An evaluation method for the oxide scale stripping performance of welding wire steel ER70S-6

Abstract

A method for evaluating the peeling performance of oxidized iron scale of welding wire steel ER70S-6, the steps are as follows: take welding wire steel ER70S-6 wire rod; use a torsion device to obtain the oxidized iron scale on the surface of the sample, and collect the oxidized iron scale in the collection bag; install two layers of upper and lower screens, the mesh number of the upper screen is 8 meshes, and white paper is laid on the surface of the lower screen, and the oxidized iron scale in the collection bag is placed on the upper screen for screening; weigh and calculate the ratio of the weight of the oxidized iron scale of the upper screen to the weight of the oxidized iron scale of the lower screen, and rate it according to the rating standard, and the rating standard is as follows: use A, B, C and D four grades to represent the peeling of oxidized iron scale, when the ratio is ≥4, it is A grade; when 2≤ratio<4, it is B grade; when 1≤ratio<2, it is C grade; when the ratio is <1, it is D grade. Using the evaluation method of the present invention, it can provide guidance for the adjustment of the production process, improve the mechanical descaling effect of the wire rod and the market competitiveness of welding wire steel.

Description

Technical Field

[0001] The invention relates to the technical field of metal processing, and in particular to an evaluation method for the oxide scale stripping performance of welding wire steel ER70S-6. Background Art

[0002] Since 2020, mechanical peeling has replaced pickling and has become an industry development trend. It is currently widely used in the downstream wire drawing industry. Changes in the scale removal process have put forward new technical requirements for steel mill raw materials, among which welding wire steel is the most affected. It is mainly affected by the following factors. First, downstream welding wire processing users have improved production efficiency. Since 21 years, downstream welding wire mills have introduced high-speed drawing lines, and the drawing speed has increased by 50%. The requirements for easy removal of iron oxide scale are extremely strict. In addition, the requirements for the drawing performance and purity of raw materials are also constantly tightened; second, welding wire steel ER70S-6 is affected by the Si element. Si combines with Fe in the matrix at high temperature to form Fe-Si phase, which complicates the structure of the iron oxide scale. Therefore, how to evaluate the scale stripping performance of welding wire steel has become the main research object of welding wire steel production in various steel mills. Summary of the invention

[0003] Technical problem to be solved: In view of the problems existing in the prior art, the present invention provides an evaluation method for the oxide scale stripping performance of welding wire steel ER70S-6. The evaluation method can be used to provide guidance for the adjustment of the production process, thereby improving the mechanical descaling effect of the wire rod and the market competitiveness of the welding wire steel.

[0004] Technical solution: A method for evaluating the peeling performance of oxide scale of welding wire steel ER70S-6, the steps are as follows:

[0005] Step 1. Take the welding steel ER70S-6 wire rod, the wire rod surface oxidation preservation is required to be perfect, the wire rod surface temperature is less than 50℃, and the sample is Z-shaped;

[0006] Step 2. Lay a collection bag on the torsion equipment platform, use the torsion equipment to obtain the iron oxide scale on the surface of the sample, and collect the iron oxide scale in the collection bag;

[0007] Step 3. Install two layers of sieves, the mesh number of the upper sieve is 8 meshes, and white paper is laid on the surface of the lower sieve. Place the iron oxide in the collection bag on the upper sieve and screen it. Pay attention to the speed during screening to avoid the iron oxide from breaking due to rapid screening;

[0008] Step 4. Weigh the iron oxide scale on the upper and lower screen surfaces, calculate the ratio of the weight of the iron oxide scale on the upper screen to the weight of the iron oxide scale on the lower screen, and grade it according to the rating standards. The rating standards are as follows: Use four grades of A, B, C and D to indicate the peeling of iron oxide scale. When the ratio is ≥4, it is grade A; when 2≤ratio<4, it is grade B; when 1≤ratio<2, it is grade C; when the ratio is <1, it is grade D.

[0009] Preferably, the wire rod is ∮5.5 mm ER70S-6 wire rod.

[0010] Preferably, the composition of the welding wire steel ER70S-6 wire rod is controlled as follows: C content 0.06~0.1 wt.%; Si content 0.8~1.0 wt.%; Mn content 1.4~1.7 wt.%; P content ≤0.025wt.%; S content ≤0.025wt.%.

[0011] Preferably, the rolling process of the welding wire steel ER70S-6 wire rod is as follows: the heating temperature is 1050~1090℃, the starting rolling temperature is 980~1010℃, the finishing rolling temperature is 920~950℃, the wire laying temperature is 890~930℃, and the roller speed is 0.2~0.3m / s.

