Welding method suitable for unequal-thickness / unequal-material pipe blanks

Abstract

According to the welding method suitable for the unequal-thickness / unequal-material pipe blanks, a proper welding mode is flexibly selected according to the overall thickness of the pipe blanks, the thickness ratio between different pipe sections, strength and surface material characteristic combination, on this basis, mechanical property experiments for weld joints and products are combined, accurate optimization of welding parameters can be achieved, and the welding quality is improved. Therefore, the forming quality and the production efficiency of various types of pipe blanks are remarkably improved, and the defect that the follow-up process effect and the finished product quality are affected due to low material performance in the existing manufacturing process of the unequal-thickness pipe blanks based on the TRB rolling process is effectively overcome.

Description

Technical Field

[0001] This invention belongs to the field of welding technology for heterogeneous and irregularly shaped metal tube blanks, and specifically relates to a welding method for tube blanks with unequal thickness / unequal material. Background Technology

[0002] With the increasing demands for lightweighting and structural safety in automobiles, higher performance requirements are being placed on components such as body tubing. Currently, to ensure that components simultaneously meet multiple performance indicators such as strength, toughness, and formability, the field mainly employs combinations of tube blanks with different thicknesses, strength grades, and even surface conditions. In practice, the TRB (Tailor Rolled Blank) rolling process is often used to first produce plates of unequal thickness, which are then rolled and welded to obtain tube blanks of unequal thickness. After processing, the materials generally exhibit numerous problems such as increased yield strength, increased tensile strength, decreased elongation, and severe work hardening, which in turn affect the stability and performance of subsequent thermal forming processes. Furthermore, this process is quite complex, making it difficult to reduce labor and material costs. On the other hand, existing welding methods suitable for tube blanks of equal thickness or the same material cannot adequately meet the welding requirements of unequal thicknesses, different strengths, and combinations of coated and uncoated materials. Welding quality and consistency are difficult to guarantee, easily leading to coating damage, substandard strength indicators, and even further exacerbation of work hardening. Summary of the Invention

[0003] In view of this, and to address the technical problems existing in this field, the present invention provides a welding method suitable for tube blanks of unequal thickness / unequal material, specifically including the following steps:

[0004] Step 1: Select the slab raw materials corresponding to different pipe sections based on the wall thickness and strength design parameters of the target tube blank;

[0005] Step 2: Based on the combination of the overall thickness of the target tube blank and the thickness ratio of its adjacent tube sections, determine the specific slab welding method, including:

[0006] ① When the overall thickness of the target tube blank is less than 3mm and the thickness ratio of adjacent tube sections is less than 2, use fillerless laser welding or fillerless argon arc welding to provide better welding operation efficiency.

[0007] ② When the overall thickness of the target tube blank is greater than 3mm and the thickness ratio of adjacent tube sections is greater than 2, filler wire laser welding or filler wire argon arc welding should be selected to provide higher weld joint strength and toughness.

[0008] ③ For other combinations of the overall thickness of the target tube blank and the thickness ratio of adjacent tube sections, select the no-filler welding or filler welding method according to the actual efficiency or joint strength and toughness index;

[0009] Step 3: Based on the combinations and corresponding welding methods determined in Step 2, determine the following combination of characteristics for the target tube blank:

[0010] ① Adjacent pipe sections have the same thickness but different strengths;

[0011] ② Adjacent pipe sections have different thicknesses but equal strength;

[0012] ③ Adjacent pipe sections have different thicknesses and strengths;

[0013] ④ The adjacent pipe sections are respectively coated pipe sections and uncoated pipe sections;

[0014] Select the appropriate laser welding or argon arc welding method based on the combination of characteristic types, efficiency, and welding joint performance requirements.

[0015] Step 4: For any target tube blank, the overall thickness, the thickness ratio of adjacent tube segments, and the combination of characteristics, verify the final selected welding method, and optimize the welding parameters in conjunction with product mechanical property experiments.

[0016] Furthermore, when manufacturing target pipe blanks with different strengths for adjacent pipe sections, the slab material is specifically selected from any combination of high-strength steel, ultra-high-strength steel, duplex steel, martensitic steel, and austenitic steel.

[0017] Furthermore, the product mechanical performance tests performed in step four specifically include verification tests on weld strength, product toughness, elongation, and fatigue life; the optimized welding parameters include welding current, voltage, welding speed, and shielding gas flow rate.

[0018] Accordingly, the present invention also provides a method for manufacturing automotive unequal thickness / unequal material tube blank components, wherein the welding process utilizes the welding method for unequal thickness / unequal material tube blanks provided by the present invention.

[0019] Furthermore, after obtaining the integral slab by performing the method provided by the present invention, the target tube blank is obtained by rolling or drawing and combining welding processes; the target tube blank can be further processed by straightening, bending, annealing, thermal expansion forming and secondary coating to obtain the vehicle body component product.

