Nickel-based brazing filler metal for brazing red copper oxygen lance nozzle and brazing process method

Abstract

The invention belongs to the technical field of welding, and particularly relates to nickel-based brazing filler metal for brazing of a red copper oxygen lance nozzle and a brazing process method.The nickel-based brazing filler metal is prepared from, by mass, 5.5%-8.0% of Cr, 1.5%-3.0% of Se, 1.0%-2.5% of Mo, 1.0%-3.5% of W, 3.5%-6.0% of Si, 2.5%-4.0% of B, 2.0%-3.5% of Fe, 1.5%-3.5% of Ti, 3.5%-6.0% of Cu, 3.0%-5.5% of Zn, 1.0%-3.5% of Re, 1.0%-2.0% of Ag and the balance Ni. The added metallic silver and selenium can improve the conductivity and expandability of the brazing filler metal, improve the cutting performance and reduce the brazing temperature, and the added metallic titanium can refine crystal grains and is combined with chromium, molybdenum and tungsten to generate excellent alloying performance, so that the corrosion resistance and the post-welding stability are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of welding, and in particular relates to a nickel-based brazing filler metal for brazing a copper oxygen lance nozzle and a brazing process method. Background Art

[0002] At present, oxygen lance nozzles are widely used in steelmaking oxygen blowing by taking advantage of the high thermal conductivity of copper materials. For brazing of copper oxygen lance nozzles, silver-containing brazing materials are often used, such as ternary alloy brazing materials with the brazing material model of BAg45CuZn (containing 45% silver, copper and zinc as the remaining components) and quaternary alloy brazing materials of BAg50CuZnCd. This type of silver-based brazing material has the characteristics of low melting point, high strength, good plasticity and processing performance, good corrosion resistance and good conductivity in various media, and good wettability, and can be well combined with copper. Silver can reduce the melting point of the brazing material and improve the fluidity of the brazing material on the surface of copper, thereby ensuring the quality of brazing. However, since the melting point of silver element is 961.93℃, and the basic ambient temperature of steel smelting is above 1000℃, there may be a risk of melting and opening the weld if it is used for a long time in a high temperature environment. In addition, due to the high price of silver, the brazing production and maintenance costs of copper oxygen lance spraying are high. Summary of the invention

[0003] Based on the above problems, the present invention aims to provide a nickel-based brazing filler metal which can achieve good conductivity, wettability and fluidity while increasing its use strength and welding performance after welding, for brazing of copper oxygen lance nozzles.

[0004] The technical scheme adopted by the present invention is: a nickel-based brazing filler metal for brazing of copper oxygen lance nozzles, which is composed of 5.5% to 8.0% Cr (chromium), 1.5% to 3.0% Se (selenium), 1.0% to 2.5% Mo (molybdenum), 1.0% to 3.5% W (tungsten), 3.5% to 6.0% Si (silicon), 2.5% to 4.0% B (boron), 2.0% to 3.5% Fe (iron), 1.5% to 3.5% Ti (titanium), 3.5% to 6.0% Cu (copper), 3.0% to 5.5% Zn (zinc), 1.0% to 3.5% Re (rhenium), 1.0% to 2.0% Ag (silver), and the rest is Ni (nickel);

[0005] According to the above mass percentage ratio, the present invention adopts Cu-Ni alloy, Ni-Cr alloy, B-Ti alloy, Mo-Re alloy, Fe-Ag alloy, W-Cr-Si alloy and Mo-Zn-Se alloy and obtains the required nickel-based brazing filler metal for brazing of copper oxygen lance nozzle by smelting and combining in a smelting furnace.

[0006] In addition, the present invention also provides a brazing process method using the nickel-based brazing filler metal, comprising the following steps:

[0007] Step 1: Pre-treat the various components of the copper oxygen lance nozzle;

[0008] Step 2: Assemble and position the components that make up the copper oxygen lance nozzle;

[0009] Step 3: Perform vacuum brazing;

[0010] Step 4: Cooling and post-processing.

