Hot-rolled strip steel for low crack sensitivity metal cold cutting saw and preparation method thereof

Abstract

The present application relates to the technical field of steel preparation, and in particular to a hot-rolled steel strip for a low crack sensitivity metal cold cutting saw and a preparation method thereof; the chemical composition of the hot-rolled steel strip comprises: C, Si, Mn, P, S, Al, Cr, V, and the rest is Fe and unavoidable impurities; wherein the chemical composition of the hot-rolled steel strip satisfies: C: 0.5% to 0.8%, Si: 0.1% to 0.5%, Mn: 0.7% to 1.5%, P≤0.02%, S≤0.005%, Al: 0.01% to 0.05%, Cr :0.2%~0.8%, V:0.1%~0.3%, and the rest are Fe and inevitable impurities; the method comprises: obtaining molten iron; pre-treating the molten iron, and then sequentially performing converter smelting, LF refining and RH refining, and then continuously casting to obtain a cast billet containing the chemical composition of steel; sequentially heating, rolling, cooling and coiling the cast billet, and then slowly cooling to obtain a hot-rolled strip with low crack sensitivity; through the chemical composition and preparation method of the hot-rolled strip, a steel product with low crack sensitivity and excellent comprehensive mechanical properties can be prepared.

Description

Technical Field

[0001] The present application relates to the technical field of steel preparation, and in particular to a hot-rolled strip steel for a low crack-sensitivity metal cold-cutting saw and a preparation method thereof. Background Art

[0002] Metal cold cutting saw is a tool that is used to saw metal materials at room temperature with cooling water. Its application objects include various types of workpieces such as high-frequency welded pipes, cold-bent steel, small steel, etc. Therefore, metal cold cutting saws are widely used in high-frequency welded pipe or cold-bent steel enterprises and hot-rolled steel or round steel production enterprises; metal cold cutting saws are generally circular saw blades, and the base material of the saw blade is often made of high-quality spring steel. The general preparation process of high-quality spring steel is to quench and temper the hot-rolled steel so that the final steel product can achieve high strength, high hardness and good toughness, thereby meeting the preparation of high-quality spring steel.

[0003] Since metal cold cutting saws need to rotate at high speed during the sawing process, they need to be sharpened after a period of continuous sawing and the crack status of the saw blade needs to be evaluated. If there are many cracks and the depth is large, the saw blade cannot continue to serve. That is, the crack sensitivity of the saw blade is directly related to the service life of the saw blade. Therefore, how to provide a saw blade with low crack sensitivity is a technical problem that needs to be solved urgently. Summary of the invention

[0004] The present application provides a hot-rolled strip steel for a metal cold cutting saw with low crack sensitivity and a preparation method thereof, so as to solve the technical problem of high crack sensitivity of the metal cold cutting saw in the prior art.

[0005] In a first aspect, the present application provides a hot-rolled steel strip for a low crack sensitivity metal cold cutting saw, wherein the chemical composition of the hot-rolled steel strip comprises, by mass fraction:

[0006] C: 0.5%~0.8%, Si: 0.1%~0.5%, Mn: 0.7%~1.5%, P≤0.02%, S≤0.005%, Al: 0.01%~0.05%, Cr: 0.2%~0.8%, V: 0.1%~0.3%, and the rest are Fe and unavoidable impurities.

[0007] Optionally, the metallographic structure of the hot-rolled steel strip comprises, by volume fraction: ferrite: 5% to 10% and pearlite: 90% to 95%.

[0008] Optionally, the particle size of the pearlite is 200nm to 400nm.

[0009] Optionally, the single-sided decarburization layer depth h of the hot-rolled steel strip is ≤1.5% of the plate thickness H of the hot-rolled steel strip.

[0010] In a second aspect, the present application provides a method for preparing the hot-rolled steel strip according to the first aspect, the method comprising:

[0011] Obtain molten iron;

[0012] The molten iron is pretreated, and then successively subjected to converter smelting, LF refining and RH refining, and then continuously cast to obtain a cast billet containing the chemical composition of the steel material described in the first aspect;

[0013] The ingot is heated, rolled, cooled and coiled in sequence, and then slowly cooled to obtain a hot-rolled steel strip with low crack sensitivity.

