Welding-following strain method for high-strength steel

Abstract

The invention relates to a welding-following strain method for high-strength steel, and belongs to the technical field of high-strength steel welding.The method comprises the steps that a preset temperature is obtained according to the Ar1 value of high-strength steel base metal to be welded during welding cooling; at least two high-strength steel base materials to be welded are subjected to test welding, and a temperature-time curve of a heat affected zone of a weld joint formed through test welding is obtained; according to the temperature-time curve, the time required for cooling the heat affected zone from the peak temperature to the preset temperature is determined; according to the moving speed and time of the welding gun for test welding, the distance between the welding gun and the plastic deformation point of the high-strength steel base metal to be welded is obtained, and therefore the relative position of the welding gun for welding and a plastic deformation device is determined; and in the formal welding process, the plastic deformation device is synchronously welded and started, so that plastic deformation is started when a heat affected zone of a welding seam formed by welding is cooled to a preset temperature. According to the embodiment of the invention, the plastic deformation is synchronously introduced in the welding of the same pass, and more retained austenite is retained for toughening by utilizing the mechanical stabilization of the supercooled austenite.

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] The application of high-strength steel in automobiles mainly includes body structure, chassis suspension system, safety parts, etc. The use of high-strength steel is aimed at improving the structural strength and safety performance of automobiles, while reducing vehicle weight, improving fuel economy and performance.

[0003] However, high-strength steel generally contains a higher carbon content or alloy content, resulting in higher hardenability. Coarse grains and brittle martensitic structures will be formed in the heat-affected zone of the weld formed by welding, resulting in cracking of the weld structure. Summary of the invention

[0004] The present application provides a welding strain method for high-strength steel 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 welding strain 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] According to the temperature-time curve, determining the time T required for the heat affected zone to cool from the peak temperature to the preset temperature;

[0010] According to the moving speed V of the welding gun of the trial welding and the time T, the distance S between the welding gun and the plastic deformation point of the high-strength steel base material to be welded is obtained;

[0011] According to the distance S, determining the relative position of the welding torch and the plastic deformation device;

[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~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 radius of curvature of the hammer head 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 welding strain method of high-strength steel provided in an embodiment of the present application comprises: obtaining the Ar1 value of the high-strength steel base material to be welded during welding cooling; obtaining a preset temperature according to 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 according to 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 according to a speed V of movement of a welding gun of the trial welding and the time T; determining the relative position of the welding gun and a plastic deformation device according to 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 preset temperature is determined based on the Ar1 value of the high-strength steel base material to be welded during the cooling process of welding, and based on the obtained Ar1 value. 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, and 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, thereby ensuring 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, plastic deformation is applied to the heat affected zone, which 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 paying any creative labor.

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

[0032] Figure 3 A metallographic structure diagram of a 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 a 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 a 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 a heat-affected zone of a high-strength steel welded plate provided in Comparative Example 2 of the present 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] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work 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 rigid 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 numerical values ​​within the range. For example, the range description 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 apply 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 specified, directional words such as "upper" and "lower" used refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of the specification of this application, the terms "include", "comprise", etc. mean "including but not limited to".

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

[0042] The application of high-strength steel in automobiles mainly includes body structure, chassis suspension system, safety parts and other aspects. The use of high-strength steel is intended to improve the structural strength and safety performance of the automobile, while reducing the weight of the vehicle, improving fuel economy and performance. However, high-strength steel generally contains a higher carbon content or alloy content, resulting in higher hardenability. Coarse grains and brittle martensitic structures will be formed in the heat-affected zone of the weld formed by welding, causing cracking of the welded structure.

