A method for connecting TiC steel-bonded carbide and Q235 steel

Abstract

The present invention belongs to the field of welding technology, specifically a method for connecting TiC steel-bonded hard alloy and Q235 steel. Nano zinc oxide is applied to the connection portion of the TiC steel-bonded hard alloy with Q235 steel using epoxy resin AB glue, and then metal arc welding is performed using nickel alloy welding wire and argon gas. The welding parameters are: current 110-200A, voltage 24-32V, welding speed 0.7-1.2mm / s, and argon gas flow rate 12-18L / min. During welding, the TiC near the deposited metal decomposes to produce Ti and C, and the nano zinc oxide decomposes into Zn and O. C and O react to generate CO2, and Zn directly evaporates, thereby reducing the carbon content in the molten pool, reducing the tendency to crack, reducing the brittleness of the weld joint, and increasing the bonding strength between the TiC steel-bonded hard alloy and Q235 steel.

Description

Technical Field

[0001] The invention belongs to the technical field of welding, and in particular relates to a method for connecting TiC steel-bonded hard alloy and Q235 steel. Background Art

[0002] Production equipment in industries like mining, cement, and coal all share a common characteristic: critical components that come into contact with foreign materials require high surface wear resistance while maintaining excellent internal toughness. As is well known, increased toughness reduces hardness, so this conflicting requirement for high wear resistance and excellent toughness presents a difficult challenge for industry technicians.

[0003] TiC steel-bonded carbide is a material produced through powder metallurgy using micron- or nano-sized TiC powder as the hard phase and alloy steel or carbon steel as the bonding phase. It features high hardness, wear resistance, and the weldability advantages of alloy steel or carbon steel, but also suffers from the disadvantages of being brittle and prone to fracture. Therefore, technicians use TiC steel-bonded carbide as the wear-resistant surface material and Q235 steel, a low-carbon steel, as the internal material, combining the two to form a composite material used to manufacture key components in production equipment in industries such as mining, cement, and coal, meeting their application requirements.

[0004] However, the connection between TiC steel-bonded cemented carbide and Q235 steel is technically difficult: if brazing is used, the connection strength is low, the service life of the workpiece is short, and the required equipment is large, making it difficult to complete the operation on large workpieces; if fusion welding is used, it can be constructed on large workpieces and can improve the strength of the connection between the two. However, since TiC in the molten pool of TiC steel-bonded cemented carbide is easily decomposed into Ti and C during welding, the C element content in the molten pool is too high, crack sources exist in the finally formed deposited metal, and the brittleness is increased, which reduces the mechanical properties of the fusion-welded connection between TiC steel-bonded cemented carbide and Q235 steel. Summary of the Invention

[0005] The invention provides a method for connecting TiC steel-bonded cemented carbide and Q235 steel, which solves the following technical problem: how to effectively reduce the C content generated by TiC decomposition in the molten pool when TiC steel-bonded cemented carbide and Q235 steel are fusion-welded.

[0006] The present invention adopts the following technical solutions:

[0007] A method for connecting TiC steel-bonded cemented carbide and Q235 steel, characterized by comprising the following steps:

[0008] S1: At room temperature, nano zinc oxide is uniformly mixed with component A of epoxy resin AB glue to obtain substance X; at room temperature, nano zinc oxide is uniformly mixed with component B of epoxy resin AB glue to obtain substance Y; the epoxy resin AB glue is Caihong brand epoxy resin AB glue (trade name: strong AB glue), type E7, produced by Foshan Caihong Building Materials Co., Ltd.; the volume ratio of nano zinc oxide to component A of epoxy resin AB glue is (6-10):1, the volume ratio of nano zinc oxide to component B of epoxy resin AB glue is (6-10):1, the particle size of nano zinc oxide is 50nm-100nm, and S1 takes no more than 10 minutes.

[0009] S2: At room temperature, mix substance X obtained in S1 with substance Y and stir them evenly to obtain substance Z. The time required for mixing X and Y evenly shall not exceed 10 minutes, and the interval between the end of S1 and the start of S2 shall not exceed 5 minutes.

[0010] S3: At room temperature, the substance Z obtained in S2 is evenly applied on the TiC steel-bonded carbide. The application area is the area to be connected to the Q235 steel. The thickness of the substance Z is 0.3mm-0.6mm. The total time from the start of S1 to the end of S3 is no more than 60min.

[0011] S4: The TiC steel-bonded carbide coated with substance Z is allowed to stand at room temperature for 24-48 hours;

[0012] S5: placing the TiC steel-bonded carbide coated with substance Z obtained in S4 and the Q235 steel at relative positions as required;

[0013] S6: The TiC steel-bonded carbide coated with substance Z is welded to Q235 steel by gas metal arc welding. The welding wire used is solid nickel alloy welding wire. The model of the solid nickel alloy welding wire is any one of SNi6012, SNi6022, SNi6057, SNi6058, SNi6059, SNi6200, SNi6276, SNi6452, SNi6455, SNi6625, SNi6650, SNi6660, SNi6686, and SNi7725. The technical requirements are in accordance with GB / T 15620-2008. The diameter of the welding wire is 1.6 mm or 2.0 mm. The shielding gas used is argon with a purity of more than 99%.