[0014] Optionally, the heating exit temperature is 1180°C to 1270°C, and the heating time in the furnace is ≥180min.

[0015] Optionally, the rolling includes rough rolling and finish rolling, and the final rolling temperature of the rough rolling is 1020°C to 1100°C.

[0016] Optionally, the final rolling temperature of the finish rolling is 850°C to 910°C.

[0017] Optionally, the cooling includes laminar cooling, and the terminal temperature of the laminar cooling is 600°C to 750°C.

[0018] Optionally, the slow cooling time is 24h to 96h.

[0019] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0020] The present application provides a hot-rolled strip steel for metal cold cutting saws with low crack sensitivity. The steel adopts a relatively low C content on the basis of ensuring the hardenability of the steel by adding an appropriate amount of C element to improve the toughness of the saw blade; the steel matrix is ​​strengthened by the Si element; the hardenability of the steel is ensured by a sufficient amount of Mn element; the hardenability of the steel is improved by adding the Cr element, the hardenability of the thick-gauge saw blade is ensured, and the strength and hardness of the saw blade are improved; the heat treatment tempering resistance of the steel is effectively increased by adding the V element, and the tempering temperature can be appropriately increased to increase the toughness of the steel, thereby obtaining a steel for a metal cold cutting saw matrix with low crack sensitivity and wider applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0023] Figure 1 A flowchart of the method provided in the embodiment of the present application. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0025] In one embodiment of the present application, a hot-rolled steel strip for a low crack sensitivity metal cold cutting saw is provided. The chemical composition of the hot-rolled steel strip, measured by mass fraction, includes:

[0026] C: 0.5%~0.8%, Si: 0.1%~0.5%, Mn: 0.7%~1.5%, P≤0.02%, S≤0.005%, Al: 0.01%~0.05%, Cr: 0.2%~0.8%, V: 0.1%~0.3%, and the rest are Fe and unavoidable impurities.

[0027] In the embodiment of the present application, the positive effect of the mass fraction of C being 0.5% to 0.8% is that within this mass fraction range, since C is an austenitic element, for martensitic transformation strengthened steels, the C content largely determines the tensile strength level, hardness and wear resistance of the hot-rolled strip after heat treatment; when the mass fraction value is greater than the maximum value of the endpoint of the range, the adverse effect that will result is increased brittleness of the steel, which is prone to induce crack initiation; when the mass fraction value is less than the minimum value of the endpoint of the range, the adverse effect that will result is insufficient hardenability of the steel and insufficient hardness after heat treatment.

[0028] The positive effect of Si's mass fraction of 0.1% to 0.5% is that Si is a ferrite-forming element and a strong solid solution strengthening element, which can significantly improve the strength of ferrite; when the mass fraction is greater than the maximum value at the endpoint of this range, the adverse effect that will result is that Si will promote the formation of red phosphorus defects on the surface of the steel and cause the surface quality to deteriorate; when the mass fraction is less than the minimum value at the endpoint of this range, the adverse effect that will result is insufficient solid solution strengthening effect.

[0029] The positive effect of Mn's mass fraction of 0.7% to 1.5% is that within the range of this mass fraction, Mn can delay the pearlite transformation and, as a main alloying element, ensure the hardenability of steel, increase the wear resistance of steel, and thus increase the sawing life of steel; when the mass fraction is greater than the maximum value of the endpoint of this range, the adverse effect that will result is the enhanced sensitivity of steel to temper brittleness; when the mass fraction is less than the minimum value of the endpoint of this range, the adverse effect that will result is insufficient hardenability, resulting in insufficient strength and hardness of the steel after heat treatment.

[0030] The positive effect of P≤0.02% is that within the range of this mass fraction, since P is generally dissolved in ferrite and has a strong solid solution strengthening effect, it can be used to increase the strength of steel, thereby reducing the toughness of steel; when the mass fraction value is greater than the maximum value of the endpoint of this range, the adverse effect that will result is that too much P will be detrimental to welding performance and is a harmful element, so the P content should be minimized.

