Preparation method of high-expansion alloy strip

Abstract

The invention relates to a preparation method of a high-expansion alloy strip. Specifically, the high-expansion alloy strip is produced by adopting a process route of electric furnace (or intermediate frequency furnace)-AOD-LF-die casting slab ingot-cogging-hot continuous rolling-cold rolling. Compared with a traditional process, the process has the advantages that the quality fluctuation among batches is reduced, the yield is greatly improved, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the field of material manufacturing, and in particular to a method for preparing a high expansion alloy strip. Background Art

[0002] High expansion alloy is an alloy with high thermal expansion coefficient within a certain temperature range (20~100℃). It is rarely used alone and is often used as an active layer and paired with low expansion alloy to form a thermal bimetal. Thermo bimetal is a composite of two or more metals with different thermal expansion coefficients. The active layer alloy should have a very high expansion coefficient and an average linear expansion coefficient higher than 15×10 −6 / ℃, it should also have the characteristics of not causing significant changes in expansion characteristics within the use temperature range, and the elastic modulus is similar to that of the passive layer, firmly combined with the passive layer alloy, with good heat resistance and ductility, easy to make into plates and strips with uniform performance, with certain resistance, and conducive to deformation processing and other properties. The working principle of thermal bimetallic materials is to obtain temperature rise through environmental heat conduction or self-heating (generally self-heating by power on). The difference in thermal expansion coefficients between component layers causes elastic bending and deformation of the entire material. At this time, the material will convert thermal energy into mechanical energy to achieve different functional requirements. Thermal bimetallic materials are widely used in temperature control, temperature indication, temperature compensation and overload thermal protectors. With the rapid development of my country's industrial control electrical appliances, household appliances and portable electronic products, the use of thermal bimetallic composite materials has also increased.

[0003] At present, most of the raw materials are melted in a vacuum induction furnace with a small furnace capacity and then cast into ingots. The ingots generally weigh 1-2 tons, and then they are rolled. The width of the finished strip is between 200mm-300mm. The quality fluctuation between batches is large, the yield rate is low and the cost is high. In response to the above problems, this patent proposes a new process route to solve the problem. The process route is to prepare strips using a large furnace capacity electric furnace (or medium frequency furnace) → AOD → LF → mold casting flat ingot → billeting → hot rolling → cold rolling. Compared with the traditional process, this process reduces the quality fluctuation between batches, greatly improves the yield rate, and reduces production costs.

[0004] The present invention relates to a method for preparing a high expansion alloy strip, specifically, the method adopts an electric furnace (or medium frequency furnace) → AOD → LF → die casting flat ingot → blanking → hot continuous rolling → cold rolling to produce the high expansion alloy strip. Compared with the traditional process, this process reduces the quality fluctuation between batches, greatly improves the yield rate, and reduces the production cost. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a high expansion alloy strip in view of the above problems.

[0006] The object of the present invention is achieved as follows: A method for preparing a high expansion alloy strip comprises the following steps: Step 1: a die-casting flat ingot is produced by an electric furnace → AOD → LF → die-casting process to produce a 7.5-11.5 ton die-casting flat ingot; AOD blowing adopts argon blowing throughout the process, lime is added at 40-55 kg / ton steel during the oxidation period, slag replacement treatment is performed when C≤0.35%, the slag removal amount is 70-75%, lime is added at 55-60 kg / ton steel during the subsequent oxidation period, and the terminal temperature control target is 1660-1 700℃; AOD reduction temperature is 1710-1740℃, Al is used as reducing agent, the amount of Al added is 10-50kg / t steel, the reduction time is 10-15 minutes, Al powder is used to adjust the slag according to the reduction S and deoxidation conditions, and the composition is adjusted according to the target composition; the ladle is required to control the ladle age to ≤30 times, the ladle baking temperature is 800-900℃, and the ladle is emptied by argon before tapping; LF furnace requires that the ladle be blown with argon to dissipate the slag after arriving at the station, and then the argon blowing flow rate is 100 -300L / min, argon blowing time 5-15min, then the argon blowing flow rate is changed to 60-220L / min, argon blowing time 5-15min, Ar blowing must not expose molten steel, the temperature after argon blowing is 1355±5℃; the mold temperature during casting is ≥80℃, and the ingot mold is purged with argon for 3-6 minutes before casting; Step 2: Opening: Open the mold casting ingot, the billet size is 120-150mm thick × 900-1000mm wide × 6000-6500mm long; Step 3 : Strip rolling: The surface of the billet is ground, and there shall be no visible defects after grinding. Before heating, the ground billet is sprayed with anti-oxidation coating, and then hot rolled. The target thickness of the hot rolled coil is 4.0-5.0mm. The hot rolled coil is annealed and pickled and then ground. The roughness Ra after grinding is 0.3-0.5, and then cold rolled. The target thickness of the cold rolled coil is 2.0-2.5mm. Finally, bright annealing is performed. The bright annealing temperature is 950-1000℃, and the TV value is between 20-25.

