Production process of HPB300 plain round steel bar

Abstract

The invention relates to an HPB300 plain round steel bar production process, and belongs to the technical field of metal smelting, when HPB300 plain round steel bars are produced by the HPB300 plain round steel bar production process, the weight percentage of manganese (Mn) in chemical components in molten steel is adjusted, the weight percentage of manganese (Mn) is 0.42-0.55%, the market price of manganese (Mn) iron ore is about 6000 yuan / ton, and the production cost is greatly reduced. Generally, the cost of adding 0.01% of manganese into each ton of casting blank is about 1 yuan, 87914 tons of HPB300 phi 6 and phi 8 plain round steel bars can be produced within 7 months, 0.10 Mn is saved for each ton of steel, the yield of HPB300 phi 10 is 13872 tons, and 0.20 manganese is saved for each ton of casting blank, namely 87914 * 10 + 13872 * 20 = 1154780 yuan. Besides, in the process of adjusting the production process of the HPB300 plain round steel bars, the time of steel billets in a furnace is controlled, the rolling temperature is reduced, the finish rolling temperature and the spinning temperature are adjusted, the finish rolling temperature is controlled, the cooling time is controlled, and the situation that the mechanical properties of the HPB300 plain round steel bars are affected due to adjustment of the use amount of manganese (Mn) is avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of metal smelting, and in particular relates to a production process of HPB300 smooth round steel bars. Background Art

[0002] HPB300 round steel bars are mainly used for stirrups and tie bars, as well as horizontal and vertical bars in shear walls, and most of them need to be bent during use. HPB300 steel bars have a yield strength of 300MPa and a tensile strength of no less than 420MPa. They have good ductility and welding properties and are suitable for a variety of construction engineering occasions. In the prior art, HPB300 plain round steel bars have different production grades, and each production grade of HPB300 plain round steel bars has different requirements for the weight percentage of manganese in the chemical composition of the ingot, and the steel ingot has poor versatility, which causes certain difficulties in production flexibility. HPB300 plain round steel bars of multiple production grades need to be produced in separate furnaces, for example, HPB300φ6 and φ8 plain round steel bars are produced in one furnace, HPB300φ10 plain round steel bars are produced in one furnace, HPB300φ6, φ8, and φ10 are produced in one furnace, and HPB300φ12 plain round steel bars are produced in one furnace; separate furnace production needs to adapt to a variety of steel billets, which increases production costs. At the same time, stacking of a variety of steel billets takes up space. Summary of the invention

[0003] In order to overcome the problems existing in the background technology, the present invention discloses a production process of HPB300 plain round steel bars. When producing HPB300 series plain round steel bars, the weight percentage of manganese (Mn) in the chemical composition of molten steel is adjusted, and the weight percentage of manganese (Mn) is reduced to 0.42%-0.55%. The market price of manganese (Mn) iron ore is about 6,000 yuan / ton. Generally, the cost of adding 0.01% manganese to each ton of ingot is about 1 yuan. Within 7 months, 87,914 tons of HPB300φ6 and φ8 plain round steel bars are produced, and 0.10 manganese (Mn) is saved per ton of steel. The output of HPB300φ10 is 13,872 tons, and 0.20 manganese is saved per ton of ingot, that is, 87,914×10+13,872× 20=1154780 yuan; In addition, the production process of HPB300 plain round steel bars is adjusted to control the time of steel billets in the furnace, reduce the rolling temperature, adjust the finishing rolling temperature and wire drawing temperature, control the final rolling temperature, and control the cooling time to avoid affecting the mechanical properties of HPB300 series plain round steel bars due to adjusting the amount of manganese (Mn).

[0004] To achieve the above object, the present invention is implemented through the following technical solutions: The HPB300 smooth round steel bar production process is characterized in that the process route comprises the following steps: (1) Converter smelting: molten iron from blast furnace enters converter for smelting; (2) LF refining: After converter smelting, the molten steel enters the LF refining furnace for refining; (3) Billet continuous casting: After refining, the molten steel enters the billet continuous casting machine for billet casting. The billet will be ready for use after passing the quality inspection. (4) Billet rolling: Billet rolling includes the steps of initial rolling, finishing rolling, final rolling, water cooling, wire rolling and air cooling; (5) Post-processing: The rolled steel bars are coiled, cut, inspected, bundled, weighed, and unloaded to obtain finished steel bars. The finished products are then stored for future use.

[0005] The chemical composition and weight percentage of the molten steel in the converter are: C: 0.20-0.24%, Si: 0.18-0.28%, Mn: 0.42-0.55%; S: ≤0.045%; P: ≤0.040%, and the remainder is iron and inevitable impurities.

[0006] Preferably, the chemical composition and weight percentage of the molten steel in the converter are: C: 0.22%, Si: 0.23%, Mn: 0.45%; S: ≤0.035%; P: ≤0.035%, and the remainder is iron and unavoidable impurities.

[0007] Preferably, the converter steelmaking time is 30-45 min.

[0008] Preferably, the cast slab is subjected to soaking furnace soaking and high-pressure water descaling treatment before rolling, wherein the soaking temperature is 1100-1150°C.