[0031] The positive effect of S≤0.005% is that within this mass fraction range, the excellent forming performance of the steel can be guaranteed; when the mass fraction is greater than the maximum value at the endpoint of this range, the adverse effect will be that too much S will lead to the formation of a large amount of sulfides, and at the same time, the size of the formed sulfides will be too large, which is not good for the fatigue resistance of the steel.

[0032] The positive effect of Al mass fraction of 0.01% to 0.05% is within this range. Al acts as a deoxidizer to ensure the deoxidation effect of molten steel and plays a role in refining grains to a certain extent. When the mass fraction is greater than the maximum value of the endpoint of this range, the adverse effect will be to increase the graphitization tendency of the steel and deteriorate the high-temperature toughness of the steel. When the mass fraction is less than the minimum value of the endpoint of this range, the adverse effect will be that the steel liquid cannot be fully deoxidized and oxide inclusions are easily formed.

[0033] The positive effect of Cr's mass fraction of 0.2% to 0.8% is that within the range of this mass fraction, Cr has the effect of solid solution strengthening and is an effective element for improving the hardenability of steel, while also improving the corrosion resistance of steel; when the mass fraction is greater than the maximum value of the endpoint of this range, the adverse effect will be an increase in the temper brittleness of the steel; when the mass fraction is less than the minimum value of the endpoint of this range, the adverse effect will be insufficient hardenability of the steel, resulting in insufficient strength and hardness of thick-gauge saw blade steel after heat treatment.

[0034] The positive effect of V mass fraction of 0.1% to 0.3% is that within the range of this mass fraction, since V is a stronger element among carbide-forming elements, its carbide has a high melting point, high hardness and high dispersion, so it can significantly improve the wear resistance of steel. At the same time, V can also refine the grains, improve the tempering resistance of steel, and ensure the hot hardness of steel, thereby reducing the crack sensitivity of steel; when the mass fraction value is greater than the maximum value of the endpoint of this range, the adverse effect that will result is an increase in the deformation resistance of the steel during the rolling process, and when the mass fraction value is less than the minimum value of the endpoint of this range, the adverse effect that will result is a decrease in the toughness of the steel after tempering.

[0035] In some optional embodiments, the metallographic structure of the hot-rolled steel strip comprises, by volume fraction, ferrite: 5% to 10% and pearlite: 90% to 95%.

[0036] In the embodiment of the present application, the positive effect of the ferrite volume fraction of 5% to 10% is that the ferrite has good plasticity, preferentially deforms under external force conditions, reduces the brittleness of the steel, and improves the plasticity and toughness of the steel; when the volume fraction value is greater than the end value of the range, the adverse effect that will result is insufficient strength and hardness of the steel; when the volume fraction value is less than the end value of the range, the adverse effect that will result is excessive brittleness of the steel, and the saw blade is easy to break,

[0037] The positive effect of the pearlite volume fraction of 90% to 95% is to provide sufficient carbon content to ensure the hardness of the martensite after quenching of the steel, and to precipitate a sufficient amount of fine carbides after tempering to ensure the strength and hardness of the saw blade; when the volume fraction value is greater than the end value of the range, the adverse effect will be that the steel is too brittle and the saw blade is easy to break; when the volume fraction value is less than the end value of the range, the adverse effect will be insufficient hardenability of the steel, insufficient strength and hardness.

[0038] In some optional embodiments, the particle size of the pearlite is 200 nm to 400 nm.

[0039] In the embodiments of the present application, the positive effect of the pearlite particle size of 200nm to 400nm is to ensure reasonable mechanical properties of the hot-rolled steel and a suitable original structure during the heat treatment heating process; when the particle size is greater than the endpoint value of the range, the adverse effect that will result is difficulty in homogenizing the austenite structure during the heat treatment heating process; when the particle size is less than the endpoint value of the range, the adverse effect that will result is difficulty in rolling and coiling due to the high strength and hardness of the hot-rolled steel and poor plate shape.

[0040] In some optional embodiments, the single-sided decarburization layer depth h of the hot-rolled steel strip is ≤1.5% of the plate thickness H of the hot-rolled steel strip.

