A welding strain method for high-strength steel

Abstract

The present application relates to a method for strain-following welding of high-strength steel, belonging to the technical field of high-strength steel welding. The method comprises: obtaining a preset temperature based on the Ar1 value of the high-strength steel base material to be welded during cooling during welding; trial welding at least two pieces of high-strength steel base material to be welded to obtain a temperature-time curve of the heat-affected zone of the test weld; determining the time required for the heat-affected zone to cool from the peak temperature to the preset temperature based on the temperature-time curve; obtaining the distance between the welding gun and the plastic deformation point of the high-strength steel base material to be welded based on the speed and time of movement of the welding gun during the trial welding, thereby determining the relative position of the welding gun and the plastic deformation device; in the formal welding, synchronously welding and starting the plastic deformation device so that the heat-affected zone of the weld formed by welding begins to plastically deform when it cools to the preset temperature. The embodiment of the present application introduces plastic deformation synchronously in the same welding pass, and utilizes the mechanical stabilization of supercooled austenite to retain more residual austenite for toughening.

Description

Technical Field

[0001] The present application relates to the technical field of high-strength steel welding, and in particular to a welding strain method for high-strength steel. Background Art

[0002] High-strength steel is primarily used in automotive applications, including body structures, chassis suspension systems, and safety components. The use of high-strength steel aims to enhance the structural strength and safety of vehicles while reducing weight and improving fuel economy and performance.

[0003] However, high-strength steel generally contains a high carbon content or alloy content, resulting in high hardenability. Coarse grains and brittle martensite structure will form in the heat-affected zone of the weld during welding, causing cracking of the weld structure. Summary of the Invention

[0004] The present application provides a high-strength steel welding strain method to solve the following technical problem: how to improve the toughness of the heat-affected zone of high-strength steel welding.

[0005] In a first aspect, the present application provides a method for strain following welding of high-strength steel, the method comprising:

[0006] Obtain the Ar1 value of the high-strength steel base material to be welded during welding cooling;

[0007] According to the Ar1 value, a preset temperature is obtained;

[0008] Conducting trial welding on at least two pieces of the high-strength steel base materials to be welded, and obtaining a temperature-time curve of a heat-affected zone of a weld formed by the trial welding;

[0009] Determining the time T required for the heat-affected zone to cool from the peak temperature to the preset temperature according to the temperature-time curve;

[0010] Obtaining a distance S between the welding gun and the plastic deformation point of the high-strength steel base material to be welded based on the moving speed V of the welding gun during the trial welding and the time T;

[0011] Determining the relative positions of the welding torch and the plastic deformation device according to the distance S;

[0012] Using the same welding parameters as the trial welding, at least two pieces of the high-strength steel base materials to be welded are welded, and the plastic deformation device is synchronously started during the welding process so that the heat-affected zone of the weld formed by the welding begins to undergo plastic deformation when it cools to the preset temperature.

[0013] Optionally, the preset temperature is (Ar1-10)°C to Ar1°C.

[0014] Optionally, the distance S between the welding gun and the plastic deformation point of the high-strength steel base material to be welded satisfies the following relationship:

[0015] S=VT

[0016] Where S represents the distance between the welding gun and the plastic deformation point of the high-strength steel base material to be welded, V represents the speed of the welding gun movement, and T represents the time required for the heat-affected zone to cool from the peak temperature to the preset temperature. If the unit of S is cm, the unit of V is cm / min, and the unit of T is s.

[0017] Optionally, the distance of the plastic deformation is the same as the length of the weld.

[0018] Optionally, the welding method is carbon dioxide gas shielded welding.

[0019] Optionally, the welding parameters include: welding voltage of 18V to 24V, welding voltage of 150A to 220A, and welding speed of 30cm / min to 50cm / min.

[0020] Optionally, the plastic deformation method of the plastic deformation device includes one of the following: hammering, shot peening, ultrasonic vibration, roller rolling, and vibration friction.

[0021] Optionally, the curvature radius of the hammer head when struck by the small hammer satisfies the following relationship:

[0022] 0.05cm≤a≤0.5b

[0023] Where a represents the radius of curvature of the hammer head; b represents the thickness of the high-strength steel base material to be welded; the units of a and b are the same.

[0024] Optionally, the process parameters of the small hammer hammering include: a hammering frequency of 50Hz to 100Hz, and a hammering force of 400N to 800N.