[0009] Preferably, the initial rolling temperature of the cast billet is 890-950°C.

[0010] Preferably, the finishing rolling temperature of the cast billet is 950-1050°C.

[0011] Preferably, the final rolling temperature of the cast billet is 900-950°C.

[0012] Preferably, the spinning temperature of the ingot rolling is 890-930°C.

[0013] Preferably, the air cooling rate of the rolled ingot is 80°C / min, and the air cooling time is 2.5-3.5 h.

[0014] Beneficial effects of the present invention: The HPB300 plain round steel bar production process adjusts the weight percentage of manganese (Mn) in the chemical composition of molten steel when producing HPB300 series plain round steel bars. The weight percentage of manganese (Mn) is 0.42-0.55%. The market price of manganese (Mn) iron ore is about 6,000 yuan / ton. Usually, the cost of adding 0.01% manganese to each ton of ingot is about 1 yuan. HPB300φ 6, φ 8 can be produced within 7 months. 87,914 tons of plain round steel bars were produced, saving 0.10 manganese (Mn) per ton of steel. The output of HPB300φ10 was 13,872 tons, saving 0.20 manganese per ton of ingot, i.e. 87,914×10+13,872×20=1,154,780 yuan. In addition, the production process of HPB300 plain round steel bars was adjusted to control the time the steel billet was in the furnace, reduce the start rolling temperature, adjust the finishing rolling temperature and the wire laying temperature, control the final rolling temperature, and control the cooling time to avoid affecting the mechanical properties of the HPB300 series plain round steel bars due to adjusting the amount of manganese (Mn). DETAILED DESCRIPTION

[0015] In order to make the above-mentioned purpose, technical scheme and beneficial effects clearer and more specific, the present invention is specifically described below in conjunction with embodiments.

[0016] Example 1: Production of Φ6mm HPB300 round steel bars: The production process of Φ6mm HPB300 round steel bars is as follows: (1) Converter smelting: The molten iron from the blast furnace is smelted in the converter, and the time in the converter is 30 min. The chemical composition and weight percentage of the molten steel in the converter are: C: 0.20%, Si: 0.18%, Mn: 0.42%; S: 0.04%; P: 0.03%, and the balance is iron and unavoidable impurities. (2) LF refining: After converter smelting, the molten steel enters the LF refining furnace for refining, and the furnace time is 30 minutes; (3) Billet continuous casting: After refining, the molten steel enters the billet continuous casting machine for billet casting. The billet is heated in a soaking furnace and descaled with high-pressure water. The soaking temperature is 1100°C. The billet is ready for use after passing the quality inspection. (4) Billet rolling: Billet rolling includes initial rolling at 890°C, finishing rolling at 950°C, final rolling at 900°C, water cooling, steel wire drawing at 890°C, and air cooling rate of billet rolling at 80°C / min for 3.5h. (5) Post-processing: The rolled steel bars are coiled, cut, inspected, bundled, weighed, and unloaded to obtain finished steel bars, which are then stored for future use. The Ceq of Φ6 mm HPB300 round steel bars is 0.28.

[0017] Example 2: Production of Φ8mm HPB300 round steel bars The production process of Φ8mm HPB300 round steel bars is as follows: (1) Converter smelting: The molten iron from the blast furnace is smelted in the converter, and the time in the converter is 45 minutes. The chemical composition and weight percentage of the molten steel in the converter are: C 0.24%, Si: 0.28%, Mn: 0.55%; S: 0.045%; P: 0.040%, and the balance is iron and unavoidable impurities; (2) LF refining: After converter smelting, the molten steel enters the LF refining furnace for refining, and the furnace time is 45 minutes; (3) Billet continuous casting: After refining, the molten steel enters the billet continuous casting machine for billet casting. The billet is heated in a soaking furnace and descaled with high-pressure water. The soaking temperature is 1150°C. The billet is kept ready for use after passing the quality inspection. (4) Billet rolling: Billet rolling includes initial rolling at a temperature of 950°C, finishing rolling at a temperature of 1050°C, final rolling at a temperature of 950°C, water cooling, steel rolling and wire drawing at a temperature of 930°C. The cooling rate of billet rolling during air cooling is 90°C / min, and the air cooling time is 3.5 h. (5) Post-processing: The rolled steel bars are coiled, cut, inspected, bundled, weighed, and unloaded to obtain finished steel bars, which are then stored for future use. The Ceq of Φ8 mm HPB300 round steel bars is 0.30.

[0018] Example 3: Production of Φ10mm HPB300 round steel bars The production process of Φ8mm HPB300 round steel bars is as follows: (1) Converter smelting: The molten iron from the blast furnace is smelted in the converter, and the time in the converter is 40 minutes; the chemical composition and weight percentage of the molten steel in the converter are: C: 0.22%, Si: 0.23%, Mn: 0.45%; S: 0.035%; P: 0.035%, and the balance is iron and unavoidable impurities; (2) LF refining: After converter smelting, the molten steel enters the LF refining furnace for refining, and the furnace time is 40 minutes; (3) Billet continuous casting: After refining, the molten steel enters the billet continuous casting machine for billet casting. The billet is heated in a soaking furnace and descaled with high-pressure water. The soaking temperature is 1120°C. The billet is ready for use after passing the quality inspection. (4) Billet rolling: Billet rolling includes initial rolling at a temperature of 930°C, finishing rolling at a temperature of 1000°C, final rolling at a temperature of 930°C, water cooling, wire drawing at a temperature of 920°C, air cooling, and air cooling rate of billet rolling at 85°C / min for 3.5 h. (5) Post-processing: The rolled steel bars are coiled, cut, inspected, bundled, weighed, and unloaded to obtain finished steel bars, which are then stored for future use. The Ceq of Φ10 mm HPB300 round steel bars is 0.31.

