Processing method of low-temperature deformed steel bar tensile sample
By using friction welding and handheld water spray cooling, the problem of notchless performance testing of low-temperature rebar tensile specimens was solved, ensuring that the joint strength and dimensions meet the requirements and achieving effective testing of low-temperature tensile properties.
Patent Information
- Application Number
- CN202510875709.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-27
- Publication Date
- 2025-10-31
AI Technical Summary
Existing technologies cannot effectively solve the problem of unnotched performance testing of low-temperature rebar tensile specimens, especially since the strength and dimensions of the thickness tensile joints cannot meet the requirements of low-temperature rebar.
Friction welding was used with a Hanzhong Shuangji C200 friction welding machine. By setting the friction time and top pressure, and combining it with handheld water spray cooling, a 34mm diameter round bar was welded to both ends of the threaded steel as an extension. Performance tests were then conducted under low-temperature conditions.
This method enables unnotch-free performance testing of low-temperature threaded steel tensile specimens, ensuring that the joint strength and dimensions meet the requirements and guaranteeing the effectiveness of low-temperature tensile performance.
Smart Images
Figure CN120869722A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of steel bar welding technology and relates to a method for processing low-temperature threaded steel tensile specimens. Background Technology
[0002] Liquefied natural gas (LNG) storage tanks need to operate at extremely low temperatures, typically stored in cryogenic tanks with slight positive pressure at -162°C. Cryogenic steel reinforcement plays a crucial role in the construction of LNG storage tanks, ensuring their stability and safety. The performance of cryogenic rebar produced by steel mills is key to ensuring stable subsequent production and application. However, cryogenic tensile test specimens of cryogenic rebar require unnotch-free performance testing, which presents a new challenge for cryogenic tensile testing.
[0003] Patent CN114918630A discloses a method for processing steel plate thickness tensile specimens, effectively solving the problem of not being able to process and test 8-15mm thick steel plates after tensile sampling. It also ensures the strength of the welded joint. Compared with other welding methods, friction welding is used to add an extension bar to the thickness specimen, eliminating the need for beveling and filler material. This simplifies the process, effectively reducing the width of the heat-affected zone and thus minimizing the impact of welding on the base material's properties, ensuring the normal processing and testing of the thickness tensile specimen. However, the joint strength of the thickness tensile specimen cannot meet the requirements for low-temperature rebar tensile specimens, and it cannot guarantee that the joint dimension is greater than the fracture dimension. Summary of the Invention
[0004] To achieve the above objectives, this invention provides a method for processing low-temperature rebar tensile specimens, aiming to solve the problem of... The processing of low-temperature threaded steel tensile specimens is an issue that needs to be addressed to ensure the effectiveness of the test.
[0005] The technical solution adopted in this invention is a method for processing low-temperature rebar tensile specimens, the specific steps of which are as follows:
[0006] S1: Take a sample from the low-temperature rebar used in the test and cut it to the length required for the test;
[0007] S2: Select bars of similar strength grade to process two round bars with a length of 60mm and a diameter of 34mm, and weld them to both ends of the threaded steel as extension parts;
[0008] S3: Remove the rust and oil stains from both ends of the test threaded steel obtained in step S1, revealing a metallic luster; remove the rust and oil stains from one end of the extended round bar obtained in step S2.
[0009] S4: Clamp the threaded steel obtained in step S3 onto the clamp at one end of the friction welding machine, and clamp the extended round bar onto the clamp at the other end of the friction welding machine.
[0010] S5: Set the relevant parameters of the friction welding machine, and weld one end of the threaded steel bar and one end of the first section of round bar. During the welding process, use a handheld water sprayer to spray water on the joint to quickly cool the joint and obtain martensitic structure; then weld the other end of the threaded steel bar and one end of the second section of round bar.
[0011] S6: Thread the extended rods at both ends of the sample that has been welded in step S5.
[0012] S7: Place the tensile specimen with the thread processed in step S6 on a low-temperature tensile testing machine for performance testing.
[0013] Furthermore, the low-temperature rebar used in the experiment was HRB500DW, with the following chemical composition by mass percentage: C: 0.08-0.10%, Si: 0.28-0.32%, Mn: 1.4%-1.6%, Ni: 1.10-1.30%, P: 0.007-0.01%, S: 0.005-0.007%, and diameter... The mechanical properties at room temperature are: yield strength 520MPa-630MPa, tensile strength ≥575MPa.
[0014] Furthermore, the length required for the test in S1 is 510 mm.
[0015] Furthermore, the friction welding machine in S5 is a Hanzhong Shuangji C200 friction welding machine with the following parameters: friction time 3-5s, top pressure 200-250MPa, and upsetting time 3-5s.
