CN119589296A - A method for improving the performance of high-strength wheel rim steel butt welding joints - Google Patents

Abstract

The invention discloses a method for improving the performance of a butt-welded joint of high-strength rim steel, which comprises the steps of carrying out flash butt welding or resistance butt welding on strip-shaped plates after being circled to form a cylindrical rim prefabricated blank with the butt-welded joint, quickly transferring the cylindrical rim prefabricated blank to a slag scraping station to scrape metal extruded by the butt-welded joint in the welding process, directly transferring the cylindrical rim prefabricated blank to a cooling station without rolling after slag scraping to quickly cool the butt-welded joint, and polishing the upper surface and the lower surface of the butt-welded joint in a polishing station, wherein the cylindrical rim prefabricated blank is welded on the upper surface of the butt-welded joint, and the lower surface of the butt-welded joint is polished in the polishing station. The method can eliminate surface defects caused by rolling, eliminate or inhibit necking cracking of the joint in flaring and sizing, and reduce various losses caused by small gap repair welding and large gap scrapping caused by necking cracking, thereby achieving the final purposes of improving production efficiency and reducing production cost.

Description

Method for improving performance of butt-welded joint of high-strength rim steel

Technical Field

The invention relates to a rim production method, in particular to a rim production method based on flash butt welding and resistance butt welding.

Background

Flash butt welding and resistance butt welding have high welding speed and high production efficiency, but belong to welding methods with large heat input, the heat cycle is complex in the welding process, and the heat affected zone is more than ten millimeters and is far higher than that of common arc welding and laser welding.

The high-strength rim steel is usually steel with C-Si-Mn as a main component or other similar component systems, the breaking strength is generally above 500MPa, and the performance requirements are met through fine-grain strengthening, two-phase strengthening, solid solution strengthening or precipitation strengthening.

However, high strength rim steels are particularly sensitive to large heat inputs and complex thermal cycles and are very susceptible to joint softening. The softening area cannot be deformed in coordination with the base material in the subsequent flaring and sizing processes. When the deformation is concentrated in the softening area, the deformation amount of the softening area is too large, and necking and cracking phenomena occur in the area. Particularly when the post-weld joint cools at a slower rate, some tempered structure is also likely to occur, more severe softening of the joint part area, and eventually neck cracking of the joint during flaring and sizing.

In addition, in the process of manufacturing the rim, the strip blank is generally required to be subjected to flashing or resistance butt welding after a circle winding process to form a cylinder shape, then slag scraping and rolling are performed on a welding joint, and then the finished rim is manufactured through the processes of flaring, rolling, sizing and valve hole opening. The rolling process is an important process for rim production, and the thickness of the joint after slag scraping is usually larger than that of a base material, namely the thickness is remained high. The thickness of the joint can be reduced by rolling, the rolling deformation can generate work hardening to improve the hardness and strength of the welding line, and the steel roller rolls over the welding line and can absorb a part of heat of the welding line to reduce the temperature of the joint. However, because the thickness of the large-sized wheel material is larger, more metal is extruded after flash and resistance butt welding, more welding slag and burrs remain after slag scraping than the small wheel, and for a plurality of large-sized commercial vehicle rim production lines only having a rolling procedure between slag scraping and flaring, the burrs and the welding slag can be rolled into the joint or the surface of a base metal after rolling to form surface quality defects.

If the polishing process is introduced to replace the rolling process, burrs, weld residues and welding slag can be truly polished off together, surface defects caused by pressing the burrs and the welding slag into the joint and the base metal are eliminated, but the problems that the welding joint loses the possibility of improving strength through work hardening, the temperature of the welding seam is very high after slag scraping, the temperature of the polishing is also adversely affected, the temperature is very high when the joint is flared finally, the mechanical property of the joint is reduced due to high temperature, the joint is high in temperature and the cooling speed is low, the joint tissue is easily softened, necking crack is more easily caused due to overlarge deformation of a softening area during sizing, the heat input has to be reduced as much as possible in order to reduce the softening of the joint and improve the cooling speed of the joint, the welding process interval is narrowed, and the problems of non-welding and the like are easily caused.

Due to the problems mentioned above, in the rim production line with only the grinding process between the skim and the flaring, the necking cracking of the joint is very easy to occur due to the temperature, strength and thickness when producing high-strength rim steel materials, and the rejection rate and repair welding cost are greatly increased.

