CORROSION-RESISTANT ALLOY STEEL BAR AND PREPARATION METHOD THEREFOR

Abstract

Provided in the present application are a corrosion-resistant alloy steel bar and a preparation method therefor, wherein the corrosion-resistant alloy steel bar comprises, in percentage by weight: 0.05-0.25% of C, 1.05-2% of Si, 0.3-1.5% of Mn, 0.5-2.5% of Cr, 0.05-1% of Ni, 0.001-0.005% of O, 0.001-0.0035% of S, 0.005-0.1% of Ti, 0.005-0.1% of Al, 0.005-0.03% of V, and 0.005-0.03% of Nb, with the balance being Fe and inevitable impurities. The preparation method therefor comprises the successive steps of smelting, refining, continuous casting, rolling and cooling. In the present application, elements such as Si, Ti, Al and Mn are used for compensating for the reduction in corrosion resistance caused by a decrease in the content of Cr, such that the production cost of the corrosion-resistant alloy steel bar are greatly reduced.

Claims

1. A corrosion-resistant alloy steel bar, wherein, in percentage by weight, the corrosion-resistant alloy steel bar comprises 0.05% to 0.25% of C, 1.05% to 2% of Si, 0.3% to 1.5% of Mn, 0.5% to 2.5% of Cr, 0.05% to 1% of Ni, 0.001% to 0.005% of O, 0.001% to 0.0035% of S, 0.005% to 0.1% of Ti, 0.005% to 0.1% of Al, 0.005% to 0.03% of V, 0.005% to 0.03% of Nb, and the balance of Fe and inevitable impurities; wherein, the content of Si and Mn satisfies 2Si/Mn5; the content of Si and Cr satisfies 0.75Si/Cr1.5; and the content of Ti and Al satisfies 0.02%(Ti+Al)0.2%.

2. The corrosion-resistant alloy steel bar of claim 1, wherein the content of Si is in a range from 1.2% to 1.8%; and/or, the content of Mn is in a range from 0.4% to 1%; and/or, the content of Cr is in a range from 0.85% to 2%.

3. The corrosion-resistant alloy steel bar of claim 2, wherein, the content of Si is in a range from 1.35% to 1.65%; and/or, the content of Mn is in a range from 0.45% to 0.75%; and/or, the content of Cr is in a range from 1.35% to 1.75%.

4. The corrosion-resistant alloy steel bar of claim 1, wherein the content of C is in a range from 0.05% to 0.15%.

5. The corrosion-resistant alloy steel bar of claim 4, wherein the content of C is in a range from 0.07% to 0.12%.

6. The corrosion-resistant alloy steel bar of claim 1, wherein, the content of Ti is in a range from 0.01% to 0.075%; and/or, the content of Al is in a range from 0.01% to 0.075%.

7. A method for preparing the corrosion-resistant alloy steel bar of claim 1, wherein the method comprises the processes of smelting, refining, continuous casting, rolling and cooling in sequence.

8. The method of claim 7, wherein raw materials for preparing the corrosion-resistant alloy steel bar comprise ferro-silicon alloy and silicon-manganese alloy, and a mass ratio of ferro-silicon alloy to silicon-manganese alloy is in a range from 2:1 to 5:1.

9. The method of claim 7, wherein, during the process of continuous casting, a casting speed is in a range from 2.5 m/min to 3.5 m/min; and/or, during the process of cooling, a temperature of steel bar when moved onto a cooling bed is in a range from 820 C. to 1,000 C.; and/or, the process of rolling comprises the steps of heating the continuous casting steel billet, rough rolling and finish rolling.

10. The method of claim 9, wherein a temperature for heating the continuous casting steel billet is in a range from 1,150 C. to 1,250 C.; a temperature for the rough rolling is in a range from 1,000 C. to 1,120 C.; and a temperature for the finish rolling is 1000 C. or higher.

11. A method for preparing the corrosion-resistant alloy steel bar of claim 2, wherein the method comprises the processes of smelting, refining, continuous casting, rolling and cooling in sequence.

12. A method for preparing the corrosion-resistant alloy steel bar of claim 3, wherein the method comprises the processes of smelting, refining, continuous casting, rolling and cooling in sequence.