[0025] Optionally, the radius of curvature of the hammer head of the small hammer is 1 mm, the hammering force of the small hammer is 600 N, and the hammering frequency of the small hammer is 100 Hz.

[0026] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0027] The embodiment of the present application provides a method for strain following welding of high-strength steel, the method comprising: obtaining an Ar1 value of a high-strength steel base material to be welded during cooling during welding; obtaining a preset temperature based on the Ar1 value; trial welding at least two pieces of the high-strength steel base materials to be welded to obtain a temperature-time curve of a heat-affected zone of a weld formed by the trial welding; determining the time T required for the heat-affected zone to cool from a peak temperature to the preset temperature based on the temperature-time curve; obtaining a distance S between the welding gun and a plastic deformation point of the high-strength steel base material to be welded based on a speed V of movement of the welding gun of the trial welding and the time T; determining the relative position of the welding gun and a plastic deformation device based on the distance S; welding at least two pieces of the high-strength steel base materials to be welded using the same welding parameters as the trial welding, and synchronously starting the plastic deformation device during the welding process so that the heat-affected zone of the weld formed by the welding begins to undergo plastic deformation when it cools to the preset temperature. The Ar1 value of the high-strength steel base material to be welded during the cooling process of welding is used to determine the preset temperature. The preset temperature can be used to guide the timing of subsequent plastic deformation. The high-strength steel base material to be welded is subjected to trial welding. During the trial welding process, the temperature-time curve of the heat-affected zone is recorded. The curve describes the change of the temperature of the heat-affected zone with time. According to the temperature-time curve, the time T required for the heat-affected zone to cool from the peak temperature to the preset temperature is determined. According to the time and the moving speed V of the welding gun, the distance S between the welding gun and the plastic deformation point of the high-strength steel base material to be welded is obtained, thereby determining the relative position of the welding gun and the plastic deformation device. Therefore, in the subsequent formal welding process of the high-strength steel base material to be welded, welding and starting the plastic deformation device are carried out simultaneously to ensure that the heat-affected zone of the weld formed by the trial welding begins to undergo plastic deformation when it cools to the preset temperature. In summary, when the temperature of the heat-affected zone of welding is cooled to a preset temperature, applying plastic deformation to the heat-affected zone can mechanically stabilize the supercooled austenite in the heat-affected zone, thereby retaining residual austenite in the heat-affected zone, thereby improving the toughness of the heat-affected zone of high-strength steel welding. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0030] Figure 1 A schematic flow chart of a strain-with-welding method for high-strength steel provided in an embodiment of the present application;

[0031] Figure 2 A schematic diagram of a small hammer hammering simulation method for strain-with-weld of high-strength steel provided in an embodiment of the present application;

[0032] Figure 3 A metallographic structure diagram of the heat-affected zone of a high-strength steel welded plate provided in Example 1 of the present application;

[0033] Figure 4 A metallographic structure diagram of the heat-affected zone of a high-strength steel welded plate provided in Example 2 of the present application;

[0034] Figure 5 A metallographic structure diagram of a heat-affected zone of a high-strength steel welded plate provided in Example 3 of the present application;

[0035] Figure 6 A metallographic structure diagram of the heat-affected zone of a high-strength steel welded plate provided in Comparative Example 1 of the present application;

[0036] Figure 7 A metallographic structure diagram of the heat-affected zone of a high-strength steel welded plate provided in Comparative Example 2 of this application;

[0037] Figure 8 This is a metallographic structure diagram of the heat-affected zone of a high-strength steel welded plate provided in Comparative Example 3 of the present application. DETAILED DESCRIPTION

[0038] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0039] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a hard limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numbers within the range. For example, the description of a range from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0040] In this application, unless otherwise indicated, directional words such as "upper" and "lower" refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of this application specification, the terms "including" and "comprising" mean "including but not limited to".

[0041] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0042] High-strength steel is primarily used in automotive applications, including body structures, chassis suspension systems, and safety features. The use of high-strength steel aims to improve vehicle structural strength and safety, while also reducing weight and improving fuel economy and performance. However, high-strength steel typically contains high carbon or alloy content, resulting in high hardenability. This can lead to the formation of coarse grains and a brittle martensitic structure in the heat-affected zone of welds, causing cracking in the welded structure.

