RU2349434C2 - Medium-alloyed electrode for welding of high-strength steel - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: electrode can be used for welding with small 50°C temperature of tempering of martensite and bainitic class high-strength steel. To the bar of the electrode made of wire of sort "Св-03ХН3МД" or "Св-07ХН3МД" it is coated covering, containing component in a following ratio, wt %: marble 37.0-52.0, fluorspar 18.0-26.0, high-silica sand 3.0-10.0, titanium dioxide 3.0-12.0, ferrosilicon 0.5-5.0, ferrotitanium 5.0-14.0, ferromanganese or metallic manganese 1.0-5.0, rare-earth metals oxides 0.1-1.0, metal oxides 0.2-3.0, aluminium powder 0,2-4,0, sodium liquid glass to the mass of dry charge 23.0-28.0. Ratio of oxides content of rare-earth metals to content of iron oxides must be not less than 0.5.

EFFECT: electrode allows high efficiency and welding-functional specifications.

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Description

The invention relates to the field of production of welding consumables and can be used in various industries for welding high-strength steels with a yield strength of 700 to 1000 MPa.

Known electrodes used for this purpose in the relevant industries such as H-1. These electrodes do not meet modern requirements in terms of service characteristics such as strength and toughness of the weld metal, in addition, they are prone to the formation of starting pores and provide an increased hydrogen content in the deposited metal.

The closest to the application electrode for the purpose and composition of the components and taken as a prototype is an H-1 electrode of type E60 (Electrodes for arc welding of steels and nickel alloys, I.A. Zaks, ed. St. Petersburg: "WELCOME", 1996 ., p.336, 337), consisting of a rod-wire of the brand Sv-08XH2M and an electrode coating containing, wt.%:

Marble 54.0 Fluorspar 18.0 Quartz sand 9.0 Ferromanganese (metal manganese) 2.0 Ferrotitanium 14.0 Ferrosilicon 3.0 Sodium water glass to the mass of dry charge 28.0-30.0

The main disadvantages of these electrodes are the reduced toughness of the weld metal at negative temperatures up to minus 40 ° С, the low level of strength characteristics, the high content of diffusion hydrogen in the deposited metal, and therefore, the edges must be preheated at least 100 ° С, in addition, the electrodes prone to the formation of starting pores.

The technical result of the invention is the creation of an electrode for welding high-strength steels operating at temperatures up to minus 40 ° C, providing high strength and toughness of the weld metal, low diffusion hydrogen content and a tendency to porosity.

The technical result is achieved by the fact that the electrode consisting of a rod-wire of the brand Sv-03XH3MD, Sv-07XH3MD and an electrode coating containing marble, fluorspar, quartz sand, ferrosilicon, metallic manganese, ferrotitanium and sodium liquid glass, according to the invention, additionally containing dioxide titanium, aluminum powder and a joint composition of REM and iron oxides in the following ratio of components, wt.%:

Marble 37.0-52.0 Fluorspar 18.0-26.0 Quartz sand 3.0-10.0 Titanium dioxide 3.0-12.0 Ferrosilicon 0.5-5.0 Ferrotitanium 5.0-14.0 Ferromanganese (metal manganese) 1.0-5.0 REM oxides 0.1-1.0 Iron oxides 0.2-3.0 Aluminum powder 0.2-4.0 Sodium water glass to the mass of dry charge 23.0-28.0

the ratio of the content of REM oxides to the content of iron oxides should be no more than 0.5.

The increase in the welding and technological characteristics of the electrodes and the decrease in the tendency of the weld metal to porosity is explained by the introduction of rare-earth metals and iron and titanium dioxide into the coating, which together with the marble - fluorspar - quartz sand composition allow to obtain favorable weld metal formation, spontaneous separability of the slag crust and low content diffusion hydrogen.

The introduction of rare-earth metals and iron oxides into the coating leads to a decrease in the content of diffusion hydrogen in the deposited metal and a tendency to porosity. An increase in the content of rare-earth metals and iron oxides in the coating (more than 4%) makes it difficult to weld in positions other than the lower one and leads to the oxidation of alloying elements, while exceeding the ratio of the content of rare-earth metals and iron oxides more than 0.5 leads to an increase in non-metallic inclusions and a decrease in viscosity seam metal.

The introduction into the coating of titanium dioxide in an amount of 3-12% and aluminum powder from 0.2 to 4% allows to obtain, along with good welding and technological properties and high resistance of the weld metal to pore formation, a guaranteed content of 0.015-0.02% titanium in the metal a seam, which contributes to an increase in toughness at low temperatures. An increase in the content of titanium dioxide in the coating by more than 12% and aluminum powder by more than 4% leads to an increase in the content of titanium in the weld metal and, as a consequence, a decrease in the mechanical characteristics of the weld metal. The combined effect of the coating components allows to obtain a weld metal with a minimum number of defects and a fine-grained bainitic-martensitic structure, which allows for high impact strength at temperatures up to minus 40 ° С.

