CN116871636A - Welding method of pulse arc transfer using flux-cored wire for super duplex stainless steel - Google Patents

Abstract

The invention discloses a welding method for super duplex stainless steel using flux cored wire pulse arc transition. The equipment adopts GMAW (gas shielded metal arc welding) welding equipment. The equipment adopts variable slope and variable inductance control and has the ability to generate pulse arc. A constant voltage power supply with current capability; the pulse arc transfer method is adopted, which specifically uses two power supplies to provide bipolar output power, and the power supply is converted to provide pulses; the process specifically includes the following steps: processing bevels and blunt edges at the welding joints of stainless steel The alignment gap should be consistent; use welding materials to weld the weld in the protective gas; the welding arc starting point is welded on the welding joint itself, and the arc starting point outside the welding area can be removed by fine grinding; use mechanical positioning for positioning welding . The use of this welding method allows the weld metal and base metal to adjust toward higher austenite to improve toughness and compensate for the loss of toughness caused by the increase in oxygen content in the weld metal due to the use of flux.

Description

Welding method of pulse arc transfer using flux-cored wire for super duplex stainless steel

Technical field

The invention relates to a welding method for pulse arc transition using flux-cored wire for super duplex stainless steel, and belongs to the technical field of welding technology.

Background technique

Super duplex stainless steel means that the metallographic structure is austenite + ferrite, and the two-phase structure accounts for about 50% each. Therefore, it has the dual properties of austenitic stainless steel and ferritic stainless steel, and has good mechanical properties and Corrosion resistance: It has excellent resistance to pitting corrosion, stress corrosion and crevice corrosion. It can be used in environments with harsh regulations, high temperatures and strong corrosive media, and is widely used. In traditional welding processes, the use of flux increases the oxygen content of the weld metal, causing a loss of product toughness. Therefore, it is necessary to design a welding process to adjust the weld metal and base metal to the higher austenite direction to improve toughness and further improve corrosion resistance.

Contents of the invention

In view of the problems existing in the above-mentioned prior art, the present invention provides a welding method of super duplex stainless steel using flux-cored wire pulse arc transfer, thereby solving the above technical problems.

In order to achieve the above object, the technical solution adopted by the present invention is: a welding method of pulse arc transfer with flux-cored wire for super duplex stainless steel, which is characterized by:

The equipment adopts GMAW (gas shielded metal arc welding) welding equipment, which adopts variable slope and variable inductance control, and has a constant voltage power supply capable of generating pulse arc current; the pulse arc transition method is adopted, which specifically uses two The power supply provides bipolar output power, which is converted into pulses;

The process specifically includes the following steps: processing grooves and blunt edges at the stainless steel welds, and the alignment gaps should be consistent; using welding materials to weld the welds in protective gas; the welding arc starting point is welded at the welding joint itself, and the welding area Other arc starting points can be removed by fine grinding; positioning welding can be performed using mechanical positioning.

Further, the protective gas includes argon, helium, nitrogen, oxygen and carbon dioxide, wherein the argon content accounts for 80% of the protective gas volume content, and the helium, nitrogen, oxygen and carbon dioxide account for 20% of the protective gas volume content.

Furthermore, the gas flow rate range for welding welds using welding materials in protective gas is 12-16L/min.

Furthermore, the flux-cored wire is selected as the welding material, and the filling flux is automatically supplied through the welding torch. The flux provides part of the alloying elements and welding slag of the weld metal. The current and voltage are 150-200A and 22-28V during horizontal and vertical welding. and 60-110A, 20-24V.

Furthermore, the interlayer temperature of each pass is cooled to below 150°C, so that the heat-affected zone of subsequent weld passes has sufficient cooling time.

Further, the flux is a flux material with a high nickel content as the filler metal.

Furthermore, the diameter of the welding wire should be Φ1-Φ1.6mm, keep it clean and dry, and place it in a covered container. The flat welding position has the best welding effect. The welding torch should be kept as close to vertical as possible to ensure that the amount of air sucked into the protective gas is least.

Furthermore, in order to meet various material thickness and joint design requirements, the flexibility in selecting heat input can be calculated according to the following formula; the heat input is within the range of 0.5-2.5KJ/mm;

Heat input (KJ/mm) = (V*A)/(S*1000)

Among them: V=voltage, A=current, S=moving speed.

