Method for connecting TiC steel bond hard alloy and Q235 steel

Abstract

The invention belongs to the technical field of welding, and particularly relates to a method for connecting TiC steel bond hard alloy and Q235 steel. The method comprises the following steps: coating nano-zinc oxide on the connecting part of TiC steel bond hard alloy and Q235 steel by utilizing epoxy resin AB glue, then carrying out gas metal arc welding, and adopting a nickel alloy welding wire and argon. The welding parameters are as follows: the current is 110 to 200A, the voltage is 24 to 32V, the welding speed is 0.7 to 1.2 mm / s, and the argon flow is 12 to 18L / min. According to the TiC steel bonded hard alloy and the preparation method thereof, during welding, TiC of the part near deposited metal is decomposed to generate Ti and C, nano-zinc oxide is decomposed into Zn and O, C reacts with O to generate CO2, Zn is directly evaporated, the carbon content in a molten pool is reduced, the tendency of generating cracks is reduced, the brittleness of a welded joint is reduced, and the bonding strength of the TiC steel bonded hard alloy and Q235 steel is improved.

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] The production equipment in the mining, cement, coal and other industries have the same characteristics, that is, the key parts that come into contact with foreign materials have high wear resistance requirements on the surface, while the internal toughness requirements are good. As we all know, good toughness leads to lower hardness, so the contradictory requirements of high wear resistance and good toughness are a difficult problem facing the technicians in this industry.

[0003] TiC steel bonded carbide is a material prepared by powder metallurgy method with micron or nano TiC powder as hard phase and alloy steel or carbon steel as bonding phase. It is characterized by high hardness and wear resistance, and has the advantages of alloy steel or carbon steel being weldable, but also has the disadvantages of being brittle and easy to break. Therefore, technicians use TiC steel bonded carbide as surface wear-resistant material and Q235 steel, a low-carbon steel, as internal material. The two are combined to form a composite material, which is used to manufacture key parts of production equipment in mining, cement, coal and other industries to meet the use requirements.

[0004] However, there are great technical difficulties in connecting TiC steel-bonded cemented carbide and Q235 steel: 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 of 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, but 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, and crack sources exist in the finally formed deposited metal, which increases the brittleness and reduces the mechanical properties of the fusion-welded connection of TiC steel-bonded cemented carbide and Q235 steel. Summary of the invention

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

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

[0007] A method for connecting TiC steel-bonded hard alloy and Q235 steel, characterized in that it comprises the following steps:

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

[0009] S2: At room temperature, mix substance X obtained in S1 with substance Y, stir evenly, and obtain substance Z. The time for mixing X and Y evenly shall not exceed 10 minutes, and the interval between the end time of S1 and the start time 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 applied part is the part to be connected with 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: leaving the TiC steel-bonded cemented carbide coated with substance Z to stand at room temperature for 24h-48h;

[0012] S5: placing the relative positions of the TiC steel-bonded cemented carbide coated with substance Z obtained in S4 and the Q235 steel 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 is formed at the connection between TiC steel-bonded hard alloy and Q235 steel, but part of TiC is decomposed to produce Ti and C, and nano zinc oxide is decomposed into Zn and O, wherein C and O react chemically to produce CO2, while Zn evaporates directly, effectively reducing the content of carbon in the molten pool, reducing the tendency to generate cracks and reducing the brittleness of the welded metal of the welded joint, and increasing the bonding strength between TiC steel-bonded hard alloy and Q235 steel. The tensile test shows that the fracture is the heat-affected zone of Q235 steel, while the welded metal and TiC steel-bonded hard alloy are not broken, indicating that the tensile strength of the welded metal of the welded joint prepared by the technology of the present invention and the interface combined with TiC steel-bonded hard alloy is greater than the other side of the parent material Q235 steel, and fully meets the use requirements; while the tensile strength of directly connecting TiC steel-bonded hard alloy to Q235 steel is 280MPa, and the fracture occurs at the interface between the welded metal and the TiC steel-bonded hard alloy. 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, accounting for 35% by mass, and 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 10 mm, leaving a gap of 0.3 mm to 0.8 mm between the two (where the TiC steel-bonded carbide is coated with material Z).

[0020] Embodiment 1:

[0021] A method for connecting TiC steel-bonded hard alloy and Q235 steel comprises the following steps:

[0022] S1: At room temperature, nano zinc oxide is mixed evenly with component A in epoxy resin AB glue to obtain substance X; at room temperature, nano zinc oxide is mixed evenly with component B in 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 in epoxy resin AB glue is 6:1, the volume ratio of nano zinc oxide to component B in 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, stirred evenly, and substance Z is obtained. The time for X and Y to be mixed evenly is 7 minutes, and the interval between the end time of S1 and the start time of S2 is 3 minutes.

[0024] S3: At room temperature, the substance Z obtained in S2 is evenly applied on the TiC steel-bonded carbide. The applied area is the area to be connected with 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 cemented 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 in relative positions as required, with a gap of 0.3 mm between the two.

