Flux-cored wire and method for enhancing acid corrosion resistance of low-carbon steel surface

Abstract

The present invention discloses a flux-cored wire for enhancing the acid corrosion resistance of the surface of low-carbon steel, which comprises a flux core and a wire sheath. The flux core is composed of the following components by mass percentage: Mn powder: 50-60%; CrN powder: 5-8%; Al powder: 5%-8%; Si powder: 1%; Fe powder: the balance, and the sum of the mass percentages of the above components is 100%. It is used to improve the disadvantages of the acid corrosion resistance of the surface of low-carbon steel, thereby effectively prolonging the service life of low-carbon steel structural parts in a corrosive environment. A method for enhancing the acid corrosion resistance of the surface of low-carbon steel is also disclosed.

Description

Technical Field

[0001] The present invention belongs to the technical field of surface property strengthening of carbon steel metal materials, and particularly relates to a flux-cored wire for enhancing the acid corrosion resistance of the surface of low-carbon steel, and also relates to a method for enhancing the acid corrosion resistance of the surface of low-carbon steel. Background Art

[0002] Due to its good mechanical properties and weldability, low-carbon steel is widely used in industrial production and manufacturing. Moreover, compared with other steel materials, its greatest advantage lies in its low price, and the application fields of low-carbon steel are constantly expanding. However, the corrosion resistance of low-carbon steel is poor, and the performance of single low-carbon steel materials often fails to meet the usage requirements of the working environment, thus restricting its application in acidic corrosion environments and corrosive media.

[0003] In order to effectively solve the problem of the corrosion performance defect of low-carbon steel, researchers at home and abroad have conducted a large number of experiments and studies on the surface modification and strengthening methods of low-carbon steel. Currently, nickel-chromium stainless steel is commonly used for the selection of surface modification materials, but its high price makes it impossible to be applied to large-scale equipment. While nickel-saving high-manganese austenitic steel not only has good corrosion resistance but also low price, and has gradually been taken seriously by researchers in various countries. By consulting a large number of literature methods, there are few studies on modifying the acid corrosion resistance of the surface of low-carbon steel based on arc cladding at present. Therefore, the present invention aims to improve the acid corrosion resistance of the cladding layer of low-carbon steel. Ordinary nickel and chromium austenitic steels have high costs, low strength and poor wear resistance. Therefore, high-manganese austenitic steel is introduced as the cladding layer of low-carbon steel to improve the corrosion resistance of the cladding layer of low-carbon steel and extend the service life of low-carbon steel in acidic corrosion environments. Summary of the Invention

[0004] The first object of the present invention is to provide a flux-cored wire for enhancing the acid corrosion resistance of the surface of low-carbon steel, which is used to improve the disadvantages of the acid corrosion resistance of the surface of low-carbon steel, thereby effectively extending the service life of low-carbon steel structural parts in corrosive environments.

[0005] The second object of the present invention is to provide a method for enhancing the acid corrosion resistance of the surface of low-carbon steel.

[0006] The first technical solution adopted by the present invention is a flux-cored wire for enhancing the acid corrosion resistance of the surface of low-carbon steel, which includes a flux core and a wire sheath. The flux core is composed of the following components by mass percentage: Mn powder: 50-60%; CrN powder: 5-8%; Al powder: 5%-8%; Si powder: 1%; Fe powder: the balance, and the sum of the mass percentages of the above components is 100%.

[0007] The present invention is further characterized in that

[0008] Control the powder filling rate to be 25 wt.% - 27 wt.%.

[0009] The outer skin is made of low-carbon steel strip, and the specific components are: C: 0.021%; Mn: 0.15%; S: 0.006%; P: 0.007%; Si: 0.19%; Fe: the balance.