13. A method for preparing the corrosion-resistant alloy steel bar of claim 4, wherein the method comprises the processes of smelting, refining, continuous casting, rolling and cooling in sequence.

14. A method for preparing the corrosion-resistant alloy steel bar of claim 5, wherein the method comprises the processes of smelting, refining, continuous casting, rolling and cooling in sequence.

15. A method for preparing the corrosion-resistant alloy steel bar of claim 6, wherein the method comprises the processes of smelting, refining, continuous casting, rolling and cooling in sequence.

Description

DETAILED DESCRIPTION

[0029] The following examples are provided for a better understanding of the present application, are not limited to the best embodiments, and do not constitute a limitation on the content and scope of protection of the present application. Any product identical or similar to the present application, derived by anyone under the inspiration of the present application or by combining the present application with other features of the prior art, falls within the scope of protection of the present application.

[0030] Where specific experimental steps or conditions are not indicated in the examples, the operations or conditions of conventional experimental steps described in the literatures in the present art can be followed. The reagents or instruments used without the manufacturer indicated are conventional reagents and products that are commercially available.

[0031] The particle diameter of the ferro-silicon alloy in the present application is in a range from 10 mm to 30 mm, and its main components in weight percentage are: 75% of Si, 0.002% of S, 0.01% of C, 0.1% of Al, 0.01% of Ti, 0.02% of P, the balance of iron and impurities, purchased from Qinghai Baitong High Purity Materials Co., Ltd.

[0032] The particle diameter of the silicon-manganese alloy in the present application is in a range from 10 mm to 30 mm, and its main components in weight percentage are: 83% of Mn, 1.94% of Si, 0.65% of C, 0.15% of P, 0.005% of S, and the balance of iron and impurities, purchased from Ningxia Yitong Industrial Co., Ltd.

[0033] The particle diameter of the ferro-chromium alloy in the present application is in a range from 30 mm to 50 mm, and its main components in weight percentage are: 60% of Cr, 0.87% of Si, 0.14% of C, 0.002% of S, 0.034% of P, and the balance of iron and impurities, purchased from Tianjin Haoyuan Metal Materials Co., Ltd.

[0034] The particle diameter of the ferro-titanium alloy in the present application is in a range from 10 mm to 30 mm, and its main components in weight percentage are: 1.85% of Si, 0.014% of S, 0.04% of C, 1.35% of Al, 32.94% of Ti, 0.042% of P, 1.57% of Mn, and the balance of iron and impurities, purchased from Jinzhou Haixin Metal Materials Co., Ltd.

[0035] The particle diameter of the ferro-niobium alloy in the present application is in a range from 5 mm to 30 mm, and its main components in weight percentage are: 65.92% of Nb, 1.97% of Si, 0.12% of C, 0.94% of Al, 0.018% of S, 0.258% of P, and the balance of iron and impurities, purchased from Beijing Hi-Tech New Materials Technology Co., Ltd.

[0036] The particle diameter of the vanadium-nitrogen alloy in the present application is in a range from 5 mm to 10 mm, and its main components in weight percentage are: 77.69% of V, 0.075% of S, 5.53% of C, 14.1% of N, 0.045% of P, and the balance of iron and impurities, purchased from Jiangsu Runfeng Synthetic Technology Co., Ltd.

[0037] In the present application, nickel is added in the manner of nickel plate which has a nickel content of 99.9% and the balance of iron and impurity elements, and was purchased from Jiangsu Guoyan Special Steel Co., Ltd.

[0038] In the present application, aluminum is added in the manner of aluminum particles, which has an aluminum content of 99.5% and the balance of iron and impurity elements, and was purchased from Xuchang Shengtong Metal Materials Co., Ltd.

EXAMPLE 1

[0039] The present application provides a corrosion-resistant alloy steel bar, in percentage by weight, comprising: 0.07% of C, 1.35% of Si, 0.45% of Mn, 1.35% of Cr, 0.05% of Ni, 0.001% of O, 0.001% of S, 0.01% of Ti, 0.01% of Al, 0.005% of V, 0.005% of Nb, and the balance of Fe and inevitable impurities; [0040] wherein the content of Si and Mn satisfies Si/Mn=3; the content of Si and Cr satisfies Si/Cr=1; and the content of Ti and Al satisfies Ti+Al=0.02%.

