Corrosion-resistant steel

 

(57) Abstract:

The invention relates to metallurgy, in particular, to the composition of corrosion-resistant steel used in the manufacture of critical components used in mechanical engineering and working in hostile environments. Essence: corrosion-resistant steel containing carbon, silicon, manganese, chromium, sulfur, phosphorus and iron, further comprises germanium and vanadium in the following ratio, wt. %:

Carbon - 0,12-0,63

Silicon - 0,21-0,38

Manganese - 0,38-0,46

Chrome - 14,0-16,5

Germanium - 0,60-1,50

Vanadium - 0,15-0,25

Sulfur - 0,015-0,025

Phosphorus - 0,015-0,025

Iron - Rest

3 table.

The invention relates to metallurgy, in particular, compositions of the steels used in the manufacture of critical components used in mechanical engineering, mainly in aggressive environments.

Known steel containing components, wt.

Carbon is 0.27-0.34

Silicon 0,17-0,37

Manganese 0,30-0,60

Chrome 2,30-2,70

Molybdenum 0,20-0,30

Vanadium 0,06-0,12

Iron Rest

(see steel HTMP, GOST 4543-71. Steel, alloy, structural, grades and specifications.)

The disadvantage of this clitney corrosion.

Also known steel containing components, wt.

Carbon < 40

Silicon 0,56-1,50

Manganese 0,30-2,00

Vanadium 0,21-1,00

Chrome 0,71-3,00

Aluminum < 0,30

Iron Rest

(Japan's bid N 52-27584, MKI C 22 C 37/24, 1978)

The disadvantage of this steel is that it does not provide the required combination of properties, particularly ductility, eliminate fragility and susceptibility to intergranular corrosion.

Closest to the technical essence and the achieved result is corrosion-resistant steel containing carbon, silicon, manganese, chromium, titanium, sulfur, phosphorus and iron in the following ratio, wt.

Carbon 0,06-0,08

Silicon 0,40-0,80

Manganese 0,40-0,80

Chrome 16,0-18,0

Titanium 0,40-0,80

Sulfur 0,015-0,025

Phosphorus 0,020-0,035

Iron Rest

The disadvantage of this corrosion-resistant steel is that it has relatively low strength and hardness at a satisfactory plasticity across the cross-section of products made from this steel, as after traditional methods of hardening (quenching, tempering) and after low-temperature nitriding (chemical heat treatment), high stand"ptx2">

The basis of the invention the goal: increase strength and viscosity characteristics, the elimination of the phenomenon intergranular corrosion and the reduction of production cost.

The essence of the invention is that corrosion-resistant steel containing carbon, silicon, manganese, chromium, sulfur, phosphorus and iron, further comprises germanium and vanadium in the following ratio, wt.

Carbon is 0.12 to 0.63

Silicon 0,21-0,38

Manganese 0,38-0,46

Chrome of 14.0 to 16.5

Germanium 0,60-1,50

Vanadium 0,15-0,25

Sulfur 0,015-0,025

Phosphorus 0,015-0,025

Iron Rest

The above set of essential features aimed at the achievement of the technical result and is in causal connection with it, as:

to improve anti-corrosion properties of the steel in oxidizing environments and eliminate the effects of intergranular corrosion due to the formation on the surface of the dense protective passive film of oxide Cr2O3and the presence in the composition of steel Germany;

to ensure high strength, viscosity and tverdostyu properties of steel due to specified chemical composition of steel.

In addition, the invention is industrial otvetstvennyh parts and components, used in mechanical engineering.

Thus, we can conclude that the claimed technical solution meets the conditions of patentability of an invention.

For the manufacture of an experimental batch of corrosion-resistant steel is used induction furnace. Then the metal (steel) rolled into shapes (rods) diameter from 14 to 250 mm, which is subjected to tempering at a temperature of 1100 oC and low temperature tempering at a temperature of 180-250oC. and then determine the standard mechanical properties: ultimate strength (tensile strengthin), the yield strength02elongation relative narrowing j impact strength KCU+20, hardness, Rockwell superficial layer of HRC and corrosion characteristics, especially for intergranular corrosion, typical for high-alloy steels. Mechanical characteristics define traditional ways. Corrosion studies conducted in the laboratory on cylindrical samples with a diameter of 10-20 mm and height 40 mm, using a gravimetric method or an electrochemical method by determining the change in the potential of the steel. Studies conducted rapidly, that is, when amplified is ovadiah use of polarization curves, which calculate the corrosion rate of steel. Also produce special laboratory studies, which establish the influence of mechanical loads, pressure, temperature, flow rate. These tests are conducted in order to detect intergranular corrosion, stress corrosion, corrosion fatigue, friction corrosion and pitangui corrosion. The main indicator of the speed of corrosion damage both at local and at uniform corrosion is the penetration depth. In both cases, the depth of corrosion damage is measured in millimeters per year. When uniform corrosion with the depth of corrosion penetration (CP, mm/year) calculate the mass loss of the material (PM, g/m2h).

In table. 1 shows the compositions of the steels in table. 2-mechanical properties of steels after heat treatment, in table. 3 resistance of steels and corrosive environments.

The application of the proposed corrosion-resistant steel will improve the reliability and durability made from this machine components operating in hostile environments, and to reduce the cost of their production 1.3-1.4 times.

Corrosion-resistant steel, stereoimage and vanadium in the following ratio of components, wt.

Carbon 0,12 0,63

Silicon 0,21 0,38

Manganese 0,38 0,46

Chrome 14,0 16,5

Sulfur 0,015 0,025

Phosphorus 0,015 0,025

Germanium 0,60 1,50

Vanadium 0,15 0,25

Iron Ostalnoe

 

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1 ex

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1 tbl, 1 ex

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1 tbl, 1 ex

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1 tbl, 1 ex

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