[0043] Retained austenite refers to the austenite structure that remains in the material after the steel has been quenched. The presence of this austenite has a great influence on the performance and service life of the steel. Retained austenite is a plastic phase, and only a small amount of retained austenite can significantly improve the toughness of the steel without causing excessive loss of strength. The common GCr15 steel is toughened with 5% retained austenite. Inspired by this, the embodiment of the present application intends to introduce retained austenite in the heat-affected zone of high-strength steel for toughening. The technical idea of ​​the embodiment of the present application: when the temperature of the welding heat cycle in the heat-affected zone drops to near the Ar1 point of the steel, plastic deformation is applied to it to mechanically stabilize the supercooled austenite, thereby retaining more retained austenite in the heat-affected zone and toughening the heat-affected zone.

[0044] Therefore, in the first aspect, the present application provides a method for strain following welding of high-strength steel. Figure 1 This is a flow chart of a method for strain-following welding of high-strength steel provided in an embodiment of the present application; see Figure 1 , the method comprising:

[0045] S1, obtain the Ar1 value of the high-strength steel base material to be welded during welding cooling;

[0046] S2. Obtaining a preset temperature according to the Ar1 value;

[0047] In some embodiments, the preset temperature is (Ar1-10)°C to Ar1°C.

[0048] Welding is a local heating process. When a heat source (such as an arc, laser, etc.) acts on the weldment, heat is transferred from the center of the weld to the surrounding parent material. Due to the existence of heat conduction, the temperature of the parent material near the weld will rise, and it will undergo different thermal cycles, which will cause changes in structure and performance. These areas of change are the heat-affected zone of the weld. It is worth noting that in the coarse-grained area of ​​the heat-affected zone, due to the effect of high temperature and a relatively long residence time at high temperature, the grains of the parent material will grow significantly. Grain growth may increase the strength of the material, but the toughness and plasticity will be significantly reduced, and brittle fracture is prone to occur. This is because the resistance to dislocation movement inside the coarse grains is reduced, and when subjected to external forces, crack propagation is more likely to occur. Therefore, the embodiments of the present application focus on plastic deformation of the coarse-grained area of ​​the heat-affected zone.

[0049] Retained austenite is a plastic phase. Only a small amount of retained austenite can significantly improve the toughness of steel without causing excessive loss of strength. In an embodiment of the present application, when the temperature of the heat-affected zone of the weld is cooled to a preset temperature, plastic deformation is applied to the heat-affected zone, which can mechanically stabilize the supercooled austenite in the heat-affected zone, thereby retaining retained austenite in the heat-affected zone, thereby improving the toughness of the heat-affected zone of high-strength steel welding. The mechanical stabilization of the supercooled austenite is manifested as follows: plastic deformation of austenite at a temperature above the martensite transformation start temperature (Md point) will make the subsequent martensite transformation difficult, the martensite transformation start temperature will decrease, causing the austenite to stabilize, thereby increasing the amount of residual austenite and reducing the amount of martensite.

[0050] Ar1 refers to the temperature at which austenite begins to transform into pearlite or other transformation products during the cooling process of steel. It is one of the critical temperatures of steel. When steel cools from a high-temperature austenite state and the temperature drops to Ar1, the stability of austenite decreases and phase transformation begins. This Ar1 can be used to measure the temperature of the high-strength steel base material to be welded during welding cooling using a thermal expansion instrument. The preset temperature can be (Ar1-10)℃~Ar1℃, which can retain a sufficient amount of supercooled austenite in the heat-affected zone of the weld (austenite is an interstitial solid solution of carbon dissolved in γ-Fe and is a microstructure state of steel at high temperatures. When austenite cools below the critical temperature (such as that of eutectoid steel), it should undergo a phase transformation thermodynamically, but due to the supercooling phenomenon, it temporarily remains in the austenite state. The austenite at this time is called supercooled austenite), fully improving the toughness of the heat-affected zone of high-strength steel welding and avoiding brittle fracture of subsequent high-strength welded plates. If the preset temperature is higher than Ar1°C, the amount of supercooled austenite retained in the heat-affected zone of the weld may be low, making it difficult to achieve a good effect of subsequent plastic deformation; if the preset temperature is lower than (Ar1-10)°C, the supercooled austenite in the heat-affected zone of the weld may transform into martensite, thereby increasing the hardness and decreasing the toughness of the heat-affected zone, making it easy to produce defects such as welding cracks. Exemplarily, the preset temperature may be (Ar1-10)°C, (Ar1-9)°C, (Ar1-8)°C, (Ar1-7)°C, (Ar1-6)°C, (Ar1-5)°C, (Ar1-4)°C, (Ar1-3)°C, (Ar1-2)°C, (Ar1-1)°C, Ar1°C, etc.