[0020] Furthermore, after obtaining the integral slab by performing the method provided by the present invention, the weld seam is subjected to necessary shaping and heat treatment.

[0021] The welding method for tube blanks of unequal thickness / unequal material provided by the present invention allows for flexible selection of a suitable welding method based on the overall thickness of the tube blank, the thickness ratio and strength between different tube sections, and the combination of surface material properties. On this basis, combined with mechanical property experiments on the weld and the product, the welding parameters can be precisely optimized, thereby significantly improving the forming quality and production efficiency of various types of tube blanks. It also effectively avoids the drawbacks of low material properties affecting subsequent process effects and finished product quality in the existing manufacturing of unequal thickness tube blanks based on TRB rolling process. Attached Figure Description

[0022] Figure 1 A schematic diagram of a tube blank with unequal thickness but equal strength for adjacent tube segments manufactured based on the present invention;

[0023] Figure 2 A schematic diagram of a tube blank with adjacent tube segments of equal thickness but different strengths manufactured based on the present invention;

[0024] Figure 3 This is a schematic diagram of a tube blank with unequal thickness and strength between adjacent tube segments manufactured based on the present invention. Detailed Implementation

[0025] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] This invention provides a welding method suitable for tube blanks of unequal thickness / unequal material, specifically including the following steps:

[0027] Step 1: Select the slab raw materials corresponding to different pipe sections based on the wall thickness and strength design parameters of the target tube blank;

[0028] Step 2: Based on the combination of the overall thickness of the target tube blank and the thickness ratio of its adjacent tube sections, determine the specific slab welding method, including:

[0029] ① When the overall thickness of the target tube blank is less than 3mm and the thickness ratio of adjacent tube sections is less than 2, use fillerless laser welding or fillerless argon arc welding to provide better welding operation efficiency.

[0030] ② When the overall thickness of the target tube blank is greater than 3mm and the thickness ratio of adjacent tube sections is greater than 2, filler wire laser welding or filler wire argon arc welding should be selected to provide higher weld joint strength and toughness.

[0031] ③ For other combinations of the overall thickness of the target tube blank and the thickness ratio of adjacent tube sections, select the no-filler welding or filler welding method according to the actual efficiency or joint strength and toughness index;

[0032] Step 3: Based on the combinations and corresponding welding methods determined in Step 2, determine the following combination of characteristics for the target tube blank:

[0033] ① Adjacent pipe sections have the same thickness but different strengths;

[0034] ② Adjacent pipe sections have different thicknesses but equal strength;

[0035] ③ Adjacent pipe sections have different thicknesses and strengths;

[0036] ④ The adjacent pipe sections are respectively coated pipe sections and uncoated pipe sections;

[0037] Select the appropriate laser welding or argon arc welding method based on the combination of characteristic types, efficiency, and welding joint performance requirements.

[0038] Step 4: For any target tube blank, the overall thickness, the thickness ratio of adjacent tube segments, and the combination of characteristics, verify the final selected welding method, and optimize the welding parameters in conjunction with product mechanical property experiments.

[0039] In a preferred embodiment of the present invention, when manufacturing target pipe blanks with different strengths for adjacent pipe sections, the slab material is specifically selected from any combination of high-strength steel, ultra-high-strength steel, duplex steel, martensitic steel, and austenitic steel. The slab thickness can be selected from 0.8 to 3.0 mm, and the splicing method between adjacent pipe sections can be longitudinal splicing, circumferential splicing, or multi-segment splicing.

[0040] In a preferred embodiment of the present invention, the product mechanical performance test performed in step four specifically includes verification tests on weld strength, product toughness, elongation and fatigue life; the optimized welding parameters include: welding current, voltage, welding speed and shielding gas flow rate.

[0041] Accordingly, the present invention also provides a method for manufacturing automotive unequal thickness / unequal material tube blank components, wherein the welding process utilizes the welding method for unequal thickness / unequal material tube blanks provided by the present invention.

[0042] In a preferred embodiment of the present invention, after the integral slab is obtained by performing the method provided by the present invention, the final target tube blank is obtained by rolling or drawing and welding. The target tube blank can be further processed by straightening, bending, annealing, thermal expansion forming and secondary coating to obtain the vehicle body component product.

[0043] In a preferred embodiment of the present invention, after obtaining the integral slab by performing the method provided by the present invention described above, the weld seam is further subjected to necessary shaping and heat treatment.

[0044] In a specific embodiment of the present invention, the following process was used to manufacture the product as follows: Figure 1 The target tube blank shown has different thicknesses but equal strength for adjacent tube sections:

[0045] (1) Select strips of the same strength grade, such as 1500MPa high-strength steel, but with thicknesses of 1.5mm and 2.0mm respectively.