[0016] Furthermore, the welding process involves spraying water onto the joint using a handheld water sprayer. Specifically, during the friction welding process, when the joint turns red, water is sprayed using a water sprayer with a nozzle diameter of 1-2mm for 3-4 seconds at a speed of 5-8ml / s.
[0017] The beneficial effects of this invention are: by adopting the technical solution of this invention, it is possible to ensure that the low-temperature tensile test of HRB500DW low-temperature rebar with a diameter of 20-32mm is required to perform unnotched performance testing, solve the processing problem of low-temperature tensile test of rebar, and effectively test the low-temperature tensile performance. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1This is a schematic diagram of the test steel reinforcement dimensions;
[0020] Figure 2 This is a schematic diagram of the dimensions of the extended round bar;
[0021] Figure 3 This is a picture showing the completed welding of the extended rod;
[0022] Figure 4 This is a diagram showing the fracture location of the tensile sample. Detailed Implementation
[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.
[0024] This invention aims to solve The processing of low-temperature threaded steel tensile specimens is an issue that needs to be addressed to ensure the effectiveness of the test.
[0025] A low-temperature rebar, HRB500DW, was selected as the experimental material. The chemical composition of the material is: C: 0.08-0.10%, Si: 0.28-0.32%, Mn: 1.4%-1.6%, Ni: 1.10-1.30%, P: 0.007-0.01%, S: 0.005-0.007%, and diameter... Mechanical properties at room temperature: yield strength (520MPa-630MPa), tensile strength ≥575MPa. The welding equipment used in the test was a Hanzhong Shuangji C200 friction welding machine.
[0026] The specific steps are as follows:
[0027] (1) Samples were taken from the low-temperature rebar used in the experiment and sawn to a length of 510 mm, such as Figure 1 As shown;
[0028] (2) Select bars of similar strength grade and process them into two round bars approximately 60mm long and 34mm in diameter, such as... Figure 2 As shown, this is an extended section welded to both ends of the threaded steel bar;
[0029] (3) Grind the rust and oil stains at both ends of the test threaded steel to expose the metallic luster, and grind the rust and oil stains on one end of the extended round bar.
[0030] (4) Clamp the threaded steel bar on the clamp at one end of the friction welding machine and clamp the extended round bar on the clamp at the other end of the friction welding machine;
[0031] (5) Set the relevant parameters of the friction welding machine, friction time 3-5s, top pressure 200-250MPa, upsetting time 3-5s, and start welding the threaded steel and one end of the round bar. During the welding process, use a handheld water sprayer to spray water at the joint. When the joint turns red, use a water sprayer with a nozzle diameter of 1-2mm to spray water for 3-4s. The water spraying speed is 5-8ml / s to make the joint cool quickly to obtain martensitic structure, thereby ensuring the strength of the joint. Then follow the same steps to weld the other end.
[0032] (6) After all welding is completed, as follows Figure 3 As shown, threads are machined on the extended rods at both ends;
[0033] (7) The tensile specimens with the finished threads are placed on a low-temperature tensile testing machine for performance testing. The fracture surface of the tensile specimen is located outside the welded joint area, such as... Figure 4 As shown, this ensures the effectiveness of the performance testing.
[0034] The following description, in conjunction with the embodiments, further illustrates the tensile properties of the embodiments, as shown in Table 1.
[0035] Experimental Example 1:
[0036] The specific steps are as follows:
[0037] (1) In the test Samples were taken from HRB500DW rebar and sawn to the required dimensions for the test. Figure 1 As shown.
[0038] (2) Select bars of similar strength grade and process two round bars with a length of about 60 mm and a diameter of 34 mm, which are used as the extended parts welded to both ends of the rebar.
[0039] (3) Grind the rust and oil stains at both ends of the test threaded steel to expose the metallic luster, and grind the rust and oil stains on one end of the extended round bar.
[0040] (4) Clamp the threaded steel bar on the fixture at one end of the friction welding machine and clamp the extended round bar on the fixture at the other end of the friction welding machine.
[0041] (5) Set the relevant parameters of the friction welding machine: friction time 3-5s, top pressure 200-250MPa, upsetting time 3-5s, and start welding the threaded steel and one end of the round bar. During the welding process, use a handheld water sprayer to spray water at the joint. Use a water sprayer with a nozzle diameter of 1-2mm to spray water for 3-4s. The water spraying speed is 5-8ml / s to make the joint cool quickly and obtain martensitic structure, thereby ensuring the strength of the joint. Then follow the same steps to weld the other end.
[0042] (6) After all welding is completed, threading is performed on the extension rods at both ends.
