Production method of low-alloy high-strength structural steel Q460M steel grade

Abstract

The invention relates to the technical field of structural steel production, and particularly discloses a production method of a low-alloy high-strength structural steel Q460M steel grade, a hot rolling process adopts a cold billet heating mode, and the heating temperature, the in-furnace time and the soaking section heating time are controlled according to the billet charging temperature; a finish rolling inlet reference temperature, a finish rolling temperature, a coiling temperature and a cooling strategy are respectively set according to different thickness specifications of produced steel coils; the thickness specifications and the width specifications of produced steel coils are different, and the convexity value interval is 20-90 m; in the rolling machining process of a steel billet, the thickness reference value of an intermediate billet is set to be 38-50 mm according to different thickness specifications of produced steel coils; descaling control is conducted, specifically, a descaling box of the roughing mill unit is normally put into use, two descaling passes of the roughing mill unit R1 and two descaling passes of the roughing mill unit R2 are respectively put into use, and a descaling box of the finishing mill unit is normally put into use; the coiled steel coil enters a coil warehouse and then is slowly cooled in a wind-sheltering manner; the produced steel coil is excellent in mechanical property, energy consumption is reduced, the process is simplified, and low-cost manufacturing is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of structural steel production, in particular to a production method of low-alloy high-strength structural steel Q460M. BACKGROUND

[0002] The component design technology of Q460M structural steel mostly adopts C-Mn-Nb-V-Ti component system, and the strength of the steel plate is improved by increasing the content of C and adding more alloy elements such as Nb, V and Ti. Some technologies also adopt low-carbon niobium and titanium micro-alloyed component design, which reduces the content of C and reduces the alloy cost while ensuring the performance of the steel. The shape control technology uses a comprehensive shape control technology that takes into account the full width and multiple targets to ensure the shape quality of the steel plate, reduce the edge shape defects such as edge folding, and improve the size accuracy and appearance quality of the product.

[0003] In the traditional C-Mn-Nb-V-Ti component system, too high carbon content can cause poor elongation, low temperature toughness, welding performance and other indicators while improving the strength of the steel plate. Unreasonable rolling parameter setting may cause rolling failure risks. There are problems such as intermediate billet camber, buckling head, and strip deviation between the rolling stands in rough rolling, which may cause steel stacking, tail throwing and other failures, causing unplanned shutdown and equipment damage, affecting production efficiency and cost. Therefore, it is necessary to design a production method of low-alloy high-strength structural steel Q460M to solve the problems of poor production performance of existing cold-rolled tinplate and unreasonable rolling parameter setting, which causes low production efficiency and high cost. SUMMARY

[0004] In view of the problems existing in the prior art, the purpose of the present application is to provide a production method of low-alloy high-strength structural steel Q460M.

[0005] The technical scheme adopted by the present application to solve its technical problems is: a production method of low-alloy high-strength structural steel Q460M, comprising the following steps: S1, the hot rolling process adopts cold billet heating mode, the heating temperature, furnace time and soaking section heating time are controlled according to the billet charging temperature; S2, the thickness specifications of the produced steel coils are different, and the entry reference temperature, finish rolling temperature, coiling temperature and cooling strategy are set respectively; S3, the thickness specifications and width specifications of the produced steel coils are different, and the crown value interval is set to 20-90 mu m; S4, during the rolling process of the billet, the intermediate billet thickness reference value is set to 38-50 mm according to the thickness specifications of the produced steel coils; S5, descaling control: the descaling box of the rough rolling mill is normally used, the descaling of the rough rolling mill R1 and R2 is two passes respectively, and the descaling box of the finishing rolling mill is normally used; S6, the steel coil after coiling enters the coil library to avoid wind and slow cooling.

[0006] Specifically, the heating temperature in step S1 is set according to different thickness specifications of the steel coil, the steel coil thickness specification is 3.0-5.0mm, the first heating temperature is 1280±20℃, the soaking temperature is 1270±20℃, and the target reference temperature for discharging is 1230±20℃; the steel coil thickness specification is 5.01-10.0mm, the first heating temperature is 1260±20℃, the soaking temperature is 1250±20℃, and the target reference temperature for discharging is 1220±20℃; the steel coil thickness specification is 10.01-16.5mm, the first heating temperature is 1250±20℃, the soaking temperature is 1240±20℃, and the target reference temperature for discharging is 1220±20℃.