[0007] The high expansion alloy components and their mass percentages involved in this method are as follows: 0.25≤C≤0.35%, Si≤0.30%, Mn≤0.6%, P≤0.025%, S≤0.025%, 2.0%≤Cr≤4.0%, 21.0%≤Ni≤23.0%, Fe balance.

[0008] The beneficial effect of the present invention is that the present invention adopts a large-capacity electric furnace (or medium-frequency furnace) → AOD → LF → die-casting flat ingot → billeting → hot continuous rolling → cold rolling process route to prepare strips. Compared with the traditional process, this process reduces the quality fluctuation between batches, greatly improves the yield rate, and reduces the production cost. DETAILED DESCRIPTION

[0009] The present invention designs a production process route according to the requirements of high quality and low cost for expansion alloy strips, namely: large-capacity electric furnace (or medium-frequency furnace) → AOD → LF → die-casting flat ingot → blanking → hot rolling → cold rolling process route to prepare strips.

[0010] The specific technical scheme is as follows: (1) The high expansion alloy components involved in the present invention are as follows (%): 0.25≤C≤0.35%, Si≤0.30%, Mn≤0.6%, P≤0.025%, S≤0.025%, 2.0%≤Cr≤4.0%, 21.0%≤Ni≤23.0%, Fe balance.

[0011] (2) Die-casting ingots: 7.5-11.5 tons of die-casting ingots are produced by electric furnace → AOD → LF → die-casting process. AOD blowing adopts argon blowing throughout the process, and lime is added at 40-55 kg / ton of steel during the oxidation period. When C≤0.35% is calculated based on the residual phosphorus and chromium content of the steel in the middle oxidation period, slag replacement treatment is carried out, and the slag removal amount is 70-75%. In the subsequent oxidation period, lime is added at 55-60 kg / ton of steel. The terminal temperature control target is 1660-1700℃ to prevent the temperature from being too high after aluminum reduction.

[0012] The reduction temperature is 1710-1740℃, the reducing agent is Al reduction, the addition amount is 10-50kg / t steel, the reduction time is 10-15 minutes, and the reduction slag and deoxidation are observed before reduction analysis. After good deoxidation, the composition analysis is performed. According to the reduction composition and the deoxidation of the molten steel, some slag is removed (according to the reduction S and deoxidation), and Al powder is used to adjust the slag, and the composition is adjusted according to the target composition. The ladle tapping requires that the ladle age is controlled at ≤30 times, and the ladle baking temperature is 800-900℃ (use continuous red bags as much as possible). Pay special attention to confirming the ladle tapping conditions in advance, and it must be ensured that there is no residual steel or residue in the ladle. The ladle is emptied by argon blowing before tapping.

[0013] LF furnace requires that after the ladle arrives at the station, argon blowing should be carried out to slag first. The argon blowing flow rate is 100-300L / min, and the argon blowing time is 5-15min. Then the argon blowing flow rate is changed to 60-220L / min, and the argon blowing time is 5-15min. The molten steel must not be exposed during Ar blowing to ensure the argon blowing effect. The temperature after argon blowing is 1355±5℃.

[0014] During casting, the ingot mold should be clean, smooth and free of residue on the surface. The ingot plate and ingot mold of the casting system must be dry, clean, unobstructed, and the mold temperature must be ≥80℃. Before pouring, the mold and the center pouring pipe must be cleaned by exhaust. It is strictly forbidden to use cold molds and cold ingot plates. The cap mouth must be straight, the insulation board must be installed flat, and it must be tightened with asbestos rope to prevent the insulation board from floating and producing thorns. The ingot mold must be purged with argon for 3-6 minutes before pouring.

[0015] (3) Opening: The mold-cast ingot is opened, and the size of the billet is 120-150 mm thick × 900-1000 mm wide × 6000-6500 mm long.

[0016] (4) Strip rolling: The surface of the billet is ground, and there should be no visible defects after grinding. Anti-oxidation coating is sprayed before heating, and then hot rolling is carried out. The target thickness of the hot-rolled coil is 4.0-5.0mm. The hot-rolled coil is annealed and pickled, and then ground. The annealing temperature is 900-950℃. The roughness Ra after grinding is 0.3-0.5, and then cold rolling is carried out. The target thickness of the cold-rolled coil is 2.0-2.5mm. Finally, bright annealing is carried out. The bright annealing temperature is 950-1000℃, and the TV value is between 20-25.

