A macroscopic analysis method for studying the phenomenon of no obvious yield platform of wire rod

Abstract

The application discloses a macro analysis method for researching the phenomenon of no obvious yield platform of wire rod in the technical field of steel smelting and high-speed wire rod rolling, and adopts the following technical scheme: selecting straight threaded steel and wire rod threaded steel of certain specifications, respectively comparing tensile curve diagrams of straightening under cold and hot states of the wire rod; respectively comparing tensile curve diagrams of straightening at normal temperature of hot bending and cold bending of the straight threaded steel, comparing tensile curve diagrams of straightening of the straight threaded steel and the wire rod threaded steel under the same hot state or the same cold state through the same specification threaded steel under different process conditions, and obtaining macro performance of the phenomenon of no obvious yield platform through differences in the tensile curve diagrams. Compared with similar technologies, the analysis method has strong operability, is intuitive and convenient, and can more intuitively analyze and research the phenomenon of no yield platform.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel smelting and high-speed wire rod rolling, in particular to a macroscopic analysis method for studying the phenomenon of no obvious yield platform of wire rod. BACKGROUND

[0002] After the wire rod is stretched, the phenomenon of no obvious yield platform generally occurs. After the straight bar steel is stretched, the yield platform is very obvious. The industry has related documents that mention that the existence of a large amount of granular bainite in the steel bar causes the phenomenon. The analysis method is to carry out related work around metallographic analysis. The metallographic analysis belongs to a microscopic analysis method, which requires a very professional metallographic analysis personnel to test it out. The method needs to process the sample, and the sample is observed through a microscope. If the sample processing is not standardized, or the grinding, polishing, and corrosion are not in place, the post staff is difficult to observe the granular bainite. The inaccurate analysis result will directly affect the improvement direction of the product quality problem.

[0003] For example, patent number CN202110986405.7 "a method for solving the problem of no yield platform of 400Mpa grade Nb-containing steel bar", which solves the problem of no yield platform of 400Mpa grade Nb-containing steel bar by controlling the composition of the billet, the heating system of the billet, and the temperature control of the rolling process. The patent believes that the cause of the no yield platform is the abnormal microstructure, and the microscopic analysis method needs to process the sample, and polish, grind, and corrode, and analyze it using a microscope. The analysis process is complicated.

[0004] In view of the related technology in the above, the present application provides a macroscopic analysis method for studying the phenomenon of no obvious yield platform of wire rod. SUMMARY

[0005] The present application provides a macroscopic analysis method for studying the phenomenon of no obvious yield platform of wire rod. By comparing the tensile curve diagrams of straight thread steel and wire rod thread steel under different process conditions, the macroscopic performance of the phenomenon of no obvious yield platform is obtained. Through the analysis of this method, it is more conducive for technical personnel to understand the reasons for the no obvious yield platform of wire rod, and to develop improvement measures to improve the quality performance of wire rod. The present research analysis method has strong operability, is intuitive and convenient, and can more intuitively analyze the phenomenon of no yield platform. It can better guide the process technical personnel to improve the product quality.

[0006] The application provides a macro analysis method for studying the phenomenon of no obvious yield platform of a wire rod, and adopts the following technical scheme: selecting straight thread steel and wire rod of a certain specification, and comparing the tension curve diagrams of the wire rod in cold and hot states after straightening; and comparing the tension curve diagrams of the straight thread steel after hot bending and cold bending and normal temperature straightening, and the specific steps are as follows:

[0007] Step A: selecting wire rod of a certain specification, continuously cutting 6 samples of 400mm long at the same position after wire drawing, and dividing the 6 samples into two groups to compare the tension curve diagrams of the two groups of wire rod after hot straightening and normal temperature straightening;

[0008] Step B: selecting straight thread steel of a certain specification, continuously cutting 6 samples of 1000mm long at the same steel at room temperature, and dividing the 6 samples into two groups to compare the bending radius of the two groups of straight thread steel after hot simulation wire drawing and the tension curve diagrams of the two groups of straight thread steel after normal temperature straightening;

[0009] Step C: selecting straight thread steel of a certain specification, continuously cutting 6 samples of 1000mm long at the same steel at room temperature, and dividing the 6 samples into two groups to compare the bending radius of the two groups of straight thread steel after normal temperature simulation wire drawing and the tension curve diagrams of the two groups of straight thread steel after normal temperature straightening.