[0041] The method for preparing the corrosion-resistant alloy steel bar above comprises the following steps: [0042] the process of smelting: ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy, ferro-silicon alloy, silicon-manganese alloy, nickel plate and aluminum particles were smelted at 1,610 C. to obtain molten steel: wherein, the mass ratio of ferro-silicon alloy to silicon-manganese alloy is 3.3:1; the mass ratio of ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy and silicon-manganese alloy is 3.3:0.05:0.1:0.05:1; the addition amount of nickel plate is 60 kg; the addition amount of aluminum particles is 25 kg; and the addition amount of silicon-manganese alloy is 750 kg; [0043] the process of refining: argon gas was introduced into the molten steel and the materials were continuously refined at 1,550 C. for 40 minutes; [0044] the process of continuous casting: a continuous casting machine was used to make a continuous casting steel billet from the refined molten steel; the casting speed was set to 3 m/min during continuous casting, and the cross-sectional size of the obtained continuous casting steel billet is 140 mm.sup.2; [0045] the process of rolling: the continuous casting steel billet obtained in the process of continuous casting was heated to 1,190 C. for a time period of 100 min, then the temperature for the rough rolling was set to 1,035 C., the temperature for the finish rolling was set to 1,000 C., and the materials were rolled to obtain steel bars with a diameter of 14 mm; and [0046] the process of cooling: after the steel bars obtained in the process of rolling were cooled to 920 C., they were firstly moved onto the cooling bed for cooling and then air-cooled; and the conveying speed of the cooling bed is 2 m/min.

EXAMPLE 2

[0047] The present application provides a corrosion-resistant alloy steel bar, in percentage by weight, comprising: 0.1% of C, 1.5% of Si, 0.55% of Mn, 1.5% of Cr, 0.5% of Ni, 0.003% of O, 0.0025% of S, 0.05% of Ti, 0.05% of Al, 0.015% of V, 0.015% of Nb, and the balance of Fe and inevitable impurities;

[0048] wherein the content of Si and Mn satisfies Si/Mn=2.7; the content of Si and Cr satisfies Si/Cr=1; and the content of Ti and Al satisfies Ti+Al=0.1%.

[0049] The method for preparing the corrosion-resistant alloy steel bar above comprises the following steps: [0050] the process of smelting: ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy, ferro-silicon alloy, silicon-manganese alloy, nickel plate and aluminum particles were smelted at 1,630 C. to obtain molten steel; wherein, the mass ratio of ferro-silicon alloy to silicon-manganese alloy is 3.1:1; the mass ratio of ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy and silicon-manganese alloy is 3.1:0.15:0.5:0.15:1; the addition amount of nickel plate is 600 kg; the addition amount of aluminum particles is 130 kg; and the addition amount of silicon-manganese alloy is 920 kg; [0051] the process of refining: argon gas was introduced into the molten steel and the materials were continuously refined at 1,555 C. for 40 minutes; [0052] the process of continuous casting: a continuous casting machine was used to make a continuous casting steel billet from the refined molten steel; the casting speed was set to 3 m/min during continuous casting, and the cross-sectional size of the obtained continuous casting steel billet is 140 mm.sup.2; [0053] the process of rolling: the continuous casting steel billet obtained in the process of continuous casting was heated to 1,210 C. for a time period of 110 min, then the temperature for the rough rolling was set to 1,025 C., the temperature for the finish rolling was set to 1,010 C., and the materials were rolled to obtain steel bars with a diameter of 25 mm; and [0054] the process of cooling: after the steel bars obtained in the process of rolling were cooled to 930 C., they were firstly moved onto the cooling bed for cooling and then air-cooled; and the conveying speed of the cooling bed is 1.5 m/min.

EXAMPLE 3

[0055] The present application provides a corrosion-resistant alloy steel bar, in percentage by weight, comprising: 0.12% of C, 1.65% of Si, 0.75% of Mn, 1.75% of Cr, 1% of Ni, 0.005% of O, 0.0035% of S, 0.075% of Ti, 0.075% of Al, 0.03% of V, 0.03% of Nb, and the balance of Fe and inevitable impurities; [0056] wherein, the content of Si and Mn satisfies Si/Mn=2.2; the content of Si and Cr satisfies Si/Cr=0.94; and the content of Ti and Al satisfies Ti+Al=0.15%.

