Method for improving scale of high strength welding wire rod without pickling

Abstract

The application discloses an acid-free high-strength welding wire rod iron scale improvement method and relates to the technical field of steel rolling, which comprises the following steps: pretreating a blank; controlling residual oxygen content, soaking section temperature and furnace time of the blank so that the oxidation amount of the blank in the heating furnace is within a threshold range; controlling the wire drawing temperature within a preset range through water tank water amount control; and adopting a two-stage cooling process to cool the rod, wherein the first-stage cooling is air cooling and the second-stage cooling is slow cooling. The application effectively improves the flatness of the high-strength welding wire rod iron scale and the base body bonding interface, and is beneficial to improving the sandpaper polishing performance of the rod. Meanwhile, high-temperature antioxidant coating is not needed, and there is no obvious cost increase compared with other rod production processes.

Description

A method for improving the iron oxide scale of high-strength welding wire rod without pickling Technical Field

[0001] This invention relates to the field of steel rolling technology, and in particular to a method for improving the iron oxide scale on high-strength welding wire rods that do not require pickling. Background Technology

[0002] During the drawing process, pickling-free welding wire rods require grinding to remove the hot-rolled iron oxide scale. High-strength welding wire often contains high levels of Si and Ni. The addition of these elements leads to poor smoothness at the interface between the hot-rolled iron oxide scale and the matrix, resulting in significant pinning and embedding phenomena, thus making the grinding performance of high-strength welding wire rods generally poor. Furthermore, due to the high alloy content, the incidence of billet cracks is high, and surface cracks in the rolled material occur frequently. These factors result in a large consumption of sandpaper during the grinding process. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an improved method for removing iron oxide scale from high-strength welding wire rods without acid washing.

[0004] To solve the above technical problems, the technical solution of the present invention is as follows:

[0005] A method for improving the iron oxide scale on high-strength welding wire rod without acid washing includes:

[0006] Pre-treat the billet;

[0007] Controlling the residual oxygen content, the temperature of the soaking zone, and the time the billet spends in the furnace during the billet heating process ensures that the amount of oxidation of the billet in the heating furnace is within the threshold range.

[0008] The silk-spinning temperature is controlled within a preset range by adjusting the water volume in the water tank.

[0009] A two-stage cooling process is used to cool the wire rod, with the first stage being air cooling and the second stage being slow cooling.

[0010] As a preferred embodiment of the method for improving the iron oxide scale of acid-free high-strength welding wire rod according to the present invention, the pretreatment of the billet includes:

[0011] The blank is chamfered and its entire surface is ground.

[0012] As a preferred embodiment of the improved method for reducing iron oxide scale on acid-free high-strength welding wire rod according to the present invention, the step of controlling the residual oxygen content, the temperature of the soaking zone, and the time the billet spends in the furnace during the billet heating process, so that the amount of oxidation of the billet in the heating furnace is within a threshold range, includes:

[0013] Control the residual oxygen content in the heating furnace to be less than 3%;

[0014] The temperature of the heat spreader should be kept below 1000℃.

[0015] The time the billet spends in the furnace should be controlled to be less than 4 hours.

[0016] As a preferred embodiment of the improved method for reducing iron oxide scale on acid-free high-strength welding wire rod according to the present invention, wherein controlling the wire feeding temperature within a preset range by controlling the water volume in the water tank includes:

[0017] The water level in the water tank is controlled to keep the spinning temperature above the AC3 temperature by 50°C.

[0018] As a preferred embodiment of the improved method for removing iron oxide scale from high-strength welding wire rod without acid washing according to the present invention, the duration of the first-stage cooling is less than 30 seconds.

[0019] As a preferred embodiment of the improved method for reducing iron oxide scale on high-strength welding wire rod without acid washing according to the present invention, the temperature of the wire rod after the first stage of cooling is 750~800℃.

[0020] As a preferred embodiment of the improved method for removing iron oxide scale from high-strength welding wire rod without acid washing according to the present invention, the second-stage cooling is carried out slowly inside the heat-insulating cover, and the roller speed is less than 0.1m / s.

[0021] The beneficial effects of this invention are:

[0022] (1) The present invention effectively improves the flatness of the interface between the iron oxide scale of high-strength welding wire rod and the substrate, which is beneficial to improving the sanding performance of the wire rod.

