RU2492981C1 - Tube wire blend - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention may be used for hard-surfacing the working surfaces of metallurgical equipment parts to be operated at high stresses. Proposed blend contains components in the following ratio in wt %: carbon - 1-3.6, 6; chromium - 6.5-14.0; molybdenum - 5-21, tungsten - 1-8, vanadium - 2-6, aluminium - 1-4.5; nickel - 3.2-20; dust of aluminium production electrostatic precipitators - 1-15, iron making the rest.

EFFECT: higher wear resistance and hardness and stability arc fire, better forming of built-up metal, extra gas protection, ruled out crack formation, lower costs.

3 tbl

Description

The invention relates to welding production, in particular to the production of flux-cored wire, and can be used for surfacing of the working surfaces of parts of metallurgical equipment, which have high demands on hardness and wear resistance.

Known selected as a prototype [1], a flux-cored wire mixture containing carbon, chromium, tungsten, vanadium, sodium silicofluoride, sulfur, cobalt, molybdenum and aluminum in the ratio of components, wt.%:

Carbon 1-3,6 Chromium 6.5-12.0 Tungsten 6-21 Molybdenum 8-17 Vanadium 2-6 Aluminum 1-4.5 Siliceous sodium 0.6-3.6 Sulfur 0.9-3 Cobalt 12-13 Iron Rest

The disadvantages of this mixture of cored wire are;

- reduced mechanical properties of the deposited metal, in particular wear resistance and hardness, due to increased contamination of steel with non-metallic oxide inclusions and insufficient alloying of residual austenite;

- poor stability of arc burning due to the absence of elements in the charge that facilitate ionization in the arc column;

- low quality deposited metal due to pore formation associated with a high hydrogen content;

- the possibility of the formation of cold cracks in the process of multilayer deposition due to insufficient stabilized austenite in the deposition process and high hydrogen content;

- the high cost of the welding process due to the use of expensive materials in significant quantities (tungsten, molybdenum, aluminum and sodium silicofluoride).

The technical results of the invention are:

- increasing the mechanical properties of the deposited metal, in particular wear resistance and hardness, due to the reduction of steel contamination by non-metallic oxide inclusions and the effect of dispersion hardening of highly alloyed austenite during tempering;

- increasing the stability of arc burning by introducing elements that facilitate ionization in the arc column;

- improving the formation of deposited metal and the elimination of pore formation due to the introduction of fluorine-containing components and the creation of additional gas protection;

- preventing the formation of cold cracks in the process of multilayer deposition by increasing the amount of stabilized austenite in the deposition process and reducing the hydrogen content in the deposited metal;

- reducing the cost of the welding process by optimizing the composition of the charge and the use of waste products.

To do this, we propose a flux-cored wire mixture containing carbon, chromium, molybdenum, tungsten, vanadium, aluminum and iron, which additionally contains nickel and dust from aluminum electrostatic precipitators with a ratio of components, wt.%:

Carbon 1-3,6 Chromium 6.5-14.0 Molybdenum 5-21 Tungsten 1-8 Vanadium 2-6 Aluminum 1-4.5 Nickel 3.2-20 Dust of aluminum electrostatic precipitators 1-15 Iron Rest

the dust of aluminum electrostatic precipitators has the following composition, wt.%: Al ₂ O ₃ = 20-48; F ⁺ = 18-27; Na ₂ O = 4-16; K ₂ O = 0.4 - 6%, CaO = 0.7-1.8; SiO ₂ = 0.5-2.48; Fe ₂ O ₃ = 1.7-3.27; C _total = 12-31, MnO = 0.07-1.3, MgO = 0.06-0.9, S = 0.09-0.59, P = 0.1-0.18.

The claimed limits are selected empirically, based on the quality of the metal obtained during surfacing, the stability of the welding process, preventing the formation of cold cracks and the required mechanical properties.