[0007] Specifically, when the billet charging temperature in step S1 is <400℃, the billet in-furnace time is ≥180 minutes, and the soaking heating time is ≥30 minutes; when the billet charging temperature is ≥400℃, the billet in-furnace time is ≥150 minutes, and the soaking heating time is ≥24 minutes.

[0008] Specifically, the steel coil thickness specification in step S2 is 3.0-5.0mm, the finishing rolling inlet reference temperature is 1050±30℃, the finish rolling temperature is 860±20℃, the coiling temperature is 630±20℃, and the cooling strategy adopts low-pressure sparse; the steel coil thickness specification is 5.01-10.0mm, the finishing rolling inlet reference temperature is 1040±30℃, the finish rolling temperature is 860±20℃, the coiling temperature is 610±20℃, and the cooling strategy adopts low-pressure dense; the steel coil thickness specification is 10.01-16.5mm, the finishing rolling inlet reference temperature is 1030±30℃, the finish rolling temperature is 860±20℃, the coiling temperature is 600±20℃, and the cooling strategy adopts low-pressure dense.

[0009] Specifically, the steel coil thickness specification in step S3 is 3.0-8.0mm, the width specification is 1300-1600mm, and the crown value is 45±25µm; the steel coil thickness specification is 3.0-8.0mm, the width specification is 1601-2000mm, and the crown value is 50±25µm; the steel coil thickness specification is 8.01-12.0mm, the width specification is 1300-1600mm, and the crown value is 50±25µm; the steel coil thickness specification is 8.01-12.0mm, the width specification is 1601-2000mm, and the crown value is 55±25µm; The thickness specification of the steel coil is 12.01-16.5 mm, the width specification is 1300-1600 mm, and the convexity value is 55±30 μm; The thickness specification of the steel coil is 12.01-16.5 mm, the width specification is 1601-2000 mm, and the convexity value is 60±30 μm.

[0010] Specifically, the thickness specification of the steel coil in the step S4 is 3.00-3.60 mm, and the intermediate blank thickness reference value is 38 mm; The thickness specification of the steel coil is 3.61-4.80 mm, and the intermediate blank thickness reference value is 40 mm; The thickness specification of the steel coil is 4.81-7.55 mm, and the intermediate blank thickness reference value is 42 mm; The thickness specification of the steel coil is 7.56-8.20 mm, and the intermediate blank thickness reference value is 45 mm; The thickness specification of the steel coil is 8.21-12.0 mm, and the intermediate blank thickness reference value is 48 mm; The thickness specification of the steel coil is 12.01-16.5 mm, and the intermediate blank thickness reference value is 50 mm.

[0011] Specifically, the finishing mill group control in the step S5 is for the thickness specification of the steel coil less than 5.5 mm, and the operator adjusts the descaling pass of the roughing mill group according to the finishing mill group inlet temperature.

[0012] The present application has the following beneficial effects: The production method of the low-alloy high-strength structural steel Q460M steel designed by the present application has excellent mechanical properties, the yield strength can reach 460 MPa or above, the tensile strength is between 550-720 MPa, the elongation is not less than 17%, the impact energy (0°C) is ≥34 J, can withstand large load and impact, and is suitable for severe working environment.

[0013] The production method of the low-alloy high-strength structural steel Q460M steel designed by the present application has good processing and welding performance, good plastic processing performance at room temperature, can be processed into various shapes, and can be connected by conventional welding method, the welding joint has high strength and is not easy to produce cracks, and is convenient for construction operation.

[0014] The production method of the low-alloy high-strength structural steel Q460M steel designed by the present application has strong corrosion resistance, has certain corrosion resistance, can resist environmental erosion, prolongs the service life, reduces the maintenance cost, and can be used in open or corrosive engineering environment.