[0010] Optionally, the tension curve diagrams of the straight thread steel and the wire rod of Φ12mm after bending and straightening at different temperature states are compared.

[0011] Optionally, in the step A, 3 samples are marked as group A samples: A-1, A-2 and A-3; and the other 3 samples are marked as group B samples: B-1, B-2 and B-3.

[0012] Optionally, the group A samples are straightened immediately after wire drawing at a hot state, and the tension detection is carried out after cooling to room temperature, and the tension curve diagram is recorded; the group B samples are straightened after cooling to room temperature, and the tension detection is carried out, and the tension curve diagram is recorded.

[0013] Optionally, in the step B, 3 samples are marked as group C samples: C-1, C-2 and C-3; and the other 3 samples are marked as group D samples: D-1, D-2 and D-3.

[0014] Optionally, the group C samples are bent immediately after simulating the radius of the wire rod at a red steel hot state, and 3 samples of 400mm long are cut respectively after cooling to room temperature, and the tension is carried out after straightening the normal temperature samples, and the tension curve diagram is recorded; the group D samples are cut into 3 samples of 400mm long respectively after tension detection, and the tension curve diagram is recorded.

[0015] Optionally, in the step C: wherein 3 test samples are marked as E group test samples: E-1, E-2, E-3; and another 3 test samples are marked as F group test samples: F-1, F-2, F-3.

[0016] Optionally, the E group test samples are curved in an arc state at room temperature, 3 400mm long tensile test samples are cut from the curved test samples respectively, and the tensile test samples are stretched at room temperature after correction, and the tensile curve is recorded; the F group test samples are cut into 3 400mm long tensile test samples respectively, and the tensile test samples are stretched at room temperature, and the tensile curve is recorded.

[0017] According to the comparative analysis of the tensile curves corresponding to the above-mentioned step A, it can be concluded that the yield platform of the hot state straightening of the coil bar screw thread steel is obvious, and the yield platform of the cold state straightening is not obvious, which can indicate that the yield platform of the coil screw is not obvious and is related to the straightening temperature; according to the comparative analysis of the tensile curves corresponding to the step B and the step C, it can be known that the yield platform of the straight screw thread steel with obvious yield platform is not obvious after being straightened and stretched at room temperature after being curved. According to the above-mentioned step A, step B and step C, and in combination with the tensile curve, it can be concluded that the yield platform is not obvious, and is only related to whether the straightening is performed before stretching.

[0018] In summary, the present application includes at least one of the following beneficial effects:

[0019] By comparing the tensile curves of the straight screw thread steel and the coil bar screw thread steel under different process conditions, the macroscopic manifestation of the yield platform not obvious phenomenon can be obtained. Compared with the existing similar technology, the research and analysis method is strong in operability, intuitive and convenient, and can more intuitively research and analyze the phenomenon of no yield platform. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating laborious work.

[0021] Figure 1 the tensile curve recorded by the tensile detection of the A-1 test sample of the first embodiment A group,

[0022] Figure 2 the tensile curve recorded by the tensile detection of the A-2 test sample of the first embodiment A group,

[0023] Figure 3Tensile curve recorded for the tensile test of Example 1 Group A Sample A-3,

[0024] Figure 4 Tensile curve recorded for the tensile test of Example 1 Group B Sample B-1,

[0025] Figure 5 Tensile curve recorded for the tensile test of Example 1 Group B Sample B-2,

[0026] Figure 6 Tensile curve recorded for the tensile test of Example 1 Group B Sample B-3,

[0027] Figure 7 Tensile curve recorded for the tensile test of Example 2 Group C Sample C-1,

[0028] Figure 8 Tensile curve recorded for the tensile test of Example 2 Group C Sample C-2,

[0029] Figure 9 Tensile curve recorded for the tensile test of Example 2 Group C Sample C-3,

[0030] Figure 10 Tensile curve recorded for the tensile test of Example 2 Group D Sample D-1,

[0031] Figure 11 Tensile curve recorded for the tensile test of Example 2 Group D Sample D-2,

[0032] Figure 12 Tensile curve recorded for the tensile test of Example 2 Group D Sample D-3,

[0033] Figure 13 Tensile curve recorded for the tensile test of Example 3 Group E Sample E-1,

