CN115805389A - Gas protection solid welding wire suitable for being matched with sulfuric acid dew point corrosion resistant pipeline - Google Patents

Abstract

The invention provides a gas protection solid welding wire suitable for being matched with a sulfuric acid dew point corrosion resistant pipeline, which comprises the following chemical components in percentage by weight: 0.07 to 0.09 weight percent of C, 1.20 to 1.60 weight percent of Mn, 0.26 to 0.38 weight percent of Si, 0.90 to 1.00 weight percent of Cr, less than or equal to 0.025 weight percent of S, less than or equal to 0.025 weight percent of P, 0.07 to 0.09 weight percent of Sb, 0.25 to 0.35 weight percent of Cu, and the balance of Fe and inevitable impurities, wherein the sum of the mass fractions of the components is 100 percent. The welding wire provided by the invention has the advantages that the chemical components are scientifically proportioned, the welding performance is stable, and the obtained cladding metal has comprehensive mechanical properties, acid resistance, high temperature resistance and the like.

Description

A gas-shielded solid welding wire suitable for supporting sulfuric acid dew point corrosion-resistant pipelines

technical field

The invention belongs to the field of welding wire processing, and in particular relates to a gas-shielded solid welding wire suitable for supporting pipelines resistant to sulfuric acid dew point corrosion.

Background technique

In metallurgy, electric power, petrochemical and other industrial fields, flue gas treatment systems that use heavy oil or coal as the main industrial fuel, such as air preheaters, heat exchangers, economizers, flues, chimneys and desulfurization devices in low-temperature parts of boilers etc. It is generally encountered that the sulfur content in the fuel is high, and SO ₂ will be generated after combustion, and part of it will be regenerated into SO ₃ . When SO ₂ reaches the dew point temperature, it combines with water vapor to form H ₂ SO ₄ , which changes from dilute to concentrated, causing corrosion of equipment. This phenomenon is called "sulfuric acid dew point corrosion". Different from ordinary atmospheric corrosion phenomena, it not only corrodes ordinary carbon steel, but also can corrode stainless steel, etc., which is extremely harmful to industrial production equipment.

In order to solve the problem of sulfuric acid corrosion of equipment, technicians have proposed a variety of methods, such as fuel or flue gas desulfurization, increasing the temperature of the heating surface wall, using sulfuric acid corrosion resistant materials, etc., but each has its own advantages and disadvantages. After a long period of continuous experimental research and production practice, from the perspective of cost control, process simplification, and energy saving, the use of sulfuric acid corrosion-resistant materials has the best effect. Sulfuric acid dew point corrosion resistant steel has been widely used in economizers, flue and exhaust gas desulfurization equipment due to its low cost and excellent acid resistance, and has achieved good practical results. At present, the welding consumables that match the sulfuric acid dew point corrosion-resistant steel are all conventional welding consumables, and the welds do not have the characteristics of acid resistance, which makes the welds prone to corrosion and greatly reduces the service life of industrial production equipment. Therefore, it is urgent to develop welding materials suitable for sulfuric acid dew point corrosion resistant pipelines.

Compared with welding rods and flux-cored wires, gas-shielded solid wires have the advantages of good operational performance, beautiful weld shape, and easy operation by welders. At the same time, the preparation process of gas-shielded solid wires is relatively simple.

Due to its harsh service environment, while the sulfuric acid corrosion-resistant welding material requires acid resistance, the weld metal needs to meet the requirements of heat resistance and high temperature resistance. Moreover, in order to reduce the self-weight and withstand high pressure, low-alloy high-strength steel is generally used, so the design of welding materials should also meet the requirements of low-alloy high-strength and high-toughness.

Contents of the invention

In view of this, the present invention aims to propose a gas-shielded solid welding wire suitable for supporting pipelines resistant to sulfuric acid dew point corrosion.

