SU908926A1 - Foundary steel - Google Patents

Description

(54) CASTING STEEL

one

The invention relates to metallurgy, in particular, to martensitic stainless steel, which has become for shaped castings with a high level of casting, mechanical and operational properties.

Closest to the proposed steel martensitic class 10X14NDL, containing wt.%:

CarbonUp to 0.10

Silicon0,2-0,4

Manganese 0.3-0.6

Chromium 13.5-15.-Nickel1, 2-1.6.

Copper 1,2-1,6

Iron Else til,

The disadvantages of the known steel are the low complex of casting and mechanical properties, as well as the low corrosion resistance in seawater. Low casting properties in a number of cases lead to defects on the foundry defects and the low quality of the cast surface. The relatively low level of mechanical properties and corrosion resistance reduces the service life of propeller castings made on this steel, etc., working in seawater.

The purpose of the invention is to increase the complex of casting and mechanical properties, corrosion resistance in seawater.

This goal is achieved by the fact that cast steel containing carbon, silicon, manganese, chromium, nickel, copper, and iron additionally contains aluminum, titanium, calcium, and rare earth metals with the following component ratio, wt%:

Carbon

0.03-0.1

Silicon 0.2-0.4

Manganese 0.3-0.6

15

13.5-15

Chromium

Nickel 1.2-1.6 1.2-1.6

Copper

Aluminum

0.01-0.05

Titanium

0.01-0.08

20

Calcium 0, (Y5-0,05

Rare earth

0.005-0.08

Metals Else

Eile 390 The addition of alumish and titanium to the composition of steel is associated with their ability to bind free nitrogen into refractory nitrides and thereby neutralize its harmful effects. In addition, nitrides dehumidify the grain, as strong aluminum deoxidants, titanium reduces the oxygen content in steel, which improves the foundry properties of steel, especially fluidity. The effective contents in the steel are determined from 0.01-0.05% alumish and 0.01-0.08% titanium. Their smaller contents do not contribute to favorable changes in the steel structure and, accordingly, its properties, and large, above the upper limit, lead to the formation of excessive amounts of oxides and 1 crystals in the steel, which in this case are concentrated in whole colonies at the grain boundaries. As a result of this, the properties of the steel are sharply reduced. The additional introduction of calcium and rare earth metals of rare-earth metals into steel is explained by their exceptionally favorable effect on the whole complex of its properties. These elements simultaneously provide deep deoxidation, refining, microalloying and modification. At the same time, the sulfur content and non-metallic inclusions are sharply reduced. In addition, inclusions are redistributed in the metal with a more uniform background, take on a globular shape, and clean the grain boundaries of the steel, which increases the corrosion resistance of the steel. The optimal contents are determined to be between 0.005-0.05% calcium and 0.005-0.08%. Their smaller contents do not provide favorable changes in the structure of the steel and, accordingly, its properties. Large contents, above the upper limit, due to their high deoxidizing ability, cause the formation of an excessive amount of inclusions, which in this case, in whole colonies, concentrate on the grain boundaries and sharply reduce the properties of the steel. To determine the optimal composition of the developed steel, pilot melts are carried out and its corrosion resistance, casting and mechanical properties are investigated depending on the different content of the components. The metal is smelted into 160 kg of an induction furnace by remelting. In fractional casting, steel is treated with additives of 0.1-0.5% by weight of a master alloy containing calcium, rare-earth metals, aluminum, titanium and nickel. In tab. 1 shows the chemical composition of experiment, 1x steel; in tab. 2 - physico-chemical properties. Table 1 Note: Samples for mechanical testing and corrosion resistance in seawater were made from steels of experienced formulations poured into molds. The fluidity and cracking of castings are fixed by vacuum suction and a ring sample. Thus, the proposed martensitic cast steel of compositions No. 2-6 is superior to the well-known steel 10X14NDL of a similar class in the entire range of properties studied, which determine the quality and durability of castings. Steel of compositions No. 7 and 8 is practically unacceptable, since by its properties it is at the level of the known steel. This makes it possible to determine that the proposed steel No. 2-6 has an optimal chemical composition and is recommended for industrial use. The area of use of the proposed steel casting operating in sea water (propellers, etc.) as a substitute for the well-known steel 10Kh14NDL, as well as steel grades 15X1ZL and 20X13L, which it is superior in basic properties. The technology of steel production does not differ from the well-known steel 10X14NDL, does not require additional technical solutions and Table 2 Thermal treatment of samples from experimental compositions includes quenching at 1100 ° C with air cooling and cold air 660-670 ° C. roystv. Some difference lies in the modification of steel when extruded from the smelting unit of a complex bi-silicon ligature containing calcium, REM, aluminum, titanium and nickel. Formula of the Invention The foundry steel containing carbon, silicon, manganese, chromium, nickel, copper and iron, is such that, in order to improve the complex of casting and mechanical properties, corrosion resistance in seawater, it additionally contains aluminum, titanium, calcium and rare earth metals in the following ratio of components, wt.%: Carbon 0.03-0.1 0.2-0.4 Silicon 0.3-0.6 Manganese 13.5-15 1.2-1.6 Nickel 1, 2-1,6 0,01-0,05 Aluminum 0,01-0,08 Titanium 0,005-0,05 Calcium 7 Rare-earth metals 0,005-0,08 IronEverything 908926 8 Information sources taken into account e for examination 1. GOST 2176-77. Steel 10H14NDL.

Claims (1)

Claim Foundry steel containing carbon, silicon, manganese, chromium, nickel, copper and iron, characterized in that, in order to increase the complex of casting and mechanical properties, corrosion resistance in sea water, it additionally contains aluminum, titanium, calcium and rare earth metals in the following ratio of components, wt.%: Carbon 0.03-0.1 Silicon 0.2-0.4 Manganese 0.3-0.6 Chromium 13.5-15 Nickel 1.2-1.6 Copper 1.2-1.6 Aluminum 0.01-0.05 Titanium 0.01-0.08 Calcium '0.005-0.05 Rare Earth Metals Iron 0.005-0.08 Rest