[0034] Figure 14 Tensile curve recorded for the tensile test of Example 3 Group E Sample E-2,

[0035] Figure 15 Tensile curve recorded for the tensile test of Example 3 Group E Sample E-3,

[0036] Figure 16 Tensile curve recorded for the tensile test of Example 3 Group F Sample F-1,

[0037] Figure 17 Tensile curve recorded for the tensile test of Example 3 Group F Sample F-2,

[0038] Figure 18 The tensile curve recorded for the tensile test of the sample F-3 of the third embodiment F group of the present application. DETAILED DESCRIPTION

[0039] The following description will be made in conjunction with the accompanying drawings as follows: Figures 1-18 The present application is further described in detail.

[0040] Embodiment I

[0041] The present application discloses a macroscopic analysis method for studying the phenomenon of no obvious yield platform of wire rod, comprising the following steps:

[0042] Step (1): On-line randomly extract 12 specification wire rod deformed steel of the same batch, after the product is wire drawing, straighten the wire rod in hot state, and mark A-1, A-2, A-3 respectively;

[0043] Step (2): On-line randomly extract 12 specification wire rod deformed steel of the same batch, after the product is wire drawing, straighten the wire rod in cold state, and mark B-1, B-2, B-3 respectively;

[0044] Step (3): The tensile test is carried out on the above two groups of samples respectively, and the corresponding Figure 1 , Figure 2 , Figure 3 ; Figure 4 , Figure 5 , Figure 6 ;

[0045] From the above figure, it can be seen that: by comparing the straightening after wire drawing of 12 specification wire rod (simulating the cooling condition of straight steel bar) and the straightening in cold state, it can be initially seen that the yield platform of the tensile curve is obvious after the straightening in hot state and natural cooling, and the strain process displacement is long. The yield platform of the tensile curve graph is not obvious even the parabolic slope rises, and some have a short platform but the strain process displacement is short.

[0046] It can be concluded that the yield platform of the tensile curve is obvious after the straightening in hot state of wire rod deformed steel, and the yield platform of the tensile curve is not obvious after the straightening in cold state, which can indicate that the yield platform of the wire rod is not obvious and related to the temperature of straightening.

[0047] Embodiment II

[0048] A macroscopic analysis method for studying the phenomenon of no obvious yield platform of wire rod comprises the following steps:

[0049] Step (1): On-line randomly extract 12 specification straight steel bar of the same batch, after the product is wire drawing, straighten the wire rod in hot state, and mark A-1, A-2, A-3 respectively;

[0050] Step (2): Among them, 3 samples are bent into 3 samples with circular arc type by simulating the disc type shape of wire rod in hot state.

[0051] Step (3): The 3 samples with circular arc type are cut into 400 mm long arc samples at the maximum arc of each sample, and the sample numbers are marked as C-1, C-2, and C-3.

[0052] Step (4): Another 3 samples of 1000 mm without heat bending are cut into straight bar samples of 400 mm long, and the sample numbers are marked as D-1, D-2, and D-3.

[0053] Step (5): After cooling to room temperature, the bent samples are straightened and corresponding tensile test is carried out, and the corresponding tensile curve is recorded Figure 7 , Figure 8 , Figure 9 .

[0054] Step (6): After cooling to room temperature, the straight bar samples are directly subjected to corresponding tensile test, and the corresponding tensile curve is recorded Figure 10 , Figure 11 , Figure 12 .

[0055] From the above figure, it can be seen that after the 12 straight screw is bent in hot state and naturally cooled, the yield platform disappears, and some samples have a short platform but it is not obvious, which is basically consistent with the yield platform of disc screw. The straight bar screw is not subjected to heat bending, and the yield platform is very obvious after natural cooling.

[0056] From the comparison of the tensile curves, it can be seen that the straight bar screw with obvious yield platform after heat bending and straightening at room temperature, the yield platform is not obvious. It is related to whether the sample is straightened before detection.

[0057] Example Three

[0058] A macroscopic analysis method for studying the phenomenon of no obvious yield platform of wire rod includes the following steps:

[0059] Step (1): Randomly select 12 specification straight bar steels in line from the same batch, and continuously cut 6 samples of 1000 mm long on the same steel on the cooling bed after the finished product is discharged.