[0017] The specific implementation manner of the present invention is described in detail below in conjunction with the embodiments, but the specific implementation manner of the present invention is not limited to the following embodiments. Embodiment 1

[0018] (1) A 9.5-ton die-casting flat ingot was produced by the process of electric furnace → AOD → LF → die-casting. The composition (% by mass) is: C 0.30, Si 0.10, Mn 0.35, P 0.01, S 0.005, Cr3.0, Ni 22.0, and the rest is iron and unavoidable impurities.

[0019] (2) Die-casting ingot: 9.5 tons of die-casting ingots are produced by electric furnace → AOD → LF → die-casting process. AOD blowing adopts argon blowing throughout the process, and lime is added at 40 kg / ton steel during the oxidation period. When C is 0.3% in the middle oxidation period according to the residual phosphorus and chromium content of the steel, slag replacement treatment is carried out, and the slag removal amount is 70% to prevent P and Cr from returning after reduction. In the subsequent oxidation period, lime is added at 55 kg / ton steel. The terminal temperature control target is 1660°C to prevent the temperature from being too high after aluminum reduction.

[0020] The reduction temperature is 1710℃, and the reducing agent is Al reduction, the addition amount is 20kg / t steel, and the reduction time is 10 minutes. Observe the reduction slag and deoxidation before reduction analysis, and perform component analysis after good deoxidation. According to the reduction composition and the deoxidation of the molten steel, remove part of the slag (according to the reduction S and deoxidation), and use Al powder to adjust the slag, and adjust the composition according to the target composition. If the composition needs to be adjusted after reduction, use electrolytic manganese, pure nickel or pure iron. Fluorite and low-carbon lime are used to adjust the slag after reduction to prevent silicon increase in the molten steel.

[0021] The ladle tapping requires a ladle age of 20 times and a ladle baking temperature of 850°C (use continuous red ladle as much as possible). Pay special attention to confirming the ladle tapping conditions in advance and ensure that there is no residual steel or slag in the ladle. Before tapping, the ladle is emptied by blowing argon.

[0022] The LF furnace requires that the ladle be blown with argon to deslagging after arriving at the station. The argon blowing flow rate is 200L / min and the argon blowing time is 7min. The argon blowing flow rate is then changed to 80L / min and the argon blowing time is 6min. The molten steel must not be exposed during Ar blowing to ensure the argon blowing effect. The temperature after argon blowing is 1355℃.

[0023] During casting, the ingot mold should be clean, smooth and free of residue on the surface. The ingot plate and ingot mold of the casting system must be dry, clean, unobstructed, and the mold temperature must be 85°C. Before pouring, the mold and the center pouring pipe should be cleaned by exhaust. It is strictly forbidden to use cold molds and cold ingot plates. The cap mouth should be seated correctly, the insulation board should be installed flat, and asbestos rope should be used to tighten it to prevent the insulation board from floating and producing thorns. The ingot mold must be purged with argon for 4 minutes before pouring.

[0024] (3) Opening: The mold-cast ingot is opened, and the size of the billet is 120 mm thick × 900 mm wide × 6000 mm long.

[0025] (4) Strip rolling: The surface of the billet is ground, and there shall be no visible defects after grinding. Anti-oxidation coating is sprayed before heating, and then hot rolling is carried out, and the target thickness of the hot-rolled coil is 5.0 mm. The hot-rolled coil is annealed and pickled, and then ground, the annealing temperature is 950°C, and the roughness after grinding is Ra0.5, and then cold rolling, the target thickness of the cold-rolled coil is 2.0 mm, and finally bright annealing is carried out, the bright annealing temperature is 1000°C, and the TV value is 20. Embodiment 2

[0026] (1) The process of electric furnace → AOD → LF → die casting was used to produce 11.5 ton die-casting flat ingots. The composition (% by mass) was: C 0.32, Si 0.15, Mn 0.40, P 0.015, S 0.006, Cr3.5, Ni 22.5, and the rest was iron and unavoidable impurities.

[0027] (2) Die-casting ingot: 11.5 tons of die-casting ingots are produced by electric furnace → AOD → LF → die-casting process. AOD blowing adopts argon blowing throughout the process, and lime is added at 45 kg / ton steel during the oxidation period. According to the residual phosphorus and chromium content of the steel, when C is calculated to be 0.32% in the middle oxidation period, slag replacement treatment is carried out, and the slag removal amount is 75% to prevent P and Cr from returning after reduction. In the subsequent oxidation period, lime is added at 60 kg / ton steel. The terminal temperature control target is 1700°C to prevent the temperature from being too high after aluminum reduction.

[0028] The reduction temperature is 1720℃, and the reducing agent is Al reduction, the addition amount is 30kg / t steel, and the reduction time is 15 minutes. Observe the reduction slag and deoxidation before reduction analysis, and perform component analysis after good deoxidation. According to the reduction composition and the deoxidation of the molten steel, remove part of the slag (according to the reduction S and deoxidation), and use Al powder to adjust the slag, and adjust the composition according to the target composition. If the composition needs to be adjusted after reduction, use electrolytic manganese, pure nickel or pure iron. Fluorite and low-carbon lime are used to adjust the slag after reduction to prevent silicon increase in the molten steel.