[0010] The second technical solution adopted by the present invention is a method for enhancing the acid corrosion resistance of the low-carbon steel surface, which is specifically implemented according to the following steps:

[0011] Step 1: Preparation of the flux-cored wire for enhancing the acid corrosion resistance of the low-carbon steel surface:

[0012] Weigh the following raw material powders by mass percentage respectively: Mn powder: 50 - 60%; CrN powder: 5 - 8%; Al powder: 5% - 8%; Si powder: 1%; Fe powder: the balance, and the sum of the mass percentages of the above components is 100%;

[0013] Step 2: First, dry the weighed powders to remove the moisture contained in the powders; then carry out alloying treatment using a planetary ball mill; after the ball mill finishes the powder mixing treatment, let the powders stand still in a dry place for 2 - 3 h; use low-carbon steel strip as the outer skin, fill the powder on the outer skin, control the powder filling rate to be 25 wt.% - 27 wt.%, and the diameter reduction of the flux-cored wire is carried out every 0.2 mm until the diameter is 1.2 mm. After the wire is prepared, store it in a constant temperature box;

[0014] Step 3: Treat the surface of the low-carbon steel plate by mechanical grinding to remove surface impurities;

[0015] Step 4: Carry out cladding on the low-carbon steel plate by MIG (inert gas shielded welding);

[0016] Step 5: Use an electric spark cutting device to cut the top of the cladding layer flat.

[0017] The present invention is further characterized in that,

[0018] In Step 4, MIG is used as the cladding method, where the cladding voltage is 20 - 25 V, the cladding current is 180 - 190 A, the welding speed is 0.3 m / min - 0.4 m / min, the shielding gas is argon with a volume fraction of 99.99%, and the gas flow rate is 10 - 15 L / min.

[0019] The beneficial effects of the present invention are:

[0020] (1) The present invention uses a flux-cored wire to carry out cladding on the low-carbon steel surface to enhance the acid corrosion resistance of the low-carbon steel surface. Compared with traditional nickel and chromium stainless steels, it has higher strength and considerable economy, and its non-magnetic property can be applied to occasions with specific requirements for magnetic permeability;

[0021] (2) The flux-cored wire of the present invention can conveniently adjust the flux composition according to the composition and performance requirements of the base material, so as to obtain the optimal surface modification effect. This method can prepare a cladding layer with good bonding to the low-carbon steel matrix and good acid corrosion resistance, which can greatly improve the service life of the component and has good application prospects;

[0022] (3) The flux-cored wire provided by the present invention can reduce the precipitates during the welding process and improve the pitting corrosion resistance of the material. Description of the Drawings

[0023] Figure 1 is the microstructure diagram of the bonding interface between the low-carbon steel and the acid corrosion-resistant layer prepared in Example 1 of the present invention. Detailed Embodiments

[0024] The present invention will be described in detail below with reference to the drawings and specific embodiments.

[0025] The present invention provides a flux-cored wire for enhancing the acid corrosion resistance of the surface of low-carbon steel, which includes a flux core and a wire sheath. The flux core is composed of the following components by mass percentage: Mn powder: 50-60%; CrN powder: 5-8%; Al powder: 5%-8%; Si powder: 1%; Fe powder: the balance, and the sum of the mass percentages of the above components is 100%.

[0026] Among them, the powder filling rate is controlled to be 25wt.% - 27wt.%.

[0027] The sheath is a low-carbon steel strip, and the specific composition is C: 0.021%; Mn: 0.15%; S: 0.006%; P: 0.007%; Si: 0.19%; Fe: the balance.

[0028] The present invention also provides a method for enhancing the acid corrosion resistance of the surface of low-carbon steel, which is specifically implemented according to the following steps:

[0029] Step 1: Preparation of the above-mentioned flux-cored wire for enhancing the acid corrosion resistance of the surface of low-carbon steel:

[0030] Weigh the following raw material powders respectively by mass percentage: Mn powder: 50-60%; CrN powder: 5-8%; Al powder: 5%-8%; Si powder: 1%; Fe powder: the balance, and the sum of the mass percentages of the above components is 100%;

[0031] Step 2: The weighed powder is first dried to remove the moisture contained in the powder; then it is subjected to alloying treatment using a planetary ball mill; after the ball mill finishes the powder mixing treatment, the powder is left to stand in a dry place for 2 - 3 h; a low-carbon steel strip is used as the outer skin, and powder is filled on the outer skin, controlling the powder filling rate to be 25 wt.% - 27 wt.%, and the diameter of the flux-cored wire is reduced by 0.2 mm at intervals until the diameter reaches 1.2 mm. After the wire is prepared, it is stored in a constant temperature oven;