In order to achieve the above object, technical solution of the present invention is achieved in that way:

A gas-shielded solid welding wire suitable for supporting pipelines resistant to sulfuric acid dew point corrosion. The chemical composition of the solid welding wire is calculated by weight percentage, including: C 0.07-0.09wt%, Mn1.20-1.60wt%, Si 0.26-0.38wt% , Cr 0.90-1.00wt%, S≤0.025wt%, P≤0.025wt%, Sb 0.07-0.09wt%, Cu 0.25-0.35wt%, the balance is Fe and unavoidable impurities, the mass fraction of each component The sum is 100%.

Further, the mass percentage of S is ≤0.008wt%.

Further, the mass percentage of P is ≤0.015wt%.

Further, the mass percentage of Mn is 1.20-1.30wt%.

Further, the mass percentage of Cu is 0.25-0.30wt%.

Further, the mechanical properties of the welding wire cladding metal are as follows: yield strength Rp0.2≥490MPa; tensile strength Rm≥620MPa; elongation after fracture A≥19%, low temperature impact toughness: -20 ° C weld impact energy Up to 47J or more.

A welding method using the gas-shielded solid welding wire suitable for sulfuric acid dew-point corrosion-resistant pipelines, characterized in that it includes the following steps: using a rich welding wire composed of 70-90% Ar and 10-30% CO ₂ by volume. Ar mixed gas is used for welding, welding parameters are: welding speed: 4-8mm/s, gas flow rate: 15-25L/min, current: 260-300A, voltage: 27-32V, channel temperature: 150-180°C.

Further, the volume percent composition of the Ar-rich mixed gas is Ar 80-90%, CO ₂ 10-20%.

Carbon element (C): Carbon is the basic element in low-alloy welding wire steel. Its existence improves the strength of the weld, but too high a carbon content affects the welding performance of the steel, so the carbon content in the steel should be controlled at within an appropriate range. The increase of carbon content will reduce the corrosion resistance of the weld. High carbon steel in the open air is particularly prone to corrosion and rust. In addition, the increase of carbon content will increase the cold brittleness and aging sensitivity of the weld correspondingly. Studies have shown that low-carbon copper-containing steel has the best corrosion resistance.

Manganese element (Mn): Manganese is a basic constituent element in low-alloy welding wire steel, which can properly increase the strength of the weld and improve processing performance, but manganese element has an adverse effect on the corrosion resistance of steel. Therefore, manganese must take into account the dual effects of corrosion resistance and nitrogen fixation performance.

Silicon (Si): Silicon is also a basic element in low-alloy welding wire steel. When silicon and copper coexist, it can properly improve the corrosion resistance of the weld. However, if the silicon content in welding wire steel is too high, the processing of the steel will Performance deteriorates.

Chromium (Cr): The addition of chromium can not only improve the thermal strength and high temperature oxidation resistance of the weld, but also improve the corrosion resistance of the weld. The potential of chromium is low, and it has a tendency of passivation, so as to improve the corrosion resistance, and the corrosion resistance effect of chromium is more obvious under the cooperation of copper. Chromium will combine with carbon in the molten pool, so the corrosion resistance of chromium will decrease with the increase of carbon. The ratio of carbon to chromium in the welding wire must be reasonably controlled to better play the role of chromium. Corrosion resistance.

Antimony element (Sb): The addition of antimony element is of great help to improve the sulfuric acid corrosion resistance and wear resistance of the weld. Antimony can inhibit the anode reaction, and the formation of Cu ₂ Sb film on the surface of the weld can also inhibit the cathode reaction . However, high antimony content will reduce the weld strength and increase brittleness.

Copper element (Cu): Copper element plays a role in strengthening ferrite in the weld, and at the same time plays an important role in improving the corrosion resistance of the weld. Copper plays the role of an active cathode in the corrosion process of the weld. Under certain conditions, it can promote the anode passivation of the weld, thereby reducing the corrosion rate of the weld. At the same time, copper is easy to combine with sulfur in the steel, and the A Cu ₂ S passivation film is formed on the surface, thereby inhibiting the anode reaction and the cathode electrochemical reaction, and alleviating sulfuric acid dew point corrosion. When the content of copper element exceeds 0.50%, the plasticity of the weld will be greatly reduced, and the hot workability of the weld will be affected.

