Production method of ferrite stainless steel 022Cr18NbTi wire rod

Abstract

The invention relates to a production method of a ferrite stainless steel 022Cr18NbTi wire rod. The production method comprises the following steps: 1, using a continuous casting square billet; 2, heating the steel billet by a walking beam furnace; and 3, a two-roller reversible cogging mill is used, 11 passes of rolling are conducted, the initial rolling temperature ranges from 950 DEG C to 1050 DEG C, and round steel of phi 85 mm is obtained through rolling. Hot collecting and coiling after hot rolling and hot charging after rolling are carried out on an on-line roller hearth furnace process route, the charging temperature is larger than or equal to 400 DEG C, the temperature of a heating section of a roller hearth furnace is 760-780 DEG C, the temperature of a soaking section is 770-790 DEG C, the roller way speed is 0.6-0.9 m / min, air cooling is carried out to the normal temperature after discharging, and packaging and collecting are carried out. The purpose of on-line annealing is achieved, and various properties of the steel, such as tensile strength and elongation, are controlled within a qualified range.

Description

Technical Field

[0001] The invention relates to a production method of ferritic stainless steel 022Cr18NbTi wire rod, specifically to a method for producing ferritic stainless steel 022Cr18NbTi wire rod, and specifically to a method for producing ferritic stainless steel 022Cr18NbTi wire rod having good mechanical properties, tensile strength and elongation that meet requirements by subjecting 022Cr18NbTi steel billets with certain chemical composition to reasonable heating, hot rolling and controlled rolling and controlled cooling, hot coiling after rolling, and hot rolling online hot charging roller hearth furnace annealing processes. Background Art

[0002] 022Cr18NbTi contains Mn, S, P, Cr, Ni, Ti, Nb and other elements. It has a ferrite structure at room temperature and a ferrite structure when heated at high temperature. It is mainly used to produce wire rods, which are mainly used for processing and welding wires, and are ultimately used in the manufacture of corrosion-resistant hangers, support frames and automobile exhaust treatment devices. 022Cr18NbTi hot rolled wire rod has low magnetism, high brittleness of precipitated brittle phase, low strength, and internal stress after heating, which is easy to cause cracks. Ferritic stainless steel has a high tendency of grain growth after heating and hot rolling, fast crystallization rate, and well-developed columnar crystals. If it is not timely heat-transferred and heat-treated after hot rolling, it may cause fracture and cracks. Internal stress after hot rolling and cracks exist. The internal grains of the material after hot rolling are coarse. The tensile strength is reduced, the elongation is increased, and the mechanical properties are improved through hot rolling and online heat treatment. Therefore, the hot coiling and online roller hearth furnace annealing process after hot rolling of 022Cr18NbTi wire rod and hot charging after rolling are the key to production. Hot charging and hot annealing process are required. After heat treatment, the fracture problem is solved, the elongation is increased, the tensile strength is reduced, and the mechanical properties are improved, which is conducive to drawing processing.

[0003] In view of the above problems, the present invention provides a method for producing ferritic stainless steel 022Cr18NbTi wire rod to solve the above problems and obtain a wire 022Cr18NbTi wire rod product with qualified mechanical properties, tensile strength and elongation. Summary of the invention

[0004] The purpose of the present invention is to provide a method for producing ferritic stainless steel 022Cr18NbTi wire rod in view of the above problems.

