CN100532004C - Ultra-low hydrogen basic welding rod for P92 steel welding - Google Patents

Abstract

The ultra-low hydrogen basic electrode for welding P92 steel belongs to the field of welding in material processing engineering, and is mainly used in the welding of P92 steel. The development of calcium oxide slag-based P92 steel ultra-low hydrogen alkaline electrode has not yet been related to patents and literature reports at home and abroad. The present invention is characterized in that the electrode coating is a material containing the following mass percentages: 1-7% ferromanganese, 4-9% ferrosilicon, 1.5-2.5% aluminum, 3-8% nickel powder, 1-4% quartz, 3% ～6% ferroniobium, 0.5～1.0% ferrovanadium, 4.5～6% titanium dioxide, 20～30% fluorite, 40～60% marble. The technological performance of the developed electrode is good. Compared with the imported electrode, the developed electrode has good welding process characteristics such as small spatter, good fluidity of molten pool, uniform slag coverage, fine and beautiful weld shape, and easy slag removal. The diffusible hydrogen content of the deposited metal is effectively controlled, and the diffusible hydrogen content of the deposited metal is 1.985mL/100g, which meets the requirements of the ultra-low hydrogen standard.

Description

Ultra-low hydrogen alkaline electrode for welding P92 steel

technical field

The invention belongs to the field of welding technology in material processing engineering, and the invention is mainly applied to the welding of P92 steel.

Background technique

Since the 1980s, countries such as the United States, Germany, France, and Japan have successively developed a series of new 9-12% chromium martensitic heat-strength steels, which can be used for supercritical and supercritical steels with steam parameters up to 600/610°C and 25MPa. Supercritical boiler unit. Typical steel grades are: T/P91, T/P92 (NF616) containing 9% Cr and T/P122 (HCM12A) containing 12% Cr. These steel types are high-performance heat-strength steels obtained by improving the original T/P9 and F12, and their high-temperature durable mechanical properties are significantly better than low-alloy pearlitic heat-resistant steels. The emergence of new martensitic heat-resistant steel provides the possibility and safety guarantee for the development of power plant units in the direction of large capacity and high parameters.

On the basis of T/P91 steel, T/P92 steel appropriately reduces the content of molybdenum (0.5% Mo), and at the same time adds a certain amount of tungsten (1.8% W) to change the molybdenum equivalent (Mo+0.5W) of the material from T 1% of /P91 steel refers to about 1.5%, and a small amount of boron is also added. Compared with other chromium-molybdenum heat-resistant steels, the high-temperature corrosion and oxidation resistance of T/P92 steel improved by alloying is similar to that of 9% Cr steel, but the high-temperature strength and creep properties of the material have been further improved, which has been Close to austenitic steel TP347H. The main advantage is that under the same working temperature, pressure or design life conditions, the weight of the power plant boiler and piping system can be further reduced; or under the same structural size, the design working temperature of the structure can be further increased, thereby improving the thermal efficiency of the system. Compared with T/P91 steel, T/P92 steel has excellent comprehensive performance, and has attracted widespread attention from all over the world and has been applied in coal-fired power stations in developed countries. At the same time, the United States has included P92 steel in its ASME standard in 2002. P92 steel has been used in the four major pipelines of the 4×1000MW unit of the Huaneng Yuhuan Power Plant built in my country. Shandong Zouxian Power Plant and Jiangsu Changshu Power Plant also used T/P92 steel in their expansion projects. Moreover, with the development of my country's units in the direction of high efficiency, large capacity, and high clean coal technology, it is expected that the general application of the new martensitic heat-strength steel T/P92 will be inevitable in the maintenance and renovation of old power plants and new power plants in my country in the future. trend.

Develop welding consumables with various performance indicators that are at or close to the level of similar foreign products that match T/P92 steel and are cheap, change the current situation that T/P92 steel welding consumables are completely dependent on imports, and realize the localization of T/P92 steel welding consumables, not only It can save a lot of foreign exchange for the country, and it has important practical significance and significant economic benefits for promoting the wide application of T/P92 steel in power stations in my country.

The development of calcium oxide slag-based P92 steel ultra-low hydrogen alkaline electrode has not yet been related to patents and literature reports at home and abroad.

Contents of the invention

The purpose of the present invention is to solve the formula problem of P92 welding rod, because T/P92 steel works under high temperature and high pressure, the alloy content is higher and has certain crack tendency, so the coating slag system of the welding rod is required to be able to ensure that the welding core composition has The higher alloy transition coefficient can also ensure that the weld metal has less impurity content, less hydrogen content and good crack resistance. Therefore, the basic low-hydrogen type slag system composed of CaCO ₃ -CaF ₂ -SiO ₂ was selected as the coating type of the developed electrode, and effective measures were taken to limit the content of diffusible hydrogen in the weld metal to 5mL/ Ultra-low hydrogen range electrodes within 100g (mercury method). The invention provides an ultra-low hydrogen basic electrode (abbreviated as P92 electrode) for welding calcium oxide slag-based P92 steel.