[0032] In step 2, the flux-cored wire is prepared by mechanical drawing. Among them, the outer skin of the flux-cored wire is made of a low-carbon steel strip with a specification of 7×0.2 mm;

[0033] Step 3: The surface of the low-carbon steel plate is treated by mechanical grinding to remove surface impurities;

[0034] In step 3, Q345B is used for the process exploration test, with a specification of 150 mm×100 mm×15 mm;

[0035] Step 4: Cladding is carried out on the low-carbon steel plate by MIG (inert gas shielded welding);

[0036] In step 4, MIG is used as the cladding method, where the cladding voltage is 20 - 25 V, the cladding current is 180 - 190 A, the welding speed is 0.3 m / min - 0.4 m / min, the shielding gas is argon with a volume fraction of 99.99%, and the gas flow rate is 10 - 15 L / min.

[0037] Step 5: The top of the cladding layer is cut flat using an electric discharge cutting device.

[0038] Example 1

[0039] Step 1: Preparation of a flux-cored wire for enhancing the acid corrosion resistance of the low-carbon steel surface: Weigh the raw material powders according to mass percentages: Mn powder: 50%; CrN powder: 8%; Al powder: 5%; Si powder: 1%; Fe powder: 36%.

[0040] Step 2: The weighed powder is first dried to remove the moisture contained in the powder; then it is subjected to alloying treatment using a planetary ball mill; after the ball mill finishes the powder mixing treatment, the powder is left to stand in a dry place for 2 h; then powder is filled on the outer skin. The outer skin is made of a low-carbon steel strip with a specification of 7×0.2 mm, and the powder filling rate is 25 wt.%. The diameter of the flux-cored wire is reduced by 0.2 mm at intervals until the diameter reaches 1.2 mm. After the wire is prepared, it is stored in a constant temperature oven; among them, the outer skin of the flux-cored wire is made of a low-carbon steel strip with a specification of 7×0.2 mm;

[0041] Step 3: The surface of the low-carbon steel plate (using Q345B plate) is treated by mechanical cleaning to remove surface impurities;

[0042] Step 4: Use the flux-cored wire prepared in Step 2 to prepare a clad layer on the surface of low-carbon steel; the cladding voltage is 22 V, the cladding current is 180 A, the welding speed is 0.3 m / min, the shielding gas is argon with a volume fraction of 99.99%, and the gas flow rate is 15 L / min;

[0043] Step 5: Use an electric discharge cutting device to cut the top of the clad layer flat;

[0044] Step 6: Conduct a full immersion corrosion test on the specimen in Step 5 to compare the corrosion rates of low-carbon steel and the clad layer.

[0045] For the clad layer obtained in Example 1, as Figure 1 shown, it can be seen that the corrosion layer structure is austenite structure, which has good corrosion resistance. At the same time, it forms a good metallurgical bond with the steel, and a clad layer with good bonding to the low-carbon steel substrate and good acid corrosion resistance can be prepared, which can greatly improve the service life of the component and has good application prospects. After the full immersion corrosion test (the corrosion environment is 3.5 wt.% NaCl solution), its highest corrosion rate is 0.18 mm / a, while the original average corrosion rate of low-carbon steel is 1.065 mm / a.

[0046] Example 2

[0047] Step 1: Preparation of a flux-cored wire for enhancing the acid corrosion resistance of the low-carbon steel surface: Weigh the raw material powders by mass percentage: Mn powder: 55%; CrN powder: 8%; Al powder: 5%; Si powder: 1%; Fe powder: 31%.

[0048] Step 2: First, dry the weighed powders to remove the moisture contained in the powders; then carry out alloying treatment using a planetary ball mill; after the ball mill finishes the powder mixing treatment, let the powders stand at a dry place for 2 h; then fill the powders in the outer skin, the outer skin selects a low-carbon steel strip with a specification of 7×0.2 mm, the powder filling rate is 26 wt.%, the wire diameter of the flux-cored wire needs to be reduced by 0.2 mm every interval until the diameter is 1.2 mm, and after the wire is prepared, store it in a constant temperature oven; among them, the outer skin of the flux-cored wire selects a low-carbon steel strip with a specification of 7×0.2 mm;

[0049] Step 3: Use a mechanical cleaning method to treat the surface of the low-carbon steel plate (using Q345B plate) to remove surface impurities;

[0050] Step 4: Use the flux-cored wire prepared in Step 2 to prepare a clad layer on the surface of low-carbon steel; the cladding voltage is 25 V, the cladding current is 190 A, the welding speed is 0.3 m / min, the shielding gas is argon with a volume fraction of 99.99%, and the gas flow rate is 15 L / min;

[0051] Step 5: Use an electric discharge machining equipment to cut the top of the cladding layer flat;

[0052] Step 6: Conduct a full immersion corrosion test on the specimen in Step 5, and compare the corrosion rates of low-carbon steel and the cladding layer.