Disclosure of Invention

The invention aims to provide a method for improving the performance of a high-strength rim steel butt welding joint, which is different from the conventional rim manufacturing method, does not carry out a rolling process between slag scraping and flaring processes, and adopts a rapid cooling and polishing process to replace the original rolling process so as to finally improve the joint strength and inhibit the risk of necking cracking of the joint during flaring and sizing.

In order to achieve the above object, the present invention provides a method for improving the performance of a butt weld joint of high-strength rim steel, comprising the steps of:

100, performing flash butt welding or resistance butt welding after the strip-shaped plate is circled to form a cylindrical rim prefabricated blank with a butt welding joint;

Rapidly transferring the tubular rim prefabricated blank to a slag scraping station to scrape the metal extruded by the butt welding joint in the welding process;

300, directly transferring the tubular rim prefabricated blank to a cooling station without rolling after slag scraping so as to rapidly cool the butt welding joint;

And 400, polishing the upper and lower surfaces of the welding head at a polishing station.

In the rim manufacturing process, flash butt welding or resistance butt welding is performed, and a part of molten metal is burned and extruded, so that the heat input amount is large. The temperature of the welded joint part is above 800 ℃, the whole rim can reach above 200 ℃, and the whole rim needs tens of minutes to be naturally cooled to room temperature. However, all the working procedures after the existing welding are stopped, and the joint temperature after slag scraping, grinding or slag scraping and rolling still can reach 300-400 ℃. At this time, when the flaring process is performed, the temperature of the joint part is higher than 200-300 ℃ of the base metal. This results in a coarse structure in the joint, and the joint temperature is higher than that of the base material, and the tensile strength, yield strength and elongation are lower than those of the base material, so that neck cracking easily occurs in the joint portion during flaring.

In addition, in the subsequent roll forming process, even if the temperature of the joint continuously drops due to the action of cooling liquid and the temperature during sizing is lower than 100 ℃, the heat treatment system and the strengthening mechanism of the high-strength rim steel are complex in the production process, the coarse grain and subcritical heat affected zone of the joint are easy to soften in the cooling process of tens of minutes after welding, the strength of the area during sizing is low, the joint cannot be deformed together with a base metal in a coordinated manner, all deformation is concentrated in the area, and finally necking cracking occurs.

In addition, the burrs and welding slag remained after the slag scraping can be ground into the joint or the base metal to form surface quality defects only by adopting a rolling process between the slag scraping and the flaring.

Based on the method, the rapid cooling process is adopted to rapidly cool the temperature of the joint part to room temperature, so that the problem that the temperature is too high when the joint enters the flaring process, the tensile strength and the yield strength are too low, and the necking crack is caused in the flaring process is avoided. The adoption of the rapid cooling process can greatly reduce the time for cooling the joint to the room temperature, and can inhibit the tempering and softening tissues of partial areas of the joint in the long cooling process due to tempering effect, thereby preventing deformation from being concentrated in the softening areas in the flaring and sizing process and finally generating necking cracking.

The polishing procedure after rapid cooling can completely remove the surplus height, welding slag and burrs of the joint after slag scraping, so as to improve the surface quality of the joint.

Further, in the method for improving the performance of the butt-welded joint of the high-strength rim steel, the thickness of the butt-welded joint is 2-15 mm.

Further, in the method for improving the butt welding joint performance of the high-strength rim steel, the total time for completing the step 200 is controlled to be 3-30 s.

Further, in the method for improving the butt welding joint performance of the high-strength rim steel, in step 300, the time for transferring the rim prefabricated blank to the cooling station is controlled to be 3-20 s.

Further, in the method for improving the performance of the butt-welded joint of the high-strength rim steel, in step 300, a plurality of spray holes arranged in a matrix are adopted to spray cooling media to the upper surface and the lower surface of the butt-welded joint so as to rapidly cool.

Further, in the method for improving the performance of the butt weld of the high-strength rim steel according to the present invention, a cooling medium is used in the grinding in step 400.

Further, in the method for improving the performance of the butt welded joint of the high-strength rim steel, the method further comprises the following steps of step 500, flaring the tubular rim prefabricated blank, and step 600, rolling, sizing and valve perforating.

