A method for controlling mechanical decrustation of an oxide layer of SWRH82B

Abstract

This invention discloses a method for controlling the mechanical peeling of the SWRH82B oxide layer, comprising the following steps: (1) a precise temperature control process during rolling; (2) a pretreatment process; (3) an auxiliary process for oxide layer structure regulation; (4) a mechanical peeling process; and (5) a post-treatment process. The purpose of this invention is to provide a method for controlling the mechanical peeling of the SWRH82B oxide layer, aiming to solve the problems of incomplete peeling, significant matrix damage, and poor environmental performance in existing SWRH82B oxide layer treatment processes. By precisely controlling the temperature during rolling to optimize the oxide layer phase structure and interface bonding state, and combining the synergistic technology of "pretreatment-precise mechanical peeling-post-treatment," the technical goals of achieving an oxide layer residue rate ≤0.5%, a matrix damage depth ≤10μm, and a 30% reduction in peeling energy consumption are achieved.

Description

Technical Field

[0001] This invention belongs to the field of metal material surface treatment technology, and particularly relates to a method for controlling the mechanical peeling of SWRH82B oxide layer, which is applicable to the efficient removal of oxide layer and surface quality control of SWRH82B wire rod for prestressed steel strand and steel wire. Background Technology

[0002] SWRH82B, as a core grade of high-carbon steel wire rod, is widely used in high-end machinery manufacturing, construction engineering, and other fields. The presence of its surface oxide layer (mainly composed of FeO, Fe2O3, Fe3O4, and alumina inclusions) severely affects the stability of subsequent processing steps such as drawing and phosphating, leading to increased wire breakage rate and shortened product lifespan. Existing oxide layer treatment methods mainly suffer from the following defects:

[0003] While chemical pickling can remove the oxide layer, it causes environmental pollution and easily corrodes the base metal, resulting in excessive surface roughness.

[0004] Conventional mechanical peeling processes use a single crushing method, making it difficult to precisely control the peeling force. This results in either a high residual oxide layer (especially alumina inclusions that are difficult to remove) or excessive damage to the matrix, leading to a decrease in metal yield.

[0005] The existing process is not specifically designed for the structural characteristics of the SWRH82B oxide layer (such as the irregular brittle structure of alumina inclusions). After mechanical peeling, the iron oxide scale is mostly left in fragments, which makes subsequent cleaning difficult.

[0006] Existing technologies have overlooked the critical impact of temperature control during the rolling process on the oxide layer peeling performance. Excessively high or low final rolling temperature, excessive fluctuations in wire drawing temperature, and improper cooling rate can lead to excessive adhesion between the oxide layer and the substrate, insufficient FeO phase ratio, and significantly increase the difficulty of mechanical peeling. Under conventional processes, the peeling length of iron oxide scale is generally only 30-50mm, resulting in low peeling efficiency.

[0007] Industry research confirms that the FeO phase in the oxide layer possesses excellent plasticity and easy peeling properties. When the FeO layer accounts for ≥60% and its thickness is ≥9μm, the mechanical peeling resistance can be reduced by more than 40%. However, the roller peeling technology for low-hardness metals such as copper is not suitable for the high hardness and high alumina inclusion content of SWRH82B material and cannot be directly applied to the oxide layer treatment of high-carbon steel wire rod. Therefore, there is an urgent need to develop a control method that coordinates the entire process of "rolling temperature control - structural regulation - mechanical peeling" to optimize the oxide layer characteristics from the source and achieve efficient peeling. Summary of the Invention

[0008] The purpose of this invention is to provide a control method for mechanically peeling the oxide layer of SWRH82B, aiming to solve the problems of incomplete peeling, large matrix damage, and poor environmental performance in the existing SWRH82B oxide layer treatment process. By precisely controlling the temperature during the rolling process to optimize the phase structure and interface bonding state of the oxide layer, and combining the synergistic technology of "pretreatment-precise mechanical peeling-post-treatment", the technical goals of achieving an oxide layer residual rate of ≤0.5%, matrix damage depth of ≤10μm, and a 30% reduction in peeling energy consumption are achieved.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] This invention discloses a method for controlling the mechanical peeling of the oxide layer on SWRH82B, comprising the following steps:

[0011] (1) Precise temperature control process during rolling: High-speed wire rod mill is used for multi-pass continuous rolling, and the final rolling temperature is controlled at 850-880℃ to ensure that FeO phase is rapidly generated and accumulated in the initial stage of oxide layer formation; the wire drawing temperature is controlled at 860-890℃, and the No. 1 cooling fan is turned off during wire drawing to form a micro-pore layer with a thickness of 1-2μm at the interface between oxide layer and matrix, which weakens the interface bonding strength; after wire drawing, a segmented controlled cooling process is adopted: the first stage: the front section of the air cooling line 0-8m, the cooling rate is 10-12℃ / s, which quickly inhibits the formation of Fe2O3; the second stage: the rear section of the air cooling line 8-15m, the cooling rate is 4-6℃ / s, which avoids the FeO phase from undergoing co-deposition to Fe3O4, and finally ensures that the FeO content in the oxide layer is ≥60% and the thickness is ≥9μm;

[0012] (2) Pretreatment process: The rolled SWRH82B wire rod is placed in a continuous heating furnace and preheated in two stages with temperature control. The first stage temperature is 650-700℃ and the holding time is 30-40min. The second stage temperature is 800-850℃ and the holding time is 20-25min.

[0013] (3) Auxiliary process for oxide layer structure regulation: Before mechanical peeling, spray rare earth cerium-based pretreatment agent evenly on the surface of SWRH82B wire rod, with a dosage of 10-15g / m², and air dry for 5-8min; utilize the modification effect of cerium element on alumina inclusions to transform irregular alumina inclusions into near-spherical cerium aluminate inclusions, reduce peeling resistance during mechanical peeling, and promote the large-scale peeling of iron oxide scale.

[0014] (4) Mechanical peeling process: A double-roller linkage peeling device is adopted. The device includes a drive motor, an adjustable spacing shaft, wear-resistant rubber-coated rollers and a real-time pressure sensor. The pre-treated wire rod is fed between the two rollers. The roller spacing is adjusted to 0.92-0.95 times the wire rod diameter. The drive motor speed is controlled at 300-400 r / min. The peeling pressure is fed back in real time by the pressure sensor and maintained at 15-20 MPa. The roller surface is provided with a spiral anti-slip texture with a texture depth of 0.3-0.5 mm and a pitch of 5-8 mm. The oxide layer is efficiently peeled off through the synergistic action of shearing force and extrusion force.

[0015] (5) Post-processing: After mechanical peeling, the peeled iron oxide scale debris is removed by high-pressure water mist rinsing and then sent to a low-temperature drying oven for drying; finally, the surface roughness is tested online by a surface roughness tester to control the surface roughness Ra≤0.8μm. Unqualified products are returned to the mechanical peeling process for reprocessing to form a quality closed loop.

[0016] Furthermore, the concentration of the rare earth cerium-based pretreatment agent is 0.8-1.2 wt%.

[0017] Furthermore, the water pressure of the high-pressure water mist rinsing is 1.0-1.2 MPa.

[0018] Furthermore, the temperature of the low-temperature drying oven is 120-150℃, and the drying time is 15-20 minutes.

[0019] Furthermore, in step (3), after preheating, the surface dust and loose oxide layer are blown away by high-pressure air, and the blowing pressure is controlled at 0.6-0.8MPa to further reduce the subsequent peeling load.

[0020] Furthermore, take SWRH82B wire rods with a diameter of 12mm, specifically including:

[0021] Rolling temperature control: final rolling temperature 860℃, wire drawing temperature 870℃, cooling fan No. 1 turned off; first stage cooling rate 11℃ / s, second stage cooling rate 5℃ / s; oxide layer detection: FeO content 63%, thickness 10.2μm, interface microporosity 18%;

[0022] Pretreatment: First stage: heat preservation at 680℃ for 35 min; second stage: heat preservation at 820℃ for 22 min; high-pressure air purging pressure: 0.7 MPa.

[0023] Spray with 0.9wt% cerium-based pretreatment agent at a dosage of 12g / m², and allow to air dry for 6 minutes.

[0024] Mechanical peeling: Roller spacing adjusted to 11.4mm, 0.95 times the wire rod diameter, motor speed 350r / min, peeling pressure 18MPa;

[0025] Post-treatment: 1.1MPa high-pressure water mist rinsing, 130℃ drying for 18min.

[0026] Test results: Oxide layer residue rate 0.3%, substrate damage depth 8μm, surface roughness Ra=0.6μm, average length of iron oxide scale 120mm, metal recovery rate 99.2%, and peeling energy consumption reduced by 32% compared with conventional process.