[0015] The production method of the low-alloy high-strength structural steel Q460M designed by the application has low production cost, part of the production method reduces the use of noble alloy elements by optimizing the composition, and at the same time, the TMCP technology is used to fully develop the potential of the equipment, save energy, simplify the process, and realize low-cost manufacturing. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the application will be further clearly and completely described below. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application. Embodiment 1

[0017] The production method of the Q460MC steel grade (the thickness specification of the steel coil is 3.0-16.5 mm) comprises the following steps: 1. The hot rolling process adopts a cold billet heating mode, and the heating temperature, the in-furnace time and the soaking section heating time are controlled according to the billet charging temperature.

[0018] The heating temperature is set respectively according to different thickness specifications of the steel coil, the heating temperature of the steel coil with a thickness specification of 3.0-5.0 mm is 1260℃, the soaking section temperature is 1250℃, and the target reference temperature of the out-of-furnace is 1210℃.

[0019] The heating temperature of the steel coil with a thickness specification of 5.01-10.0 mm is 1240℃, the soaking section temperature is 1230℃, and the target reference temperature of the out-of-furnace is 1200℃.

[0020] The heating temperature of the steel coil with a thickness specification of 10.01-16.5 mm is 1230℃, the soaking section temperature is 1220℃, and the target reference temperature of the out-of-furnace is 1200℃.

[0021] When the billet charging temperature is 390℃, the in-furnace time of the billet is 185 minutes, and the soaking section heating time is 34 minutes.

[0022] When the billet charging temperature is 410℃, the in-furnace time of the billet is 160 minutes, and the soaking section heating time is 28 minutes.

[0023] 2. The finish rolling inlet reference temperature, the finish rolling temperature, the coiling temperature and the cooling strategy are set respectively according to different thickness specifications of the steel coil.

[0024] The finish rolling inlet reference temperature of the steel coil with a thickness specification of 3.0-5.0 mm is 1020℃, the finish rolling temperature is 840℃, the coiling temperature is 610℃, and the cooling strategy adopts low-pressure rarefaction.

[0025] The thickness specification of the steel coil is 5.01-10.0 mm, the reference temperature at the entry of the finishing rolling is 1010°C, the finish rolling temperature is 840°C, the coiling temperature is 590°C, and the cooling strategy adopts low pressure dense.

[0026] The thickness specification of the steel coil is 10.01-16.5 mm, the reference temperature at the entry of the finishing rolling is 1000°C, the finish rolling temperature is 840°C, the coiling temperature is 580°C, and the cooling strategy adopts low pressure dense.

[0027] 3. The convexity value interval is set to 20-90µm for different thickness specifications and width specifications of the steel coil.

[0028] The thickness specification of the steel coil is 3.0-8.0 mm, the width specification is 1300-1600 mm, and the convexity value is 20µm.

[0029] The thickness specification of the steel coil is 3.0-8.0 mm, the width specification is 1601-2000 mm, and the convexity value is 25µm.

[0030] The thickness specification of the steel coil is 8.01-12.0 mm, the width specification is 1300-1600 mm, and the convexity value is 25µm.

[0031] The thickness specification of the steel coil is 8.01-12.0 mm, the width specification is 1601-2000 mm, and the convexity value is 30µm.

[0032] The thickness specification of the steel coil is 12.01-16.5 mm, the width specification is 1300-1600 mm, and the convexity value is 25µm.

[0033] The thickness specification of the steel coil is 12.01-16.5 mm, the width specification is 1601-2000 mm, and the convexity value is 30µm.

[0034] 4. The intermediate billet thickness reference value is set to 38-50 mm according to different thickness specifications of the steel coil in the rolling process.

[0035] The thickness specification of the steel coil is 3.00-3.60 mm, and the intermediate billet thickness reference value is 38 mm.

[0036] The thickness specification of the steel coil is 3.61-4.80 mm, and the intermediate billet thickness reference value is 40 mm.

[0037] The thickness specification of the steel coil is 4.81-7.55 mm, and the intermediate billet thickness reference value is 42 mm.

[0038] The thickness specification of the steel coil is 7.56-8.20 mm, and the intermediate billet thickness reference value is 45 mm.