The invention provides an ultra-low hydrogen basic electrode for welding P92 steel, which is characterized in that the coating of the electrode contains the following mass percentages: 1-7% ferromanganese, 4-9% ferrosilicon, 1.5-2.5% Aluminum, 3-8% nickel powder, 1-4% quartz, 3-6% ferroniobium, 0.5-1.0% ferrovanadium, 4.5-6% titanium dioxide, 20-30% fluorite, 40-60% marble.

Wherein the effect of each component is as follows:

Ferromanganese: Deoxidation, transition metal manganese to the weld, plays the role of weld alloying, and its main function is to strengthen and improve the strength of the weld metal. Mn can reduce the phase transition temperature from austenite to ferrite, inhibit the phase transition of austenite to pro-eutectoid ferrite and side lath ferrite at higher temperatures, and promote the formation of acicular ferrite , while improving the strength of the weld metal, it also improves the toughness of the weld metal.

Ferrosilicon: deoxidizes, transitions silicon into the weld, and strengthens the weld metal at the same time.

Aluminum: deoxidized.

Nickel powder: the alloying effect transfers nickel to the weld. Adding a certain amount of Ni is beneficial to improve the impact toughness of the weld metal, and at the same time offset the high temperature red brittleness trend caused by the existence of Cu.

Quartz: making slag and adjusting the viscosity of the coating.

Ferroniobium: Alloying, transitioning niobium into the weld.

Ferrovanadium: Alloying, transitioning vanadium into the weld.

Titanium dioxide: Improves the characteristics of the slag, stabilizes the arc and refines the droplet.

Fluorite: slagging, dehydrogenation, improving the viscosity of slag, etc.

Marble: making slag, making gas, stabilizing the arc, and refining the molten droplet.

The main task of welding metallurgy is to deoxidize and transfer alloys to the weld so that the weld can obtain good comprehensive mechanical properties. Due to the selection of better matching of metal powder and alloy powder, coupled with moderate slagging, gas-generating substances and arc stabilizing agents, the electrode has obtained good process performance; the cladding metal composition, mechanical properties and process performance of the electrode See Table 1, and see Table 2 for the diffusible hydrogen content.

The technological performance of the developed electrode is good. Compared with the imported electrode, the developed electrode has good welding process characteristics such as small spatter, good fluidity of molten pool, uniform slag coverage, fine and beautiful weld shape, and easy slag removal. The diffusible hydrogen content of the deposited metal is effectively controlled, and the diffusible hydrogen content of the deposited metal is 1.985mL/100g, which meets the requirements of the ultra-low hydrogen standard.

The preparation method of the present invention adopts prior art, comprises the following steps:

1. According to the developed electrode coating formula, the electrode coating pressing drug powder is prepared.

2. The production of welding rods is produced in the welding rod press coating machine. Add the powder prepared according to the developed formula into the press coating machine, and use ordinary welding rods with steel core H08Mn2SiA or high chromium molybdenum steel wire rods to press into welding rod products.

Detailed ways

All embodiment welding rods are all made by common welding rod pressure coating machine:

1. Choose Φ2.5 high chromium molybdenum steel wire rod as the steel core. Take 20 grams of ferromanganese, 40 grams of ferrosilicon, 15 grams of aluminum, 30 grams of nickel powder, 10 grams of quartz, 30 grams of ferro-niobium, 5 grams of ferro-vanadium, 50 grams of titanium dioxide, 200 grams of fluorite, 600 grams of marble, a total of 1000 grams And 40 grams of water glass, put into the powder mixer and mix for 10 minutes, then add the mixed powder in the welding rod press coater. Pressed into electrodes, the welding process parameters are: electrode drying (°C h): 350×2; preheating temperature (°C): 150-200; interlayer temperature (°C): 200-250; welding current (A): 110～130; welding voltage (V): 25～28; post-weld heat treatment specification (℃ h): 770±10×2～4; heating rate (℃/h): 100～120; cooling rate (℃/h ): 120~150. The results of mechanical properties are shown in Table 3, and the content of diffusible hydrogen is shown in Table 4.

2. Choose Φ3.2 high chromium molybdenum steel wire rod as the steel core. Take 30 grams of ferromanganese, 60 grams of ferrosilicon, 22 grams of aluminum, 38 grams of nickel powder, 30 grams of quartz, 50 grams of ferro-niobium, 6 grams of ferro-vanadium, 50 grams of titanium dioxide, 250 grams of fluorite, 464 grams of marble, a total of 1000 gram and 60 grams of water glass, put into the powder mixer and mix for 10 minutes, then add the mixed powder in the welding rod press coater. Pressed into electrodes, the welding process parameters are: electrode drying (°C h): 350×2; preheating temperature (°C): 150-200; interlayer temperature (°C): 200-250; welding current (A): 110～130; welding voltage (V): 25～28; post-weld heat treatment specification (℃ h): 770±10×2～4; heating rate (℃/h): 100～120; cooling rate (℃/h ): 120~150. The results of mechanical properties are shown in Table 5, and the content of diffusible hydrogen is shown in Table 6.

