Production method for civil hardware continuous annealing structural steel product

Abstract

The invention discloses a production method for a civil hardware continuous annealing structural steel product, which ensures the mechanical properties of the product by fully identifying the requirements of customers on the product, the service environment of the product and the inspection requirements of the product and adding C and Mn elements and microalloy elements; meanwhile, by means of the measures of adjusting the hot rolling temperature system, the acid rolling reduction rate and the galvanizing furnace area process temperature system, on the basis that the optimal configuration of the product cost is guaranteed, products which are qualified in performance and meet the use requirements of customers can be produced in batches. The invention aims to produce a product with the thickness of 0.70-2.00 mm and the strength grade of 195 MPa. According to product standard requirements and use purposes of customers, production process characteristics of other products on a production line are fully identified, and a large-batch and stable production process is formulated.

Description

Technical Field

[0001] The invention relates to a production method for civil hardware continuous annealing structural steel products. Background Art

[0002] Hardware products are a broad category that covers a variety of different metal products and tools. According to the search results, hardware products can be divided into multiple categories, including locks, handles, door and window hardware, home decoration hardware, plumbing hardware, architectural decoration hardware, tools, etc. Each category contains a variety of specific products. On the premise of fully identifying the process characteristics of other products on the production line, the product production process system and the transition process principles between products and other products have been formulated, so that products with qualified performance and meeting customer requirements can be mass-produced.

[0003] The existing patent research is as follows:

[0004] The patent "A cold-rolled steel strip for high-hardness hardware and its manufacturing method" is for the production of products with a thickness range of 0.50-0.70mm and a tensile strength range of 550-600MPa. It has no overlap with this patent in thickness and strength range, and has different chemical composition design and production process. Summary of the invention

[0005] The purpose of the present invention is to provide a production method for civil hardware continuous annealing structural steel products, which can produce products with a thickness of 0.70-2.00 mm and a strength level of 195 MPa; in accordance with product standard requirements and based on customer use, the production process characteristics of other products on the production line are fully identified, and a large-scale and stable production process is developed.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The present invention provides a production method for civil hardware continuous annealing structural steel products, comprising:

[0008] 1) Smelting process

[0009] 1.1) Converter smelting: The molten iron is pre-treated for desulfurization and then smelted in the converter. Oxygen is blown for decarburization and temperature is raised. In the later stage of smelting, ferrosilicon and ferromanganese are added for deoxidation and alloying. The P and S components are controlled to prevent overoxidation of the molten steel. The tapping temperature is ≥1620℃ to ensure that the composition and temperature are coordinated for tapping. If there is a new tapping port or an abnormal turnover ladle, the tapping temperature is increased by 10-15℃ on the basis of the upper limit as appropriate. The converter tapping [P] ≤0.010%, [S] ≤0.008%;

[0010] 1.2) Refining: Adopt argon blowing process throughout LF, maintain good reducing atmosphere during the refining process, use Al wire for deoxidation, add ferromanganese and ferrotitanium for alloying in the later stage of LF, and carry out calcium treatment after LF;

[0011] 1.3) Continuous casting: The temperature of molten steel entering the tundish is controlled at 1545-1570°C, the superheat is 25-40°C, and the casting speed is controlled at 1.00-1.40m / min;

[0012] 2) Hot rolling process

[0013] The billet is heated by a walking beam heating furnace (see Table 1 for the heating process), the rough rolling adopts a double-stand R1 and R2 reciprocating rolling, the rough rolling mode adopted is 3+3 or 1+5, and the finishing rolling adopts the F1~F7 continuous rolling process; the specific hot rolling process is shown in the following table:

[0014]

[0015] 3) Acid rolling process

[0016] The pickling rolling adopts the F1~F5 stand continuous rolling process. The rolling procedures for different finished product thicknesses are shown in the following table:

[0017]

[0018]

[0019] 4) Annealing process

[0020] Annealing uses a vertical continuous annealing furnace, and the furnace is cooled by a reducing atmosphere and a nitrogen-hydrogen mixed protective atmosphere; the outlet temperature control of each section of the heating furnace is shown in Table 4, and the elongation control of the flattener at different thicknesses is shown in the following table:

[0021]

[0022] The chemical composition of the structural steel by mass percentage is: C 0.05-0.07%; Si≤0.03%; Mn0.15-0.25%; P≤0.020%; S≤0.012%; the rest is Fe and unavoidable impurities.

[0023] Furthermore, the chemical composition of the structural steel in terms of mass percentage is: C 0.06%; Si 0.0100.015%; Mn 0.10-0.015%; P 0.010-0.016%; S 0.002-0.009%; and the rest is Fe and unavoidable impurities.