[0053] After the full immersion corrosion test on the cladding layer obtained in Example 2, it is found that (the corrosion environment is 3.5 wt.% NaCl solution), its highest corrosion rate is 0.192 mm / a, while the original average corrosion rate of low-carbon steel is 1.065 mm / a.

[0054] Example 3

[0055] Step 1: Preparation of a flux-cored wire for enhancing the acid corrosion resistance of the low-carbon steel surface: Weigh the raw material powders by mass percentage: Mn powder: 60%; CrN powder: 8%; Al powder: 8%; Si powder: 1%; Fe powder: 23%.

[0056] Step 2: First, dry the weighed powders to remove the moisture contained in the powders; then carry out alloying treatment using a planetary ball mill; after the ball mill finishes the powder mixing process, let the powders stand still in a dry place for 2 h; then fill the powders into the outer skin. The outer skin is made of low-carbon steel strip with a specification of 7×0.2 mm, the powder filling rate is 27 wt.%, and the diameter of the flux-cored wire is reduced by 0.2 mm every interval until the diameter reaches 1.2 mm. After the wire is prepared, store it in a constant temperature oven; among them, the outer skin of the flux-cored wire is made of low-carbon steel strip with a specification of 7×0.2 mm;

[0057] Step 3: Use a mechanical cleaning method to treat the surface of the low-carbon steel plate (using Q345B plate) to remove surface impurities;

[0058] Step 4: Use the flux-cored wire prepared in Step 2 to prepare a cladding layer on the surface of the low-carbon steel; the cladding voltage is 20 V, the cladding current is 190 A, the welding speed is 0.4 m / min, the shielding gas is argon with a volume fraction of 99.99%, and the gas flow rate is 15 L / min;

[0059] Step 5: Use an electric discharge machining equipment to cut the top of the cladding layer flat;

[0060] Step 6: Conduct a full immersion corrosion test on the specimen in Step 5, and compare the corrosion rates of low-carbon steel and the cladding layer.

[0061] After the full immersion corrosion test on the cladding layer obtained in Example 3, it is found that (the corrosion environment is 3.5 wt.% NaCl solution), its highest corrosion rate is 0.203 mm / a, while the original average corrosion rate of low-carbon steel is 1.065 mm / a.

[0062] Example 4

[0063] Step 1: Preparation of the flux-cored wire for enhancing the acid corrosion resistance of the low-carbon steel surface: Weigh the raw material powders by mass percentage: Mn powder: 55%; CrN powder: 7%; Al powder: 6%; Si powder: 1%; Fe powder: 31%.

[0064] Step 2: First, dry the weighed powders to remove the moisture contained in the powders; then carry out alloying treatment using a planetary ball mill; after the ball mill finishes the powder mixing process, let the powders stand still in a dry place for 2 h; then fill the powder in the outer skin. The outer skin selects a low-carbon steel strip with a specification of 7×0.2 mm, and the powder filling rate is 26 wt.%. The diameter reduction of the flux-cored wire is carried out every 0.2 mm until the diameter reaches 1.2 mm. After the wire is prepared, store it in a constant-temperature box; among them, the outer skin of the flux-cored wire selects a low-carbon steel strip with a specification of 7×0.2 mm;

[0065] Step 3: Treat the surface of the low-carbon steel plate (using Q345B plate) by mechanical cleaning method to remove surface impurities;

[0066] Step 4: Use the flux-cored wire prepared in Step 2 to prepare the cladding layer on the low-carbon steel surface; the cladding voltage is 22 V, the cladding current is 180 A, the welding speed is 0.3 m / min, the shielding gas uses argon with a volume fraction of 99.99%, and the gas flow rate is 10 L / min;

[0067] Step 5: Use an electric spark cutting device to cut the top of the cladding layer flat;

[0068] Step 6: Carry out a full immersion corrosion test on the specimen in Step 5 to compare the corrosion rates of the low-carbon steel and the cladding layer.