Further, in the method for improving the butt welding joint performance of the high-strength rim steel, the tensile strength of the strip-shaped plate is 500-1300 MPa.

The strip-shaped strip comprises, by mass, 0.05% -0.5% of C, 0.01% -25% of Mn and 0.1% -5% of Si.

Further, in the method for improving the butt welding joint performance of the high-strength rim steel, in step 300, the rapid cooling speed is controlled to be 50-500 ℃ per second.

Further, the rapid cooling speed is controlled to be 100-500 ℃ per second.

Further, in the method for improving the performance of the butt welded joint of the high-strength rim steel, in step 300, the rapid cooling time is 2-10 s.

According to the invention, the rapid cooling step only cools the butt joint part, in some embodiments, the cooling medium sprays the upper surface and the lower surface of the butt joint simultaneously, so that the cooling of the joint part with the thickness of 2-15 mm can be completed within 2-10 s, and the production beat is not influenced.

The method for improving the performance of the butt welding joint of the high-strength rim steel has the following advantages:

By adopting the method of the invention, the hardness and the tensile strength of the butt welding joint are increased, and the temperature is rapidly reduced to room temperature or lower. When the rim prefabricated blank is expanded or sized, the joint does not generate necking cracking or necking cracking proportion is reduced, and the surface of the rim has no surface defects caused by welding slag, burrs, excess heights and the like.

According to the invention, the rim is prepared by adopting a rapid cooling and polishing process between the slag scraping and flaring processes, the improvement on the mechanical property and the surface quality of the rim joint is superior to that of the process adopting only the rolling step, and the improvement on the mechanical property of the joint is superior to that of the process adopting only the polishing step.

The method can eliminate surface defects caused by rolling, eliminate or inhibit necking cracking of the joint in flaring and sizing, and reduce various losses caused by small gap repair welding and large gap scrapping caused by necking cracking, thereby achieving the final purposes of improving production efficiency and reducing production cost.

Drawings

FIG. 1 shows a flow chart of the steps of a method of improving the performance of a high strength rim steel butt weld according to one embodiment of the present invention.

Fig. 2 shows hardness profiles of joints obtained in example 1, comparative example 1 and comparative example 2.

Fig. 3 shows hardness profiles of joints obtained in example 2 and comparative example 3.

Detailed Description

The method for improving the performance of the welded joint by the high-strength rim steel according to the invention will be further explained and illustrated with reference to specific examples and the accompanying drawings, but the explanation and illustration do not unduly limit the technical scheme of the invention.

FIG. 1 shows a flow chart of the steps of a method of improving the performance of a high strength rim steel butt weld according to one embodiment of the present invention.

As shown in fig. 1, in this embodiment, the method for improving the performance of the butt weld joint of the high-strength rim steel according to the present invention includes the steps of:

100, performing flash butt welding or resistance butt welding after the strip-shaped plate is circled to form a cylindrical rim prefabricated blank with a butt welding joint;

Rapidly transferring the tubular rim prefabricated blank to a slag scraping station to scrape the metal extruded by the butt welding joint in the welding process;

300, directly transferring the cylindrical rim prefabricated blank to a cooling station without rolling after slag scraping so as to rapidly cool the butt welding joint at the cooling speed of 50-500 ℃ per second, wherein the cooling medium can adopt water, and the cooling time is 2-10 s;

400, polishing the upper and lower surfaces of the welding joint at a polishing station, wherein a cooling medium is adopted during polishing, and after slag scraping on the surface of the welding joint is performed, all residual slag, burrs and residual heights are flattened, the white and bright metal surface is exposed, and surface defects possibly caused by the slag, the burrs and the residual heights are completely eliminated;

The tubular rim prefabricated blank is flared;

600 roll forming, sizing and valve opening.

In some embodiments, a rapid cooling device may be used to rapidly cool the butt joint. The rapid cooling device can be arranged on the fixed base or the robot through a clamp frame, and can comprise an upper clamp, a lower clamp, an upper clamp cooling nozzle, a lower clamp cooling nozzle, a cooling medium recovery box, an infrared temperature probe, a clamp action servo motor, a controller, a clamp frame, a cooling medium pipeline, a cooling medium flow measuring and controlling device, a cooling medium container and a cooling medium pressurizing pump.