[0057] The method for preparing the corrosion-resistant alloy steel bar above comprises the following steps: [0058] the process of smelting: ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy, ferro-silicon alloy, silicon-manganese alloy, nickel plate and aluminum particles were smelted at 1,635 C. to obtain molten steel; wherein, the mass ratio of ferro-silicon alloy to silicon-manganese alloy is 2.5:1; the mass ratio of ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy and silicon-manganese alloy is 2.7:0.3:0.8:0.3:1; the addition amount of nickel plate is 1,200 kg; the addition amount of aluminum particles is 250 kg; and the addition amount of silicon-manganese alloy is 1,250 kg; [0059] the process of refining: argon gas was introduced into the molten steel and the materials were continuously refined at 1,515 C. for 50 minutes; [0060] the process of continuous casting: a continuous casting machine was used to make a continuous casting steel billet from the refined molten steel; the casting speed was set to 2.6 m/min during continuous casting, and the cross-sectional size of the obtained continuous casting steel billet is 140 mm.sup.2; [0061] the process of rolling: the continuous casting steel billet obtained in the process of continuous casting was heated to 1,210 C. for a time period of 110 min, then the temperature for the rough rolling was set to 1,025 C., the temperature for the finish rolling was set to 1,010 C., and the materials were rolled to obtain steel bars with a diameter of 32 mm; and [0062] the process of cooling: after the steel bars obtained in the process of rolling were cooled to 880 C., they were firstly moved onto the cooling bed for cooling and then air-cooled; and the conveying speed of the cooling bed is 1.1 m/min.

EXAMPLE 4

[0063] The present application provides a corrosion-resistant alloy steel bar, in percentage by weight, comprising: 0.05% of C, 1.2% of Si, 0.4% of Mn, 0.85% of Cr, 0.05% of Ni, 0.001% of O, 0.001% of S, 0.005% of Ti, 0.025% of Al, 0.005% of V, 0.005% of Nb, and the balance of Fe and inevitable impurities; [0064] wherein, the content of Si and Mn satisfies Si/Mn=3; the content of Si and Cr satisfies Si/Cr=1.41; and the content of Ti and Al satisfies Ti+Al=0.03%.

[0065] The method for preparing the corrosion-resistant alloy steel bar above comprises the following steps: [0066] the process of smelting: ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy, ferro-silicon alloy, silicon-manganese alloy, nickel plate and aluminum particles were smelted at 1,600 C. to obtain molten steel: wherein, the mass ratio of ferro-silicon alloy to silicon-manganese alloy is 3.5:1; the mass ratio of ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy and silicon-manganese alloy is 2.5:0.05:0.05:0.05:1; the addition amount of nickel plate is 60 kg; the addition amount of aluminum particles is 70 kg; and the addition amount of silicon-manganese alloy is 670 kg; [0067] the process of refining: argon gas was introduced into the molten steel and the materials were continuously refined at 1,540 C. for 30 minutes; [0068] the process of continuous casting: a continuous casting machine was used to make a continuous casting steel billet from the refined molten steel; the casting speed was set to 3 m/min during continuous casting, and the cross-sectional size of the obtained continuous casting steel billet is 140 mm.sup.2; [0069] the process of rolling: the continuous casting steel billet obtained in the process of continuous casting was heated to 1,230 C. for a time period of 120 min, then the temperature for the rough rolling was set to 1,070 C., the temperature for the finish rolling was set to 1,050 C., and the materials were rolled to obtain steel bars with a diameter of 28 mm; and [0070] the process of cooling: after the steel bars obtained in the process of rolling were cooled to 920 C., they were firstly moved onto the cooling bed for cooling and then air-cooled; and the conveying speed of the cooling bed is 1.2 m/min.

EXAMPLE 5

[0071] The present application provides a corrosion-resistant alloy steel bar, in percentage by weight, comprising: 0.15% of C, 1.8% of Si, 0.9% of Mn, 2% of Cr, 1% of Ni, 0.005% of O, 0.0035% of S, 0.1% of Ti, 0.1% of Al, 0.03% of V, 0.03% of Nb; and the balance of Fe and inevitable impurities; [0072] wherein, the content of Si and Mn satisfies Si/Mn=2; the content of Si and Cr satisfies Si/Cr=0.9; and the content of Ti and Al satisfies Ti+Al=0.2%.