[0039] The thickness specification of the steel coil is 8.21-12.0 mm, and the intermediate billet thickness reference value is 48 mm.

[0040] The thickness specification of the steel coil is 12.01-16.5 mm, and the reference value of the intermediate blank thickness is 50 mm.

[0041] 5, Descaling control: the descaling box of the rough rolling mill set is normally put into use, the rough rolling mill set R1 and R2 descaling each two passes, and the descaling box of the finishing rolling mill set is normally put into use. The finishing rolling mill set controls the thickness specification of the steel coil less than 5.5 mm, and the operator adjusts the rough rolling mill set descaling pass according to the inlet temperature of the finishing rolling mill set.

[0042] 6, The steel coil after coiling enters the coil storehouse to avoid wind and slow cooling.

[0043] The composition design optimizes the composition design method of low carbon plus niobium and titanium micro-alloying, such as controlling the carbon content to be not more than 0.12%, and adding appropriate amount of Nb and Ti composite micro-alloying. There is also through appropriate amount of Mn, B and other cheap metal alloying, using phase transformation strengthening to meet the performance requirements, or using low C low Nb micro B design to obtain mixed structure of ferrite, pearlite and bainite, and reducing the use of Mo, Cr and other noble alloy elements.

[0044] The front section is concentrated cooling, the cooling rate is controlled at 11 ℃ / s, and the final cooling temperature is controlled at 600-630 ℃, forming a medium temperature bainite structure. At the same time, through cross stacking, the cooling rate is controlled at 5.4 ℃ / h, the stacking time is 48h-55h, the bainite brittleness is reduced, and the mechanical properties are improved. Example 2

[0045] The production method of Q460MD steel (the thickness specification of the steel coil is 3.0-16.5 mm) includes the following steps: 1, The hot rolling process adopts cold billet heating mode, and the heating temperature, in-furnace time and soaking section heating time are controlled according to the billet charging temperature.

[0046] The heating temperature is set according to the thickness specification of the steel coil, the thickness specification of the steel coil is 3.0-5.0 mm, the first stage heating temperature is 300 ℃, the soaking section temperature is 1290 ℃, and the target reference temperature of the discharge is 1250 ℃.

[0047] The thickness specification of the steel coil is 5.01-10.0 mm, the first stage heating temperature is 1280 ℃, the soaking section temperature is 1270 ℃, and the target reference temperature of the discharge is 1240 ℃.

[0048] The thickness specification of the steel coil is 10.01-16.5 mm, the first stage heating temperature is 1270 ℃, the soaking section temperature is 1260 ℃, and the target reference temperature of the discharge is 1240 ℃.

[0049] When the billet charging temperature is 390 ℃, the billet in-furnace time is 180 minutes, and the soaking section heating time is 30 minutes.

[0050] The billet charging temperature is 400℃, the billet time in the furnace is 150 minutes, and the heating time in the soaking section is 24 minutes.

[0051] 2. The finishing entry reference temperature, the finishing temperature, the coiling temperature and the cooling strategy are set according to the thickness specification of the produced steel coil.

[0052] When the thickness specification of the steel coil is 3.0-5.0mm, the finishing entry reference temperature is 1080℃, the finishing temperature is 880℃, the coiling temperature is 650℃, and the cooling strategy is low pressure and sparse.

[0053] When the thickness specification of the steel coil is 5.01-10.0mm, the finishing entry reference temperature is 1070℃, the finishing temperature is 880℃, the coiling temperature is 630℃, and the cooling strategy is low pressure and dense.

[0054] When the thickness specification of the steel coil is 10.01-16.5mm, the finishing entry reference temperature is 1060℃, the finishing temperature is 880℃, the coiling temperature is 620℃, and the cooling strategy is low pressure and dense.

[0055] 3. The crown value interval is set to 20-90µm according to the thickness specification and the width specification of the produced steel coil.

[0056] When the thickness specification of the steel coil is 3.0-8.0mm and the width specification is 1300-1600mm, the crown value is 45µm.

[0057] When the thickness specification of the steel coil is 3.0-8.0mm and the width specification is 1601-2000mm, the crown value is 50µm.