[0023] (2) This invention does not require the use of high-temperature antioxidant coatings and does not significantly increase costs compared to other wire rod production processes. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 is a schematic diagram of the interface between the iron oxide scale and the machine body in the welding wire rod produced using the original process;

[0026] Figure 2 is a schematic diagram of the interface between the iron oxide scale and the machine body in the welding wire rod produced by process 2;

[0027] Figure 3 is a schematic diagram of the bonding surface between the iron oxide scale and the machine body in the welding wire rod produced by the improved method for removing iron oxide scale from high-strength welding wire rod without acid washing provided by the present invention. Detailed Implementation

[0028] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0029] This application provides a method for improving the iron oxide scale on high-strength welding wire rod without pickling, the method specifically including the following steps:

[0030] Step S101: Pre-treat the billet.

[0031] Specifically, the blank is chamfered and the entire surface is ground, with the grinding standard being that there are no visible surface cracks.

[0032] Step S102: Control the residual oxygen content, the temperature of the soaking zone, and the time the billet spends in the furnace during the billet heating process so that the amount of oxidation of the billet in the heating furnace is within the threshold range.

[0033] Specifically, the control indicators for each item are as follows:

[0034] a. Control the residual oxygen content in the heating furnace to be less than 3%;

[0035] b. Control the temperature of the heat spreader section to be less than 1000℃;

[0036] c. Control the time the billet is in the furnace to be less than 4 hours.

[0037] Step S103: Control the silk spinning temperature within a preset range by controlling the water volume in the water tank.

[0038] Specifically, the wire-spinning temperature is controlled by the water volume in the tank. The actual wire-spinning temperature is adjusted according to the alloy content, and in principle, the wire-spinning temperature should be at least 50°C higher than the AC3 temperature.

[0039] Step S104: The wire rod is cooled using a two-stage cooling process, with the first stage being air cooling and the second stage being slow cooling.

[0040] Specifically, the first-stage cooling lasts no more than 30 seconds. By adjusting the fan airflow, the temperature entering the cover at the end of the first-stage cooling is within the range of 750~800℃. The second-stage cooling is carried out inside the insulated cover, with a roller conveyor speed of <0.1m / s.

[0041] The following specific examples will provide further details.

[0042] Example: 1. Taking a certain grade of high-strength welding wire rod as an example, the alloy composition is relatively high, with Si content of 0.7wt% and Ni content of 2.4wt%. The AC3 temperature of this steel grade is 850°C. The iron oxide scale of the welding wire rod produced by conventional process has poor flatness at the interface between the iron oxide scale and the body, and the oxide embedding along the grain boundary is relatively serious. See Figure 1. The grinding performance of the wire rod is poor.

[0043] 2. After the billet is ground and the spinning temperature is increased (process 2), the interface is improved to some extent, but there is still oxidation embedding along the grain boundary, see Figure 2.

[0044] 3. Based on process 2, the heating temperature is further reduced, and a two-stage cooling process (process 3) is adopted. The first stage of cooling is air cooling, lasting 45 seconds, and the measured temperature of the wire rod at the end of the first stage is 760°C. The second stage of cooling is carried out inside an insulated cover, with a roller speed of 0.1 m / s. This process results in good flatness of the interface between the iron oxide scale and the substrate, and a low degree of oxide embedding, as shown in Figure 3. The grinding performance of the wire rod is significantly improved.

[0045] For a detailed comparison of the processes, please refer to Table 1.

[0046]

[0047] Table 1

[0048] Therefore, the technical solution of this application effectively improves the smoothness of the interface between the iron oxide scale and the substrate of high-strength welding wire rod, which is beneficial to improving the sanding performance of the wire rod. At the same time, it eliminates the need for high-temperature anti-oxidation coatings and does not significantly increase costs compared to other wire rod production processes.

[0049] In addition to the above embodiments, the present invention may have other implementation methods; all technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

Claims

1. A method for improving the iron oxide scale on high-strength welding wire rod without pickling, characterized in that: include: Pre-treatment of the billet includes chamfering and full-surface grinding; controlling the residual oxygen content, homogenization zone temperature, and billet time in the furnace during heating to ensure the oxidation level of the billet in the furnace is within a threshold range, including: controlling the residual oxygen content in the furnace to be less than 3%; controlling the homogenization zone temperature to be less than 1000℃; controlling the billet time in the furnace to be less than 4 hours; controlling the wire drawing temperature within a preset range by controlling the water volume in the water tank, including: controlling the wire drawing temperature to be more than 50℃ higher than the AC3 temperature by controlling the water volume in the water tank; employing a two-stage cooling process to cool the wire rod, with the first stage cooling being air cooling, the duration of which is less than 30 seconds, and the temperature of the wire rod after the first stage cooling being 750~800℃; and the second stage cooling being slow cooling, which is carried out slowly within an insulated cover, with the roller speed being less than 0.1m / s.

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