The upper clamp and the lower clamp can be arranged on the clamp frame and can move along the clamp frame, so that the upper clamp and the lower clamp are used for clamping prefabricated blanks of cylindrical rims with different thicknesses and widths, and the pressure and the action of the upper clamp and the lower clamp can be controlled by the clamp action servo motor and the controller.

The upper and lower clamps are respectively provided with upper and lower clamp cooling nozzles, and during the rapid cooling process, the cooling nozzles spray cooling mediums, such as water, to the upper and lower surfaces of the butt joint at the same time to rapidly cool. The upper clamp and the lower clamp are respectively provided with a plurality of spray holes, and the spray holes are arranged in a matrix and are uniformly distributed on the upper clamp and the lower clamp.

In a more specific example, the upper and lower clamps may be provided with spray holes having a width of 50mm to cool a width range of 50mm of the butt joint, the spray hole intervals may be 6-10 mm, the spray hole angles may be 5-45 °, and the spray hole diameters may be 0.5-10 mm.

The cooling medium recovery box can be positioned below the lower clamp, and the upper clamp, the lower clamp and the cooling medium recovery box are communicated.

For measuring the surface temperature of the butt-welded joint, an infrared temperature probe can also be arranged on the upper clamp or the lower clamp. The cooling medium flow measurement and control device is connected with the cooling medium pressure pump, can adjust the flow and the flow speed of the cooling medium by controlling the cooling medium pressure pump, and controls the cooling speed based on the temperature data fed back by the infrared temperature measurement probe.

The present invention was conducted by verifying the effect of the present invention by using examples 1 to 6 and comparative examples 1 to 3.

Wherein the strip plates of examples 1-3 and comparative examples 1-2 are B650CL hot rolled plates, the base material structure is mainly ferrite and a small amount of pearlite, the tensile strength is 650MPa, and the mass percentages of the components are that C is 0.056%, si is 0.099%, mn is 1.67%, P is 0.01%, S is 0.001%, and the balance is Fe and other unavoidable impurities.

Examples 1-3 and comparative examples 1-2 in step 100, a strip-shaped plate was first subjected to coiling with a coiling machine, and then both ends of the coiled strip were subjected to flash butt welding to form a tubular rim preform. Wherein, flash butt welding adopts a pulse flash butt welding machine, the preheating current is 200A (primary current), the preheating distance is 3.5mm, the burning amount is 4.0mm, the upsetting charging time is 0.2s, and the upsetting distance is 3.5mm.

The strip plates of examples 4-6 and comparative example 3 all used B780CL hot rolled plates, the parent metal structure was mainly ferrite, bainite and martensite, the tensile strength was 750MPa, the mass percentages of the components were C0.12%, si 0.3%, mn 0.2%, P0.02%, S0.005%, als 0.015%, and the balance Fe and other unavoidable impurities.

Examples 4-6 and comparative example 3 in step 100, a strip-shaped plate was first subjected to coiling by a coiling machine, and then both ends of the coiled strip were subjected to resistance butt welding to form a cylindrical blank. Wherein, the preheating current of example 4 is 200kA, the welding current is 300kA, the preheating time is 2s, the welding time is 2s, the upsetting charging time is 0.5s, the preheating current of example 5 is 100kA, the welding current is 200kA, the preheating time is 0.5s, the welding time is 0.7s, the upsetting charging time is 0.2s, the preheating current of example 6 is 400kA, the welding current is 800kA, the preheating time is 2.5s, the welding time is 4s, and the upsetting charging time is 1s.

Comparative example 1 did not employ the rapid cooling step 300 and the polishing step 400, and there was only a rolling step between step 200 and step 500, and the remaining steps were the same as in example 1.

Comparative example 2 did not employ the rapid cooling step 300, and there was only a polishing step between step 200 and step 500, and the remaining steps were the same as in example 1.

Comparative example 3 did not employ the rapid cooling step 300, and there was only a polishing step between step 200 and step 500, and the remaining steps were the same as example 2.

Table 1 shows the specific process parameters of inventive examples 1-6 and comparative examples 1-3 in each step.

Table 1.

Table 2 shows the surface temperatures of butt joints at the time of entering the flaring step and the proportions of neck cracking occurring in the flaring and sizing steps of examples 1 to 6 and comparative examples 1 to 3 of the present invention.

Note that the data in table 2 are the average values of the surface temperatures and the statistical results of the neck cracking rate of the sizing for 1000 samples produced for each of the examples and comparative examples.