[0051] S3, performing trial welding on at least two pieces of the high-strength steel base materials to be welded, and obtaining a temperature-time curve of a heat-affected zone of a weld formed by the trial welding;

[0052] S4. Determine the time T required for the heat-affected zone to cool from the peak temperature to the preset temperature according to the temperature-time curve;

[0053] S5. Obtaining a distance S between the welding gun and the plastic deformation point of the high-strength steel base material to be welded based on the moving speed V of the welding gun during the trial welding and the time T;

[0054] In some embodiments, the distance S between the welding gun and the plastic deformation point of the high-strength steel base material to be welded satisfies the following relationship:

[0055] S=VT

[0056] Where S represents the distance between the welding gun and the plastic deformation point of the high-strength steel base material to be welded, V represents the speed of the welding gun movement, and T represents the time required for the heat-affected zone to cool from the peak temperature to the preset temperature. If the unit of S is cm, the unit of V is cm / min, and the unit of T is s.

[0057] In an embodiment of the present application, the distance S=VT between the welding gun and the plastic deformation point of the high-strength steel base material to be welded can give the heat-affected zone of the weld a certain cooling time to a preset temperature, so that the application point of the plastic deformation has a sufficient amount of supercooled austenite. Exemplarily, a thermocouple is spot-welded near the weld seam (i.e., the heat-affected zone) of the high-strength steel plate to be welded, and the trial welding is carried out with the welding process to be adopted. The temperature-time curve generated by the thermocouple is recorded. The time when the thermocouple generates the peak temperature is recorded as T1, and the time when the thermocouple temperature drops to (Ar1-8)°C is recorded as T2, then T2-T1=T, and the speed of movement of the welding gun is recorded as V, so that S is calculated based on the above S=VT.

[0058] S6. Determine the relative position of the welding torch and the plastic deformation device according to the distance S;

[0059] S7. Using the same welding parameters as the trial welding, at least two pieces of the high-strength steel base materials to be welded are welded, and the plastic deformation device is synchronously started during the welding process so that the heat-affected zone of the weld formed by the welding begins to undergo plastic deformation when it cools to the preset temperature.

[0060] The Ar1 value of the high-strength steel base material to be welded during the cooling process of welding is used to determine the preset temperature. The preset temperature can be used to guide the timing of subsequent plastic deformation. The high-strength steel base material to be welded is subjected to trial welding. During the trial welding process, the temperature-time curve of the heat-affected zone is recorded. The curve describes the change of the temperature of the heat-affected zone with time. According to the temperature-time curve, the time T required for the heat-affected zone to cool from the peak temperature to the preset temperature is determined. According to the time and the moving speed V of the welding gun, the distance S between the welding gun and the plastic deformation point of the high-strength steel base material to be welded is obtained, thereby determining the relative position of the welding gun and the plastic deformation device. Therefore, in the subsequent formal welding process of the high-strength steel base material to be welded, welding and starting the plastic deformation device are carried out simultaneously to ensure that the heat-affected zone of the weld formed by welding begins to undergo plastic deformation when it cools to the preset temperature. Therefore, when the temperature of the heat-affected zone of the weld cools to a preset temperature, applying plastic deformation to the heat-affected zone can mechanically stabilize the supercooled austenite in the heat-affected zone, thereby retaining residual austenite in the heat-affected zone and thereby improving the toughness of the heat-affected zone of high-strength steel welding.

[0061] In some embodiments, the distance of the plastic deformation is the same as the length of the weld.

[0062] In some embodiments, the welding method is carbon dioxide gas shielded welding.

[0063] In some embodiments, the welding parameters include: a welding voltage of 18V to 24V, a welding voltage of 150A to 220A, and a welding speed of 30cm / min to 50cm / min.

[0064] In the embodiments of the present application, the welding method can be carbon dioxide gas shielded welding, which is a metal arc welding method. It uses carbon dioxide gas as the shielding gas. During the welding process, carbon dioxide gas is continuously ejected from the welding torch nozzle, isolating the welding area from the air and preventing oxygen, nitrogen, and other gases in the air from harmfully affecting the weld pool. This welding method has the advantages of high welding efficiency, low cost, and good weld quality. Among the welding parameters, the welding voltage can be 18V to 24V, the welding current can be 150A to 220A, and the welding speed can be 30cm / min to 50cm / min, which can achieve good welding quality. For example, the welding voltage can be 18V, 19V, 20V, 21V, 22V, 23V, or 24V; the welding current can be 150A, 160A, 170A, 180A, 190A, 200A, 210A, or 220A; and the welding speed can be 30cm / min, 33cm / min, 35cm / min, 38cm / min, 40cm / min, 43cm / min, 45cm / min, 48cm / min, or 50cm / min. In one embodiment, the welding voltage can be 21V, the welding current can be 180A, and the welding speed can be 40cm / min. Furthermore, the welding speed is the same as the welding speed, and the welding parameters throughout the method are the same.