The resistance of the deposited metal against the formation of cold cracks can be significantly improved by controlling the temporary stresses due to the appropriate choice of the chemical composition of the deposited metal. The linear expansion coefficient, the nature and volumetric effect of structural transformations depend on it. The introduction of strong austenite-forming elements into the composition of the deposited metal increases the amount of residual austenig, which reduces the likelihood of the formation of cold cracks (quenching hypogenesis). Resistance against the formation of cold cracks also increases with a decrease in hydrogen in the composition of the deposited metal (the hydrogen hypothesis of preventing cold cracks).

The inventive mixture of flux-cored wire additionally contains Nickel in order to reduce the likelihood of the formation of cold cracks in the process of multilayer surfacing. The introduction of Nickel in the composition of the charge allows you to:

- reduce the likelihood of cracking due to an increase in the amount of residual austenite and a decrease in the volumetric effect of martensitic transformation.

Obtaining deposited metal of increased hardness and wear resistance is achieved by tempering the residual austenite at 580 ° C.

Introduction to the composition of a powder wire charge of dust from aluminum electrostatic precipitators is associated with the content of the latter elements, allowing:

- carry out the removal of hydrogen due to a complex of fluorine-containing compounds (such as Na ₃ AlF ₆ , Na ₂ SiF ₆ , NaF, KF, CF _x (1≥x> 0), AlF ₃ ,) decomposing at temperatures of welding processes with the release of F, which in turn, interacts with hydrogen dissolved in steel to form a gaseous HF compound. Reducing the hydrogen content in the weld metal reduces the likelihood of pores and cold cracks in the weld metal;

- increase the stability of arc burning due to elements that facilitate ionization in the arc column - potassium and sodium;

- carry out intensive carburization during the interaction of carbon fluoride CF _x (1≥x> 0) with carbide-forming elements, which allows to increase the amount of carbide component in the structure of the deposited metal and to further increase its hardness.

For the manufacture of a charge of flux-cored wire used dust of aluminum electrostatic precipitators with the following chemical composition, wt.%: Al ₂ O ₃ = 20-48; F ⁺ = 18-27; Na ₂ O = 4-16; K ₂ O = 0.4-6%, CaO = 0.7-1.8; SiO ₂ = 0.5-2.48; Fe ₂ O ₃ = 1.7-3.27; C _total = 12-31, MnO = 0.07-1.3, MgO = 0.06-0.9, S = 0.09-0.59, P = 0.1-0.18.

The change in the nickel and dust content of aluminum electrostatic precipitators in the composition of the inventive charge was made taking into account the production of high-quality deposited metal (stable arc burning, good formation, dense weld metal without cracks, pores and non-metallic inclusions), while taking into account the content of other components. The flux-cored wire was made of 08 kp steel cold-rolled tape (sheath) measuring 15 × 0.8 mm. The mixture was mixed in a special device to obtain a homogeneous mass. The flux-cored wire was calcined to remove moisture at a temperature of 250-350 ° C. The fill factor was 0.32-0.33, the diameter of the finished wire was 3.7 mm. The flux-cored wire with the proposed charge was used for plasma surfacing of work roll blanks with a working part diameter of 150 mm and a length of 425 mm. Surfacing was carried out in a nitrogen-containing protective alloying medium in the following modes:

Welding current 160-170 A Arc voltage 50-60 V Surfacing speed 11 m / h Cored wire feed rate 47 m / h Arc length 20 mm Zenith Offset 20 mm Protective gas Nitrogen Plasma gas Argon

Surfacing was carried out with controlled low-temperature heating above the temperature of the onset of phase transformations and amounted to 200-250 ° C.

In the process of surfacing, an expert assessment of the stability of arc burning, the quality of formation of the weld metal was carried out. The presence of cracks in the surfacing process was visually assessed; after surfacing, the presence of cracks, pores and non-metallic inclusions was evaluated by ultrasonic and magnetic particle methods, as well as on metallographic sections. The hydrogen content in the deposited metal was determined by vacuum heating on a Batalin apparatus and on an EAH-220 Balzers exchalograph. Hydrogen content was varied in the range of 0.3-0.6 cm ^3/100 g of weld metal with an acceptable hydrogen content in the high alloy weld metal to 2 cm ³ / 100g metal. The hardness of the deposited metal was monitored immediately after surfacing and after four-hour tempering at a temperature of 580 ° C. The hardness of the deposited metal after surfacing was 52-56 HRC, after four-hour tempering at 580 ° C - 62-66 HRC. Defects (cracks, pores, and non-metallic inclusions) during surfacing with flux-cored wire with a batch of the claimed composition containing nickel and dust from aluminum electrostatic precipitators were not detected.