[0012] Preferably, the torsion device includes a rectangular stage and a sample, the stage includes four stage fixing screws for fixing the stage and distributed on the edge of the stage, a groove, a sample tail fixing device and a sample end fixing device, the sample tail fixing device is arranged at the center of the top of the stage and is higher than the stage, the sample end fixing device is arranged at the center of the bottom of the stage and is higher than the stage, the groove is a rectangular groove, the groove is arranged on the central axis of the upper surface of the stage and the head and tail are respectively vertically connected to the sample tail fixing device and the sample end fixing device, one end of the sample is fixedly connected to the sample tail fixing device, and the other end is rotatably connected to the sample end fixing device, the sample is parallel to the groove and the diameter of the sample is smaller than the width of the groove.

[0013] Preferably, in step 2, a collection bag is laid on the surface of the groove of the torsion device platform, and the sample is rotated three times using the sample end fixing device in the torsion device to obtain the iron oxide scale on the sample surface, and the iron oxide scale in the collection bag is collected.

[0014] Beneficial effect: Due to the high Si content of welding wire steel ER70S-6, the oxide scale of wire rod is more complicated. The following is the composition control of ER70S-6:

[0015]

[0016] The iron oxide scale remaining on the surface of the wire rod after the torsion test was analyzed using a scanning electron microscope. The experiment showed that the iron oxide scale is roughly divided into four layers, from the outside to the inside, Fe2O3, Fe3O4, FeO, and the innermost layer Fe2SiO4. The iron oxide scale phase structure of the welding wire steel ER70S-6 was analyzed by X-ray diffraction, and the proportion of the four-layer structure of the iron oxide scale was calculated and obtained. The FeO phase and Fe2SiO4 phase are highly viscous, and the Fe3O4 phase is hard and brittle. Therefore, Fe3O4 is the main component of the iron oxide scale in an ideal state. The advantage of this patent is that it provides guidance for the actual production process operation through big data calculation and summary analysis, and has achieved successful cases. For example, the ∮5.5mm ER70S-6 produced in the fifth workshop of Shagang High-speed Wire has a rolling temperature of 980-1010℃, a wire laying temperature of 900-920℃, a heat preservation cover is completely closed, and a roller speed of 0.25m / s. The measured iron oxide scale peeling effect is above grade B, accounting for 77%. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The present invention shows the physical picture of the peeling grade, in which (a) is the physical picture of the peeling of the iron oxide scale of the wire rod in the A-level; (b) is the physical picture of the peeling of the iron oxide scale of the wire rod in the B-level; (c) is the physical picture of the peeling of the iron oxide scale of the wire rod in the C-level; (d) is the physical picture of the peeling of the iron oxide scale of the wire rod in the D-level;

[0018] Figure 2 is a schematic top view of the twisting device structure;

[0019] Figure 3 is a schematic structural diagram of the sample tail fixing device;

[0020] Figure 4 is a schematic structural diagram of the sample end fixing device;

[0021] Figure 5 It is a left view schematic diagram of the torsion device structure.

[0022] The numbers in the figure represent the following: 1. Specimen tail fixture; 2. Stage fixing screw; 3. Stage; 4. Groove; 5. Specimen; 6. Specimen end fixture. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0024] Example 1

[0025] An evaluation method for the oxide scale stripping performance of welding wire steel ER70S-6, the steps are as follows:

[0026] Step 1. Take the welding steel ER70S-6 wire rod, the wire rod surface oxidation preservation is required to be perfect, the wire rod surface temperature is less than 50℃, and the sample is Z-shaped;

[0027] Step 2. Lay a collection bag on the torsion equipment platform, use the torsion equipment to obtain the iron oxide scale on the surface of the sample, and collect the iron oxide scale in the collection bag;

[0028] Step 3. Install two layers of sieves, the mesh number of the upper sieve is 8 meshes, and white paper is laid on the surface of the lower sieve. Place the iron oxide in the collection bag on the upper sieve and screen it. Pay attention to the speed during screening to avoid the iron oxide from breaking due to rapid screening;

[0029] Step 4. Weigh the iron oxide scale on the upper and lower screens, calculate the ratio of the weight of the iron oxide scale on the upper screen to the weight of the iron oxide scale on the lower screen, and grade it according to the rating standard. The rating standard is as follows: Use four grades, A, B, C and D, to indicate the peeling of iron oxide scale. When the ratio is ≥4, it is grade A; when 2≤ratio<4, it is grade B; when 1≤ratio<2, it is grade C; when the ratio is <1, it is grade D. For specific physical pictures, see Figure 1 .