[0014] The welding parameters of metal arc welding are: current 110A-200A, voltage 24V-32V, welding speed 0.7mm / s-1.2mm / s, and argon flow rate 12L / min-18L / min.

[0015] The present invention has the following beneficial technical effects:

[0016] During welding, under the high temperature of the arc, a molten pool forms at the junction of the TiC steel-bonded carbide and Q235 steel. However, some TiC decomposes to produce Ti and C, while nano-zinc oxide decomposes into Zn and O. The C and O react chemically to produce CO2, while the Zn evaporates directly. This effectively reduces the carbon content in the molten pool, reduces the tendency to crack, reduces the brittleness of the welded joint deposit, and increases the bonding strength between the TiC steel-bonded carbide and Q235 steel. Tensile tests show that the fracture sites are all in the heat-affected zone of the Q235 steel, while the deposited metal and the TiC steel-bonded carbide do not break. This indicates that the tensile strength of the welded joint deposited metal prepared using the present invention and the interface with the TiC steel-bonded carbide is greater than that of the other side of the parent material Q235 steel, fully meeting the requirements of use. In contrast, the tensile strength of the TiC steel-bonded carbide directly connected to Q235 steel is 280MPa, with fracture occurring at the interface between the deposited metal and the TiC steel-bonded carbide. DETAILED DESCRIPTION

[0017] The principles and features of the present invention are described below in conjunction with embodiments and comparative examples. The enumerated embodiments and comparative examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0018] The hard phase used in TiC steel-bonded cemented carbide is TiC particles, which account for 35% by mass. The chemical composition (mass fraction) of the bonding phase is: 8.3% C, 6.2% manganese, 1.3% molybdenum, 1.8% nickel, 33.5% titanium, and the balance is iron.

[0019] TiC steel-bonded carbide and Q235 steel are both welded on single layer, single pass and double sides with a thickness of 10mm, leaving a gap of 0.3mm-0.8mm between the two (wherein the TiC steel-bonded carbide is coated with substance Z).

[0020] Example 1:

[0021] A method for connecting TiC steel-bonded cemented carbide and Q235 steel, comprising the following steps:

[0022] S1: At room temperature, nano zinc oxide is uniformly mixed with component A of epoxy resin AB glue to obtain substance X; at room temperature, nano zinc oxide is uniformly mixed with component B of epoxy resin AB glue to obtain substance Y; the epoxy resin AB glue is Caihong brand epoxy resin AB glue (trade name: strong AB glue), type E7, produced by Foshan Caihong Building Materials Co., Ltd.; the volume ratio of nano zinc oxide to component A of epoxy resin AB glue is 6:1, the volume ratio of nano zinc oxide to component B of epoxy resin AB glue is 6:1, the particle size of nano zinc oxide is 50nm-100nm, and S1 takes 8 minutes.

[0023] S2: At room temperature, substance X obtained in S1 is mixed with substance Y and stirred evenly to obtain substance Z. The time for X and Y to mix evenly is 7 minutes, and the interval between the end of S1 and the start of S2 is 3 minutes.

[0024] S3: At room temperature, the substance Z obtained in S2 is evenly applied to the TiC steel-bonded carbide at the location to be connected to the Q235 steel. The thickness of the substance Z is 0.3 mm. The total time from the start of S1 to the end of S3 is 50 min.

[0025] S4: The TiC steel-bonded carbide coated with substance Z is left to stand at room temperature for 28 hours.

[0026] S5: The TiC steel-bonded carbide coated with substance Z obtained in S4 and the Q235 steel are placed relative to each other as needed, with a gap of 0.3 mm between them.

[0027] S6: TiC steel-bonded carbide coated with substance Z was welded to Q235 steel using the metal arc welding method. The welding wire used was a solid nickel alloy welding wire of model SSNi6625. Its technical requirements were in accordance with GB / T 15620-2008, and the welding wire diameter was 1.6 mm. The shielding gas used was argon with a purity of 99%.

[0028] The welding parameters of the metal arc welding are: current 110A, voltage 24V, welding speed 0.7mm / s, and argon flow rate 12L / min.

