RU2226571C2 - Low-carbon alloyed steel for cold-drawn welding wire - Google Patents

Abstract

FIELD: steelmaking. SUBSTANCE: alloyed steel for cold-drawn welding wire suited to weld structures operated under low-temperature conditions is composed of, wt %: carbon 0.05-0.10, silicon 0.1-0.35, manganese 1.5-2.0, nickel 0.6-0.9, chromium up to 0.20, phosphorus up to 0.012, sulfur up to 0.010, molybdenum up to 0.01, copper up to 0.2, nitrogen up to 0.012, aluminum up to 0.05, and iron - the balance, provided that manganese-to-nickel ratio is 1.7-3.3 and sum of wt parts of nickel and manganese is within a range of 2.1-2.9. EFFECT: increased low-temperature strength of wear, reduced its cost, and enabled its use with molten fluxes. 1 tbl

Description

The invention relates to the field of production of alloy steel for the manufacture of cold drawn welding wire used for welding structures operating in low temperature conditions.

Known mild steel containing, wt.%:

Carbon 0.08-0.16

Manganese 0.40-1.25

Silicon 0.20-0.42

Nickel 1.80-2.20

Copper 1.20-1.50

Vanadium 0.08-0.15

Aluminum 0.02-0.08

Calcium 0.006-0.01

Molybdenum 0.15-0.25

Iron Else

and at least one item selected from the group

Niobium 0.02-0.04

Cerium 0.08-0.15

Steel may contain impurities, wt.%

Sulfur up to 0.015

Phosphorus Up to 0.015

Chrome Up to 0.30

Nitrogen Up to 0.03

Oxygen Up to 0.0035

(Aut. St. No. 503933, M. cl. C 22 C 38/00, 1976)

This steel has a significantly higher tensile strength compared to welded steels used in shipbuilding, gas pipelines and other similar structures operating at low temperatures.

This steel uses expensive alloying elements, such as vanadium.

Known low-carbon alloy steel for the production of cold-drawn welding wire brand CB 10 GN, containing, wt.%:

Carbon Not more than 0.12

Silicon 0.15-0.35

Manganese 0.90-1.20

Chrome Not more than 0.20

Nickel 0.90-1.20

Sulfur Not more than 0,025

Phosphorus Not more than 0,030

Iron Else

(GOST 2246-70 “Welding steel wire”, technical specifications. Publishing house of standards. - M., table 2).

This steel has a wide range of changes in the carbon content and, thus, conditions are created for a wide spread of mechanical properties. At the request of shipbuilding standards, for example, the tensile strength of a welded joint should not differ from the tensile strength of the metal being welded (steel grades D-32, E-32, D-40, E-40, 10KHSND) by more than 10%.

Welded joints made by welding wire of steel CB 10 GN (GOST 2246-70) under fused fluxes cannot be used for welding structures operating at low temperatures, for example, in shipbuilding, since the requirements for welded joints on mechanical joints are not met properties (impact strength) and their correspondence to the metal being welded.

This steel has a low total mass fraction of nickel and manganese (within 1.8-2.4%), which does not allow to obtain high impact strength of welded joints at temperatures below -40 ° C. In addition, the yield strength of this steel of the order of 420-440 N / mm ² does not correspond to the yield strength of 500-570 N / mm ^{2 of} class F 500 steels and similar steels of Russian manufacture.

Known closest to the proposed low-carbon alloy steel for cold drawn welding wire, containing, wt.%:

Carbon 0.04-0.06

Silicon Not more than 0.20

Manganese 1.1-1.5

Chrome Not more than 0.10

Nickel 1.7-1.9

Molybdenum Not more than 0.08

Copper Not more than 0.15

Sulfur Not more than 0.006

Phosphorus Not More than 0.008

Titanium 0.05-0.12

Aluminum Not more than 0.04

Vanadium Not more than 0.03

Arsenic Not more than 0.005

Nitrogen Not more than 0.008

Oxygen Not more than 0.004

Iron Else

the total content of Nickel and manganese is 3.0-3.3 wt.%, and the ratio of the content of manganese to Nickel of 0.6-0.9. (RF patent No. 2148674, M. cl. 7 C 22 C 38/50, 38/58; B 23 K 35/30).

This steel is used for the manufacture of cold-drawn welding wire used for welding structures operating at low temperatures and providing a yield strength of welded joints of 500-570 N / mm ² and impact work of at least 60 J at a temperature of -40 ° C and at least 50 J at a temperature of -60 ° C.

Typically, in steels with a high total content of manganese and nickel, the required mechanical properties of steels (increase in toughness) are achieved by increasing the nickel content, while the ratio of manganese to nickel is taken to be less than 1.0, which leads to an increase in the cost of steel and the cost of the finished manufacturing process wire, requiring the use of sophisticated and expensive pickling technology similar to stainless metal.