[0005] The object of the present invention is achieved in this way: a production method of ferritic stainless steel 022Cr18NbTi wire rod, comprising the following steps: step 1: the steel billet uses a continuous casting square billet, the cross-sectional size of the steel billet is (210-220) × (210-220) mm, and the weight of the steel billet is 1150-1250kg; step 2: the steel billet is heated by a walking beam heating furnace, the heating temperature of the first stage is 850-1050°C, and the heating time of the first stage is 1 hour-2.5 hours; the heating temperature of the second stage is 1100-1120°C, and the heating time of the second stage is 1.5 hours-3 hours; the temperature of the soaking section is 1080-1100°C, and the heating time of the soaking section is 1.5 hours-3.5 hours; step 3: the steel billet heated by the heating furnace is rolled 9-11 times using a two-roll reversible blanking machine, the reduction of each time is 13mm-18mm, the rolling temperature is 950-1050°C, and the rolling The round steel bars are hot rolled into Φ85mm-Φ86.5mm round steel bars. The round steel bars enter the high-speed wire rod horizontal and vertical alternating continuous rolling mill for hot rolling. The high-speed wire rod rolling mill layout is as follows: roughing mill-intermediate rolling mill-pre-finishing mill-finishing mill-reducing and sizing mill. During the rolling process, the finished wire rods are finally rolled out through the sizing mill after hot rolling of each unit rolling mill. The average reduction is 2.25mm-2.65mm. During the process, the temperature of the rolled piece is controlled at 850-950℃, and the wire laying temperature is The temperature is 850-950℃, and 1#, 2# and 3# water tanks are used according to the spinning temperature. The speed of the air-cooled roller section 1 and 2 is 9-12m / min. Step 4: After hot rolling, hot coiling and hot rolling online hot charging and hot annealing processes are performed. The furnace entry temperature is ≥400℃. After hot coiling, hot rolling online hot charging is performed and annealing is performed in a roller hearth furnace. The heating section temperature is 760-780℃, the soaking section temperature is 770-790℃, and the roller speed is 0.6-0.9 m / min. After leaving the furnace, air cool to room temperature and package and collect.

[0006] The chemical composition and mass percentage of the ferritic stainless steel 022Cr18NbTi wire rod involved in the method are C: 0.015%-0.03%, Si: 1.0%-1.5%, Mn: 0.20%-0.50%, P: 0.015%-0.035%, S: 0.010%-0.030%, Cr: 17.2%-18.0%, Ni: 0.20%-0.50%, Ti: 0.05%-0.50%, and Nb: 0.35%-0.45%.

[0007] The beneficial effect of the present invention is that the method can achieve the purpose of obtaining good heat treatment mechanical properties, tensile strength and elongation of ferrite stainless steel 022Cr18NbTi wire rod, and meet the requirements of subsequent processing and use. DETAILED DESCRIPTION

[0008] The invention discloses a production method of a ferrite stainless steel 022Cr18NbTi wire rod, a production method of hot rolling, hot coiling after rolling and hot charging after rolling, and an online roller hearth furnace annealing process.

[0009] The invention can achieve the purpose of obtaining good heat treatment mechanical properties, tensile strength and elongation of the ferrite stainless steel 022Cr18NbTi wire rod.

[0010] The technical solution of the present invention is as follows: 1. The chemical composition range of the ferritic stainless steel 022Cr18NbTi wire rod applicable to the present invention is as follows: C: 0.015%~0.03%, Si: 1.0%~1.5%, Mn: 0.20%~0.50%, P: 0.015%~0.035%, S: 0.010%~0.030%, Cr: 17.2%~18.0%, Ni: 0.20%~0.50%, Ti: 0.05%~0.50%, Nb: 0.35%~0.45%.

[0011] 2. Use continuous casting square billets with a cross-sectional size of (210-220) × (210-220) mm and a billet weight of 1150-1250 kg. There should be no defects on the billet surface that would affect the processing and use of wire rods.

[0012] 3. The steel billet is heated in a walking beam heating furnace, with the first heating temperature at 850-1050°C and the first heating time at 1 hour to 2.5 hours; the second heating temperature at 1100-1120°C and the first heating time at 1.5 hours to 3 hours; the soaking section temperature at 1080-1100°C and the soaking section heating time at 1.5 hours to 3.5 hours.