[0029] Example 2:

[0030] A method for connecting TiC steel-bonded cemented carbide and Q235 steel, comprising the following steps:

[0031] S1: At room temperature, nano zinc oxide is uniformly mixed with component A of epoxy resin AB glue to obtain substance X; at room temperature, nano zinc oxide is uniformly mixed with component B of epoxy resin AB glue to obtain substance Y; the epoxy resin AB glue is Caihong brand epoxy resin AB glue (trade name: strong AB glue), type E7, produced by Foshan Caihong Building Materials Co., Ltd.; the volume ratio of nano zinc oxide to component A of epoxy resin AB glue is 10:1, the volume ratio of nano zinc oxide to component B of epoxy resin AB glue is 10:1, the particle size of nano zinc oxide is 50nm-100nm, and S1 takes 10 minutes.

[0032] S2: At room temperature, substance X obtained in S1 is mixed with substance Y, stirred evenly, and substance Z is obtained. The time for X and Y to be evenly mixed is 10 minutes, and the interval between the end time of S1 and the start time of S2 is 5 minutes.

[0033] S3: At room temperature, the substance Z obtained in S2 is evenly applied to the TiC steel-bonded carbide at the location to be connected to the Q235 steel. The thickness of the substance Z is 0.6 mm. The total time from the start of S1 to the end of S3 is 60 min.

[0034] S4: The TiC steel-bonded carbide coated with substance Z is left to stand at room temperature for 48 h;

[0035] S5: The TiC steel-bonded carbide coated with substance Z obtained in S4 and the Q235 steel are placed relative to each other as needed, with a gap of 0.8 mm between them.

[0036] S6: TiC steel-bonded carbide coated with substance Z was welded to Q235 steel using the metal arc welding method. The welding wire used was solid nickel alloy welding wire, model SNi6276, and its technical requirements were in accordance with GB / T 15620-2008. The welding wire diameter was 2.0 mm, and the shielding gas used was argon with a purity of 99%.

[0037] The welding parameters of the metal arc welding are: current 200A, voltage 32V, welding speed 1.2mm / s, and argon flow rate 18L / min.

[0038] Example 3:

[0039] A method for connecting TiC steel-bonded cemented carbide and Q235 steel, characterized by comprising the following steps:

[0040] S1: At room temperature, nano zinc oxide is uniformly mixed with component A of epoxy resin AB glue to obtain substance X; at room temperature, nano zinc oxide is uniformly mixed with component B of epoxy resin AB glue to obtain substance Y; the epoxy resin AB glue is Caihong brand epoxy resin AB glue (trade name: strong AB glue), type E7, produced by Foshan Caihong Building Materials Co., Ltd.; the volume ratio of nano zinc oxide to component A of epoxy resin AB glue is 8:1, the volume ratio of nano zinc oxide to component B of epoxy resin AB glue is 8:1, the particle size of nano zinc oxide is 50nm-100nm, and S1 takes 8 minutes.

[0041] S2: At room temperature, substance X obtained in S1 is mixed with substance Y and stirred evenly to obtain substance Z. The time for X and Y to be evenly mixed is 9 minutes, and the interval between the end time of S1 and the start time of S2 is 4 minutes.

[0042] S3: At room temperature, the substance Z obtained in S2 is evenly applied to the TiC steel-bonded carbide at the location to be connected to the Q235 steel. The thickness of the substance Z is 0.45 mm. The total time from the start of S1 to the end of S3 is 55 min.

[0043] S4: The TiC steel-bonded carbide coated with substance Z was left to stand at room temperature for 36 h;

[0044] S5: The TiC steel-bonded carbide coated with substance Z obtained in S4 and the Q235 steel are placed relative to each other as needed, with a gap of 0.8 mm between them.

[0045] S6: TiC steel-bonded carbide coated with substance Z was welded to Q235 steel using the metal arc welding method. The welding wire used was a solid nickel alloy welding wire of model SNi6455. Its technical requirements were in accordance with GB / T 15620-2008, and the welding wire diameter was 2.0 mm. The shielding gas used was argon with a purity of 99%.

[0046] The welding parameters of the metal arc welding are: current 160A, voltage 28V, welding speed 1.0mm / s, and argon flow rate 16L / min.

[0047] Comparative Example 1:

[0048] TiC steel-bonded carbide and Q235 steel were positioned relative to each other, with a gap of 0.8 mm between them. The two were welded together using MIG / MAG welding. The solid welding wire used was SNi6455, 2.0 mm in diameter, and the technical requirements were in accordance with GB / T 15620-2008. The shielding gas used was argon with a purity of 99%. The MIG / MAG welding parameters were: current 160 A, voltage 28 V, welding speed 1.0 mm / s, and argon flow rate 16 L / min.

[0049] Comparative Example 2:

[0050] The method is basically the same as Example 3, except that nano zinc oxide is replaced with micron-sized zinc oxide.

[0051] Comparative Example 3:

[0052] The method is basically the same as Comparative Example 1, except that the surface of the SNi6455 solid welding wire used is coated with nano zinc oxide (using epoxy resin AB glue).