For steels with a low total content of these alloying elements with a manganese to nickel ratio of less than 1.0, a yield strength in the range of 390-430 N / mm ^{2 is} characteristic, which does not allow them to be used for the construction of structures of F 500 steels with a yield strength of 500-570 N / mm ² .

This steel can provide the necessary yield strength at temperatures up to -60 ° C only when welding under ceramic fluxes, for example, 1062 ESAB, when welding under fused fluxes, for example, AN-47 and FIMS-20, it provides the necessary yield strength only up to -40 ° C. Given that ceramic fluxes are much more expensive than fused fluxes, their use in welding significantly increases the cost of welding.

An object of the invention is to reduce the cost of production of low-carbon alloy steel for the manufacture of cold drawn welding wire and to ensure that it can be used with fused fluxes while maintaining strength corresponding to class F 500 steels and Russian-made steels used in the construction of structures operating at temperatures up to -60 ° C.

This task is achieved by the fact that in mild alloyed steel for cold drawn welding wire containing carbon, silicon, manganese, nickel, chromium, phosphorus, sulfur, iron and impurities: molybdenum, copper, aluminum, the ratio of the content of manganese to nickel is taken 1.7- 3.3, and the sum of the mass fractions of nickel and manganese in the range of 2.1-2.9% in the following ratio of components, wt.% In steel:

Carbon 0.05-0.010

Silicon 0.1-0.35

Manganese 1.5-2.0

Nickel 0.6-0.9

Chrome Not more than 0.20

Phosphorus Not more than 0.012

Sulfur Not more than 0.010

Molybdenum Not more than 0.01

Copper Not more than 0.20

Nitrogen Not more than 0.012

Aluminum Not more than 0.05

Iron Else

The ratio of the content of manganese to nickel of 1.7-3.3 and the content of the sum of the mass fractions of nickel and manganese 2.1-2.9% are established experimentally based on the requirements for the yield strength of welded joints from 480-570 N / mm ² , and ensuring impact work from 47 to 100 J at temperatures up to -60 ° C.

Studies have shown that the temperature at which the impact begins to decrease sharply is in the range from -59 to -62 ° C.

A decrease in the nickel content to 0.6-0.9% and an increase in the manganese content to 1.5-2.0% with a total content of 2.1-2.9% and a ratio of manganese to nickel 1.7-3.3 the required yield strength is achieved with a slight decrease in toughness while maintaining the requirements for welded structures made of steel of class F 500.

A decrease in the ratio of manganese to nickel content below 1.7 leads to a decrease in the yield strength of welded joints, which does not allow the use of this steel for welding structures made of F 500 steel and similar Russian-made steels.

An increase in the ratio of manganese to nickel content of more than 3.3 leads to an increase in the yield strength above 600 N / mm ² and the appearance of cold cracks in the welding process without heating.

The test results of welded joints made of the proposed steel wire are shown in the table.

Steel is smelted in 100-ton arc furnaces using single-slag processes and up to 30% cast iron in casting. The oxidation period begins at the end of the melting, which helps to obtain a low gas content in the metal.

A slight decrease in ductility characteristics compared to the prototype allows the use of wire from this steel for welding structures operating at low temperatures from -40 to -60 ° C in accordance with the requirements for structures made of steel of class F 500.

At the same time, nickel consumption is reduced in comparison with the prototype for every 100 tons of steel by an average of 1100 kg.

In addition, for the smelting of steel of the prototype due to the low carbon content, it is necessary to use expensive metallic manganese, and when smelting the proposed steel, cheaper silicomanganese can be used.

The proposed steel allows the efficient use of a welding wire made from it in combination with low-cost highly basic fluxes.

There is no need to use an intermediate size in the process of production of wire from wire rod for cleaning the surface of the wire after heat treatment of an expensive etching technology similar to that of stainless steel.

All this reduces the cost of production of steel and welding wire from it, as well as the welding process.

Claims (1)

Mild alloyed steel for cold drawn welding wire containing carbon, silicon, manganese, nickel, chromium, phosphorus, sulfur, nitrogen, iron and impurities: molybdenum, copper, aluminum, characterized in that the ratio of the content of manganese to nickel is taken 1.7? 3 , 3, and the sum of the mass fractions of nickel and manganese in the range of 2.1? 2.9 in the following ratio of components in steel, wt.%: Carbon 0.05-0.010 Silicon 0.1-0.35 Manganese 1.5-2.0 Nickel 0.6-0.9 Chrome Not more than 0.20 Phosphorus Not more than 0.012 Sulfur Not more than 0.010 Molybdenum Not more than 0.01 Copper Not more than 0.2 Nitrogen Not more than 0.012 Aluminum Not more than 0.05 Iron Else