[0013] 4. Use a two-roller reversible billet mill, roll 11 times, start rolling temperature 950 ~ 1050 ℃, and roll into Φ85mm round steel. Φ85mm round steel bars enter the high-speed wire rod horizontal and vertical alternating continuous rolling mill for hot rolling. The high-speed wire rod rolling mill layout is: roughing mill-intermediate rolling mill-pre-finishing mill-finishing mill-reducing and sizing mill. During the rolling process, after hot rolling through each unit rolling mill, it is finally rolled out through the rack sizing mill to produce the specified size of the finished wire rod, with an average reduction of 2.25mm-2.65mm. During the process, the temperature of the rolled piece is controlled at 850 ~ 950 ℃, and the wire laying temperature is 850 ~ 950 ℃. According to the wire laying temperature, 1#, 2# and 3# water tanks can be used, and the air-cooled roller uses 1st and 2nd sections, with a speed setting range of 9 ~ 12m / min. After rolling, hot coiling and hot rolling online hot loading and hot annealing processes are performed.

[0014] 5. For the process route of hot coiling after hot rolling and hot charging after rolling in online roller hearth furnace, the furnace entry temperature is ≥400℃, the roller hearth furnace heating section temperature is 760~780℃, the soaking section temperature is 770~790℃, the roller speed setting range is 0.6~0.9 m / min, and the steel is air-cooled to room temperature after leaving the furnace and then enters the packaging collection. The purpose of online annealing is achieved, so that the various properties of steel: mechanical properties, tensile strength, and elongation are controlled within the qualified range. Example 1

[0015] This embodiment is a method for producing 022Cr18NbTi wire rod with a specification of Φ5.5mm.

[0016] 1. The chemical composition is as follows: C: 0.017%, Si: 1.2%, Mn: 0.25%, P: 0.016%, S: 0.018%, Cr: 17.5%, Ni: 0.28%, Ti: 0.10%, Nb: 0.37%.

[0017] 2. Continuously cast square billet, the cross-sectional dimensions of the billet are 218×219 mm, the weight of the billet is 1.210 kg, and there are no defects on the billet surface that affect the processing and use of wire rods.

[0018] 3. Walking beam heating furnace, heating stage temperature 958℃, heating stage 2 temperature 1119℃, soaking stage temperature 1094℃.

[0019] 4. Use a two-roller reversible billet mill, roll 11 times, start rolling temperature 1043℃, and roll into Φ85mm round steel. Φ85mm round steel bars enter the high-speed wire rod horizontal and vertical alternating continuous rolling mill for hot rolling. After rolling through the roughing mill, intermediate rolling mill, pre-finishing mill, finishing mill, and sizing mill, the finished wire rod is finally rolled out through the stand sizing mill with a diameter of 5.50mm-5.60mm, an ovality within 0.1mm, and an average reduction of 2.34mm. During the process, the temperature of the rolled piece is controlled at 850-950℃, the wire laying temperature is 938℃, the water flow valve opening of the rolling line 1# water tank is 10%, the water flow valve opening of the 2# water tank is 5%, and the water flow valve opening of the 3# water tank is 17%. The speed setting value of the air-cooled roller 1 section is 9m / min, and the speed setting value of the 2nd section is 12m / min. After rolling, hot coiling and hot rolling online hot loading and hot annealing processes are performed.

[0020] 5. The process route of hot coiling after hot rolling and hot charging after rolling is online roller hearth furnace. The furnace entry temperature is 435℃, the roller hearth furnace heating section temperature is 775℃, the soaking section temperature is 781℃, the roller speed setting range is 0.75 m / min, and the products are air-cooled to room temperature after leaving the furnace and then enter packaging collection.

[0021] 6. Performance quality of straight bars: The 022Cr18NbTi wire rod subjected to the above online heat treatment has no residual stress inside, and its mechanical properties, tensile strength and elongation meet the requirements. The tensile strength is 491MPa and 495MPa, meeting the tensile strength standard of ≥420MPa; the elongation is 34% and 35%, meeting the elongation standard of ≥20%; meeting the requirements.