[0027] Furthermore, take SWRH82B wire rods with a diameter of 10mm, specifically including:

[0028] Rolling temperature control: final rolling temperature 850℃, wire drawing temperature 860℃, cooling fan No. 1 turned off; first stage cooling rate 10℃ / s, second stage cooling rate 4℃ / s; oxide layer detection: FeO content 61%, thickness 9.5μm, interface microporosity 16%;

[0029] Pretreatment: Hold at 650℃ for 40 min, hold at 800℃ for 25 min, purge pressure 0.6 MPa;

[0030] The concentration of the cerium-based pretreatment agent is 1.1 wt%, the dosage is 14 g / m², and it is air-dried for 5 min.

[0031] Mechanical peeling: roller spacing 9.2mm, wire rod diameter 0.92 times, rotation speed 320r / min, pressure 16MPa;

[0032] Post-treatment: Rinse with 1.0MPa water mist and dry at 140℃ for 16min.

[0033] Test results: Oxide layer residue rate 0.4%, substrate damage depth 7μm, surface roughness Ra=0.5μm, average length of iron oxide scale 110mm, metal recovery rate 99.3%, and peeling energy consumption reduced by 30% compared with conventional process.

[0034] Key control parameters

[0035] Core rolling temperature control parameters: final rolling temperature 850-880℃, wire drawing temperature 860-890℃, segmented cooling rate 10-12℃ / s → 4-6℃ / s, ensuring FeO content ≥60% and interfacial microporosity ≥15%;

[0036] Preheating temperature gradient: 650-700℃→800-850℃, using thermal stress to further separate the oxide layer from the substrate;

[0037] Mechanical peeling parameters: roller spacing is 0.92-0.95 times the diameter of the wire rod, rotation speed is 300-400 r / min, pressure is 15-20 MPa, matching the optimized oxide layer characteristics;

[0038] Rare earth cerium-based pretreatment agent dosage: 10-15 g / m², ensuring alumina inclusion modification rate ≥90%.

[0039] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0040] This invention optimizes the oxide layer phase structure and interface bonding state by precisely controlling the rolling process temperature, and combines "pretreatment-precise mechanical peeling-posttreatment" synergistic technology to achieve the technical goals of oxide layer residual rate ≤0.5%, matrix damage depth ≤10μm, and peeling energy consumption reduced by 30%.

[0041] (1) The innovative "rolling temperature control + rare earth modification + mechanical peeling" three-in-one synergistic technology is adopted. Through precise control of the final rolling temperature, wire drawing temperature and segmented cooling rate, the FeO content in the oxide layer is ≥60%, a micro-pore layer is formed at the interface, and the bonding strength between the oxide layer and the substrate is reduced by 40%, which solves the core pain point of the oxide layer being difficult to peel off in conventional processes from the source.

[0042] (2) The rolling temperature control and mechanical peeling parameters are precisely matched. The high plasticity of the FeO layer and the micro-pore structure of the interface significantly reduce the peeling resistance. The peeling pressure can be maintained in a mild range of 15-20MPa. The matrix damage depth is ≤10μm and the metal yield is ≥99%, which is 3-5 percentage points higher than the conventional process.

[0043] (3) There is no chemical pickling step throughout the process, and the optimized rolling temperature control reduces the energy consumption of subsequent peeling by more than 30%, which meets the requirements of green production. The process flow is simple and continuous, and the production efficiency is improved by more than 20% compared with the existing process.

[0044] (4) The post-processing process and mechanical peeling form a closed-loop control to ensure that the surface roughness Ra≤0.8μm, which meets the surface quality requirements of subsequent drawing and phosphating processes, and the product wire breakage rate is reduced by 60% compared with conventional processes. Detailed Implementation

[0045] Example 1

[0046] Take a 12mm diameter SWRH82B wire rod and process it according to the following steps:

[0047] Rolling temperature control: final rolling temperature 860℃, wire drawing temperature 870℃, cooling fan No. 1 turned off; first stage cooling rate 11℃ / s, second stage cooling rate 5℃ / s; oxide layer detection: FeO content 63%, thickness 10.2μm, interface microporosity 18%;

[0048] Pretreatment: First stage: heat preservation at 680℃ for 35 min; second stage: heat preservation at 820℃ for 22 min; high-pressure air purging pressure: 0.7 MPa.