[0043] Retained austenite refers to the austenite structure that remains in the material after the steel is 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 residual 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 welding strain of high-strength steel. Figure 1 A schematic diagram of a flow chart of a high-strength steel welding strain method 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 presence of heat conduction, the temperature of the parent material near the weld will rise, and it will undergo different thermal cycles, resulting in changes in organization and performance. These areas of change are the heat affected zone of the weld. It is worth noting that the coarse-grained area of ​​the heat affected zone is a region where the grains of the parent material will grow significantly due to the high temperature and a relatively long residence time at high temperature. The strength of the material may increase due to grain growth, 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, and 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 welding 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 residual 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 martensitic transformation start temperature (Md point) will make the subsequent martensitic transformation difficult, the martensitic transformation start temperature is reduced, and the austenite is stabilized, 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 the steel is cooled from the high-temperature austenite state and the temperature drops to Ar1, the stability of austenite decreases and phase change begins. The 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 welding (austenite is an interstitial solid solution of carbon dissolved in γ-Fe, and is a state of organization of steel at high temperature. When austenite is cooled below the critical temperature (such as eutectoid steel), it should undergo a phase change in thermodynamics, but due to the supercooling phenomenon, it temporarily maintains the austenite state. At this time, the austenite is called supercooled austenite), which fully improves the toughness of the heat affected zone of high-strength steel welding and avoids the 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 welding 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 welding may transform into martensite, thereby increasing the hardness and reducing the toughness of the heat affected zone, and easily causing 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, test 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 test 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 according to the moving speed V of the welding gun of 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 welding a certain cooling time to a preset temperature, so that the point where the plastic deformation is applied has a sufficient amount of supercooled austenite. Exemplarily, a thermocouple is spot welded near the weld (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. Record the temperature-time curve generated by the thermocouple. 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 according to the above S=VT, S is calculated.

[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 preset temperature is determined based on the Ar1 value of the high-strength steel base material to be welded during the cooling process of welding, and based on the obtained Ar1 value. 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, and 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, thereby ensuring 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 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 residual austenite in the heat affected zone, 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 embodiment of the present application, the welding method can be carbon dioxide gas shielded welding, which is a consumable gas shielded arc welding method. It uses carbon dioxide gas as a shielding gas. During the welding process, carbon dioxide gas is continuously ejected from the nozzle of the welding gun to isolate the welding area from the air, preventing oxygen, nitrogen, etc. in the air from having a harmful effect on the welding 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~24V, the welding current can be 150A~220A, and the welding speed can be 30cm / min~50cm / min, which can achieve good welding quality. Exemplarily, the welding voltage may be 18V, 19V, 20V, 21V, 22V, 23V, 24V; the welding current may be 150A, 160A, 170A, 180A, 190A, 200A, 210A, 220A, etc.; the welding speed may be 30cm / min, 33cm / min, 35cm / min, 38cm / min, 40cm / min, 43cm / min, 45cm / min, 48cm / min, 50cm / min, etc. As one embodiment: the welding voltage may be 21V, the welding current may be 180A, and the welding speed may be 40cm / min. In addition, the speed at which the welding gun moves is the welding speed, and the welding parameters in the entire 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 embodiment 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 to cause 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 produce plastic deformation. Shot peening is to use high-speed projectiles (such as steel shots, glass beads, etc.) to hit 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 induced. 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 produce plastic deformation. Vibration friction is the application of vibration and friction between two objects in contact. When the stress generated by the vibration and the friction force work together to exceed the yield strength of the heat-affected zone, plastic deformation will occur in the heat-affected zone.

[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 radius of curvature 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 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 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 implementation method: 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 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 , using a hammer as a plastic deformation device, a small electric hammer (plastic deformation device, the small electric hammer has a hammer head) is synchronously followed behind 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 small electric hammer is synchronously started during the welding process, so that the heat-affected zone of the weld formed by welding is cooled to the preset temperature and begins to plastically deform. At this time, the heat-affected zone of the weld formed by welding is cooled to the preset temperature. The part of the structure is supercooled austenite, which still has good plasticity. The hammer head of the small hammer can cause a large plastic deformation of the supercooled austenite with a small force. Plastic deformation of austenite at the 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 welding strain method for high-strength steel provided in the embodiments of the present application has the following advantages:

[0076] 1. Traditional high-strength steel welding often faces problems such as insufficient toughness of the heat-affected zone and easy welding cracks. This method improves the organization of the heat-affected zone by precisely controlling the temperature and distance during the welding process and applying plastic deformation simultaneously, effectively improving the toughness of the heat-affected zone, reducing welding defects, and improving 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 and synchronously. 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 embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for the unrecorded specific conditions in the following examples are usually measured according to national standards. If there is no corresponding national standard, then carry out according to general international standards, normal conditions or according to 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 materials 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 torch movement during the test welding, the distance S between the welding torch 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, two pieces of high-strength steel base materials to be welded are welded, and the plastic deformation device is synchronously started during the welding process so that plastic deformation begins when the heat-affected zone of the weld formed by welding 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°C; 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-mouth impact energy (2.5 mm thickness) at room temperature is 107 J.

[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 materials 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 torch movement during the test welding, the distance S between the welding torch 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 plastic deformation begins when the heat-affected zone of the weld formed by the welding is cooled 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°C; 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-mouth 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 materials 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 torch movement during the test welding, the distance S between the welding torch 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, two pieces of high-strength steel base materials to be welded are welded, and the plastic deformation device is synchronously started during the welding process so that plastic deformation begins when the heat-affected zone of the weld formed by welding 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°C; 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 = 80cm; hammer frequency 30Hz, hammer force 300N.

[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 the present application; see Figure 6 , indicating that there is no residual austenite in the metallographic phase and no deformation marks. The V-mouth 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 = 80cm; hammer frequency 180Hz, hammer force 1000N.

[0119] Figure 7 The 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 residual 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 residual austenite in the metallographic structure, all are lath martensite, and there is no deformation mark. The V-mouth impact energy (2.5mm thickness) at room temperature is 59J.

[0125] According to the analysis of Examples 1 to 3 and Comparative Examples 1 to 3, it is shown that the welding strain method of a high-strength steel provided in 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 high V-mouth impact energy (2.5mm thickness) at room temperature, indicating good toughness. In Comparative Example 1, S is high, the temperature of the hammer point is low, and there is almost no supercooled austenite (decomposition is complete) in the organization of the heat affected zone, and the hammer force and frequency are low, and plastic deformation cannot be introduced; in Comparative Example 2, S is high, the temperature of the hammer point is low, and there is almost no supercooled austenite (decomposition is complete) in the organization, and the hammer force and frequency are high, which may cause damage to the hammer point; in Comparative Example 3, no plastic deformation is performed, but only simple welding. Therefore, to a certain extent, the high-strength steel welded plates obtained in Comparative Examples 1 to 3 have low V-mouth impact energy (2.5mm thickness) at room temperature, indicating poor toughness.

[0126] One or more technical solutions in the embodiments of the present application also 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 zone of the heat-affected zone, and the mechanical stabilization of the supercooled austenite is utilized to retain the residual 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 realize welding forming and forming, and simultaneously 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 above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features applied for herein.

Claims

1. A welding strain method for high-strength steel, the method comprising: Obtain the Ar1 value of the high-strength steel base material to be welded during welding cooling; 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; According to the temperature-time curve, determining the time T required for the heat affected zone to cool from the peak temperature to the preset temperature; According to the moving speed V of the welding gun of the trial welding and the time T, the distance S between the welding gun and the plastic deformation point of the high-strength steel base material to be welded is obtained; According to the distance S, determining the relative position of the welding torch and the plastic deformation device; 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.

2. The method according to claim 1, characterized in that The preset temperature is (Ar1-10)°C to Ar1°C.

3. The method according to claim 1, characterized in that 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 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.

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

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

6. The method according to claim 5, characterized in that 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.

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

8. The method according to claim 7, characterized in that The radius of curvature 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.

9. The method according to claim 7 or 8, characterized in that: 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.

10. The method according to claim 7, characterized in that 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.

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