[0041] In the embodiment of the present application, the depth of the single-sided decarburized layer of the hot-rolled strip h≤1.5% of the plate thickness H of the hot-rolled strip has the positive effect of ensuring sufficient hardenability and hardenability of the steel surface; when the value of the depth ratio is greater than the end value of the range, the adverse effect will be insufficient hardenability of the steel surface, non-martensitic structure or quenching soft spot will be generated on the surface, the hardness and wear resistance of the saw blade will be reduced, the fatigue strength will be reduced, and the crack initiation depth will be easily induced.

[0042] In one embodiment of the present application, Figure 1 As shown, a method for preparing a hot-rolled steel strip for a metal cold cutting saw with low crack sensitivity is provided, the method comprising:

[0043] S1. Get molten iron;

[0044] S2. The molten iron is pretreated, followed by converter smelting, LF refining and RH refining, and then continuous casting to obtain a billet containing the chemical composition of the steel;

[0045] S3. The ingot is heated, rolled, cooled and coiled in sequence, and then slowly cooled to obtain a hot-rolled strip with low crack sensitivity.

[0046] In some optional embodiments, the outlet temperature of the heating furnace is 1180° C. to 1270° C., and the heating furnace time is ≥180 min.

[0047] In the embodiment of the present application, the positive effect of the outlet temperature of the heating furnace being 1180°C to 1260°C is to ensure the uniformity of the overall temperature of the steel billet and prepare the austenite structure for hot rolling; when the temperature value is greater than the endpoint value of this range, the adverse effects that will result are coarse austenite grains, severe decarburization, and severe overheating and overburning defects; when the temperature value is less than the endpoint value of this range, the adverse effects that will result are too low temperature of the steel billet, resulting in increased resistance to subsequent hot rolling, and uneven temperature of the steel billet resulting in uneven structural properties of the steel.

[0048] In some optional embodiments, the rolling includes rough rolling and finish rolling, and the final rolling temperature of the rough rolling is 1020°C to 1100°C.

[0049] In the embodiment of the present application, the final rolling temperature of the rough rolling is 1020℃~1100℃, and the positive effect is to ensure the rough rolling reduction and the organization and temperature preparation for the subsequent finishing rolling; when the temperature value is greater than the endpoint value of the range, the adverse effect will be to limit the rough rolling reduction; when the temperature value is less than the endpoint value of the range, the adverse effect will be that the subsequent finishing rolling temperature is too low, resulting in rolling difficulties and inability to ensure suitable organization and performance.

[0050] In some optional embodiments, the final rolling temperature of the finish rolling is 850°C to 910°C.

[0051] In the embodiment of the present application, the final rolling temperature of the finishing rolling is 850℃~910℃, which has the positive effect of making the rolling process match the deformation and temperature change process of the steel; when the temperature value is greater than the endpoint value of this range, the adverse effect will be that the rolling speed is too high, affecting the rolling stability, and affecting the subsequent cooling process, and then affecting the steel performance; when the temperature value is less than the endpoint value of this range, the adverse effect will be that the deformation resistance in the later stage of rolling increases, affecting the rolling stability, and disrupting the phase change of the steel cooling process.

[0052] In some optional embodiments, the cooling includes laminar cooling, and the terminal temperature of the laminar cooling is 600°C to 750°C.

[0053] In the embodiment of the present application, the terminal temperature of laminar cooling is 600°C to 750°C, and the positive effect is to control the phase change and prepare a suitable structure; when the temperature value is greater than the endpoint value of the range, the adverse effect will be that the phase change temperature is too high, resulting in coarse structure and failure to obtain target performance; when the temperature value is less than the endpoint value of the range, the adverse effect will be that the strength and hardness of the steel are too high, resulting in poor plate shape.

[0054] In some optional embodiments, the slow cooling time is 24 hours to 96 hours.

[0055] In the embodiment of the present application, the positive effect of the slow cooling time of 24h to 96h is to release the internal stress of the steel and make the steel structure more uniform; when the time value is greater than the endpoint value of the range, the adverse effect will be the evolution of the steel structure and the impact on the production rhythm; when the time value is less than the endpoint value of the range, the adverse effect will be uneven steel structure and excessive internal stress.

[0056] Example 1

[0057] A hot-rolled steel strip for low crack sensitivity metal cold cutting saw, wherein the chemical composition of the hot-rolled steel strip is as follows:

[0058] C: 0.65%, Si: 0.28%, Mn: 1.1%, P: 0.013%, S: 0.005%, Cr: 0.47%, Al: 0.02%, V: 0.1%, and the rest are Fe and inevitable impurities.