[0049] Spray with 0.9wt% cerium-based pretreatment agent at a dosage of 12g / m², and allow to air dry for 6 minutes.

[0050] Mechanical peeling: Roller spacing adjusted to 11.4mm (0.95 times the diameter of the wire rod), motor speed 350r / min, peeling pressure 18MPa;

[0051] Post-treatment: 1.1MPa high-pressure water mist rinsing, 130℃ drying for 18min.

[0052] Test results: Oxide layer residue rate 0.3%, substrate damage depth 8μm, surface roughness Ra=0.6μm, average length of iron oxide scale 120mm, metal recovery rate 99.2%, and peeling energy consumption reduced by 32% compared with conventional process.

[0053] Example 2

[0054] Take a 10mm diameter SWRH82B wire rod and adjust the parameters as follows:

[0055] Rolling temperature control: final rolling temperature 850℃, wire drawing temperature 860℃, cooling fan No. 1 turned off; first stage cooling rate 10℃ / s, second stage cooling rate 4℃ / s; oxide layer detection: FeO content 61%, thickness 9.5μm, interface microporosity 16%;

[0056] Pretreatment: Hold at 650℃ for 40 min, hold at 800℃ for 25 min, purge pressure 0.6 MPa;

[0057] The concentration of the cerium-based pretreatment agent is 1.1 wt%, the dosage is 14 g / m², and it is air-dried for 5 min.

[0058] Mechanical peeling: roller spacing 9.2mm (0.92 times the diameter of the wire rod), rotation speed 320r / min, pressure 16MPa;

[0059] Post-treatment: Rinse with 1.0MPa water mist and dry at 140℃ for 16min.

[0060] Test results: Oxide layer residue rate 0.4%, substrate damage depth 7μm, surface roughness Ra=0.5μm, average length of iron oxide scale 110mm, metal recovery rate 99.3%, and peeling energy consumption reduced by 30% compared with conventional process.

[0061] Comparative example (without rolling temperature control)

[0062] A 12mm diameter SWRH82B wire rod was processed using conventional rolling technology (final rolling temperature 900℃, wire drawing temperature 910℃, and constant cooling rate of 8℃ / s). The oxide layer had an FeO content of 42%, a thickness of 7.8μm, and an interface microporosity of 8%. Subsequent processing was carried out using the remaining steps of this invention. The test results showed that the oxide layer residue rate was 1.8%, the matrix damage depth was 15μm, and the peeling energy consumption was 47% higher than that of Example 1.

[0063] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for controlling the mechanical peeling of the oxide layer on SWRH82B, characterized in that, Includes the following steps: (1) Precise temperature control process during rolling: High-speed wire rod mill is used for multi-pass continuous rolling, and the final rolling temperature is controlled at 850-880℃ to ensure that FeO phase is rapidly generated and accumulated in the initial stage of oxide layer formation; the wire drawing temperature is controlled at 860-890℃, and the No. 1 cooling fan is turned off during wire drawing to form a micro-pore layer with a thickness of 1-2μm at the interface between oxide layer and matrix, which weakens the interface bonding strength; after wire drawing, a segmented controlled cooling process is adopted: the first stage: the front section of the air cooling line 0-8m, the cooling rate is 10-12℃ / s, which quickly inhibits the formation of Fe2O3; the second stage: the rear section of the air cooling line 8-15m, the cooling rate is 4-6℃ / s, which avoids the FeO phase from undergoing co-deposition to Fe3O4, and finally ensures that the FeO content in the oxide layer is ≥60% and the thickness is ≥9μm; (2) Pretreatment process: The rolled SWRH82B wire rod is placed in a continuous heating furnace and preheated in two stages with temperature control. The first stage temperature is 650-700℃ and the holding time is 30-40min. The second stage temperature is 800-850℃ and the holding time is 20-25min. (3) Auxiliary process for oxide layer structure regulation: Before mechanical peeling, spray rare earth cerium-based pretreatment agent evenly on the surface of SWRH82B wire rod, with a dosage of 10-15g / m², and air dry for 5-8min; utilize the modification effect of cerium element on alumina inclusions to transform irregular alumina inclusions into near-spherical cerium aluminate inclusions, reduce peeling resistance during mechanical peeling, and promote the large-scale peeling of iron oxide scale. (4) Mechanical peeling process: A double-roller linkage peeling device is adopted. The device includes a drive motor, an adjustable spacing shaft, wear-resistant rubber-coated rollers and a real-time pressure sensor. The pre-treated wire rod is fed between the two rollers. The roller spacing is adjusted to 0.92-0.95 times the wire rod diameter. The drive motor speed is controlled at 300-400 r / min. The peeling pressure is fed back in real time by the pressure sensor and maintained at 15-20 MPa. The roller surface is provided with a spiral anti-slip texture with a texture depth of 0.3-0.5 mm and a pitch of 5-8 mm. The oxide layer is efficiently peeled off through the synergistic action of shearing force and extrusion force. (5) Post-processing: After mechanical peeling, the peeled iron oxide scale debris is removed by high-pressure water mist rinsing and then sent to a low-temperature drying oven for drying; finally, the surface roughness is tested online by a surface roughness tester to control the surface roughness Ra≤0.8μm. Unqualified products are returned to the mechanical peeling process for reprocessing to form a quality closed loop.