[0073] The method for preparing the corrosion-resistant alloy steel bar above comprises the following steps: [0074] the process of smelting: ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy, ferro-silicon alloy, silicon-manganese alloy, nickel plate and aluminum particles were smelted at 1,639 C. to obtain molten steel; wherein, the mass ratio of ferro-silicon alloy to silicon-manganese alloy is 2:1; the mass ratio of ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy and silicon-manganese alloy is 2.5:0.3:1.2:0.3:1; the addition amount of nickel plate is 1,200 kg; the addition amount of aluminum particles is 30 kg; and the addition amount of silicon-manganese alloy is 1,500 kg; [0075] the process of refining: argon gas was introduced into the molten steel and the materials were continuously refined at 1,560 C. for 45 minutes; [0076] the process of continuous casting: a continuous casting machine was used to make a continuous casting steel billet from the refined molten steel; the casting speed was set to 2.5 m/min during continuous casting, and the cross-sectional size of the obtained continuous casting steel billet is 140 mm.sup.2; [0077] the process of rolling: the continuous casting steel billet obtained in the process of continuous casting was heated to 1,150 C. for a time period of 90 min, then the temperature for the rough rolling was set to 1,000 C., the temperature for the finish rolling was set to 1,000 C., and the materials were rolled to obtain steel bars with a diameter of 10 mm; and [0078] the process of cooling: after the steel bars obtained in the process of rolling were cooled to 820 C., they were firstly moved onto the cooling bed for cooling and then air-cooled; and the conveying speed of the cooling bed is 2.2 m/min.

EXAMPLE 6

[0079] The present application provides a corrosion-resistant alloy steel bar, in percentage by weight, comprising: 0.05% of C, 1.05% of Si, 0.3% of Mn, 0.8% of Cr, 0.05% of Ni, 0.001% of O, 0.001% of S, 0.025% of Ti, 0.005% of Al, 0.005% of V, 0.005% of Nb, and the balance of Fe and inevitable impurities; [0080] wherein the content of Si and Mn satisfies Si/Mn=3.5; the content of Si and Cr satisfies Si/Cr=1.31; and the content of Ti and Al satisfies Ti+Al=0.03%.

[0081] The method for preparing the corrosion-resistant alloy steel bar above comprises the following steps: [0082] the process of smelting: ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy, ferro-silicon alloy, silicon-manganese alloy, nickel plate and aluminum particles were smelted at 1,650 C. to obtain molten steel; wherein, the mass ratio of ferro-silicon alloy to silicon-manganese alloy is 3.8:1; the mass ratio of ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy and silicon-manganese alloy is 2.6:0.05:0.3:0.05:1; the addition amount of nickel plate is 60 kg; the addition amount of aluminum particles is 20 kg; and the addition amount of silicon-manganese alloy is 500 kg; [0083] the process of refining: argon gas was introduced into the molten steel and the materials were continuously refined at 1,550 C. for 35 minutes; [0084] the process of continuous casting: a continuous casting machine was used to make a continuous casting steel billet from the refined molten steel; the casting speed was set to 2.5 m/min during continuous casting, and the cross-sectional size of the obtained continuous casting steel billet is 140 mm.sup.2; [0085] the process of rolling: the continuous casting steel billet obtained in the process of continuous casting was heated to 1,180 C. for a time period of 100 min, then the temperature for the rough rolling was set to 1,020 C., the temperature for the finish rolling was set to 1,000 C., and the materials were rolled to obtain steel bars with a diameter of 18 mm; and [0086] the process of cooling: after the steel bars obtained in the process of rolling were cooled to 860 C., they were firstly moved onto the cooling bed for cooling and then air-cooled; and the conveying speed of the cooling bed is 1.4 m/min.