[0059] like Figure 1 As shown, a method for preparing a hot-rolled steel strip for a low crack sensitivity metal cold cutting saw comprises:

[0060] S1. Get molten iron;

[0061] S2. The molten iron is pretreated, followed by converter smelting, LF refining and RH refining, and then continuous casting to obtain a billet containing the chemical composition of the steel;

[0062] S3. The ingot is heated, rolled, cooled and coiled in sequence, and then slowly cooled to obtain a hot-rolled strip with low crack sensitivity.

[0063] The heated out-of-furnace temperature is 1250°C and the heated in-furnace time is 220 minutes.

[0064] The rolling includes rough rolling and finish rolling. The final rolling temperature of the rough rolling is 1080°C, and the final rolling temperature of the finish rolling is 890°C.

[0065] The cooling includes laminar cooling, and the terminal temperature of the laminar cooling is 700°C.

[0066] The slow cooling time is 72h.

[0067] Example 2

[0068] Comparing Example 2 with Example 1, the difference between Example 2 and Example 1 is:

[0069] The chemical composition of hot rolled strip steel, measured by mass fraction, includes:

[0070] C: 0.68%, Si: 0.29%, Mn: 1.12%, P: 0.013%, S: 0.004%, Cr: 0.5%, Al: 0.03%, V: 0.11%, and the rest are Fe and inevitable impurities.

[0071] The heated out-of-furnace temperature is 1180°C and the heated in-furnace time is 180 minutes.

[0072] The final rolling temperature of the rough rolling is 1020°C, and the final rolling temperature of the fine rolling is 850°C.

[0073] The cooling includes laminar cooling, and the terminal temperature of the laminar cooling is 600°C.

[0074] The slow cooling time is 24h.

[0075] Example 3

[0076] Comparing Example 3 with Example 1, the difference between Example 3 and Example 1 is:

[0077] The chemical composition of hot rolled strip steel, measured by mass fraction, includes:

[0078] C: 0.65%, Si: 0.31%, Mn: 1.10%, P: 0.011%, S: 0.002%, Cr: 0.48%, Al: 0.02%, V: 0.10%, and the rest are Fe and inevitable impurities.

[0079] The tapping temperature of converter smelting is 1270℃.

[0080] The final rolling temperature of the rough rolling is 1100°C, and the final rolling temperature of the fine rolling is 910°C.

[0081] The cooling includes laminar cooling, and the terminal temperature of the laminar cooling is 750°C.

[0082] The slow cooling time is 96h.

[0083] Comparative Example 1

[0084] Comparative Example 1 and Example 1 are compared. The difference between Comparative Example 1 and Example 1 is:

[0085] No Cr or V elements are added.

[0086] Comparative Example 2

[0087] Comparative Example 2 and Example 1 are compared. The difference between Comparative Example 2 and Example 1 is:

[0088] In terms of chemical composition, the mass fraction of element C is increased to 0.85%.

[0089] Related experiments:

[0090] The steel products obtained in Examples 1-3 and Comparative Examples 1-2 were collected respectively, and their properties were tested as shown in Table 1.

[0091] Test methods for related experiments:

[0092] Tensile strength: The room temperature tensile properties of hot rolled strip are measured according to GB / T 228.1-2021 "Tensile Test of Metallic Materials".

[0093] Elongation after fracture: The room temperature tensile properties of hot-rolled strip are measured according to GB / T 228.1-2021 "Tensile Test of Metallic Materials".

[0094] Hardness: The Vickers hardness of hot rolled strip is measured according to GB / T 4340.1 “Vickers hardness test for metallic materials”.

[0095] Sawing life: Through actual saw blade sawing test, the number and length of cracks of offline saw blades are evaluated according to the same sawing time. Among them, cracks with a length of ≤40mm are defined as small cracks, and cracks with a length of >40mm are defined as large cracks. The fewer the number of cracks and the shorter the length, the lower the crack sensitivity.