As can be seen from table 2, in the rim production process, the temperature of the butt welded joint before entering the flaring process can be significantly reduced by adopting the rapid cooling step, and the cracking proportion in the subsequent flaring and necking steps can be greatly reduced.

In addition, the hardness of the cross section metallographic phase of the butt welded joint of the rim preform after finishing polishing of example 1, comparative example 1 and comparative example 2 was measured, and the hardness distribution curve thereof is shown in fig. 2. As can be seen from fig. 2, the joint hardness of example 1 is the highest overall, comparative example 1 times, and comparative example 2 is the lowest. The phenomenon shows that the rapid cooling and polishing process can effectively reduce the softening of the joint part area caused by overlong joint cooling time, and can effectively inhibit necking cracking of the joint in the flaring and sizing processes.

Hardness tests were carried out on the section metallographic phases of the butt welded joints of the rim prefabricated blanks finished in the polishing of the example 2 and the comparative example 3, and the hardness distribution curves are shown in fig. 3. As can be seen from fig. 3, the butt weld joint hardness of example 2 as a whole is significantly higher than that of comparative example 3. The phenomenon shows that the rapid cooling and polishing process can effectively reduce the softening of the joint part area caused by overlong joint cooling time, and further effectively reduce the necking cracking of the joint in the flaring and sizing processes.

It should be noted that the combination of the technical features in the present invention is not limited to the combination described in the claims or the combination described in the specific embodiments, and all the technical features described in the present invention may be freely combined or combined in any manner unless contradiction occurs between them.

It should also be noted that the above-recited embodiments are merely specific examples of the present invention. It is apparent that the present invention is not limited to the above embodiments, and similar changes or modifications will be apparent to those skilled in the art from the present disclosure, and it is intended to be within the scope of the present invention.

Claims (11)

1. A method for improving the performance of high-strength rim steel butt weld joints, characterized in that it comprises the steps of: 100: After the strip plate is circled, flash butt welding or resistance butt welding is performed to form a cylindrical rim prefabricated blank having a butt welding joint; 200: quickly transferring the cylindrical rim preform to the scraping station to scrape off the metal extruded from the butt welding joint during the welding process; 300: After scraping off the slag, the cylindrical rim preform is directly transferred to the cooling station without rolling, so as to quickly cool the butt welding joint; 400: Grind the upper and lower surfaces of the butt weld joint at the grinding station. 2. The method for improving the performance of high-strength rim steel butt weld joints as claimed in claim 1, characterized in that the thickness of the butt weld joint is 2 to 15 mm. 3. The method for improving the performance of high-strength wheel rim steel butt weld joints as claimed in claim 1, characterized in that the total time required to complete step 200 is controlled to be 3 to 30 seconds. 4. The method for improving the performance of high-strength rim steel butt weld joints according to claim 1, characterized in that, in step 300, the time for transferring the rim preform to the cooling station is controlled to be 3 to 20 seconds. 5. The method for improving the performance of high-strength rim steel butt weld joints according to claim 1, characterized in that in step 300, a plurality of spray holes arranged in a matrix are used to spray cooling medium onto the upper and lower surfaces of the butt weld joint for rapid cooling. 6. The method for improving the performance of high-strength wheel rim steel butt weld joints according to claim 1, characterized in that in step 400, a cooling medium is used during grinding. 7. The method for improving the performance of high-strength rim steel butt welding joints as claimed in claim 1, characterized in that after step 400, it also includes: step 500: expanding the cylindrical rim prefabricated blank; step 600: rolling, sizing and valve opening. 8. The method for improving the performance of high-strength rim steel butt weld joints according to claim 1, wherein the tensile strength of the strip plate is 500 to 1300 MPa. 9. The method for improving the performance of high-strength wheel rim steel butt weld joints according to any one of claims 1 to 8, characterized in that in step 300, the rapid cooling rate is controlled to be 50-500°C/s. 10. The method for improving the performance of high-strength wheel rim steel butt weld joints according to claim 9, characterized in that in step 300, the speed of the rapid cooling is controlled to be 100-500°C/s. 11. The method for improving the performance of high-strength rim steel butt weld joints according to claim 1, characterized in that: In step 300, the rapid cooling time is 2 to 10 seconds.