EXAMPLE 7

[0087] The present application provides a corrosion-resistant alloy steel bar, in percentage by weight, comprising: 0.25% of C, 2% of Si, 1% of Mn, 2.5% of Cr, 1% of Ni, 0.005% of O, 0.0035% of S, 0.1% of Ti, 0.1% of Al, 0.03% of V, 0.03% of Nb, and the balance of Fe and inevitable impurities; [0088] wherein the content of Si and Mn satisfies Si/Mn=2; the content of Si and Cr satisfies Si/Cr=0.8; and the content of Ti and Al satisfies Ti+Al=0.2%.

[0089] The method for preparing the corrosion-resistant alloy steel bar above comprises the following steps: [0090] the process of smelting: ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy, ferro-silicon alloy, silicon-manganese alloy, nickel plate and aluminum particles were smelted at 1,600 C. to obtain molten steel: wherein, the mass ratio of ferro-silicon alloy to silicon-manganese alloy is 2.2:1; the mass ratio of ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy and silicon-manganese alloy is 3:0.3:1.1:0.3:1; the addition amount of nickel plate is 1,200 kg; the addition amount of aluminum particles is 250 kg; and the addition amount of silicon-manganese alloy is 1,665 kg; [0091] the process of refining: argon gas was introduced into the molten steel and the materials were continuously refined at 1,540 C. for 40 minutes; [0092] the process of continuous casting: a continuous casting machine was used to make a continuous casting steel billet from the refined molten steel; the casting speed was set to 2.7 m/min during continuous casting, and the cross-sectional size of the obtained continuous casting steel billet is 140 mm.sup.2; [0093] the process of rolling: the continuous casting steel billet obtained in the process of continuous casting was heated to 1,250 C. for a time period of 120 min, then the temperature for the rough rolling was set to 1,120 C., the temperature for the finish rolling was set to 1,100 C., and the materials were rolled to obtain steel bars with a diameter of 22 mm; and [0094] the process of cooling: after the steel bars obtained in the process of rolling were cooled to 1,000 C., they were firstly moved onto the cooling bed for cooling and then air-cooled; and the conveying speed of the cooling bed is 1.45 m/min.

EXAMPLE 8

[0095] The present application provides a corrosion-resistant alloy steel bar, in percentage by weight, comprising: 0.1% of C, 1.05% of Si, 0.35% of Mn, 0.75% of Cr, 0.15% of Ni, 0.0025% of O, 0.0025% of S, 0.03% of Ti, 0.03% of Al, 0.01% of V, 0.01% of Nb, and the balance of Fe and inevitable impurities; [0096] wherein the content of Si and Mn satisfies Si/Mn=3; the content of Si and Cr satisfies Si/Cr=1.4; and the content of Ti and Al satisfies Ti+Al=0.06%.

[0097] The method for preparing the corrosion-resistant alloy steel bar above comprises the following steps: [0098] the process of smelting: ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy, ferro-silicon alloy, silicon-manganese alloy, nickel plate and aluminum particles were smelted at 1,620 C. to obtain molten steel; wherein, the mass ratio of ferro-silicon alloy to silicon-manganese alloy is 3.3:1; the mass ratio of ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy and silicon-manganese alloy is 2.1:0.1:0.3:0.1:1; the addition amount of nickel plate is 180 kg; the addition amount of aluminum particles is 250 kg; and the addition amount of silicon-manganese alloy is 585 kg; [0099] the process of refining: argon gas was introduced into the molten steel and the materials were continuously refined at 1,545 C. for 40 minutes; [0100] the process of continuous casting: a continuous casting machine was used to make a continuous casting steel billet from the refined molten steel; the casting speed was set to 3.5 m/min during continuous casting, and the cross-sectional size of the obtained continuous casting steel billet is 140 mm.sup.2; [0101] the process of rolling: the continuous casting steel billet obtained in the process of continuous casting was heated to 1,200 C. for a time period of 100 min, then the temperature for the rough rolling was set to 1,020 C., the temperature for the finish rolling was set to 1,000 C., and the materials were rolled to obtain steel bars with a diameter of 16 mm; and [0102] the process of cooling: after the steel bars obtained in the process of rolling were cooled to 880 C., they were firstly moved onto the cooling bed for cooling and then air-cooled; and the conveying speed of the cooling bed is 1.6 m/min.