We studied 6 options for the composition of the charge (table 1) cored wire, wt.%: 1 - prokutil; 2 - the lower limit of the inventive charge; 3 - the average content of the inventive mixture; 4 - the upper limit of the inventive charge; 5 - lower foreign composition; 6 - the top foreign composition.

The effect of changes in the chemical composition on the technological properties and mechanical characteristics of the deposited metal is shown in Table 2. Line 3 indicates the hardness of the deposited metal after high-temperature tempering.

Using the inventive composition of the mixture of flux-cored wire in comparison with the basic composition (prototype) allows you to:

1. To improve the quality of the deposited metal by reducing its contamination with non-metallic inclusions, reducing the likelihood of pore formation and preventing the formation of cold cracks.

2. Reduce the hydrogen content by the introduction of fluorine-containing components and create an extra gas protection in the average of 0.3-0.6 cm ³ / 100g metal (against 1.2-1.5 cm ^3/100 g of metal in the prototype).

3. To improve the formation of the weld during welding by stabilizing the burning of the arc.

4. Increase the hardness of the weld metal to HRC 64-66.

5. To reduce the cost of manufacturing flux-cored wire by reducing the content of alloying components and the use of aluminum waste in the proposed panel.

Literature

1. Pat. RF №2088392, class B23K 35/36.

Table 1 The composition of the charge The composition of the mixture, wt.%: one 2 3 four 5 6 Carbon 2,3 1.0 2,3 3.6 0.9 3,7 Chromium 10,2 6.5 10,2 14.0 6.4 14.1 Molybdenum 13.0 5,0 13.0 21.0 4.9 21.1 Tungsten 4,5 1,0 4,5 8.0 0.9 8.1 Vanadium 4.0 2.0 4.0 6.0 1.9 6.1 Aluminum 2.7 one 3,7 4,5 0.9 4.6 Nickel - 3.2 11.5 20,0 3,1 20.1 Sodium silicofluoride 6.3 Dust of aluminum electrostatic precipitators 1,0 8.0 15.0 0.9 15.1 Iron 58.0 79.3 42.8 7.9 80.1 7.1

table 2 Characteristics of the studied parameters depending on the composition of the charge The composition of the mixture, wt.% one 2 3 four 5 6 The hydrogen content [H], ^cm3 / 100g metal 1.2-1.5 0.3-0.6 0.3-0.6 0.3-0.6 1.2-1.5 1.2-1.5 Cracks in the weld metal Single Are absent Are absent Are absent Single Single Hardness of weld metal, HRC 50-54 64-66 64-66 64-66 62-64 62-64

Claims (1)

A flux-cored wire mixture containing carbon, chromium, molybdenum, tungsten, vanadium, aluminum and iron, characterized in that it additionally contains nickel and dust from aluminum electrostatic precipitators in the following ratio, wt.%:
Carbon 1-3,6 Chromium 6.5-14.0 Molybdenum 5-21 Tungsten 1-8 Vanadium 2-6 Aluminum 1-4.5 Nickel 3.2-20 Dust of aluminum electrostatic precipitators 1-15 Iron Rest,
the dust of aluminum electrostatic precipitators has the following composition, wt.%: Al ₂ O ₃ = 20-48; F ⁺ = 18-27; Na ₂ O = 4-16; K ₂ O = 0.4-6; CaO = 0.7-1.8; SiO ₂ = 0.5-2.48; Fe ₂ O ₃ = 1.7-3.27; C _overall = 12-31; MnO = 0.07-1.3; MgO = 0.06-0.9; S = 0.09-0.59; P = 0.1-0.18.