[0027] 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, model SSNi6625, and its technical requirements are in accordance with GB / T 15620-2008. The diameter of the welding wire is 1.6 mm. The shielding gas used is 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 gas flow rate 12L / min.

[0029] Embodiment 2:

[0030] A method for connecting TiC steel-bonded hard alloy and Q235 steel comprises the following steps:

[0031] S1: At room temperature, nano zinc oxide is mixed evenly with component A in epoxy resin AB glue to obtain substance X; at room temperature, nano zinc oxide is mixed evenly with component B in 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 in epoxy resin AB glue is 10:1, the volume ratio of nano zinc oxide to component B in 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 mixed evenly 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 on the TiC steel-bonded carbide. The applied part is the part to be connected with 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 cemented carbide coated with substance Z is left to stand at room temperature for 48 hours;

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

[0036] 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, model SNi6276, and its technical requirements are in accordance with GB / T 15620-2008. The diameter of the welding wire is 2.0 mm, and the shielding gas used is argon with a purity of 99%.

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

[0038] Embodiment 3:

[0039] A method for connecting TiC steel-bonded hard alloy and Q235 steel, characterized in that it comprises the following steps:

[0040] S1: At room temperature, nano zinc oxide is mixed evenly with component A in epoxy resin AB glue to obtain substance X; at room temperature, nano zinc oxide is mixed evenly with component B in 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 in epoxy resin AB glue is 8:1, the volume ratio of nano zinc oxide to component B in epoxy resin AB glue is 8:1, the particle size of nano zinc oxide is 50nm-100nm, and S1 takes 8min.

[0041] 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 mixed evenly 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 on the TiC steel-bonded carbide. The applied part is the part to be connected with 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 cemented carbide coated with substance Z is 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 in relative positions as required, with a gap of 0.8 mm between the two.

[0045] 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, model SNi6455, and its technical requirements are in accordance with GB / T 15620-2008. The diameter of the welding wire is 2.0 mm. The shielding gas used is 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 gas flow rate 16L / min.

[0047] Comparative Example 1:

[0048] The relative position of TiC steel bonded carbide and Q235 steel is placed as required, with a gap of 0.8mm between them; TiC steel bonded carbide and Q235 steel are welded together by using the method of metal arc welding, the solid welding wire model used is SNi6455, the diameter is 2.0mm, and its technical requirements are in accordance with the provisions of GB / T 15620-2008; the shielding gas used is argon gas, with a purity of 99%. The welding parameters of metal arc welding are: current 160A, voltage 28V, welding speed 1.0mm / s, and argon gas flow rate 16L / min.

[0049] Comparative Example 2:

[0050] It is basically the same as Example 3, except that the nano zinc oxide is replaced by micron 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 conducted in each case, the average of 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 TiC steel-bonded cemented carbide.

[0060] According to the national standard GB / T 700-2006, the tensile strength of Q235 steel is 370-500MPa. The tensile strength of the Q235 steel purchased by the present invention is 430MPa, and 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 are not fully carried out in accordance with the technical requirements of the present invention, and the fracture occurs 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, through the above-mentioned description, relevant staff can make various changes and modifications without departing from the technical idea of ​​the present invention. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope 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 covered within the scope of protection of the present 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 in epoxy resin AB glue to obtain substance X; at room temperature, nano zinc oxide is mixed evenly with component B in epoxy resin AB glue to obtain substance Y; S2: At room temperature, mix substance X and substance Y obtained in S1 together and stir evenly to obtain substance Z. S3: At room temperature, the substance Z obtained in S2 is evenly applied on the TiC steel-bonded carbide, the application location is the location to be connected with the Q235 steel, and the thickness of the substance Z is 0.3mm-0.6mm; S4: leaving the TiC steel-bonded cemented carbide coated with substance Z to stand at room temperature for 24h-48h; S5: placing the relative positions of the TiC steel-bonded cemented carbide coated with substance Z obtained in S4 and the Q235 steel as required; S6: The TiC steel-bonded carbide coated with substance Z is welded to Q235 steel by using the method of metal-electrode gas shielded welding. The welding wire used is solid nickel alloy welding wire, and the shielding gas used is argon gas with a purity of more than 99%.

2. The method for connecting TiC steel-bonded hard alloy and Q235 steel according to claim 1, characterized in that: The particle size of the nano zinc oxide is 50nm-100nm.

3. The method for connecting TiC steel-bonded hard alloy and Q235 steel according to claim 1, characterized in that: 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 hard alloy and Q235 steel according to claim 1, characterized in that: S1 takes no more than 10 minutes.

5. The method for connecting TiC steel-bonded hard alloy and Q235 steel according to claim 1, characterized in that: The interval between the end time of S1 and the start time of S2 is no more than 5 minutes, and the time for mixing X and Y in S2 to be uniformly stirred does not exceed 10 minutes.

6. The method for connecting TiC steel-bonded hard alloy 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 hard alloy 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 hard alloy 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.