[0058] When the thickness specification of the steel coil is 8.01-12.0mm and the width specification is 1300-1600mm, the crown value is 50µm.

[0059] When the thickness specification of the steel coil is 8.01-12.0mm and the width specification is 1601-2000mm, the crown value is 55µm.

[0060] When the thickness specification of the steel coil is 12.01-16.5mm and the width specification is 1300-1600mm, the crown value is 55µm.

[0061] When the thickness specification of the steel coil is 12.01-16.5mm and the width specification is 1601-2000mm, the crown value is 60µm.

[0062] 4. The intermediate billet thickness reference value is set to 38-50mm according to the thickness specification of the produced steel coil.

[0063] When the thickness specification of the steel coil is 3.00-3.60mm, the intermediate billet thickness reference value is 38mm.

[0064] The thickness specification of the steel coil is 3.61-4.80mm, and the reference value of the intermediate blank thickness is 40mm.

[0065] The thickness specification of the steel coil is 4.81-7.55mm, and the reference value of the intermediate blank thickness is 42mm.

[0066] The thickness specification of the steel coil is 7.56-8.20mm, and the reference value of the intermediate blank thickness is 45mm.

[0067] The thickness specification of the steel coil is 8.21-12.0mm, and the reference value of the intermediate blank thickness is 48mm.

[0068] The thickness specification of the steel coil is 12.01-16.5mm, and the reference value of the intermediate blank thickness is 50mm.

[0069] 5, Descaling control: the descaling box of the rough rolling unit is normally put into use, the descaling of the rough rolling unit R1 and R2 is two passes respectively, and the descaling box of the finishing rolling unit is normally put into use. The finishing rolling unit controls that the thickness specification of the steel coil is less than 5.5mm, and the operator adjusts the descaling pass of the rough rolling unit according to the inlet temperature of the finishing rolling unit.

[0070] 6, The steel coil after coiling enters the coil warehouse and is wind-shielded to carry out slow cooling.

[0071] The component design optimization adopts a component design method of low-carbon plus niobium and titanium micro-alloying, such as controlling the carbon content to be not more than 0.12%, and adding appropriate Nb and Ti composite micro-alloying. There is also through appropriate Mn, B and other cheap metal alloying, using phase change strengthening to meet the performance requirements, or using low C low Nb micro B design to obtain the mixed structure of ferrite, pearlite and bainite, and reducing the use of Mo, Cr and other noble alloy elements.

[0072] The front section is concentratedly cooled, the cooling speed is controlled at 15℃ / s, the final cooling temperature is controlled at 600-630℃, and the medium-temperature bainite structure is formed. At the same time, the cooling speed is controlled at 8.3℃ / h through cross stacking, the stacking time is 48h-55h, the bainite brittleness is reduced, and the mechanical properties are improved.

[0073] The present application is not limited to the above-mentioned embodiments, and anyone should know that the structural changes made under the inspiration of the present application, any technical solution with the same or similar to the present application, falls within the protection scope of the present application.

[0074] The technologies, shapes and structures not described in detail in the present application are all known technologies.

Claims

1. A production method of a low-alloy high-strength structural steel Q460M steel grade, characterized in that, It comprises the following steps: S1, the hot rolling process adopts a cold billet heating mode, the heating temperature, the in-furnace time and the soaking section heating time are controlled according to the billet charging temperature; S2, the thickness specifications of the produced steel coils are different, the finishing rolling inlet reference temperature, the finish rolling temperature, the coiling temperature and the cooling strategy are set respectively; S3, the thickness specifications and the width specifications of the produced steel coils are different, the crown value interval is set to 20-90µm; S4, during the rolling process, the intermediate billet thickness reference value is set to 38-50mm according to the thickness specifications of the produced steel coils; S5, descaling control: the descaling boxes of the rough rolling mill set are normally put into use, the rough rolling mill set R1 and R2 each have two descaling passes, the descaling boxes of the finishing rolling mill set are normally put into use; S6, after coiling, the steel coils enter the coil storage and are wind-shielded for slow cooling.