[0069] For the cladding layer obtained in Example 4, after the full immersion corrosion test (the corrosion environment is 3.5 wt.% NaCl solution), its highest corrosion rate is 0.19 mm / a, while the original average corrosion rate of the low-carbon steel is 1.085 mm / a.

[0070] Example 5

[0071] Step 1: Preparation of the flux-cored wire for enhancing the acid corrosion resistance of the low-carbon steel surface: Weigh the raw material powders by mass percentage: Mn powder: 60%; CrN powder: 8%; Al powder: 7%; Si powder: 1%; Fe powder: 24%.

[0072] Step 2: The weighed powder is first dried to remove the moisture contained in the powder; then alloying treatment is carried out using a planetary ball mill; after the ball mill finishes the powder mixing treatment, the powder is left standing in a dry place for 3 h; then powder filling is carried out on the outer skin, the outer skin is made of low-carbon steel strip with a specification of 7×0.2 mm, the powder filling rate is 27 wt.%, the diameter of the flux-cored wire is reduced by 0.2 mm every other time until the diameter reaches 1.2 mm, and after the wire is prepared, it is stored in a constant temperature oven; among them, the outer skin of the flux-cored wire is made of low-carbon steel strip with a specification of 7×0.2 mm;

[0073] Step 3: The surface of the low-carbon steel plate (using Q345B plate) is treated by mechanical cleaning to remove surface impurities;

[0074] Step 4: The flux-cored wire prepared in Step 2 is used to prepare a clad layer on the surface of the low-carbon steel; the cladding voltage is 23 V, the cladding current is 190 A, the welding speed is 0.4 m / min, the shielding gas is argon with a volume fraction of 99.99%, and the gas flow rate is 15 L / min;

[0075] Step 5: The top of the clad layer is cut flat using an electric spark cutting device;

[0076] Step 6: The specimens in Step 5 are subjected to a full immersion corrosion test to compare the corrosion rates of the low-carbon steel and the clad layer.

[0077] For the clad layer obtained in Example 5, after the full immersion corrosion test (the corrosion environment is 3.5 wt.% NaCl solution), its highest corrosion rate is 0.193 mm / a, while the original average corrosion rate of the low-carbon steel is 1.065 mm / a.

Claims

1. A method for enhancing the acid corrosion resistance of the surface of low-carbon steel, characterized in that, The implementation is specifically carried out according to the following steps: Step 1: Preparation of the flux-cored wire for enhancing the acid corrosion resistance of the low-carbon steel surface: Weigh the following raw material powders by mass percentage respectively: Mn powder: 50 - 60%; CrN powder: 5 - 8%; Al powder: 5% - 8%; Si powder: 1%; Fe powder: the balance, and the sum of the mass percentages of the above components is 100%; Step 2: First, dry the weighed powders to remove the moisture contained in the powders; then carry out alloying treatment using a planetary ball mill; after the ball mill finishes the powder mixing treatment, let the powders stand still in a dry place for 2 - 3 h; use low-carbon steel strip as the outer skin, fill the powder on the outer skin, control the powder filling rate to be 25wt.% - 27wt.%, and the diameter reduction of the flux-cored wire is carried out every 0.2 mm until the diameter reaches 1.2 mm. After the wire is prepared, store it in an incubator; Step 3: Treat the surface of the low-carbon steel plate by mechanical grinding to remove surface impurities; Step 4: Carry out cladding on the low-carbon steel plate by MIG; Step 5: Cut the top of the cladding layer flat using an electric spark cutting device.

2. The method for enhancing the acid corrosion resistance of the surface of low-carbon steel according to claim 1, characterized in that, In Step 4, MIG is used as the cladding method, where the cladding voltage is 20 - 25 V, the cladding current is 180 - 190 A, the welding speed is 0.3 m / min - 0.4 m / min, the shielding gas is argon with a volume fraction of 99.99%, and the gas flow rate is 10 - 15 L / min.

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