[0065] In some embodiments, the plastic deformation method of the plastic deformation device includes one of the following: hammering, shot peening, ultrasonic vibration, roller rolling, and vibration friction.

[0066] In the embodiments of the present application, the plastic deformation method can be one of the following: hammering, shot peening, ultrasonic vibration, roller rolling, and vibration friction. Among them, hammering is to repeatedly hammer the surface of the heat-affected zone with a hammer, causing the grains on the surface of the heat-affected zone to slip and deform. During the hammering process, the heat-affected zone is subjected to local impact force. When the impact force exceeds the yield strength of the heat-affected zone, the material will undergo plastic deformation. Shot peening is to use high-speed projectiles (such as steel shots, glass beads, etc.) to impact the surface of the heat-affected zone. The high-speed impact of the projectile will cause plastic deformation on the surface of the heat-affected zone, forming a compressive stress layer of a certain depth. Ultrasonic vibration is to transfer ultrasonic energy to the heat-affected zone. Under the action of ultrasonic waves, the atoms and molecules inside the heat-affected zone will produce high-frequency vibrations. When the stress generated by the vibration exceeds the yield strength of the heat-affected zone, plastic deformation will be triggered. Roller rolling is to roll the heat-affected zone with one or more pairs of rollers. When the heat-affected zone passes between the rollers, the pressure applied by the rollers causes the heat-affected zone to undergo plastic deformation. Vibration friction is the application of vibration and friction between two contacting objects. When the stress generated by the vibration and the friction force exceed the yield strength of the heat-affected zone, the heat-affected zone will produce plastic deformation.

[0067] In some embodiments, the radius of curvature of the hammer head struck by the small hammer satisfies the following relationship:

[0068] 0.05cm≤a≤0.5b

[0069] Where a represents the radius of curvature of the hammer head; b represents the thickness of the high-strength steel base material to be welded; the units of a and b are the same.

[0070] In an embodiment of the present application, a hammer head of appropriate size is selected according to the width of the coarse-grained area of ​​the heat-affected zone, and the curvature radius of the hammer head is limited to 0.05cm≤a≤0.5b, thereby covering the coarse-grained heat-affected zone and ensuring that the hammer head will not hit other areas.

[0071] In some embodiments, the process parameters of the small hammer hammering include: a hammering frequency of 50 Hz to 100 Hz, and a hammering force of 400 N to 800 N.

[0072] In some embodiments, the radius of curvature of the hammer head of the small hammer is 1 mm, the hammering force of the small hammer is 600 N, and the hammering frequency of the small hammer is 100 Hz.

[0073] In an embodiment of the present application, the hammering frequency may be 50Hz to 100Hz, so that the supercooled austenite in the heat-affected zone undergoes sufficient plastic deformation and does not cause deformation and cracking in other parts. The hammering force may be 400N to 800N, so that the hammer mark can remain continuous and uninterrupted and provide sufficient energy for the hammering. Exemplarily, the hammering frequency may be 50Hz, 60Hz, 70Hz, 80Hz, 90Hz, 100Hz; the hammering force may be 400N, 450N, 500N, 550N, 600N, 650N, 700N, 750N, 800N, etc. As an embodiment: the radius of curvature of the hammer head of the small hammer hammering may be 1mm, the hammering force of the small hammer hammering may be 600N, and the hammering frequency of the small hammer hammering may be 100Hz. Exemplarily, Figure 2 This is a schematic diagram of a hammer hammering simulation of a high-strength steel welding strain method provided in an embodiment of the present application; see Figure 2 The method uses a hammer as a plastic deformation device. An electric hammer (plastic deformation device, the electric hammer has a hammer head) is synchronously followed by the welding gun. The distance between the welding gun and the hammer head is S. The high-strength steel base material to be welded is welded, and the electric hammer is synchronously started during the welding process. When the heat-affected zone of the weld formed by the welding is cooled to a preset temperature, plastic deformation begins. At this time, the heat-affected zone of the weld formed by the welding is partially cooled to the preset temperature. The microstructure is supercooled austenite, which still has good plasticity. The hammer head of the hammer can cause a large plastic deformation of the supercooled austenite with a small force. Plastic deformation of the austenite at this preset temperature can make the subsequent martensitic transformation difficult, reduce the Ms point, and cause an increase in the austenite content.