A set of laboratory and pilot works was carried out on the manufacture, testing and practical testing of electrodes for welding high-strength steels. Steel ingots of the Sv-03KhN3MD or Sv-07KhN3MD grade with the chemical composition shown in Table 1 were made, of which metal rods ⌀ 4 mm were obtained by forging, followed by rolling and drawing.

The electrodes were made in pilot production at the installation for the production of coated electrodes of the Swiss company Oerlikon.

Prototypes of the electrodes were tested on high-strength steels with a yield strength of more than 800 MPa. Welding was performed on direct current of reverse polarity without preheating. The welding modes were as follows: Isv. = 150-170A, Ud = 22-24V, the position of the seam is lower. Preheating temperature 50 ° C. Visual inspection and radiographic inspection of the weld metal showed the absence of unacceptable defects: cracks, lack of penetration, burn-throughs, large non-metallic inclusions.

Of the weld metal obtained by the electrodes of the proposed and known compositions, samples were made and tested to determine the chemical composition and mechanical properties.

The chemical composition of the coatings of the proposed and known welding electrode is presented in table 2. Data on comparative tests of the mechanical properties of the weld metal are presented in table 3.

Table 1 The chemical composition of steel grade Sv-03XH3MD and Sv-07XH3MD Wire mark from Si Mn Cr Ni Mo Cu S R no more Sv-07XH3MD 0.04-0.09 Nb 0.2 0.3-0.6 0.85-1.10 2.8-3.2 0.5-0.65 0.8-1.15 0.012 0.015 Sv-03XH3MD Nb 0.05 Nb 0.2 0.5-0.8 0.6-0.8 2.3-2.9 0.4-0.6 0.8-1.0 0.012 0.015

table 2 The chemical composition of the coatings of the known and claimed electrodes Structure Composition number The composition of the coating, wt.% Fluffy
spar Quartz
sand Dioxide
titanium Ferrotitanium Ferrosilicon Ferromanganese (Manganese Met) Marble REM oxides Iron oxides The ratio of REM oxides to iron oxides Aluminum powder Liquid glass to the mass is dry. charge The claimed one eighteen 10 12 5 5 5 37 1,0 3.0 0.33 four 23 2 21 6 7 9 3 3 47 0.5 1,5 0.33 2 25 3 26 3 3 fourteen 0.5 one 52 0.1 0.2 0.50 0.2 28 Izv. four eighteen 9 fourteen 3 2 54 28-30

Table 3 The results of comparative tests of known and claimed electrodes Structure No. Mechanical characteristics of the weld metal No. of pores (St. Taurus. Samples) Hydrogen in cm ³ per 100 gm σ ₀₂ , MPa σ _in , MPa δ,% KV stroke work, J T = 0 ° C T = -20 ° C T = -40 ° C The claimed one 819 854 eighteen 102 53 38 0 0.8 2 810 848 17 93 64 45 0 0.6 3 835 883 17 82 68 43 0 0.3 Izv. four 530 660 17 80 45 35 8 1.8 Note: 1. The data are averaged over the results of testing three samples at one point.

The results of comparative tests show that the claimed composition in comparison with the known allows to obtain higher strength characteristics of the weld metal. In addition, the claimed electrode provides a lower hydrogen content and the absence of pores in the weld metal and can reduce the temperature of the preheating of the edges.

The technical and economic effect of the use of the invention is expressed in increasing the reliability and durability of structures, by increasing the strength of the weld metal and reducing porosity.

Claims (1)

An electrode for welding high-strength steels, including a rod made of Sv-03KhNZMD or Sv-07KhN3MD wire and an electrode coating containing marble, fluorspar, quartz sand, ferrosilicon, ferromanganese or manganese metal, ferrotitanium and sodium liquid glass, characterized in that the electrode coating additionally contains titanium dioxide, aluminum powder, REM oxides and iron oxides in the following ratio of components, wt.%:
Marble 37.0-52.0 Fluorspar 18.0-26.0 Quartz sand 3.0-10.0 Titanium dioxide 3.0-12.0 Ferrosilicon 0.5-5.0 Ferrotitanium 5.0-14.0 Ferromanganese or Manganese Metallic 1.0-5.0 REM oxides 0.1-1.0 Iron oxides 0.2-3.0 Aluminum powder 0.2-4.0 Sodium water glass to the mass of dry charge 23.0-28.0
the ratio of the content of oxides of rare-earth metals to the content of oxides
iron is not more than 0.5.