[0043] (7) The tensile specimen with the threaded part is placed on a low temperature tensile testing machine for performance testing. Under the low temperature condition of -165℃, the tensile fracture is outside the welded joint area, which ensures the effectiveness of the low temperature tensile performance.
[0044] Example 2:
[0045] The specific steps are as follows:
[0046] (1) In the test Samples were taken from HRB500DW rebar and sawn to the required dimensions for the test.
[0047] (2) Select bars of similar strength grade and process two round bars with a length of about 60 mm and a diameter of 34 mm, which are used as the extended parts welded to both ends of the rebar.
[0048] (3) Grind the rust and oil stains at both ends of the test threaded steel to expose the metallic luster, and grind the rust and oil stains on one end of the extended round bar.
[0049] (4) Clamp the threaded steel bar on the fixture at one end of the friction welding machine and clamp the extended round bar on the fixture at the other end of the friction welding machine.
[0050] (5) Set the relevant parameters of the friction welding machine: friction time 3-5s, top pressure 200-250MPa, upsetting time 3-5s, and start welding the threaded steel and one end of the round bar. During the welding process, use a handheld water sprayer to spray water at the joint. Use a water sprayer with a nozzle diameter of 1-2mm to spray water for 3-4s. The water spraying speed is 5-8ml / s to make the joint cool quickly and obtain martensitic structure, thereby ensuring the strength of the joint. Then follow the same steps to weld the other end.
[0051] (6) After all welding is completed, threading is performed on the extension rods at both ends.
[0052] (7) The tensile specimen with the threaded part is placed on a low temperature tensile testing machine for performance testing. Under the low temperature condition of -165℃, the tensile fracture is outside the welded joint area, which ensures the effectiveness of the low temperature tensile performance.
[0053] Table 1 Tensile properties of HRB500DW in each embodiment
[0054]
[0055] The results from the above embodiments show that by using the technical solution of the present invention to process the tensile specimens of low-temperature rebar and conducting low-temperature tensile tests, the validity of the data can be guaranteed, and the problem of requiring unnotch performance testing for low-temperature tensile specimens of HRB500DW rebar with a diameter of 20-32mm can be solved.
[0056] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.
Claims
1. A method for processing low-temperature rebar tensile specimens, characterized in that, The specific steps are as follows: S1: Take a sample from the low-temperature rebar used in the test and cut it to the length required for the test; S2: Select bars of similar strength grade to process two round bars with a length of 60mm and a diameter of 34mm, and weld them to both ends of the threaded steel as extension parts; S3: Remove the rust and oil stains from both ends of the test threaded steel obtained in step S1, revealing a metallic luster; remove the rust and oil stains from one end of the extended round bar obtained in step S2. S4: Clamp the threaded steel obtained in step S3 onto the clamp at one end of the friction welding machine, and clamp the extended round bar onto the clamp at the other end of the friction welding machine. S5: Set the relevant parameters of the friction welding machine, and weld one end of the threaded steel bar and one end of the first section of round bar. During the welding process, use a handheld water sprayer to spray water on the joint to quickly cool the joint and obtain martensitic structure; then weld the other end of the threaded steel bar and one end of the second section of round bar. S6: Thread the extended rods at both ends of the sample that has been welded in step S5. S7: Place the tensile specimen with the thread processed in step S6 on a low-temperature tensile testing machine for performance testing.
2. The method for processing a low-temperature rebar tensile specimen as described in claim 1, characterized in that, The low-temperature rebar used in the experiment was HRB500DW, with the following chemical composition by mass percentage: C: 0.08-0.10%, Si: 0.28-0.32%, Mn: 1.4%-1.6%, Ni: 1.10-1.30%, P: 0.007-0.01%, S: 0.005-0.007%, and diameter... The mechanical properties at room temperature are: yield strength 520MPa-630MPa, tensile strength ≥575MPa.
3. The method for processing a low-temperature rebar tensile specimen as described in claim 1, characterized in that, The length required for the test in S1 is 510 mm.
4. The method for processing a low-temperature rebar tensile specimen as described in claim 1, characterized in that, The friction welding machine in S5 is a Hanzhong Shuangji C200 friction welding machine with the following parameters: friction time 3-5s, top pressure 200-250MPa, and upsetting time 3-5s.
5. The method for processing a low-temperature rebar tensile specimen as described in claim 1, characterized in that, The welding process involves spraying water onto the joint using a handheld water sprayer. Specifically, during the friction welding process, when the joint turns red, water is sprayed using a water sprayer with a nozzle diameter of 1-2mm for 3-4 seconds at a speed of 5-8ml / s.