2. The method for controlling the mechanical peeling of the SWRH82B oxide layer according to claim 1, characterized in that, The concentration of the rare earth cerium-based pretreatment agent is 0.8-1.2 wt%.

3. The method for controlling the mechanical peeling of the SWRH82B oxide layer according to claim 1, characterized in that, The water pressure for the high-pressure water mist rinsing is 1.0-1.2 MPa.

4. The method for controlling the mechanical peeling of the SWRH82B oxide layer according to claim 1, characterized in that, The temperature of the low-temperature drying oven is 120-150℃, and the drying time is 15-20 minutes.

5. The method for controlling the mechanical peeling of the SWRH82B oxide layer according to claim 1, characterized in that, In step (3), after preheating, the surface dust and loose oxide layer are blown away by high-pressure air. The blowing pressure is controlled at 0.6-0.8MPa to further reduce the subsequent peeling load.

6. The method for controlling the mechanical peeling of the SWRH82B oxide layer according to claim 1, characterized in that, Take SWRH82B wire rod with a diameter of 12mm, specifically including: Rolling temperature control: final rolling temperature 860℃, wire drawing temperature 870℃, cooling fan No. 1 turned off; first stage cooling rate 11℃ / s, second stage cooling rate 5℃ / s; oxide layer detection: FeO content 63%, thickness 10.2μm, interface microporosity 18%; Pretreatment: First stage: heat preservation at 680℃ for 35 min; second stage: heat preservation at 820℃ for 22 min; high-pressure air purging pressure: 0.7 MPa. Spray with 0.9wt% cerium-based pretreatment agent at a dosage of 12g / m², and allow to air dry for 6 minutes. Mechanical peeling: Roller spacing adjusted to 11.4mm, 0.95 times the wire rod diameter, motor speed 350r / min, peeling pressure 18MPa; Post-treatment: 1.1MPa high-pressure water mist rinsing, 130℃ drying for 18min. Test results: Oxide layer residue rate 0.3%, substrate damage depth 8μm, surface roughness Ra=0.6μm, average length of iron oxide scale 120mm, metal recovery rate 99.2%, and peeling energy consumption reduced by 32% compared with conventional process.

7. The method for controlling the mechanical peeling of the SWRH82B oxide layer according to claim 1, characterized in that, Take SWRH82B wire rod with a diameter of 10mm, specifically including: Rolling temperature control: final rolling temperature 850℃, wire drawing temperature 860℃, cooling fan No. 1 turned off; first stage cooling rate 10℃ / s, second stage cooling rate 4℃ / s; oxide layer detection: FeO content 61%, thickness 9.5μm, interface microporosity 16%; Pretreatment: Hold at 650℃ for 40 min, hold at 800℃ for 25 min, purge pressure 0.6 MPa; The concentration of the cerium-based pretreatment agent is 1.1 wt%, the dosage is 14 g / m², and it is air-dried for 5 min. Mechanical peeling: roller spacing 9.2mm, wire rod diameter 0.92 times, rotation speed 320r / min, pressure 16MPa; Post-treatment: Rinse with 1.0MPa water mist and dry at 140℃ for 16min. Test results: Oxide layer residue rate 0.4%, substrate damage depth 7μm, surface roughness Ra=0.5μm, average length of iron oxide scale 110mm, metal recovery rate 99.3%, and peeling energy consumption reduced by 30% compared with conventional process.