[0029] The ladle tapping requires a ladle age of 25 times and a ladle baking temperature of 860°C (use continuous red ladle as much as possible). Pay special attention to confirming the ladle tapping conditions in advance and ensure that there is no residual steel or slag in the ladle. The ladle is emptied by argon blowing before tapping.

[0030] LF furnace requires that after the ladle arrives at the station, argon blowing should be carried out to deslagging first. The argon blowing flow rate is 250L / min, and the argon blowing time is 10min. Then the argon blowing flow rate is changed to 100L / min, and the argon blowing time is 10min. The molten steel must not be exposed during Ar blowing to ensure the argon blowing effect. The temperature after argon blowing is 1350℃.

[0031] During casting, the ingot mold should be clean, smooth and free of residue on the surface. The ingot plate and ingot mold of the casting system must be dry, clean, unobstructed, and the mold temperature must be 90°C. Before pouring, the mold and the center pouring pipe soup channel should be cleaned by exhaust. It is strictly forbidden to use cold molds and cold ingot plates. The cap mouth should be seated correctly, the insulation board should be installed flat, and it should be tightened with asbestos rope to prevent the insulation board from floating and producing thorns. The ingot mold must be purged with argon for 5 minutes before pouring.

[0032] (3) Opening: The mold-cast ingot is opened, and the size of the ingot is 140 mm thick × 1000 mm wide × 6500 mm long.

[0033] (4) Strip rolling: The surface of the billet is ground, and there shall be no visible defects after grinding. Anti-oxidation coating is sprayed before heating, and then hot rolling is carried out. The target thickness of the hot-rolled coil is 4.0 mm. The hot-rolled coil is annealed and pickled, and then ground. The annealing temperature is 900°C, and the roughness after grinding is Ra0.3. Then cold rolling is carried out, and the target thickness of the cold-rolled coil is 2.0 mm. Finally, bright annealing is carried out. The bright annealing temperature is 950°C and the TV value is 25.

[0034] Compared with traditional processes, the high expansion alloy produced through the above steps reduces quality fluctuations between batches, greatly improves the yield rate, reduces production costs, and the product performance meets user requirements.

[0035] 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 preparing a high expansion alloy strip, characterized in that: The following steps are involved: Step 1: Die-casting ingots adopt electric furnace → AOD → LF → die-casting process to produce 7.5-11.5 tons of die-casting ingots; AOD blowing adopts argon blowing throughout the process, lime is added in the oxidation period 40-55Kg / ton steel, slag replacement treatment is carried out when C≤0.35%, the slag removal amount is 70-75%, lime is added in the subsequent oxidation period 55-60Kg / ton steel, and the terminal temperature control target is 1660-1700℃; AOD reduction temperature is 1710-1740℃, Al reduction is used as the reducing agent, the amount of Al added is 10-50kg / t steel, the reduction time is 10-15 minutes, according to the reduction S and In the case of deoxidation, Al powder is used to adjust the slag, and the composition is adjusted according to the target composition; the ladle age is required to be controlled at ≤30 times, the ladle baking temperature is 800-900℃, and the ladle is emptied by argon before tapping; the LF furnace requires that the ladle be blown with argon to deslagging after arriving at the station, and then the argon blowing flow rate is 100-300L / min, the argon blowing time is 5-15min, and then the argon blowing flow rate is changed to 60-220L / min, the argon blowing time is 5-15min, Ar blowing must not expose the molten steel, and the temperature after argon blowing is 1355±5℃; the mold temperature during casting is ≥80℃, and the ingot mold is purged with argon for 3-6 minutes before casting; Step 2: Opening: Open the mold casting ingot, the size of the billet is 120-150mm thick × 900-1000mm wide × 6000-6500mm long; Step 3: Strip rolling: Grind the surface of the billet. There should be no visible defects after grinding. Spray anti-oxidation coating on the ground billet before heating, and then hot roll. The target thickness of the hot rolled coil is 4.0-5.0mm. After annealing and pickling, the hot rolled coil is ground. The roughness Ra after grinding is 0.3-0.5, and then cold rolled. The target thickness of the cold rolled coil is 2.0-2.5mm. Finally, bright annealing is performed. The bright annealing temperature is 950-1000℃ and the TV value is between 20-25.

2. A method for preparing a high expansion alloy strip according to claim 1, characterized in that: The high expansion alloy components and their mass percentages involved in this method are as follows: 0.25≤C≤0.35%, Si≤0.30%, Mn≤0.6%, P≤0.025%, S≤0.025%, 2.0%≤Cr≤4.0%, 21.0%≤Ni≤23.0%, Fe balance.