[0046] (2) Cut it longitudinally into strips with a width of 150mm;

[0047] (3) Laser welding is used to splice 1.5mm and 2.0mm strip steel into an integral slab;

[0048] (4) After welding, the weld is shaped and stress-relieving annealing is performed;

[0049] (5) Roll the welded plates into round tube blanks with different wall thicknesses;

[0050] (6) The resulting tube blank has a thicker wall at one end to improve strength and a thinner wall at the other end to improve formability.

[0051] In a specific embodiment of the present invention, the following process was used to manufacture the product as follows: Figure 2 The target tube blank shown is of equal thickness but has different strengths among adjacent tube sections:

[0052] (1) Select the same thickness, such as 2mm, but with a strength grade of 2200MPa high-strength steel and 2000MPa high-strength steel;

[0053] (2) Cut it longitudinally into strips with a width of 160mm;

[0054] (3) Laser welding is used to splice the strip steel into an integral slab;

[0055] (4) Roll the welded plates into round tube blanks with different wall thicknesses and perform stress-relief annealing.

[0056] In a specific embodiment of the present invention, the following process was used to manufacture the product as follows: Figure 3 The target tube blanks shown are of unequal thickness and strength between adjacent tube sections:

[0057] (1) Select strip steel with a thickness of 2.5 mm and a strength of 2200 MPa and strip steel with a thickness of 2.0 mm and a strength of 2000 MPa;

[0058] (2) The parts are spliced ​​longitudinally and welded using argon arc welding;

[0059] (3) Mechanical shaping of the weld after welding;

[0060] (4) Roll it into a tube blank with a diameter of 100mm. The resulting tube blank can simultaneously meet the local high load-bearing capacity requirement and the local formability requirement.

[0061] Through relevant mechanical property experiments on the tube blanks obtained from the above three specific examples, the results show that the tube blank products obtained by using the present invention are significantly better than the existing technology using the TRB process in terms of yield strength, tensile strength, elongation and work hardening degree.

[0062] It should be understood that the sequence number of each step in the embodiments of the present invention does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0063] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A welding method applicable to tube blanks of unequal thickness / unequal material, characterized in that: Specifically, the following steps are included: Step 1: Select the slab raw materials corresponding to different pipe sections based on the wall thickness and strength design parameters of the target tube blank; Step 2: Based on the combination of the overall thickness of the target tube blank and the thickness ratio of its adjacent tube sections, determine the specific slab welding method, including: ① When the overall thickness of the target tube blank is less than 3mm and the thickness ratio of adjacent tube sections is less than 2, use fillerless laser welding or fillerless argon arc welding to ensure welding operation efficiency. ② When the overall thickness of the target tube blank is greater than 3mm and the thickness ratio of adjacent tube sections is greater than 2, filler wire laser welding or filler wire argon arc welding should be selected to improve the strength and toughness of the welded joint. ③ For other combinations of the overall thickness of the target tube blank and the thickness ratio of adjacent tube sections, select the no-filler welding or filler welding method according to the actual efficiency or joint strength and toughness index; Step 3: Based on the combinations and corresponding welding methods determined in Step 2, determine the following combination of characteristics for the target tube blank: ① Adjacent pipe sections have the same thickness but different strengths; ② Adjacent pipe sections have different thicknesses but equal strength; ③ Adjacent pipe sections have different thicknesses and strengths; ④ The adjacent pipe sections are respectively coated pipe sections and uncoated pipe sections; Based on the specific combination of characteristics, combined with efficiency and welding joint index requirements, select the appropriate laser welding or argon arc welding method. Step 4: Verify the final selected welding method for any target tube blank's overall thickness, the combination of thickness ratios of adjacent tube segments, and the combination of characteristics, and optimize the welding parameters in conjunction with product mechanical property experiments.

2. The welding method for unequal thickness / unequal material tube blanks as described in claim 1, characterized in that: When manufacturing target pipe blanks with different strengths for adjacent pipe sections, the specific material to be selected for the slab is any combination of high-strength steel, ultra-high-strength steel, duplex steel, martensitic steel, and austenitic steel.

3. The welding method for unequal thickness / unequal material tube blanks as described in claim 1, characterized in that: The product mechanical performance tests performed in step four specifically include verification tests on weld strength, product toughness, elongation, and fatigue life; the optimized welding parameters include welding current, voltage, welding speed, and shielding gas flow rate.

4. A method for manufacturing automotive unequal thickness / unequal material tube blank components, characterized in that: The welding process specifically utilizes the welding method for unequal thickness / unequal material tube blanks as described in any one of claims 1-3.

5. The manufacturing method of automotive unequal thickness / unequal material tube blank components as described in claim 4, characterized in that: After the integral slab is made, the target tube blank is obtained by rolling or drawing and welding. Then, the target tube blank is further processed by straightening, bending, annealing, thermal expansion forming and secondary coating to obtain the body component product.

6. The manufacturing method of automotive unequal thickness / unequal material tube blank components as described in claim 4, characterized in that: After the integral slab is prepared, the weld seam is subjected to necessary shaping and heat treatment.

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