Improvement method for pickling-free high-strength welding wire rod oxide scale

Abstract

The invention discloses an improvement method for pickling-free high-strength welding wire rod oxide scale, and relates to the technical field of steel rolling. The residual oxygen content, the soaking zone temperature and the blank in-furnace time in the blank heating process are controlled, so that the oxidation amount of the blank in the heating furnace is within the threshold value range; the spinning temperature is controlled within a preset range through the water quantity of the water tank; a two-stage cooling process is adopted for cooling the wire rod, the first-stage cooling is air cooling, and the second-stage cooling is slow cooling. The method effectively improves the flatness of the bonding interface of the high-strength wire rod oxide scale and the substrate, and is beneficial to improving the abrasive paper polishing performance of the wire rod. Meanwhile, no high-temperature anti-oxidation coating is needed, and the cost is not obviously increased compared with that of other wire rod production processes.

Description

Technical Field

[0001] The invention relates to the technical field of steel rolling, in particular to a method for improving the iron oxide scale of a high-strength welding wire rod without pickling. Background Art

[0002] During the drawing process of pickling-free welding wire rod, a grinder is needed to grind the surface of the wire rod to remove the hot-rolled iron oxide scale on the surface of the wire rod. For high-strength welding wire, its composition often contains high content of Si and Ni elements. The addition of these elements will lead to poor flatness of the interface between the hot-rolled iron oxide scale and the matrix, and the pinning and embedding phenomena are relatively serious, so the grinding performance of high-strength welding wire rod is often poor. In addition, due to the high alloy content, the crack incidence rate of the billet is high, and cracks on the surface of the rolled material often occur. These factors lead to 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 disadvantages of the prior art and provide a method for improving the iron oxide scale of high-strength welding wire rods without pickling.

[0004] In order to solve the above technical problems, the technical solution of the present invention is as follows: A method for improving the iron scale of pickling-free high-strength welding wire rod, comprising: Pre-treating the blank; Control the residual oxygen content, soaking zone temperature and the time the billet is in the furnace during the heating process of the billet, so that the oxidation amount of the billet in the heating furnace is within the threshold range; The spinning temperature is controlled within the preset range by the water volume in the water tank; The wire rod is cooled by a two-stage cooling process, wherein the first stage of cooling is air cooling and the second stage of cooling is slow cooling.

[0005] As a preferred solution of the method for improving the scale of the pickling-free high-strength welding wire rod of the present invention, the pretreatment of the blank comprises: The blanks are chamfered and fully surface ground.

[0006] As a preferred solution of the method for improving the scale of the pickling-free high-strength welding wire rod of the present invention, wherein: the residual oxygen content, the soaking section temperature and the time of the billet in the furnace are controlled during the heating process of the billet so that the oxidation amount of the billet in the heating furnace is within the threshold range, including: Control the residual oxygen content in the heating furnace to less than 3%; Control the temperature of the soaking section to be less than 1000℃; Control the time of the billet in the furnace to be less than 4h.

[0007] As a preferred solution of the method for improving the scale of the pickling-free high-strength welding wire rod of the present invention, wherein: the step of controlling the wire laying temperature within a preset range by using the water volume in the water tank comprises: The spinning temperature is controlled by the water volume in the water tank to be 50℃ higher than the AC3 temperature.

[0008] As a preferred solution of the method for improving the scale of the pickling-free high-strength welding wire rod of the present invention, the duration of the first stage cooling is less than 30 seconds.

[0009] As a preferred solution of the method for improving the scale of the pickling-free high-strength welding wire rod of the present invention, the temperature of the wire rod after the first stage of cooling is 750-800°C.

[0010] As a preferred solution of the method for improving the scale of the pickling-free high-strength welding wire rod described in the present invention, the two-stage cooling is carried out slowly in the heat-insulating cover, and the roller speed is less than 0.1m / s.

[0011] The beneficial effects of the present invention are: (1) The present invention effectively improves the flatness of the interface between the iron oxide scale of the high-strength welding wire wire rod and the substrate, which is beneficial to improving the sandpaper grinding performance of the wire rod.

[0012] (2) The present invention does not require the use of high-temperature anti-oxidation coatings and has no significant cost increase compared to other wire rod production processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0014] Figure 1 This is a schematic diagram of the interface between the iron oxide scale and the body of the welding wire rod produced by the original process; Figure 2 Schematic diagram of the interface between the iron oxide scale and the body in the welding wire rod produced by process 2; Figure 3 A schematic diagram of the interface between the iron oxide scale and the body in the welding wire rod produced by the method for improving the iron oxide scale of the pickling-free high-strength welding wire rod provided by the present invention. DETAILED DESCRIPTION

[0015] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific implementation modes and in combination with the accompanying drawings.

[0016] The present application provides a method for improving the scale of high-strength welding wire rod without pickling, and the method specifically comprises the following steps: Step S101: pre-treating the blank.