The beneficial effects of the present invention are:

1. The present invention adopts automatic GMAW professional equipment, utilizes variable slope and variable inductance control, and has a constant voltage power supply capable of generating pulse arc current. This method requires two power supplies to provide two levels of output power, and the power conversion provides pulses. In the spray transfer stage, the metal transfer amount is large, while in the granular droplet transfer stage, the metal transfer amount is small. This combination has the advantages of high metal deposition speed and limited heat input;

2. The present invention is suitable for economically depositing a large amount of weld metal, and can automatically weld structures with simple shapes. Supplement with GTAW method to obtain optimal control in complex operations;

3. The present invention uses flux-cored welding wire combined with the GMAW method to automatically supply filling flux through the welding torch. The flux provides part of the alloying elements and welding slag of the weld metal to protect the weld from air oxidation and pollution. It is provided through the welding torch. The protective gas protects the heat affected zone. The high nickel content in flux-cored welding wire makes the austenite content in the weld metal higher than the close-to-equilibrium base metal structure, thereby achieving stable welding and improving the toughness of the weld body.

The use of this welding method allows the weld metal and base metal to adjust toward higher austenite to improve toughness and compensate for the loss of toughness caused by the increase in oxygen content in the weld metal due to the use of flux.

Implementation

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below through examples. However, it should be understood that the specific embodiments described here are only used to explain the present invention and are not used to limit the scope of the present invention.

Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the technical field of the present invention. The terms used herein in the description of the present invention are only for describing specific implementations. The examples are not intended to limit the invention.

The invention utilizes automatic GMAW professional equipment, utilizes variable slope and variable inductance control, and is a constant voltage power supply capable of generating pulse arc current. Its advantages: This method requires two power supplies to provide two levels of output power, and the power conversion provides pulses. In the spray transfer stage, the metal transfer amount is large, while in the granular droplet transfer stage, the metal transfer amount is small. This combination has the advantage of high metal deposition rates while limiting heat input.

When welding duplex steels using the GMAW method, the most commonly used filler metals are “match” filler metals with a slightly higher nickel content. Super duplex stainless steel filler metal has been successfully used to weld 2205 base metal. The diameter of the welding wire is Φ1-Φ1.6mm. Keep it clean and dry. Place it in a covered container. The flat welding position has the best welding effect. Keep the welding torch as close to vertical as possible to minimize the amount of air sucked into the protective gas.

In order to meet various material thickness and joint design requirements, the flexibility in selecting heat input can be calculated according to the following formula. The heat input is generally in the range of 0.5-2.5KJ/mm.

Heat input (KJ/mm) = (V*A)/(S*1000)

Among them: V=voltage; A=current; S=moving speed.

GMAW is called gas metal arc welding, also known as inert gas metal arc welding (MIG). It is especially suitable for weld metals that require economical deposition of large amounts of metal. It can automatically weld simple-shaped structures. Supplement with GTAW method to obtain optimal control in complex operations.

Equipment: GMAW requires professional equipment, variable slope and variable inductance control, and a constant voltage power supply with the ability to generate pulse arc current. GMAW should be DC Reverse Polarity (DCRP).

Pulse arc transfer: This method requires two power supplies to provide two levels of output power, and the power supply is converted to provide pulses. In the spray transfer stage, the metal transfer amount is large, while in the granular droplet transfer stage, the metal transfer amount is small. This combination has the advantage of high metal deposition rates while limiting heat input.

Protection: The protective gas of GMAW method contains 80% argon, and the remaining 20% is added with helium, nitrogen, oxygen and carbon dioxide. The addition of these gases can improve the weldability of welded components and the performance of the finished product. The gas flow rate can be in the range of (12-16L) min according to the transition mode and transition speed and the diameter of the welding wire (Φ1-Φ1.6mm). During the welding process, avoid extending the welding wire too long to protect it from gas protection. Sound organization of the gas delivery system is critical, and effective measures should be taken to prevent the protective gas from being inhaled into the air.

Flux-cored wire (FCW): Flux-cored wire is combined with the GMAW method to automatically supply filling flux through the welding torch. The flux provides some of the alloying elements and welding slag of the weld metal, protecting the weld from air oxidation and pollution. The torch provides protective gas to protect the heat affected zone. The nickel content in flux-cored wire is high so that the austenite content in the weld metal is higher than the base metal structure close to equilibrium. When using flux-cored wire for production, welding wire from the same source used for welding process qualification should be used to avoid production instability. When using 1.2mm, the current and voltage during flat and vertical welding are divided into 150-200A, 22-28V and 60-110A, 20-24V.