[0053] It is basically the same as Example 3, except that the thickness of substance C in S3 is 0.25 mm.

[0054] Comparative Example 5:

[0055] It is basically the same as Example 3, except that the thickness of substance C in S3 is 0.70 mm.

[0056] The purchased Q235 steel was subjected to a tensile test, and its tensile strength was measured to be 430 MPa. The welded joints obtained in Examples 1-3 and Comparative Examples 1-5 were sampled and subjected to tensile tests according to the standard. After 5 experiments were performed in each case, the average of the 5 results was taken. The results are shown in Table 1.

[0057] Table 1

[0058] project Example 1 Example 2 Example 3 Comparative Example 1 Tensile strength / MPa 405 416 411 280 project Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Tensile strength / MPa 332 356 318 329

[0059] Note: The fracture of Example 1-3 is in the heat-affected zone of Q235 steel, and the fracture of Comparative Example 1-5 is in the interface between the deposited metal and the TiC steel-bonded cemented carbide.

[0060] According to the national standard GB / T 700-2006, the tensile strength of Q235 steel is 370-500 MPa. The tensile strength of the Q235 steel purchased by the present invention is 430 MPa. The welding heat-affected zone will be slightly lower than this value. Examples 1, 2, and 3 all broke in the welding heat-affected zone, which is a normal phenomenon, indicating that the connection between TiC steel-bonded cemented carbide and Q235 steel meets the use requirements; while Comparative Examples 1-5 did not fully comply with the technical requirements of the present invention, and the fracture occurred at the connection interface between the deposited metal and the TiC steel-bonded cemented carbide, indicating that the connection problem between TiC steel-bonded cemented carbide and Q235 has not yet been solved.

[0061] With the above-mentioned ideal embodiments of the present invention as inspiration, and through the above description, relevant personnel can make various changes and modifications without departing from the scope of the technical concept of this invention. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of this invention.

Claims

1. A method for connecting TiC steel-bonded cemented carbide and Q235 steel, characterized in that: The following steps are involved: S1: At room temperature, nano zinc oxide is mixed evenly with component A of epoxy resin AB glue to obtain substance X; at room temperature, nano zinc oxide is mixed evenly with component B of epoxy resin AB glue to obtain substance Y; S2: At room temperature, mix substance X and substance Y obtained in S1 and stir them evenly to obtain substance Z. S3: At room temperature, evenly apply the substance Z obtained in S2 on the TiC steel-bonded carbide. The application area is the area to be connected to the Q235 steel. The thickness of the substance Z is 0.3mm-0.6mm. S4: The TiC steel-bonded carbide coated with substance Z is allowed to stand at room temperature for 24-48 hours; S5: placing the TiC steel-bonded carbide coated with substance Z obtained in S4 and the Q235 steel at relative positions as required; S6: The TiC steel-bonded carbide coated with substance Z is welded to Q235 steel by using the metal-metal-shielded gas welding method. The welding wire used is solid nickel alloy welding wire, and the shielding gas used is argon with a purity of more than 99%.

2. The method for connecting TiC steel-bonded cemented carbide and Q235 steel according to claim 1, wherein: The particle size of the nano zinc oxide is 50nm-100nm.

3. The method for connecting TiC steel-bonded cemented carbide and Q235 steel according to claim 1, wherein: The volume ratio of nano zinc oxide to component A in epoxy resin AB glue in S1 is (6-10):1, and the volume ratio of nano zinc oxide to component B in epoxy resin AB glue is (6-10):

1.

4. The method for connecting TiC steel-bonded cemented carbide and Q235 steel according to claim 1, wherein: S1 takes no more than 10 minutes.

5. The method for connecting TiC steel-bonded cemented carbide and Q235 steel according to claim 1, wherein: The interval between the end time of S1 and the start time of S2 shall not exceed 5 minutes, and the time for uniform mixing of X and Y in S2 shall not exceed 10 minutes.

6. The method for connecting TiC steel-bonded cemented carbide and Q235 steel according to claim 1, characterized in that: The total time from the start of S1 to the end of S3 shall not exceed 60 minutes.

7. The method for connecting TiC steel-bonded cemented carbide and Q235 steel according to claim 1, characterized in that: The model of the solid nickel alloy welding wire is any one of SNi6012, SNi6022, SNi6057, SNi6058, SNi6059, SNi6200, SNi6276, SNi6452, SNi6455, SNi6625, SNi6650, SNi6660, SNi6686, and SNi7725, and the diameter of the welding wire is 1.6 mm or 2.0 mm.

8. The method for connecting TiC steel-bonded cemented carbide and Q235 steel according to claim 1, characterized in that: The welding parameters of metal arc welding are: current 110A-200A, voltage 24V-32V, welding speed 0.7mm / s-1.2mm / s, and argon flow rate 12L / min-18L / min.