[0024] Furthermore, the metallographic structure of the product is ferrite.

[0025] Furthermore, the product grain size is 8 to 9 levels.

[0026] Furthermore, the performance of the product with a thickness of 1 mm meets the following requirements: yield strength R p0.2 252~288MPa, tensile strength R m 370~376MPa, elongation 42.0~43%.

[0027] Furthermore, the performance of the product with a thickness of 1.20 mm meets the following requirements: yield strength R p0.2 240~274MPa, tensile strength R m 355~359MPa, elongation 42.0~44%.

[0028] Furthermore, the performance of the product with a thickness of 1.80 mm meets the following requirements: yield strength R p0.2 232~262MPa, tensile strength R m 342~356MPa, elongation 41.0~45%.

[0029] Compared with the prior art, the beneficial technical effects of the present invention are:

[0030] The purpose of the present invention is to combine the needs of users, fully identify the customer's requirements for products, product service environment, product inspection requirements, and ensure the mechanical properties of products by adding C, Mn elements and micro-alloying elements. At the same time, by adjusting the hot rolling temperature system, acid rolling reduction rate, and galvanizing furnace area process temperature system, the product cost is optimized, and mass production of products with qualified performance and meeting customer requirements is achieved.

[0031] The advantage of the present invention is that it introduces a process method for stably producing continuous annealing structural steel with a full thickness of 0.70-2.00 mm in large quantities and meeting the domestic civil hardware usage. According to different later usage purposes, the upstream and downstream processes are effectively matched to produce standard-compliant and usable continuous annealing hardware structural steel products at the optimal manufacturing cost, which has good promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described below in conjunction with the accompanying drawings.

[0033] Figure 1 The metallographic structure of the finished product;

[0034] Figure 2 For product application areas. DETAILED DESCRIPTION

[0035] A production method for civil hardware continuous annealing structural steel products, comprising:

[0036] 1. Smelting process

[0037] 1.1 Converter smelting: The molten iron is pre-treated for desulfurization and then smelted in the converter. Oxygen is blown for decarburization and temperature is raised. In the later stage of smelting, ferrosilicon and ferromanganese are added for deoxidation and alloying. The P and S components are controlled to prevent the molten steel from being over-oxidized. The tapping temperature is ≥1620℃ to ensure that the components and temperature are coordinated for tapping. If there is a new tapping port or an abnormal turnover ladle, the tapping temperature shall be increased by 10-15℃ on the basis of the upper limit. The tapping temperature of the converter [P] is ≤0.010% and [S] is ≤0.008%.

[0038] 1.2 Refining: The LF whole process argon blowing process is adopted, and a good reducing atmosphere is maintained during the refining process. Al wire is used for deoxidation. Manganese iron and titanium iron are added for alloying in the later stage of LF. Calcium treatment is carried out after the end of LF.

[0039] 1.3 Continuous casting: The temperature of molten steel entering the tundish is controlled at 1545-1570℃, the superheat is 25~40℃, and the casting speed is controlled at 1.00-1.40m / min.

[0040] 2 Hot rolling process

[0041] The ingot is heated in a walking-beam heating furnace (the heating process is shown in Table 1). The rough rolling adopts double-stand R1 and R2 reciprocating rolling. The rough rolling mode adopted is 3+3 or 1+5. The finishing rolling adopts F1~F7 continuous rolling process. The specific hot rolling process is shown in Table 2.

[0042] Table 1 Billet heating system

[0043]

[0044] Table 2 Rolling process

[0045]

[0046] 3. Acid rolling process

[0047] The pickling rolling adopts the F1~F5 frame continuous rolling process, and the rolling procedures for different finished product thicknesses are shown in Table 3.

[0048] Table 3 Pickling rolling procedures

[0049]

[0050]

[0051] 4 Annealing process

[0052] Annealing uses a vertical continuous annealing furnace, and the furnace is cooled by a reducing atmosphere and a nitrogen-hydrogen mixed protective atmosphere. The outlet temperature control of each section of the heating furnace is shown in Table 4, and the elongation control of the flattening machine at different thicknesses is shown in Table 5.

[0053] Table 4 Annealing process

[0054]

[0055] Table 5 Leveling machine process

[0056] Thickness(mm) Speed ​​requirement (m / min) 0.70<t≤1.00 150±20 1.00<t≤1.20 130±20 1.20<t<1.50 115±20 1.50≤t≤1.60 110±20 1.60<t<1.80 100±20 1.80≤t≤2.00 90±20

[0057] (6) Example Analysis

[0058] 5.1 Steelmaking ingredients

[0059] According to the above steelmaking process requirements, the actual slab chemical composition (mass percentage) is shown in Table 5 below.