[0011] The beneficial effects of the present invention are as follows: the metal chromium, molybdenum and tungsten elements used in the present invention have excellent alloying properties, and their synergistic effect can make the nickel solder plasticity, stability, service strength and cutting performance. The metal rhenium filled in the present invention can improve the expandability and wettability of the solder, and the solid-liquid phase line temperature is moderate and stable. The addition of metal silver in the present invention can improve the conductivity and expandability of the solder and improve the cutting performance. The addition of metal titanium can improve the strength of the solder, corrosion resistance and stability. The addition of element selenium can improve physical stability and improve cutting performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A flow chart of the brazing process provided by the present invention;

[0013] Figure 2 This is a schematic diagram of the structure of a forging combined oxygen nozzle;

[0014] Among them: 1. Upper oxygen inlet pipe; 2. Throat; 3. Bottom spray hole; 4. Weld. DETAILED DESCRIPTION

[0015] Firstly, the present invention provides a nickel-based brazing filler metal for brazing of copper oxygen lance nozzles based on systematic and in-depth experiments. Since the melting point of nickel is 1453°C, which is nearly 500°C higher than the melting point of silver, the nickel-based brazing filler metal has higher safety during the use of steel smelting. The melting point of the nickel-based brazing filler metal is 1045°C-1077°C. The brazing filler metal composed of these materials is suitable for high-temperature welding and has excellent wettability and fluidity.

[0016] The nickel-based solder is composed of 5.5% to 8.0% Cr, 1.5% to 3.0% Se, 1.0% to 2.5% Mo, 1.0% to 3.5% W, 3.5% to 6.0% Si, 2.5% to 4.0% B, 2.0% to 3.5% Fe, 1.5% to 3.5% Ti, 3.5% to 6.0% Cu, 3.0% to 5.5% Zn, 1.0% to 3.5% Re, 1.0% to 2.0% Ag, and the rest is Ni.

[0017] According to the above mass percentage ratio, the present invention adopts Cu-Ni alloy, Ni-Cr alloy, B-Ti alloy, Mo-Re alloy, Fe-Ag alloy, W-Cr-Si alloy and Mo-Zn-Se alloy to be smelted and combined in a smelting furnace.

[0018] The present invention finds that adding a certain proportion of metal rhenium and silver to nickel solder will affect the fluidity and expandability of the solder. Metal chromium, molybdenum, tungsten and titanium elements have excellent alloying properties. Their synergistic effect can improve the plasticity, stability, use strength and cutting performance of the nickel solder.

[0019] Here are a few examples:

[0020] Embodiment 1:

[0021] A nickel-based brazing filler metal for brazing of copper oxygen lance nozzles comprises the following proportions by mass percentage: 5.5% Cr, 1.5% Se, 1.0% Mo, 1.0% W, 3.5% Si, 2.5% B, 2.0% Fe, 1.5% Ti, 3.5% Cu, 3.0% Zn, 1.0% Re, 1.0% Ag, and the remainder is Ni.

[0022] Embodiment 2:

[0023] A nickel-based brazing filler metal for brazing of copper oxygen lance nozzles comprises the following proportions by mass percentage: 5.8% Cr, 2.0% Se, 1.5% Mo, 1.5% W, 4.0% Si, 3.0% B, 2.5% Fe, 2.0% Ti, 4.0% Cu, 3.5% Zn, 1.5% Re, 1.0% Ag, and the remainder is Ni.

[0024] Embodiment 3:

[0025] A nickel-based brazing filler metal for brazing of copper oxygen lance nozzles comprises, by mass percentage, 6.0% Cr, 2.5% Co, 2.0% Mo, 2.0% W, 4.5% Si, 3.5% B, 3.0% Fe, 2.5% Ti, 4.5% Cu, 4.0% Zn, 2.0% Re, 1.2% Ag, and the remainder Ni.

[0026] Embodiment 4:

[0027] A nickel-based brazing filler metal for brazing of copper oxygen lance nozzles comprises, by mass percentage, 6.2% Cr, 3.0% Se, 2.5% Mo, 2.5% W, 5.0% Si, 4.0% B, 3.5% Fe, 3.0% Ti, 5.0% Cu, 4.5% Zn, 2.5% Re, 1.2% Ag, and the remainder Ni.

[0028] Embodiment 5:

[0029] A nickel-based brazing filler metal for brazing of copper oxygen lance nozzles comprises, by mass percentage, 6.5% Cr, 3.0% Se, 2.5% Mo, 3.5% W, 6.0% Si, 4.0% B, 3.5% Fe, 3.5% Ti, 6.0% Cu, 5.5% Zn, 3.5% Re, 1.4% Ag, and the remainder is Ni.