[0017] Specifically, the blank is chamfered and the entire surface is ground, and the grinding standard is that there are no surface cracks visible to the naked eye.

[0018] Step S102: Control the residual oxygen content, the temperature of the soaking section and the time the billet is in the furnace during the heating process of the billet, so that the oxidation amount of the billet in the heating furnace is within a threshold range.

[0019] Specifically, the control indicators for each item are as follows: a. Control the residual oxygen content of the heating furnace to less than 3%; b. Control the temperature of the soaking section to be less than 1000℃; c. Control the time the billet spends in the furnace to less than 4 hours.

[0020] Step S103: controlling the spinning temperature to be within a preset range by adjusting the water volume in the water tank.

[0021] Specifically, the spinning temperature is controlled by the water volume in the water tank. The actual spinning temperature is adjusted according to the alloy content. In principle, the spinning temperature should be higher than the AC3 temperature by more than 50°C.

[0022] Step S104: adopt a two-stage cooling process to cool the wire rod, and the first stage of cooling is air cooling, and the second stage of cooling is slow cooling.

[0023] Specifically, the duration of the first stage cooling is no more than 30 seconds, and the temperature entering the cover at the end of the first stage cooling is in the temperature range of 750-800°C by adjusting the air volume of the fan. The second stage cooling is carried out in the heat-insulating cover, and the roller speed is <0.1m / s.

[0024] The following is further described by means of specific examples.

[0025] Example: 1. Take 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 temperature of this steel grade AC3 is 850°C. The flatness of the oxide scale and the bonding surface of the welding wire rod produced by conventional technology is poor, and the oxide embedding along the grain boundary is relatively serious. Figure 1 , the grinding performance of wire rod is poor.

[0026] 2. After the blank is ground and the spinning temperature is increased (process 2), the interface is improved to a certain extent, but there is still oxidation embedding along the grain boundary, see Figure 2 .

[0027] 3. Based on process 2, the heating temperature is further reduced, and two-stage cooling is adopted at the same time (process 3). The first stage of cooling is air cooling, which lasts for 45 seconds. At the end of the first stage of cooling, the wire rod temperature is measured to be 760°C. The second stage of cooling is carried out in the insulation cover, with a roller speed of 0.1m / s. This process has good flatness of the bonding surface between the oxidized iron scale and the substrate, and low degree of oxidized embedding, see Figure 3 The grinding performance of the wire rod is significantly improved.

[0028] See Table 1 for specific process comparison.

[0029]

[0030] Table 1 Therefore, the technical solution of the present application effectively improves the flatness of the interface between the oxide scale of the high-strength welding wire rod and the substrate, which is beneficial to improving the sandpaper grinding performance of the wire rod. At the same time, there is no need to use high-temperature anti-oxidation coating, and there is no obvious cost increase compared to other wire rod production processes.

[0031] In addition to the above embodiments, the present invention may also have other implementation modes; any technical solutions formed by equivalent replacement or equivalent transformation shall fall within the protection scope required by the present invention.

Claims

1. A method for improving the scale of high-strength welding wire rod without pickling, characterized in that: include: Pre-treating the blank; Control the residual oxygen content, soaking zone temperature and the time the billet is in the furnace during the heating process of the billet, so that the oxidation amount of the billet in the heating furnace is within the threshold range; The spinning temperature is controlled within the preset range by the water volume in the water tank; The wire rod is cooled by a two-stage cooling process, wherein the first stage of cooling is air cooling and the second stage of cooling is slow cooling.

2. The method for improving the scale of pickling-free high-strength welding wire rod according to claim 1, characterized in that: The pretreatment of the blank comprises: The blanks are chamfered and fully surface ground.

3. The method for improving the iron oxide scale of the pickling-free high-strength welding wire rod according to claim 1, characterized in that: The controlling of the residual oxygen content, the soaking zone temperature and the time the billet is in the furnace during the heating process of the billet so that the oxidation amount of the billet in the heating furnace is within a threshold range includes: Control the residual oxygen content in the heating furnace to less than 3%; Control the temperature of the soaking section to be less than 1000℃; Control the time of the billet in the furnace to be less than 4h.

4. The method for improving the iron oxide scale of the pickling-free high-strength welding wire rod according to claim 1, characterized in that: The method of controlling the spinning temperature to be within a preset range by using the water volume in the water tank includes: The spinning temperature is controlled by the water volume in the water tank to be 50℃ higher than the AC3 temperature.

5. The method for improving the scale of pickling-free high-strength welding wire rod according to claim 1, characterized in that: The duration of the first stage cooling is less than 30 seconds.

6. The method for improving the iron oxide scale of the pickling-free high-strength welding wire rod according to claim 5, characterized in that: The temperature of the wire rod after the first stage of cooling is 750~800℃.

7. The method for improving the iron oxide scale of the pickling-free high-strength welding wire rod according to claim 1, characterized in that: The second stage cooling is performed slowly in a heat-insulating shell, and the roller speed is less than 0.1 m / s.

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