[0074] In addition, before welding, the oil, dirt, rust, scale, protective layer and oxide film on the surface of the high-strength steel base material to be welded or the surface within 20mm to 30mm on both sides of the groove can be cleaned to ensure the welding quality.

[0075] In summary, the strain-with-welding method for high-strength steel provided in the embodiments of the present application has the following advantages:

[0076] 1. Conventional high-strength steel welding often faces problems such as insufficient toughness in the heat-affected zone and prone to weld cracks. This method improves the structure of the heat-affected zone by precisely controlling the temperature and distance during the welding process and simultaneously applying plastic deformation. This effectively increases the toughness of the heat-affected zone, reduces welding defects, and improves the overall quality and reliability of high-strength steel welded structures.

[0077] 2. Different from the conventional method of improving performance by heat treatment after welding, this method combines plastic deformation with the welding process in real time. Based on the grasp of key factors such as the phase change temperature and cooling time of the heat-affected zone, it realizes the direct control of the heat-affected zone structure during the welding process.

[0078] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0079] Example 1

[0080] A welding strain method for high-strength steel, comprising:

[0081] Obtain the Ar1 value of the high-strength steel base material to be welded during welding cooling;

[0082] According to the Ar1 value, the preset temperature is obtained;

[0083] Conduct trial welding on two pieces of high-strength steel base metal to be welded, and obtain the temperature-time curve of the heat-affected zone of the weld formed by the trial welding;

[0084] According to the temperature-time curve, determine the time T required for the heat-affected zone to cool from the peak temperature to the preset temperature;

[0085] According to the speed V and time T of the welding gun movement during the test welding, the distance S between the welding gun and the plastic deformation point of the high-strength steel base material to be welded is obtained;

[0086] According to the distance S, the relative position of the welding torch and the plastic deformation device is determined;

[0087] Using the same welding parameters as the test welding, the two pieces of high-strength steel base material to be welded are welded, and the plastic deformation device is synchronously started during the welding process so that the heat-affected zone of the weld formed by the welding begins to undergo plastic deformation when it cools to a preset temperature.

[0088] Among them, the welding method is carbon dioxide gas shielded welding, and the welding parameters are: welding voltage 21V, welding current 180A, welding speed 40cm / min; the preset temperature is Ar1-8=591℃; the plastic deformation method is small hammer hammering, the relative distance S=48cm, the curvature radius of the hammer head of the small hammer hammering is 1mm; the hammering frequency is 50Hz, and the hammering force is 400N.

[0089] Figure 3 This is a metallographic structure diagram of the heat-affected zone of a high-strength steel welded plate provided in Example 1 of the present application; see Figure 3, indicating that there is a small amount of retained austenite (white) in the metallographic phase. The V-notch impact energy (2.5mm thickness) at room temperature is 107J.

[0090] Example 2

[0091] A welding strain method for high-strength steel, comprising:

[0092] Obtain the Ar1 value of the high-strength steel base material to be welded during welding cooling;

[0093] According to the Ar1 value, the preset temperature is obtained;

[0094] Conduct trial welding on two pieces of high-strength steel base metal to be welded, and obtain the temperature-time curve of the heat-affected zone of the weld formed by the trial welding;

[0095] According to the temperature-time curve, determine the time T required for the heat-affected zone to cool from the peak temperature to the preset temperature;

[0096] According to the speed V and time T of the welding gun movement during the test welding, the distance S between the welding gun and the plastic deformation point of the high-strength steel base material to be welded is obtained;

[0097] According to the distance S, the relative position of the welding torch and the plastic deformation device is determined;

[0098] The two pieces of high-strength steel base materials to be welded are welded using the same welding parameters as the trial welding, and the plastic deformation device is synchronously started during the welding process so that the heat-affected zone of the weld formed by the welding begins to undergo plastic deformation when it cools to a preset temperature.