[0019] Example 4: Production of Φ12mm HPB300 round steel bars The production process of Φ12mm HPB300 round steel bars is as follows: (1) Converter smelting: The molten iron from the blast furnace is smelted in the converter, and the time in the converter is 43 minutes. The chemical composition and weight percentage of the molten steel in the converter are: C: 0.22%, Si: 0.23%, Mn: 0.46%; S: 0.035%; P: 0.035%, and the balance is iron and unavoidable impurities; (2) LF refining: After converter smelting, the molten steel enters the LF refining furnace for refining, and the furnace time is 40 min; (3) Billet continuous casting: After refining, the molten steel enters the billet continuous casting machine for billet casting. The billet is heated in a soaking furnace and descaled with high-pressure water. The soaking temperature is 1130°C. The billet is kept ready for use after passing the quality inspection. (4) Billet rolling: Billet rolling includes initial rolling at a temperature of 920°C, finishing rolling at a temperature of 1000°C, final rolling at a temperature of 900°C, water cooling, wire drawing at a temperature of 900°C, air cooling, and air cooling rate of billet rolling at 85°C / min for 3.5 h. (5) Post-processing: The rolled steel bars are coiled, cut, inspected, bundled, weighed, and unloaded to obtain finished steel bars, which are then stored for future use. The Ceq of Φ12 mm HPB300 round steel bars is 0.34.

[0020] In Example 1, Example 2, Example 3, and Example 4, HPB300 plain round steel bars of Φ6㎜, Φ8㎜, Φ10㎜, and Φ12㎜ specifications are produced in the same furnace, and the Ceq of the HPB300 plain round steel bars is 0.28-0.34, and the performance is stable; the Rel≥310Mpa, Rm≥430Mpa, and A / %≥25.5 of the HPB300 plain round steel bars are all higher than the national standard requirements, and the mechanical properties of the HPB300 plain round steel bars meet the requirements.

[0021] In summary, the HPB300 plain round steel bars of Φ6㎜, Φ8㎜, Φ10㎜ and Φ12㎜ specifications produced in the same furnace have a manganese (Mn) weight percentage of 0.42-0.55%. The HPB300 plain round steel bars produced have stable performance. By combining multiple production grades of HPB300 series plain round steel bars into one furnace, it brings convenience to steelmaking production, improves the versatility of castings, and saves billet stacking space.

[0022] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A production process for HPB300 round steel bars, characterized in that: The process route comprises the following steps: (1) Converter smelting: molten iron from blast furnace enters converter for smelting; (2) LF refining: After converter smelting, the molten steel enters the LF refining furnace for refining; (3) Billet continuous casting: After refining, the molten steel enters the billet continuous casting machine for billet casting. The billet will be ready for use after passing the quality inspection. (4) Billet rolling: Billet rolling includes the steps of initial rolling, finishing rolling, final rolling, water cooling, wire rolling and air cooling; (5) Post-processing: The rolled steel bars are coiled, cut, inspected, bundled, weighed, and unloaded to obtain finished steel bars. The finished products are then stored for future use.

2. A process for producing HPB300 smooth round steel bars according to claim 1, characterized in that: The chemical composition and weight percentage of the molten steel in the converter are: C: 0.22%, Si: 0.23%, Mn: 0.45%; S: ≤0.035%; P: ≤0.035%, and the remainder is iron and inevitable impurities.

3. A process for producing HPB300 round steel bars according to claim 1, characterized in that: The converter steelmaking time is 30-45 min.

4. A process for producing HPB300 smooth round steel bars according to claim 1, characterized in that: The cast slab is subjected to soaking furnace soaking and high-pressure water descaling treatment before rolling, wherein the soaking temperature is 1100-1150°C.

5. A process for producing HPB300 smooth round steel bars according to claim 1, characterized in that: The initial rolling temperature of the cast billet is 890-950°C.

6. A process for producing HPB300 smooth round steel bars according to claim 1, characterized in that: The finishing rolling temperature of the cast billet is 950-1050°C.

7. A process for producing HPB300 round steel bars according to claim 1, characterized in that: The final rolling temperature of the cast billet is 900-950°C.

8. A process for producing HPB300 smooth round steel bars according to claim 1, characterized in that: The spinning temperature of the ingot rolling is 890-930°C.

9. A process for producing HPB300 smooth round steel bars according to claim 1, characterized in that: The air cooling rate of the rolled ingot is 80°C / min, and the air cooling time is 2.5-3.5 h.