2. The production method of the low-alloy high-strength structural steel Q460M steel grade according to claim 1, characterized in that, The heating temperature in the step S1 is set according to the thickness specifications of the produced steel coils, the thickness specifications of the steel coils are 3.0-5.0mm, the one-stage heating temperature is 1280±20℃, the soaking section temperature is 1270±20℃, and the target reference temperature of the billet charging is 1230±20℃; The thickness specifications of the steel coils are 5.01-10.0mm, the one-stage heating temperature is 1260±20℃, the soaking section temperature is 1250±20℃, and the target reference temperature of the billet charging is 1220±20℃; The thickness specifications of the steel coils are 10.01-16.5mm, the one-stage heating temperature is 1250±20℃, the soaking section temperature is 1240±20℃, and the target reference temperature of the billet charging is 1220±20℃.

3. The production method of low-alloy high-strength structural steel Q460M steel grade according to claim 2, characterized in that, When the billet charging temperature in the step S1 is <400℃, the in-furnace time of the billet is ≥180 minutes, and the soaking section heating time is ≥30 minutes; When the billet charging temperature is ≥400℃, the in-furnace time of the billet is ≥150 minutes, and the soaking section heating time is ≥24 minutes.

4. The production method of the low-alloy high-strength structural steel Q460M steel grade according to claim 1, characterized by the fact that, The thickness specifications of the steel coils in the step S2 are 3.0-5.0mm, the finishing rolling inlet reference temperature is 1050±30℃, the finish rolling temperature is 860±20℃, the coiling temperature is 630±20℃, and the cooling strategy adopts low-pressure dilution; The thickness specifications of the steel coils are 5.01-10.0mm, the finishing rolling inlet reference temperature is 1040±30℃, the finish rolling temperature is 860±20℃, the coiling temperature is 610±20℃, and the cooling strategy adopts low-pressure concentration; The thickness specifications of the steel coils are 10.01-16.5mm, the finishing rolling inlet reference temperature is 1030±30℃, the finish rolling temperature is 860±20℃, the coiling temperature is 600±20℃, and the cooling strategy adopts low-pressure concentration.

5. The production method of low-alloy high-strength structural steel Q460M steel grade according to claim 1, characterized in that, The thickness specifications of the steel coils in the step S3 are 3.0-8.0mm, the width specifications are 1300-1600mm, and the crown value is 45±25µm; The thickness specifications of the steel coils are 3.0-8.0mm, the width specifications are 1601-2000mm, and the crown value is 50±25µm; The thickness specifications of the steel coils are 8.01-12.0mm, the width specifications are 1300-1600mm, and the crown value is 50±25µm; The thickness specifications of the steel coils are 8.01-12.0mm, the width specifications are 1601-2000mm, and the crown value is 55±25µm; The thickness of the steel coil is 12.01-16.5 mm, the width is 1300-1600 mm, and the convexity value is 55±30 µm; The thickness of the steel coil is 12.01-16.5 mm, the width is 1601-2000 mm, and the convexity value is 60±30 µm.

6. The production method of low-alloy high-strength structural steel Q460M steel grade according to claim 1, characterized in that, The thickness of the steel coil in the step S4 is 3.00-3.60 mm, and the intermediate blank thickness reference value is 38 mm; The thickness of the steel coil is 3.61-4.80 mm, and the intermediate blank thickness reference value is 40 mm; The thickness of the steel coil is 4.81-7.55 mm, and the intermediate blank thickness reference value is 42 mm; The thickness of the steel coil is 7.56-8.20 mm, and the intermediate blank thickness reference value is 45 mm; The thickness of the steel coil is 8.21-12.0 mm, and the intermediate blank thickness reference value is 48 mm; The thickness of the steel coil is 12.01-16.5 mm, and the intermediate blank thickness reference value is 50 mm.

7. The production method of low-alloy high-strength structural steel Q460M steel grade according to claim 3, characterized in that, The finishing mill group control in the step S5 is that when the thickness of the steel coil is less than 5.5 mm, the operator adjusts the descaling pass of the roughing mill group according to the inlet temperature of the finishing mill group.