[0099] Among them, the welding method is carbon dioxide gas shielded welding, and the welding parameters are: welding voltage 21V, welding current 180A, welding speed 40cm / min; the preset temperature is Ar1-8=591℃; the plastic deformation method is small hammer hammering, the relative position distance S=70cm, the curvature radius of the hammer head of the small hammer hammering is 1mm; the hammering frequency is 150Hz, and the hammering force is 800N.

[0100] Figure 4 This is a metallographic structure diagram of the heat-affected zone of a high-strength steel welded plate provided in Example 2 of the present application; see Figure 4 , indicating that there is a very small amount of retained austenite in the metallographic phase and slight deformation marks. The V-notch impact energy (2.5mm thickness) at room temperature is 89J.

[0101] Example 3

[0102] A welding strain method for high-strength steel, comprising:

[0103] Obtain the Ar1 value of the high-strength steel base material to be welded during welding cooling;

[0104] According to the Ar1 value, the preset temperature is obtained;

[0105] Conduct trial welding on two pieces of high-strength steel base metal to be welded, and obtain the temperature-time curve of the heat-affected zone of the weld formed by the trial welding;

[0106] According to the temperature-time curve, determine the time T required for the heat-affected zone to cool from the peak temperature to the preset temperature;

[0107] According to the speed V and time T of the welding gun movement during the test welding, the distance S between the welding gun and the plastic deformation point of the high-strength steel base material to be welded is obtained;

[0108] According to the distance S, the relative position of the welding torch and the plastic deformation device is determined;

[0109] Using the same welding parameters as the test welding, the two pieces of high-strength steel base material to be welded are welded, and the plastic deformation device is synchronously started during the welding process so that the heat-affected zone of the weld formed by the welding begins to undergo plastic deformation when it cools to a preset temperature.

[0110] Among them, the welding method is carbon dioxide gas shielded welding, and the welding parameters are: welding voltage 21V, welding current 180A, welding speed 40cm / min; the preset temperature is Ar1-8=591℃; the plastic deformation method is small hammer hammering, the relative position distance S=60cm, the curvature radius of the hammer head of the small hammer hammering is 1mm; the hammering frequency is 150Hz, and the hammering force is 800N.

[0111] Figure 5 This is a metallographic structure diagram of the heat-affected zone of a high-strength steel welded plate provided in Example 3 of the present application; see Figure 5 , indicating that there is a large amount of retained austenite (white) in the metallographic phase, and the V-mouth impact energy (2.5mm thickness) at room temperature is 169J.

[0112] Comparative Example 1

[0113] Based on the disclosure of Example 3, the difference between Comparative Example 1 and Example 3 is that:

[0114] Relative position distance S = 80 cm; hammer frequency 30 Hz, hammer force 300 N.

[0115] Figure 6 This is a metallographic structure diagram of the heat-affected zone of a high-strength steel welded plate provided in Comparative Example 1 of this application; see Figure 6 , indicating that there is no retained austenite in the metallographic structure and no signs of deformation. The V-notch impact energy (2.5mm thickness) at room temperature is 52J.

[0116] Comparative Example 2

[0117] Based on the disclosure of Example 3, the difference between Comparative Example 2 and Example 3 is that:

[0118] Relative position distance S = 80 cm; hammer frequency 180 Hz, hammer force 1000 N.

[0119] Figure 7 This is a metallographic structure diagram of the heat-affected zone of a high-strength steel welded plate provided in Comparative Example 2 of this application; see Figure 7 , indicating that there is no retained austenite in the metallographic phase and there are traces of deformation. The V-mouth impact energy (2.5mm thickness) at room temperature is 26J.

[0120] Comparative Example 3

[0121] A welding strain method for high-strength steel, comprising:

[0122] Two pieces of high-strength steel base materials to be welded are welded to obtain a high-strength steel welded plate.

[0123] Among them, the welding method is carbon dioxide gas shielded welding, and the welding parameters are: welding voltage 21V, welding current 180A, and welding speed 40cm / min.

[0124] Figure 8 This is a metallographic structure diagram of the heat-affected zone of a high-strength steel welded plate provided in comparative example 3 of this application; see Figure 8 , indicating that there is no retained austenite in the metallographic structure, all is lath martensite, and there is no deformation mark. The V-notch impact energy (2.5mm thickness) at room temperature is 59J.