[0060] Step (2): Among them, 3 samples are bent into 3 samples with circular arc type by simulating the disc type shape of wire rod in hot state.

[0061] Step (3): The 3 samples with circular arc type are cut into 400mm long arc samples at the maximum arc, and the sample numbers are marked as D-1, D-2 and D-3.

[0062] Step (4): 3 samples of 1000mm are cut into 400mm long straight samples, and the sample numbers are marked as F-1, F-2 and F-3.

[0063] Step (5): The curved samples E-1, E-2 and E-3 are straightened at room temperature, and corresponding tensile tests are carried out to record the corresponding tensile curves. Figure 13 Figure 14 Figure 15

[0064] Step (6): The straight samples F-1, F-2 and F-3 are directly subjected to corresponding tensile tests at room temperature, and the corresponding tensile curves are recorded. Figure 16 Figure 17 Figure 18

[0065] As can be seen from the above tensile comparison curve diagram, the yield platform of the straight thread steel of group 6 is very obvious. The samples of group 5 are subjected to large-angle bending at room temperature in the straight state, and then subjected to tensile test after straightening, and the yield platform is basically not obvious. It can be said that the yield platform is not obvious, which is related to whether the straightening is carried out before tensile test.

[0066] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, therefore: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.​​​​​​

Claims

1. A macroscopic analysis method for studying the phenomenon of wire rod without a clear yield plateau, characterized in that: Select straight and wire rod rebar of certain specifications, and compare the tensile curves of wire rod rebar straightened at cold, hot, and room temperature; compare the tensile curves of straight rebar straightened at hot bending, cold bending, and room temperature. The specific steps are as follows: Step A: Select a certain specification of wire rod rebar. After the finished product is wired, cut 6 400mm long samples from the same location. Divide the 6 samples into 2 groups. Three samples are labeled as Group A: A-1, A-2, A-3; the other 3 samples are labeled as Group B: B-1, B-2, B-3. After wire drawing, the Group A samples are straightened immediately while hot. After cooling to room temperature, tensile testing is performed, and the tensile curve is recorded. After wire drawing, the Group B samples are straightened and tensile testing is performed after cooling to room temperature. The tensile curve is recorded. Compare the tensile curves of two sets of wire rod rebar that are hot-straightened and those that are straightened at room temperature; Step B: Select straight threaded steel bars of a certain specification. Under normal temperature conditions, continuously cut 6 specimens of 1000mm length from the same straight threaded steel bar. Divide the 6 specimens into 2 groups. Three specimens are labeled as Group C specimens: C-1, C-2, and C-3; the other 3 specimens are labeled as Group D specimens: D-1, D-2, and D-3. Simulate the curvature of the coiled wire by immediately bending the Group C specimens under the hot state of the straight steel bars. After cooling to room temperature, cut 3 tensile specimens of 400mm length from each group. Straighten the room temperature specimens and then perform tensile testing, recording the tensile curve. After the Group D specimens have cooled to room temperature, cut 3 tensile specimens of 400mm length from each group and perform tensile testing, recording the tensile curve. Compare the bending curvature of two sets of straight bar rebar hot-simulated wire rods with the tensile curves of room-temperature straightened wire rods; Step C: Select straight threaded steel bars of a certain specification. Under normal temperature conditions, continuously cut 6 specimens of 1000mm length from the same steel bar. Divide the 6 specimens into 2 groups. Three specimens are labeled as Group E: E-1, E-2, and E-3; the other 3 specimens are labeled as Group F: F-1, F-2, and F-3. Bend the Group E specimens at room temperature to simulate the curvature of the wire rod. Cut 3 tensile specimens of 400mm length from each bent specimen. After straightening the tensile specimens at room temperature, perform tensile testing and record the tensile curve. Cut 3 tensile specimens of 400mm length from each of the Group F specimens and perform tensile testing at room temperature, recording the tensile curve. Compare the bending curvature and tensile curve of two sets of straight rebar wire rods simulated at room temperature during wire drawing and straightening at room temperature.

2. The macroscopic analysis method for studying the phenomenon of no obvious yield plateau in wire rod according to claim 1, characterized in that: Compare the tensile curves of Φ12mm straight threaded steel and Φ12mm wire rod threaded steel under different temperature conditions during bending and straightening.

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