Phosphorus (P): Even when the content of phosphorus is very low, cracks can nucleate on MnS, but the size is too small to be detected. However, if the phosphorus content is high, even if S is very low (S=0.001%), cracks can nucleate and propagate on oxide inclusions and grain boundaries. At the same time, P is also an element that is easy to segregate, causing cold and brittle welds, and promoting the grain boundary segregation of other harmful residual elements, further deteriorating the quality of welds, so the lower the P in the welding wire, the better.

Sulfur (S): For resistance to sulfuric acid dew point corrosion, the presence of a certain amount of sulfur can promote the formation of Cu ₂ S passivation film on the surface of the weld, thereby inhibiting the anode reaction and cathode electrochemical reaction. However, when S, Cu, and Sb appear in the steel at the same time, it is easy to produce low-melting point coexistence at the grain boundary, seriously destroying the comprehensive performance of the weld, and forming a corrosion source of sulfide inclusions, so the S content must be strictly controlled.

Compared with the prior art, the present invention has the following advantages:

The gas-protected solid welding wire suitable for supporting sulfuric acid dew point corrosion-resistant pipelines described in the present invention has the following advantages:

Compared with the traditional welding wire, it is found that the gas-shielded solid welding wire suitable for sulfuric acid dew point corrosion-resistant pipelines of the present invention has the characteristics of acid resistance and high temperature resistance, as well as high strength and high toughness. The welding wire improves the corrosion resistance of the weld by adding an appropriate amount of elements such as Cr, Cu and Sb; by controlling the appropriate elements such as Mn, Si, P and S, the good mechanical properties of the weld are guaranteed.

Detailed ways

Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are conventional biochemical reagents; the experimental methods, unless otherwise specified, are conventional methods.

The present invention will be described in detail below in conjunction with examples.

Example 1

A gas-shielded solid welding wire suitable for supporting pipelines resistant to sulfuric acid dew point corrosion. The chemical composition of the solid welding wire is calculated by weight percentage, including: C: 0.078wt.%, Mn: 1.25wt.%, Si: 0.30wt.%, Cr: 0.91wt.%, S: 0.008wt.%, P: 0.015wt.%, Sb: 0.075wt.%, Cu: 0.26wt.%, it is impossible to avoid the sum of impurity elements ≤ 0.30wt.%, the balance is Fe; the sum of the mass percentages of each component is 100%.

The deposited metal performance test was carried out on the obtained welding wire: the yield strength R _p0.2 was 545MPa; the tensile strength R _m was 652MPa; the elongation A after fracture was 19.5%; 58.3J; the sample was immersed in a 50% sulfuric acid solution at (70±2)°C for 24 hours of corrosion immersion test, and the average corrosion rate of the sample was 34.81g/m ² .h.

Example 2

A gas-shielded solid welding wire suitable for supporting pipelines resistant to sulfuric acid dew point corrosion. The chemical composition of the solid welding wire is calculated by weight percentage, including: C: 0.082wt.%, Mn: 1.21wt.%, Si: 0.35wt.%, Cr: 0.95wt.%, S: 0.007wt.%, P: 0.015wt.%, Sb: 0.078wt.%, Cu: 0.28wt.%, it is impossible to avoid the sum of impurity elements ≤ 0.30wt.%, the balance is Fe; the sum of the mass percentages of each component is 100%.

The deposited metal performance test was carried out on the obtained welding wire: the yield strength R _p0.2 was 532MPa; the tensile strength R _m was 676MPa; the elongation A after fracture was 19.0%; the low-temperature impact toughness was: 52.6J; the sample was immersed in a 50% sulfuric acid solution at a temperature of (70±2)°C for a 24-hour corrosion immersion test, and the average corrosion rate of the sample was 34.23g/m ² .h.