Process requirements: ⑴ The alignment gap of the machined grooves and blunt edges of the base metal should be consistent; ⑵ Avoid using copper backing plates, because copper will cause rapid cooling in some cases; ⑶ The welding arc starting point should be at the welding joint itself When starting welding, arc starting points outside the welding area will cause the local solder joints of autogenous welding to cool too quickly, resulting in local high ferrite content and loss of corrosion resistance. If there are arc starting points outside the welding area, they can be removed by fine grinding; ⑷ Complete gas protection should be used for positioning welding. Positioning should be based on mechanical positioning, and solder joint positioning cannot be used; ⑸ The temperature between each pass is cooled to below 150°C, so that the heat-affected zone of subsequent welding passes has sufficient cooling time.

The use of this welding method allows the weld metal and base metal to adjust toward higher austenite to improve toughness and compensate for the loss of toughness caused by the increase in oxygen content in the weld metal due to the use of flux. Welding products of duplex stainless steel, especially super duplex stainless steel, are particularly suitable for places with poor climate environments, such as coastal areas, seabeds, chemical industries and other highly corrosive places. They are also especially suitable for major and key national projects, such as, Nuclear power plants, civil air defense projects, etc. are of great significance.

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

Claims (8)

1. A welding method for super duplex stainless steel using flux-cored wire pulse arc transfer, which is characterized by: The equipment adopts GMAW (gas shielded metal arc welding) welding equipment, which adopts variable slope and variable inductance control, and has a constant voltage power supply capable of generating pulse arc current; the pulse arc transition method is adopted, which specifically uses two The power supply provides bipolar output power, which is converted into pulses; The process specifically includes the following steps: processing grooves and blunt edges at the stainless steel welds, and the alignment gaps should be consistent; using welding materials to weld the welds in protective gas; the welding arc starting point is welded at the welding joint itself, and the welding area Other arc starting points can be removed by fine grinding; positioning welding can be performed using mechanical positioning. 2. A kind of welding method for super duplex stainless steel with flux-cored wire pulse arc transfer according to claim 1, characterized in that the protective gas includes argon, helium, nitrogen, oxygen and carbon dioxide, wherein the argon content Accounting for 80% of the protective gas volume content, helium, nitrogen, oxygen and carbon dioxide account for 20% of the protective gas volume content. 3. A kind of welding method for super duplex stainless steel with flux-cored wire pulse arc transfer according to claim 1, characterized in that the gas flow rate range of using welding materials to weld the weld seam in the protective gas is 12-16L/ min. 4. A kind of welding method for super duplex stainless steel with flux-cored wire pulse arc transfer according to claim 1, characterized in that the flux-cored wire is selected as the welding material, and the filling flux is automatically supplied through the welding torch, and the flux provides a partial The alloy elements and welding slag of the weld metal, the current and voltage during horizontal and vertical welding are divided into 150-200A, 22-28V and 60-110A, 20-24V. 5. A kind of welding method for super duplex stainless steel using flux-cored wire pulse arc transfer according to claim 1, characterized in that the interlayer temperature of each pass is cooled to below 150°C, so that the heat-affected zone of the subsequent weld pass has Sufficient cooling time. 6. A welding method for pulse arc transfer using flux-cored wire for super duplex stainless steel according to claim 1, characterized in that the flux is a flux material in which the filler metal is nickel. 7. A welding method for pulse arc transfer using flux-cored wire for super duplex stainless steel according to claim 1, characterized in that the diameter of the welding wire is Φ1-Φ1.6mm, kept clean and dry, and placed in a covered container. In the flat welding position, the welding effect is best, and the welding torch should be kept as close to vertical as possible to minimize the amount of air sucked into the shielding gas. 8. A welding method for flux-cored wire pulse arc transfer for super duplex stainless steel according to claim 1, characterized in that, in order to meet various material thickness and joint design requirements, the flexibility of selecting heat input is greater, and can Calculate according to the following formula; the heat input is within the range of 0.5-2.5KJ/mm; Heat input (KJ/mm) = (V*A)/(S*1000) Among them: V=voltage, A=current, S=moving speed.