[0030] Example 2

[0031] An evaluation method for the oxide scale stripping performance of welding wire steel ER70S-6, the steps are as follows:

[0032] Step 1. Take ∮5.5 mm welding steel ER70S-6 wire rod, the wire rod surface oxidation preservation is required to be perfect, the wire rod surface temperature is less than 50°C, the sample is Z-shaped, and the two ends are bent 90°. The composition of the welding steel ER70S-6 wire rod is controlled as follows: C content 0.06~0.1 wt.%; Si content 0.8~1.0 wt.%; Mn content 1.4~1.7 wt.%; P content ≤0.025wt.%; S content ≤0.025wt.%;

[0033] Step 2. Place a collection bag on the surface of the groove on the torsion equipment platform, rotate the sample three times using the sample end fixture in the torsion equipment to obtain the iron oxide scale on the sample surface, and collect the iron oxide scale in the collection bag. Figures 2~5The torsion device includes a rectangular stage 3 and a sample 5. The stage 3 includes four stage fixing screws 2, a groove 4, a sample tail fixing device 1 and a sample end fixing device 6 for fixing the stage 3 and distributed on the edge of the stage 3. The length of the sample is greater than the length of the groove, and the length of the groove is 25 cm. The sample tail fixing device 1 is arranged at the top center of the stage 3 and is higher than the stage 3. The sample tail fixing device 1 is an upper semi-cylinder and a lower semi-cylinder with two diameter sides welded relatively at one end of the stage. The height of the gap between the upper semi-cylinder and the lower semi-cylinder is the same as the diameter of the wire rod sample. The sample end fixing device 6 is arranged at the bottom center of the stage 3 and is higher than the stage 3. The sample end fixing device 6 includes a rotating sleeve, a handle connected to the rotating sleeve and a handle embedded in the rotating sleeve. Two internal clamping plates, the height of the gap between the two clamping plates is the same as the diameter of the wire rod sample, the outer circle of the rotating sleeve is connected to the other end of the stage, and the handle is welded to the inner circle surface of the rotating sleeve. One end of the sample 5 is embedded in the gap between the upper semi-cylinder and the lower semi-cylinder in the sample tail fixture 1, and the other end is embedded between the two clamping plates in the sample end fixture 6. When in use, the handle of the sample end fixture 6 is rotated. The groove 4 is a rectangular groove. The groove 4 is arranged on the central axis of the upper surface of the stage 3 and is vertically connected to the sample tail fixture 1 and the sample end fixture 6 at the head and tail, respectively. One end of the sample 5 is fixedly connected to the sample tail fixture 1, and the other end is rotatably connected to the sample end fixture 6. The sample 5 is parallel to the groove 4 and the diameter of the sample 5 is smaller than the width of the groove 4;

[0034] Step 3. Install two layers of sieves, the mesh number of the upper sieve is 8 meshes, and white paper is laid on the surface of the lower sieve. Place the iron oxide in the collection bag on the upper sieve and screen it. Pay attention to the speed during screening to avoid the iron oxide from breaking due to rapid screening;

[0035] Step 4. Weigh the iron oxide scale on the upper and lower screens, calculate the ratio of the weight of the iron oxide scale on the upper screen to the weight of the iron oxide scale on the lower screen, and grade it according to the rating standard. The rating standard is as follows: Use four grades, A, B, C and D, to indicate the peeling of iron oxide scale. When the ratio is ≥4, it is grade A; when 2≤ratio<4, it is grade B; when 1≤ratio<2, it is grade C; when the ratio is <1, it is grade D. For specific physical pictures, see Figure 1 .

[0036] Application Example 1

[0037] The method of Example 2 was used to evaluate the scale stripping performance of the ∮5.5mm ER70S-6 wire rod produced by the fifth workshop of Shagang High-speed Wire Rope. The rolling process of the ∮5.5mm ER70S-6 wire rod produced by the fifth workshop of Shagang High-speed Wire Rope is as follows:

[0038]

[0039] Thirty samples were taken for each process, each sample was the same length and greater than 25 cm, and the iron oxide scale was collected by twisting according to the method of Example 2, and then the iron oxide scale was screened. Finally, the ratio of the weight of the iron oxide scale on the upper screen to the weight of the iron oxide scale on the lower screen was calculated, and the rating was performed according to the rating standard. The corresponding test results are as follows:

[0040]

[0041] Test results verification:

[0042] The X-ray diffraction equipment was used to perform phase analysis on the blocky iron oxide scale of the upper screen and the powdery iron oxide scale of the lower screen. Except for the different types of iron oxide scale, the other test conditions were all the same. The test parameters and analysis results are as follows:

[0043]

[0044] The test results are as follows:

[0045]

[0046] The results of equipment analysis show that the content of Fe3O4 in blocky iron oxide is higher than that in powdery iron oxide, which is consistent with the research idea of ​​increasing the specific gravity of blocky iron oxide and increasing the proportion of Fe3O4. In order to obtain the iron oxide in the ideal state, the wire rod spinning temperature is reasonably controlled to increase the cooling rate of the wire rod in the high temperature stage to avoid excessive increase in the thickness of the iron oxide at high temperature. After entering the pearlite transformation temperature of 750℃, the cooling rate is controlled and the heat preservation is carried out, and the cooling rate is controlled at 1.0℃ / s. From the FeO isothermal transformation curve, the wire rod is fully insulated above 450℃, and FeO will undergo a pre-eutectoid reaction of Fe3O4, and Fe3O4 particles are fully precipitated in the FeO layer, which is conducive to the crushing of the iron oxide. This idea not only effectively controls the thickness of the iron oxide, but also increases the weight proportion of Fe3O4 in the iron oxide. Through the evaluation method of the iron oxide peeling performance, the research results are visualized to facilitate the process replication between different production lines.

Claims

1. A method for evaluating the peeling performance of oxide scale of welding wire steel ER70S-6, characterized in that: The steps are as follows: Step 1. Take a welding steel ER70S-6 wire rod, which requires that the surface oxidation of the wire rod is well preserved, the surface temperature of the wire rod is less than 50°C, and the sample is Z-shaped; Step 2. Lay a collection bag on the torsion equipment platform, use the torsion equipment to rotate the sample (5) three times, obtain the iron oxide scale on the surface of the sample, and collect the iron oxide scale in the collection bag; Step 3. Install two layers of sieves, the mesh number of the upper sieve is 8 mesh, and white paper is laid on the surface of the lower sieve. Place the iron oxide scale in the collection bag on the upper sieve for screening; Step 4. Weigh the iron oxide scale on the upper and lower sieve surfaces, calculate the ratio of the weight of the iron oxide scale on the upper sieve to the weight of the iron oxide scale on the lower sieve, and grade it according to the grading standard. The grading standard is as follows: Use four grades, A, B, C and D, to indicate the peeling of the iron oxide scale. When the ratio is ≥4, it is grade A; when 2≤ratio<4, it is grade B; when 1≤ratio<2, it is grade C; when the ratio is <1, it is grade D; The torsion device comprises a rectangular stage (3) and a sample (5), wherein the stage (3) comprises four stage fixing screws (2) for fixing the stage (3) and distributed on the edge of the stage (3), a groove (4), a sample tail fixing device (1) and a sample end fixing device (6), wherein the sample tail fixing device (1) is arranged at the center of the top of the stage (3), and the sample end fixing device (6) is arranged at the center of the bottom of the stage (3). The groove (4) is a rectangular groove, which is arranged at the central axis of the upper surface of the stage (3) and is vertically connected to the sample tail fixing device (1) and the sample end fixing device (6) at the head and tail, respectively. One end of the sample (5) is fixedly connected to the sample tail fixing device (1), and the other end is rotatably connected to the sample end fixing device (6). The sample (5) is parallel to the groove (4) and the diameter of the sample (5) is smaller than the width of the groove (4).

2. The evaluation method for the oxide scale stripping performance of welding wire steel ER70S-6 according to claim 1, characterized in that: The wire rod is ∮5.5 mm ER70S-6 wire rod.

3. The method for evaluating the oxide scale stripping performance of welding wire steel ER70S-6 according to claim 1, characterized in that: The composition of the welding wire steel ER70S-6 wire rod is controlled as follows: C content 0.06~0.1 wt.%; Si content 0.8~1.0 wt.%; Mn content 1.4~1.7 wt.%; P content ≤0.025wt.%; S content ≤0.025wt.%.

4. The method for evaluating the oxide scale stripping performance of welding wire steel ER70S-6 according to claim 1, characterized in that: The rolling process of the welding wire steel ER70S-6 wire rod is as follows: the heating temperature is 1050~1090℃, the starting rolling temperature is 980~1010℃, the finishing rolling temperature is 920~950℃, the wire laying temperature is 890~930℃, and the roller speed is 0.2~0.3m / s.

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