[0022] Example 2

[0023] This embodiment is a method for producing 022Cr18NbTi wire rod with a specification of Φ5.5mm.

[0024] 1. The chemical composition is as follows: C: 0.025%, Si: 1.3%, Mn: 0.50%, P: 0.025%, S: 0.019%, Cr: 17.7%, Ni: 0.40%, Ti: 0.080%, Nb: 0.35%.

[0025] 2. Continuously cast square billet, the cross-sectional dimensions of the billet are 219×221mm, the weight of the billet is 1.225kg, and there are no defects on the billet surface that affect the processing and use of wire rods.

[0026] 3. Walking beam heating furnace, heating stage temperature 965℃, heating stage 2 temperature 1108℃, soaking stage temperature 1087℃.

[0027] 4. Use a two-roller reversible billet mill, roll 9 times, start rolling temperature 1037℃, and roll into Φ86.4mm round steel. Φ86.4mm round steel bars enter the high-speed wire rod horizontal and vertical alternating continuous rolling mill for hot rolling. After rolling through the roughing mill, intermediate rolling mill, pre-finishing mill, finishing mill, and sizing mill, the finished wire rod is finally rolled out through the stand sizing mill with a diameter of 5.50mm-5.60mm, an ovality within 0.1mm, and an average reduction of 2.37mm. During the process, the temperature of the rolled piece is controlled at 855-945℃, the wire laying temperature is 935℃, the water valve opening of the rolling line 1# water tank is 13%, the water valve opening of the 2# water tank is 6%, and the water valve opening of the 3# water tank is 16%. The speed setting value of the air-cooled roller 1 section is 10m / min, and the speed setting value of the 2nd section is 12m / min. After rolling, hot coiling and hot rolling online hot loading and hot annealing processes are performed.

[0028] 5. The process route of hot coiling after hot rolling and hot charging after rolling is online roller hearth furnace. The furnace entry temperature is 457℃, the roller hearth furnace heating section temperature is 774℃, the soaking section temperature is 789℃, the roller speed setting range is 0.80 m / min, and the products are air-cooled to room temperature after leaving the furnace and then enter packaging collection.

[0029] 6. Performance quality of straight bars: The 022Cr18NbTi wire rod subjected to the above online heat treatment has no residual stress inside, and its mechanical properties, tensile strength and elongation meet the requirements. The tensile strength is 483MPa and 487MPa, meeting the tensile strength standard of ≥420MPa; the elongation is 35.4% and 35.9%, meeting the elongation standard of ≥20%; meeting the requirements.

[0030] Example 3

[0031] This embodiment is a method for producing 022Cr18NbTi wire rod with a specification of Φ5.5mm.

[0032] 1. The chemical composition is as follows: C: 0.03%, Si: 1.5%, Mn: 0.40%, P: 0.035%, S: 0.020%, Cr: 18.0%, Ni: 0.30%, Ti: 0.50%, Nb: 0.45%.

[0033] 2. Continuously cast square billet, the cross-sectional dimensions of the billet are 219×223mm, the weight of the billet is 1.228kg, and there are no defects on the billet surface that affect the processing and use of wire rods.

[0034] 3. Walking beam heating furnace, heating stage temperature 968℃, heating stage 2 temperature 1105℃, soaking stage temperature 1084℃.

[0035] 4. Use a two-roller reversible billet mill, roll 9 times, start rolling temperature 1025℃, and roll into Φ85.5mm round steel. Φ85.5mm round steel bars enter the high-speed wire rod horizontal and vertical alternating continuous rolling mill for hot rolling. After rolling through the roughing mill, intermediate rolling mill, pre-finishing mill, finishing mill, and sizing mill, the finished wire rod is finally rolled out through the rack sizing mill with a diameter of 5.50mm-5.60mm, an ovality within 0.1mm, and an average reduction of 2.325mm. During the process, the temperature of the rolled piece is controlled at 850-950℃, the wire laying temperature is 929℃, the water valve opening of the rolling line 1# water tank is 12.5%, the water valve opening of the 2# water tank is 7%, and the water valve opening of the 3# water tank is 18%. The speed setting value of the air-cooled roller 1 section is 9m / min, and the speed setting value of the 2nd section is 12m / min. After rolling, hot coiling and hot rolling online hot charging and hot annealing processes are carried out.