[0096] Table 1

[0097]

[0098] Detailed analysis of Table 1:

[0099] Tensile strength refers to the maximum stress value that the prepared steel plate can withstand before it breaks. The greater the tensile strength, the greater the maximum stress value that the steel plate can withstand before it breaks.

[0100] The elongation after fracture refers to the percentage of the elongation of the steel plate after it is broken to the original gauge length. The higher the elongation after fracture, the better the toughness of the steel plate.

[0101] From the data of Examples 1-3, it can be seen that:

[0102] Within a reasonable range of composition and process, the steel can be guaranteed to have good structure and performance, but the composition and process should be kept as stable as possible within the range to avoid performance fluctuations.

[0103] From the data of Comparative Examples 1-2, it can be seen that:

[0104] If the chemical elements exceed the reasonable range or important alloy elements are not added, the good performance of the steel will not be guaranteed, and the crack sensitivity of the steel will be enhanced and the sawing life will be reduced.

[0105] One or more technical solutions in the embodiments of the present application also have at least the following technical effects or advantages:

[0106] (1) The hot-rolled steel strip provided in the embodiment of the present application adopts a relatively low C content on the basis of ensuring the hardenability of the steel by adding an appropriate amount of C element to improve the toughness of the saw blade; strengthens the steel matrix by using the Si element; ensures the hardenability of the steel by using a sufficient amount of Mn element; improves the hardenability of the steel by adding the Cr element, ensures the hardenability of thick-gauge saw blades, and improves the strength and hardness of the saw blade; effectively increases the heat treatment tempering resistance of the steel by adding the V element, and can appropriately increase the tempering temperature to increase the toughness of the steel, thereby obtaining a low crack sensitivity metal cold cutting saw matrix steel with a wider thickness applicability.

[0107] (2) The hot-rolled steel strip provided in the embodiment of the present application not only has low crack sensitivity, but also has comprehensive high mechanical properties. On the 7.6 mm hot-rolled steel strip product, its tensile strength is 1013 MPa, the elongation after fracture is 10.5% and the Vickers hardness is 315 HV.

[0108] (3) The method provided in the embodiment of the present application produces a hot-rolled strip whose metallographic structure is composed of a small amount of proeutectoid ferrite and fine lamellar pearlite, and there is no complete decarburization layer. The steel plate has good flatness after flattening, which is beneficial to the flatness of the saw blade manufactured by laser cutting and other methods.

[0109] (4) The method provided in the embodiments of the present application produces hot-rolled steel strips with high purity and uniformity, and the manufactured metal cold-cutting saw products have the characteristics of low crack sensitivity and long sawing life.

[0110] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0111] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0112] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A hot-rolled steel strip for low crack sensitivity metal cold cutting saw, characterized in that: The chemical composition of the hot rolled steel strip includes, by mass fraction: C: 0.5% ~ 0.8%, Si: 0.1% ~ 0.5%, Mn: 0.7% ~ 1.5%, P ≤ 0.02%, S ≤ 0.005%, Al: 0.01% ~ 0.05%, Cr: 0.2% ~ 0.8%, V: 0.1% ~ 0.3%, the rest is Fe and unavoidable impurities; The metallographic structure of the hot-rolled steel strip comprises, by volume fraction, ferrite: 5% to 10% and pearlite: 90% to 95%, the grain size of the pearlite is: 200nm to 400nm, the single-side decarburization layer depth h of the hot-rolled steel strip is ≤1.5% of the plate thickness H of the hot-rolled steel strip; The method for preparing the hot-rolled steel strip comprises: Obtain molten iron; The molten iron is pretreated, and then successively subjected to converter smelting, LF refining and RH refining, and then continuously cast to obtain a cast billet; The ingot is sequentially heated, rolled, cooled and coiled, and then slowly cooled to obtain a hot-rolled steel strip with low crack sensitivity; The heating furnace temperature is 1180°C to 1270°C, and the heating furnace time is ≥180min; The rolling includes rough rolling and finish rolling, and the final rolling temperature of the rough rolling is 1020° C. to 1100° C.; The final rolling temperature of the finishing rolling is 850°C to 910°C; The cooling includes laminar cooling, and the terminal temperature of the laminar cooling is 600° C. to 750° C.; The slow cooling time is 24h to 96h.

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