[0060] Table 5 Chemical composition of examples

[0061] Chemical Elements C Si Mn P S Release 0.05～0.07 ≤0.030 0.15～0.25 ≤0.020 ≤0.012 Actual range 0.06 0.010-0.015 0.20-0.22 0.010-0.016 0.002-0.009

[0062] 5.2 Finished product performance

[0063] Based on the hot-rolled mechanical properties, the finished product is produced according to the above-designed acid rolling process and annealing process. The room temperature tensile mechanical properties of the finished product are shown in Table 7. The metallographic structure is ferrite, the grain size is 8 to 9, and the organizational morphology is shown in Figure 1 .

[0064] Table 7 Mechanical properties of finished products

[0065]

[0066] The finished product is characterized by a low yield ratio and excellent elongation properties.

[0067] Hardware structural steel products are mainly designed to meet the production needs of the domestic hardware industry, and are mainly used for locks, handles, door and window hardware, home decoration hardware, plumbing hardware, building decoration hardware, tools, etc.

[0068] In summary, this product has passed performance tests and user experience and its various performances meet the current market demand, and has been widely used in the hardware market.

[0069] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for producing civil hardware continuous annealing structural steel products, characterized in that: include: 1) Smelting process 1.1) Converter smelting: The molten iron is pre-treated for desulfurization and then smelted in the converter. Oxygen is blown for decarburization and temperature is raised. In the later stage of smelting, ferrosilicon and ferromanganese are added for deoxidation and alloying. The P and S components are controlled to prevent overoxidation of the molten steel. The tapping temperature is ≥1620℃ to ensure that the composition and temperature are coordinated for tapping. If there is a new tapping port or an abnormal turnover ladle, the tapping temperature is increased by 10-15℃ on the basis of the upper limit as appropriate. The converter tapping [P] ≤0.010%, [S] ≤0.008%; 1.2) Refining: Adopt argon blowing process throughout LF, maintain good reducing atmosphere during the refining process, use Al wire for deoxidation, add ferromanganese and ferrotitanium for alloying in the later stage of LF, and carry out calcium treatment after LF; 1.3) Continuous casting: The temperature of molten steel entering the tundish is controlled at 1545-1570°C, the superheat is 25-40°C, and the casting speed is controlled at 1.00-1.40m / min; 2) Hot rolling process The billet is heated by a walking beam heating furnace (see Table 1 for the heating process), the rough rolling adopts a double-stand R1 and R2 reciprocating rolling, the rough rolling mode adopted is 3+3 or 1+5, and the finishing rolling adopts the F1~F7 continuous rolling process; the specific hot rolling process is shown in the following table: 3) Acid rolling process The pickling rolling adopts the F1~F5 stand continuous rolling process. The rolling procedures for different finished product thicknesses are shown in the following table: 4) Annealing process Annealing uses a vertical continuous annealing furnace, and the furnace is cooled by a reducing atmosphere and a nitrogen-hydrogen mixed protective atmosphere; the outlet temperature control of each section of the heating furnace is shown in Table 4, and the elongation control of the flattener at different thicknesses is shown in the following table: The chemical composition of the structural steel by mass percentage is: C 0.05-0.07%; Si≤0.03%; Mn0.15-0.25; P≤0.020%; S≤0.012%; The rest is Fe and inevitable impurities.

2. The method for producing civil hardware continuous annealing structural steel products according to claim 1, characterized in that: The chemical composition of the structural steel by mass percentage is: C 0.06%; Si 0.0100.015%; Mn 0.10-0.015%; P 0.010-0.016%; S 0.002-0.009%; the rest is Fe and unavoidable impurities.

3. The method for producing civil hardware continuous annealing structural steel products according to claim 2, characterized in that: The metallographic structure of the product is ferrite.

4. The method for producing civil hardware continuous annealing structural steel products according to claim 1, characterized in that: The product grain size is 8 to 9 levels.

5. The method for producing civil hardware continuous annealing structural steel products according to claim 1, characterized in that: Thickness 1mm product performance meets: yield strength R p0.2 252~288MPa, tensile strength R m 370~376MPa, elongation 42.0~43%.

6. The method for producing civil hardware continuous annealing structural steel products according to claim 1, characterized in that: Thickness 1.20mm Product performance meets: Yield strength R p0.2 240~274MPa, tensile strength R m 355~359MPa, elongation 42.0~44%.

7. The method for producing civil hardware continuous annealing structural steel products according to claim 1, characterized in that: Thickness 1.80mm Product performance meets: Yield strength R p0.2 232~262MPa, tensile strength R m 342~356MPa, elongation 41.0~45%.

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