[0036] 5. The process route of hot coiling after hot rolling and hot charging after rolling is online roller hearth furnace. The furnace entry temperature is 468℃, the roller hearth furnace heating section temperature is 769℃, the soaking section temperature is 785℃, the roller speed setting range is 0.85m / min, and the products are air-cooled to room temperature after leaving the furnace and then enter packaging collection.

[0037] 6. Performance quality of straight bars: The 022Cr18NbTi wire rod subjected to the above online heat treatment has no residual stress inside, and its mechanical properties, tensile strength and elongation meet the requirements. The tensile strength is 469MPa and 475MPa, meeting the tensile strength standard of ≥420MPa; the elongation is 36.4% and 37.1%, meeting the elongation standard of ≥20%; meeting the requirements.

[0038]

[0039] The above description is only a specific embodiment of the present invention, but the structural features of the protection scope of the present invention are not limited thereto. Any changes or modifications made by any technician in the field of the present invention are all covered by the patent scope of the present invention.

Claims

1. A method for producing ferritic stainless steel 022Cr18NbTi wire rod, characterized in that: The following steps are involved: Step 1: The billet uses continuous casting square billet, the billet section size is (210-220) × (210-220) mm, and the billet weight is 1150-1250 kg; Step 2: The steel billet is heated in a walking beam heating furnace, with a heating temperature of 850-1050°C for one stage and a heating time of 1-2.5 hours; a heating temperature of 1100-1120°C for the second stage and a heating time of 1.5-3 hours; a soaking temperature of 1080-1100°C and a soaking time of 1.5-3.5 hours; Step 3: The steel billet heated by the heating furnace is rolled 9-11 times by a two-roller reversible billet mill, with a reduction of 13mm-18mm in each pass, and a rolling temperature of 950-1050°C, and is rolled into Φ85mm-Φ86.5mm round steel. The round steel bar enters the high-speed wire rod horizontal and vertical alternating continuous rolling mill for hot rolling. The high-speed wire rod rolling mill layout is as follows: roughing mill-intermediate rolling mill-pre-finishing mill-finishing mill-reducing and sizing mill. During the rolling process, after hot rolling by each unit rolling mill, the finished wire rod is finally rolled out by the reducing and sizing mill, with an average reduction of 2.25mm-2.65mm. During the process, the temperature of the rolled piece is controlled at 850-950°C, and the wire laying temperature is 850-950°C. According to the wire laying temperature, 1#, 2# and 3# water tanks are put into use, and the speed of the first and second sections of the air-cooled roller is 9-12m / min; Step 4: After hot rolling, perform hot coiling and hot rolling online hot charging and hot annealing process, the furnace temperature is ≥400℃, and then hot coiling is performed online and hot charging is performed in a roller hearth furnace for annealing. The heating section temperature is 760-780℃, the soaking section temperature is 770-790℃, and the roller speed is 0.6-0.9 m / min. After leaving the furnace, air cool to room temperature and then package and collect.

2. The method for producing a ferritic stainless steel 022Cr18NbTi wire rod according to claim 1, characterized in that: The chemical composition and mass percentage of the ferritic stainless steel 022Cr18NbTi wire rod involved in the method are C: 0.015%-0.03%, Si: 1.0%-1.5%, Mn: 0.20%-0.50%, P: 0.015%-0.035%, S: 0.010%-0.030%, Cr: 17.2%-18.0%, Ni: 0.20%-0.50%, Ti: 0.05%-0.50%, and Nb: 0.35%-0.45%.

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