Example 3

A gas-shielded solid welding wire suitable for supporting pipelines resistant to sulfuric acid dew point corrosion. The chemical composition of the solid welding wire is calculated by weight percentage, including: C: 0.071wt.%, Mn: 1.21wt.%, Si: 0.32wt.%, Cr: 0.94wt.%, S: 0.006wt.%, P: 0.014wt.%, Sb: 0.078wt.%, Cu: 0.25wt.%, it is impossible to avoid the sum of impurity elements ≤ 0.30wt.%, the balance is Fe; the sum of the mass percentages of each component is 100%.

The deposited metal performance test was carried out on the obtained welding wire: the yield strength R _p0.2 was 508MPa; the tensile strength R _m was 625MPa; the elongation A after fracture was 21.0%; 72J; the sample was immersed in a 50% sulfuric acid solution at a temperature of (70±2)°C for a 24-hour corrosion immersion test, and the average corrosion rate of the sample was 33.12g/m ² .h.

Example 4

A gas-shielded solid welding wire suitable for supporting pipelines resistant to sulfuric acid dew point corrosion. The chemical composition of the solid welding wire is calculated by weight percentage, including: C: 0.082wt.%, Mn: 1.30wt.%, Si: 0.32wt.%, Cr: 0.92wt.%, S: 0.008wt.%, P: 0.014wt.%, Sb: 0.081wt.%, Cu: 0.25wt.%, it is impossible to avoid the sum of impurity elements ≤ 0.30wt.%, the balance is Fe; the sum of the mass percentages of each component is 100%.

The deposited metal performance test was carried out on the obtained welding wire: the yield strength R _p0.2 was 523MPa; the tensile strength R _m was 686MPa; the elongation A after fracture was 19.0%; the impact toughness at low temperature was: 61.5J; The sample was immersed in a 50% sulfuric acid solution at a temperature of (70±2)°C for a 24-hour corrosion immersion test, and the average corrosion rate of the sample was 32.51g/m ² .h.

Comparative example 1

A gas shielded welding wire, the chemical composition of the welding wire is calculated by weight percentage, including: C: 0.067wt.%, Mn: 1.55wt.%, Si: 0.78wt.%, Ti: 0.08wt.%, S: 0.015wt .%, P: 0.018wt.%, Cu: 0.10wt.%, it is impossible to avoid the sum of impurity elements ≤ 0.30wt.%, and the balance is Fe; the sum of the mass percentages of each component is 100%.

The deposited metal performance test was carried out on the obtained welding wire: the yield strength R _p0.2 was 531MPa; the tensile strength R _m was 620MPa; the elongation A after breaking was 20%; 76.5J; the sample was immersed in a 50% sulfuric acid solution at a temperature of (70±2)°C for a 24-hour corrosion immersion test, and the average corrosion rate of the sample was 412.23g/m ² .h.

Comparative example 2

A gas shielded welding wire, the chemical composition of the welding wire is calculated by weight percentage, including: C: 0.074wt.%, Mn: 1.67wt.%, Si: 0.60wt.%, Mo: 0.30wt.%, S: 0.012wt .%, P: 0.014wt.%, Ti: 0.07wt.%, Cu: 0.10wt.%, it is impossible to avoid the sum of impurity elements ≤ 0.30wt.%, and the balance is Fe; the sum of the mass percentages of each component is 100%.

The deposited metal performance test was carried out on the obtained welding wire: the yield strength R _p0.2 was 512MPa; the tensile strength R _m was 623MPa; the elongation A after fracture was 23.0%; the low-temperature impact toughness was: 85J; the sample was immersed in a 50% sulfuric acid solution at a temperature of (70±2)°C for a 24-hour corrosion immersion test, and the average corrosion rate of the sample was 389.12g/m ² .h.

Comparative example 3

A gas shielded welding wire, the chemical composition of the welding wire is calculated by weight percentage, including: C: 0.062wt.%, Mn: 1.45wt.%, Si: 0.87wt.%, Ti: 0.12wt.%, S: 0.006wt .%, P: 0.015wt.%, B: 0.0028wt.%, Cu: 0.10wt.%, it is impossible to avoid the sum of impurity elements ≤ 0.30wt.%, and the balance is Fe; the sum of the mass percentages of each component is 100%.