3. Choose Φ4.0 high chromium molybdenum steel wire rod as the steel core. Take 42 grams of ferromanganese, 70 grams of ferrosilicon, 25 grams of aluminum, 50 grams of nickel powder, 40 grams of quartz, 35 grams of ferro-niobium, 8 grams of ferro-vanadium, 60 grams of titanium dioxide, 260 grams of fluorite, 410 grams of marble, a total of 1000 grams , and 80 grams of water glass, put into the powder mixer and mix for 10 minutes, then add the mixed powder into the welding rod press coater. Pressed into electrodes, the welding process parameters are: electrode drying (°C h): 350×2; preheating temperature (°C): 150-200; interlayer temperature (°C): 200-250; welding current (A): 110～130; welding voltage (V): 25～28; post-weld heat treatment specification (℃ h): 770±10×2～4; heating rate (℃/h): 100～120; cooling rate (℃/h ): 120~150. The results of mechanical properties are shown in Table 7, and the content of diffusible hydrogen is shown in Table 8.

4. Choose Φ4.0H08Mn2SiA as the steel core. Take 10 grams of ferromanganese, 90 grams of ferrosilicon, 25 grams of aluminum, 30 grams of nickel powder, 40 grams of quartz, 30 grams of ferro-niobium, 8 grams of ferro-vanadium, 50 grams of titanium dioxide, 300 grams of fluorite, 417 grams of marble, a total of 1000 grams , and 80 grams of water glass, put into the powder mixer and mix for 10 minutes, then add the mixed powder into the welding rod press coater. Pressed into electrodes, the welding process parameters are: electrode drying (°C h): 350×2; preheating temperature (°C): 150-200; interlayer temperature (°C): 200-250; welding current (A): 110～130; welding voltage (V): 25～28; post-weld heat treatment specification (℃ h): 770±10×2～4; heating rate (℃/h): 100～120; cooling rate (℃/h ): 120~150. The results of mechanical properties are shown in Table 9, and the content of diffusible hydrogen is shown in Table 10.

5. Choose Φ4.0H08Mn2SiA as the steel core. Take 70 grams of ferromanganese, 40 grams of ferrosilicon, 25 grams of aluminum, 80 grams of nickel powder, 10 grams of quartz, 60 grams of ferro-niobium, 10 grams of ferro-vanadium, 45 grams of titanium dioxide, 260 grams of fluorite, 400 grams of marble, a total of 1000 grams , and 80 grams of water glass, put into the powder mixer and mix for 10 minutes, then add the mixed powder into the welding rod press coater. Pressed into electrodes, the welding process parameters are: electrode drying (°C h): 350×2; preheating temperature (°C): 150-200; interlayer temperature (°C): 200-250; welding current (A): 110～130; welding voltage (V): 25～28; post-weld heat treatment specification (℃ h): 770±10×2～4; heating rate (℃/h): 100～120; cooling rate (℃/h ): 120~150. The results of mechanical properties are shown in Table 11, and the content of diffusible hydrogen is shown in Table 12.

High chromium molybdenum steel wire rod steel core composition

C Si mn Cr Mo V 0.08-0.11 0.20-0.50 0.32-0.56 8.0-9.5 0.85-1.05 0.18-0.25

Table 1 Mechanical properties and process properties of cladding metal

Table 2 Diffusible hydrogen content of electrode deposited metal (mL/100g)

sample 1 2 3 4 average value content 1.27 1.47 2.57 2.63 1.985

Table 3 Mechanical properties and process properties of cladding metal

Table 4 Diffusible hydrogen content of electrode deposited metal (mL/100g)

sample 1 2 3 4 average value content 2.68 3.25 2.11 2.87 2.7275

Table 5 Mechanical properties and process properties of cladding metal

Table 6 Diffusible hydrogen content of electrode deposited metal (mL/100g)

sample 1 2 3 4 average value content 0.86 1.39 1.64 1.77 1.415

Table 7 Mechanical properties and process properties of cladding metal

Table 8 Diffusible hydrogen content of electrode deposited metal (mL/100g)

sample 1 2 3 4 average value content 0.78 1.25 1.34 1.68 1.2625

Table 9 Mechanical properties and process properties of cladding metal

Table 10 Diffusible hydrogen content of electrode deposited metal (mL/100g)

sample 1 2 3 4 average value content 0.80 1.35 1.44 1.68 1.3175

Table 11 Mechanical properties and process properties of cladding metal

Table 12 Diffusible hydrogen content of electrode deposited metal (mL/100g)

sample 1 2 3 4 average value content 0.76 1.26 1.54 1.72 1.32

Claims (1)

1. An ultra-low hydrogen alkaline electrode for welding P92 steel, characterized in that the electrode coating is a material containing the following mass percentages: 1-7% ferromanganese, 4-9% ferrosilicon, 1.5-2.5% aluminum, 3-8% nickel powder, 1-4% quartz, 3-6% ferroniobium, 0.5-1.0% ferrovanadium, 4.5-6% titanium dioxide, 20-30% fluorite, 40-60% marble.