[0030] Embodiment 6:

[0031] A nickel-based brazing filler metal for brazing of copper oxygen lance nozzles comprises, by mass percentage, 6.9% Cr, 3.0% Se, 2.5% Mo, 3.5% W, 6.0% Si, 4.0% B, 3.5% Fe, 3.5% Ti, 6.0% Cu, 5.5% Zn, 3.5% Re, 1.4% Ag, and the remainder is Ni.

[0032] Embodiment 7:

[0033] A nickel-based brazing filler metal for brazing of copper oxygen lance nozzles comprises, by mass percentage, 7.2% Cr, 3.0% Se, 2.5% Mo, 2.5% W, 6.0% Si, 4.0% B, 3.5% Fe, 3.5% Ti, 6.0% Cu, 5.5% Zn, 3.5% Re, 1.6% Ag, and the remainder Ni.

[0034] Embodiment 8:

[0035] A nickel-based brazing filler metal for brazing of copper oxygen lance nozzles comprises, by mass percentage, 7.5% Cr, 3.0% Se, 2.5% Mo, 3.5% W, 5.0% Si, 4.0% B, 3.5% Fe, 3.5% Ti, 6.0% Cu, 5.5% Zn, 3.5% Re, 1.8% Ag, and the remainder is Ni.

[0036] Embodiment 9:

[0037] A nickel-based brazing filler metal for brazing of copper oxygen lance nozzles comprises the following proportions by mass percentage: 7.8% Cr, 3.0% Se, 2.5% Mo, 3.5% W, 6.0% Si, 4.0% B, 3.5% Fe, 3.5% Ti, 6.0% Cu, 5.5% Zn, 2.5% Re, 1.8% Ag, and the remainder is Ni.

[0038] Embodiment 10:

[0039] A nickel-based brazing filler metal for brazing of copper oxygen lance nozzles comprises, by mass percentage, 8.0% Cr, 2.0% Se, 2.5% Mo, 3.5% W, 6.0% Si, 4.0% B, 3.5% Fe, 3.5% Ti, 6.0% Cu, 5.5% Zn, 3.5% Re, 2.0% Ag, and the remainder is Ni.

[0040] The performance indicators of the above embodiments 1 to 10 are shown in Table 1:

[0041] Table 1 Performance test data table of various embodiments of the present invention;

[0042] It can be seen from Table 1 that the nickel-based brazing alloys obtained in Examples 1 to 10 have good wetting and spreading properties, cutting performance, and other excellent technical indicators. It is found in the post-brazing processing and pressure testing of the nozzle and the feedback from customers on the service life on site that within the ratio range, nickel-based brazing alloys with different ratios have good effects during use and there is no obvious difference.

[0043] This formula improves the wettability of nickel-based brazing filler metal and refines the microstructure of the welded joint by controlling the addition amount of each alloy element, thus greatly reducing the cost.

[0044] Secondly, the present invention also provides a brazing process for the forged assembled copper oxygen lance nozzle based on the above nickel-based brazing filler metal, such as Figure 1 As shown, the following steps are included:

[0045] Step 1: Pre-treat the various components of the copper oxygen lance nozzle;

[0046] In this embodiment, Figure 2 As shown, the components constituting the copper oxygen lance nozzle are, in order according to the direction of oxygen ejection: an upper oxygen inlet pipe 1, a throat pipe 2, and a bottom spray hole 3. The throat pipe 2 and the bottom spray hole 3 need to be connected by brazing to form a weld 4.

[0047] Before brazing, the surfaces of the joints of the components need to be pretreated to remove oxides and other contaminants on the surface;

[0048] Specifically, mechanical cleaning is first performed, preferably using sandpaper to polish the surface of the connection between the throat 2 and the bottom nozzle 3 to remove impurities such as oil stains and rust on the surface to ensure that the brazing material can be in good contact with each component during brazing. The surface roughness of each component after polishing is controlled between Ra3-Ra6.3;

[0049] Then carry out chemical cleaning, which can use a dilute acid solution, preferably a 10% sulfuric acid solution, and soak for 5 minutes to 10 minutes. After that, rinse with clean water and blow dry, which can further remove oxides and other contaminants on the surface.

[0050] Step 2: Assemble and position the components that make up the copper oxygen lance nozzle;

[0051] Assemble the various components of the copper oxygen lance nozzle according to the design requirements;

[0052] Specifically, a special fixture can be used for positioning to ensure uniform gaps between components, wherein the size of the gap is preferably between 0.05mm and 0.15mm to facilitate the filling of solder. At the same time, when applying solder on the workbench, the solder is required to be applied evenly and the contact areas between components are fully filled.