The deposited metal performance test was carried out on the obtained welding wire: the yield strength R _p0.2 was 545MPa; the tensile strength R _m was 640MPa; the elongation A after fracture was 22.0%; 86.3J; the sample was immersed in a 50% sulfuric acid solution at a temperature of (70±2)°C for a 24-hour corrosion immersion test, and the average corrosion rate of the sample was 324.55g/m ² .h.

In the above examples and comparative examples, the welding wire is welded with an Ar-rich mixed gas whose volume percentage is 80% and CO2 is 20%, to obtain deposited metal, wherein the welding parameters are: welding speed: 7mm/s; gas flow rate : 22L/min; current: 280A, voltage: about 30V, channel temperature 140°C.

Table 1 summarizes the chemical composition of the welding wires of the various embodiments and comparative examples of the present invention.

Table 1 chemical composition

Table 2 shows the performance summary of the welding wire cladding metal of each embodiment and comparative example of the present invention.

Table 2 cladding metal properties

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (8)

1. The utility model provides a supporting gas shielded solid welding wire that uses suitable for sulphuric acid dew point corrosion resistant pipeline which characterized in that: the solid welding wire comprises the following chemical components in percentage by weight: 0.07 to 0.09 weight percent of C, 1.20 to 1.60 weight percent of Mn, 0.26 to 0.38 weight percent of Si, 0.90 to 1.00 weight percent of Cr, less than or equal to 0.025 weight percent of S, less than or equal to 0.025 weight percent of P, 0.07 to 0.09 weight percent of Sb, 0.25 to 0.35 weight percent of Cu, and the balance of Fe and inevitable impurities, wherein the sum of the mass fractions of the components is 100 percent.

2. The gas-shielded solid welding wire suitable for the sulfuric acid dew point corrosion-resistant pipeline as claimed in claim 1, wherein: the mass percent of S is less than or equal to 0.008wt%.

3. The gas protection solid welding wire suitable for the pipeline with the resistance to the sulfuric acid dew point corrosion as claimed in claim 1, wherein: the mass percentage of P is less than or equal to 0.015wt%.

4. The gas protection solid welding wire suitable for the pipeline with the resistance to the sulfuric acid dew point corrosion as claimed in claim 1, wherein: the mass percent of Mn is 1.20-1.30wt%.

5. The gas-shielded solid welding wire suitable for the sulfuric acid dew point corrosion-resistant pipeline as claimed in claim 1, wherein: the mass percent of the Cu is 0.25-0.30wt%.

6. The gas protection solid welding wire suitable for the pipeline with the resistance to the sulfuric acid dew point corrosion as claimed in claim 1, wherein: the mechanical properties of the welding wire cladding metal are as follows: the yield strength Rp0.2 is more than or equal to 490MPa; the tensile strength Rm is more than or equal to 620MPa; the elongation A after fracture is more than or equal to 19 percent, and the low-temperature impact toughness is as follows: the impact energy of the welding seam reaches more than 47J at the temperature of minus 20 ℃.

7. A welding method using the gas shielded solid welding wire suitable for the sulfuric acid dew point corrosion-resistant pipeline as set forth in any one of claims 1 to 6, characterized in that: the method comprises the following steps: the composition by volume percentage is Ar 70-90%, CO ₂ Welding 10-30% of Ar-rich mixed gas, wherein the welding parameters are as follows: welding speed: 4-8mm/s, gas flow, 15-25L/min, current: 260-300A, voltage: 27-32V, and the temperature is 150-180 ℃.

8. The welding method of the gas protection solid welding wire suitable for the sulfuric acid dew point corrosion resistant pipeline, which is used together with the pipeline, according to claim 7, is characterized in that: the Ar-rich mixed gas comprises 80-90% of Ar and CO in percentage by volume ₂ 10-20％。