[0125] The analysis of Examples 1 to 3 and Comparative Examples 1 to 3 shows that the strain-with-welding method for high-strength steel provided by the embodiments of the present application can realize the simultaneous introduction of strain in the same welding pass, and the mechanical stabilization of supercooled austenite is used to retain more residual austenite for toughening. The high-strength steel welded plates obtained in Examples 1 to 3 have a high V-notch impact energy (2.5 mm thickness) at room temperature, indicating good toughness. In Comparative Example 1, S is high and the hammer point temperature is low. At this time, there is almost no supercooled austenite in the structure of the heat-affected zone (decomposition is complete), and the hammer force and frequency are low, and plastic deformation cannot be introduced; in Comparative Example 2, S is high and the hammer point temperature is low. At this time, there is almost no supercooled austenite in the structure (decomposition is complete), and the hammer force and frequency are high, which may damage the hammer point; and in Comparative Example 3, no plastic deformation is performed, only simple welding. Therefore, to a certain extent, the high-strength steel welded plates obtained in Comparative Examples 1 to 3 have a low V-notch impact energy (2.5 mm thickness) at room temperature, indicating poor toughness.

[0126] One or more technical solutions in the embodiments of the present application may have at least the following technical effects or advantages:

[0127] (1) In the embodiment of the present application, the heat-affected zone of the weld is plastically deformed during the welding process, mainly targeting the coarse-grained area of ​​the heat-affected zone, and the mechanical stabilization of the supercooled austenite is utilized to retain the retained austenite in the heat-affected zone to achieve the purpose of toughening;

[0128] (2) The equipment modification of the embodiment of the present application is simple, hardly affects the welding cycle, and is low in cost;

[0129] (3) The embodiments of the present application simultaneously achieve welding forming and forming, and synchronously realize integrated control of structure and performance;

[0130] (4) The embodiments of the present application achieve a significant improvement in the toughness of the welding heat-affected zone without affecting the strength.

[0131] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for strain following welding of high-strength steel, the method comprising: Obtain the Ar1 value of the high-strength steel base material to be welded during welding cooling; Ar1 refers to the temperature at which austenite begins to transform into pearlite or other transformation products during the cooling process of steel; According to the Ar1 value, a preset temperature is obtained; Conducting trial welding on at least two pieces of the high-strength steel base materials to be welded, and obtaining a temperature-time curve of a heat-affected zone of a weld formed by the trial welding; Determining the time T required for the heat-affected zone to cool from the peak temperature to the preset temperature according to the temperature-time curve; Obtaining a distance S between the welding gun and the plastic deformation point of the high-strength steel base material to be welded based on the moving speed V of the welding gun during the trial welding and the time T; Determining the relative positions of the welding torch and the plastic deformation device according to the distance S; Using the same welding parameters as those used in the trial welding, welding at least two pieces of the high-strength steel base materials to be welded, and synchronously starting the plastic deformation device during the welding process so that the heat-affected zone of the weld formed by the welding begins to undergo plastic deformation when it cools to the preset temperature; The preset temperature is (Ar1-10)°C~Ar1°C; The distance S between the welding gun and the plastic deformation point of the high-strength steel base material to be welded satisfies the following relationship: S=VT, where S represents the distance between the welding gun and the plastic deformation point of the high-strength steel base material to be welded, V represents the speed of movement of the welding gun, and T represents the time required for the heat-affected zone to cool from the peak temperature to the preset temperature; if the unit of S is cm, the unit of V is cm / min, and the unit of T is s.

2. The method according to claim 1, characterized in that The distance of the plastic deformation is the same as the length of the weld.

3. The method according to claim 1, characterized in that The welding method is carbon dioxide gas shielded welding.

4. The method according to claim 3, characterized in that The welding parameters include: welding voltage of 18V~24V, welding voltage of 150A~220A, and welding speed of 30cm / min~50cm / min.

5. The method according to claim 1, wherein The plastic deformation method of the plastic deformation device includes one of the following: hammering, shot peening, ultrasonic vibration, roller rolling, and vibration friction.

6. The method according to claim 5, characterized in that The curvature radius of the hammer head struck by the small hammer satisfies the following relationship: 0.05cm≤a≤0.5b Where a represents the radius of curvature of the hammer head; b represents the thickness of the high-strength steel base material to be welded; the units of a and b are the same.

7. The method according to claim 5 or 6, characterized in that The process parameters of the small hammer hammering include: hammering frequency of 50Hz~100Hz, and hammering force of 400N~800N.

8. The method according to claim 5, characterized in that The curvature radius of the hammer head of the small hammer is 1 mm, the hammering force of the small hammer is 600N, and the hammering frequency of the small hammer is 100 Hz.

Images