[0053] Step 3: Perform vacuum brazing;

[0054] Specifically, a vacuum brazing furnace may be used to vacuum braze the throat pipe 2 and the bottom nozzle 3;

[0055] When using a vacuum brazing furnace for welding, first, place the parts assembled in step 2 into the effective temperature welding area of ​​the vacuum brazing furnace, and perform vacuum treatment before heating the vacuum brazing furnace. After reaching the required vacuum degree, the vacuum brazing furnace is powered on to heat and heat up, and the brazing operation is performed;

[0056] In the stable temperature stage, the temperature rise rate and the holding time need to be determined according to the characteristics of the material and the process requirements to ensure that the sample reaches the ideal temperature. In this embodiment, the temperature rise process of brazing is preferably: heating to 550°C~650°C for 100 minutes - holding for 20 minutes - heating to 800°C~900°C for 100 minutes - holding for 15 minutes - heating to 950°C~1000°C for 80 minutes - holding for 30 minutes - heating to 1020°C~1070°C for 30 minutes - holding for 70 minutes;

[0057] The purpose of heat preservation at each stage of the brazing heating process is to allow the metal in the brazing material to change its physical properties at a specified temperature for a certain period of time;

[0058] After brazing is completed, the vacuum brazing furnace is turned off and the copper oxygen gun nozzle is taken out of the vacuum brazing furnace.

[0059] Step 4: Cooling and post-processing;

[0060] After brazing, the copper oxygen gun nozzle should be cooled naturally to avoid rapid cooling, as rapid cooling may cause internal stress in the brazed joint, thus affecting the quality of the joint.

[0061] After cooling, perform an appearance inspection on the copper oxygen lance nozzle to check whether there are defects such as incomplete solder filling, pores, cracks, etc. If there are defects, repair welding or re-brazing is required, and then the oxygen lance nozzle is cleaned to remove impurities such as solder flux remaining on the surface.

[0062] The entire brazing process is completed through the above steps.

Claims

1. A nickel-based brazing filler metal for brazing copper oxygen lance nozzles, characterized in that: The nickel-based solder comprises 5.5% to 8.0% Cr, 1.5% to 3.0% Se, 1.0% to 2.5% Mo, 1.0% to 3.5% W, 3.5% to 6.0% Si, 2.5% to 4.0% B, 2.0% to 3.5% Fe, 1.5% to 3.5% Ti, 3.5% to 6.0% Cu, 3.0% to 5.5% Zn, 1.0% to 3.5% Re, 1.0% to 2.0% Ag, and the rest is Ni.

2. A brazing process, characterized in that: The method adopts the nickel-based brazing filler metal for brazing copper oxygen lance nozzles as claimed in claim 1, comprising the following steps: Step 1: Pre-treat the components that make up the copper oxygen lance nozzle; Step 2: Assemble and position the components that make up the copper oxygen lance nozzle; Step 3: Perform vacuum brazing; Step 4: Cooling and post-processing.

3. The brazing process according to claim 2, characterized in that: The step 1 specifically includes: First, mechanical cleaning is performed, and the surface of the connection between the throat and the bottom nozzle is polished with sandpaper. The surface roughness of each component after polishing is controlled between Ra3-Ra6.3; Then carry out chemical cleaning, using 10% sulfuric acid solution to soak each component for 5-10 minutes, then rinse with clean water and blow dry.

4. The brazing process according to claim 2, characterized in that: In the step 2, the size of the assembly gap is 0.05mm-0.15mm. When the brazing material is applied, the brazing material is applied evenly, and the contact area between the throat and the bottom nozzle is filled fully.

5. The brazing process according to claim 2, characterized in that: In the step 3, the heating process of vacuum brazing using vacuum brazing furnace welding is: heating to 550°C~650°C for 100 minutes - keeping warm for 20 minutes - heating to 800°C~900°C for 100 minutes - keeping warm for 15 minutes - heating to 950°C~1000°C for 80 minutes - keeping warm for 30 minutes - heating to 1020°C~1070°C for 30 minutes - keeping warm for 70 minutes.

6. The brazing process according to claim 2, characterized in that: The step 4 is specifically as follows: naturally cool the copper oxygen lance nozzle, and after cooling, visually inspect the copper oxygen lance nozzle to see if there are any defects. If there are any defects, repair welding or re-brazing is required, and then the copper oxygen lance nozzle is cleaned to remove impurities remaining on the surface.

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