 150 kg. The chemical composition of the experimental heats are given in table. one.

The steel was poured into cortical shells to obtain full-scale cast multi-way valves, as well as into trefoid casts (GOST 7565-73) for the manufacture of samples for mechanical testing. When determining mechanical characteristics for static uniaxial stretching, short cylindrical specimens No. 5K with a diameter of 10 mm according to GOST lli50-.75 were used. Mechanical tests for uniaxial static stretching were carried out on an Instron-type universal machine at temperatures of 20, -100 and -196 ° C. Type 11 specimens according to GOST 9454-78 were used to determine the viscosity characteristics during dynamic bending. The mechanical characteristics of the proposed steel and known are given in table. 2. It is evident from the above data that with a decrease in the test temperature, the strength for all the steels studied increases, and the ductility and toughness fall. Steel of the proposed composition in the lithm state (smelting 1-5). over the entire temperature range have higher strength characteristics than the known. In order to evaluate the performance of on-site products from the proposed shesh and well-known, six multi-way valves have been tested. Thin-walled cast multi-way valves are manufactured according to produced models. The cold resistance of cast valves was evaluated when tested by internal pressure and shock loading at temperatures of 20 and. The test results of multi-port cast thin-walled valves with internal pressure at temperatures and -196 ° C are given in Table. 3. Strength, viscosity and cold resistance of the proposed steel in a cast state in the temperature range from 20 to -196 ° C are higher than that of the known. The impact viscosity (LCP) at -196 ° C is twice as high, the fluidity is 60%, the consumption of liquid products when cooling thin-walled products by 30%, and the reduction of thermal stress when cooling the thermal stresses due to the possibility of producing thin-walled castings by 25.% in comparison with the famous steel. The proposed steel is more technological. Table

Table 2

Claims (1)

STEEL, manganese, chromium, calcium and iron. containing carbon, nitrogen, boron, silicon, different 1400 1450 1500 1550 T, ° С Filling temperature o This is due to the fact that, in order to increase fluidity and mechanical properties at low temperatures up to -196 C, it additionally contains cerium, copper, titanium, zirconium in the following ratio of components, wt.%: Carbon 0.02-0.15 Manganese 19-25 Chromium 12-15 Nitrogen 0.05-0.30 Boron 0.005-0.01 Silicon 0.2-0.8 Calcium 0.005-0.01 Cerium 0.05-0.2 Copper 0.4-4 Zirconium 0.005-0.2 Titanium 0.55-1.5 Iron Rest possessing vypivny vyzhidkotekachesty and operation reliability with sufficient strength for loaded and stop valves, I work-