EXAMPLE 9

[0103] The present application provides a corrosion-resistant alloy steel bar, in percentage by weight, comprising: 0.25% of C, 1.5% of Si, 0.3% of Mn, 1% of Cr, 0.05% of Ni, 0.001% of O, 0.001% of S, 0.1% of Ti, 0.05% of Al, 0.005% of V, and 0.005% of Nb;

[0104] wherein the content of Si and Mn satisfies Si/Mn=5; the content of Si and Cr satisfies Si/Cr=1.5; and the content of Ti and Al satisfies Ti+Al=0.15%.

[0105] The method for preparing the corrosion-resistant alloy steel bar above comprises the following steps: [0106] the process of smelting: ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy, ferro-silicon alloy, silicon-manganese alloy, nickel plate and aluminum particles were smelted at 1,650 C. to obtain molten steel; wherein, the mass ratio of ferro-silicon alloy to silicon-manganese alloy is 5:1; the mass ratio of ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy and silicon-manganese alloy is 3.3:0.05:1.1:0.05:1; the addition amount of nickel plate is 60 kg; the addition amount of aluminum particles is 125 kg; and the addition amount of silicon-manganese alloy is 500 kg; [0107] the process of refining: argon gas was introduced into the molten steel and the materials were continuously refined at 1,560 C. for 60 minutes; [0108] the process of continuous casting: a continuous casting machine was used to make a continuous casting steel billet from the refined molten steel; the casting speed was set to 3.1 m/min during continuous casting, and the cross-sectional size of the obtained continuous casting steel billet is 140 mm.sup.2; [0109] the process of rolling: the continuous casting steel billet obtained in the process of continuous casting was heated to 1,230 C. for a time period of 120 min, then the temperature for the rough rolling was set to 1,060 C., the temperature for the finish rolling was set to 1,000 C., and the materials were rolled to obtain steel bars with a diameter of 22 mm; and [0110] the process of cooling: after the steel bars obtained in the process of rolling were cooled to 1,000 C., they were firstly moved onto the cooling bed for cooling and then air-cooled; and the conveying speed of the cooling bed is 1.45 m/min.

Example 10

[0111] The present application provides a corrosion-resistant alloy steel bar, in percentage by weight, comprising: 0.05% of C, 1.86% of Si, 0.93% of Mn, 2.48% of Cr, 1% of Ni, 0.005% of O, 0.0035% of S, 0.005% of Ti, 0.015% of Al, 0.03% of V, and 0.03% of Nb; [0112] wherein the content of Si and Mn satisfies Si/Mn=2; the content of Si and Cr satisfies Si/Cr=0.75; and the content of Ti and Al satisfies Ti+Al=0.02%.

[0113] The method for preparing the corrosion-resistant alloy steel bar above comprises the following steps: [0114] the process of smelting: ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy, ferro-silicon alloy, silicon-manganese alloy, nickel plate and aluminum particles were smelted at 1,600 C. to obtain molten steel: wherein, the mass ratio of ferro-silicon alloy to silicon-manganese alloy is 2.2:1; the mass ratio of ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy and silicon-manganese alloy is 3.0:0.3:0.2:0.3:1; the addition amount of nickel plate is 1,200 kg; the addition amount of aluminum particles is 325 kg; and the addition amount of silicon-manganese alloy is 1,550 kg; [0115] the process of refining: argon gas was introduced into the molten steel and the materials were continuously refined at 1,540 C. for 30 minutes; [0116] the process of continuous casting: a continuous casting machine was used to make a continuous casting steel billet from the refined molten steel; the casting speed was set to 2.8 m/min during continuous casting, and the cross-sectional size of the obtained continuous casting steel billet is 140 mm.sup.2; [0117] the process of rolling: the continuous casting steel billet obtained in the process of continuous casting was heated to 1,180 C. for a time period of 90 min, then the temperature for the rough rolling was set to 1,020 C., the temperature for the finish rolling was set to 1,000 C., and the materials were rolled to obtain steel bars with a diameter of 22 mm; and [0118] the process of cooling: after the steel bars obtained in the process of rolling were cooled to 950 C., they were firstly moved onto the cooling bed for cooling and then air-cooled; and the conveying speed of the cooling bed is 1.45 m/min.

Comparative Example 1

[0119] The present application provides a corrosion-resistant alloy steel bar, in percentage by weight, comprising: 0.1% of C, 2.15% of Si, 0.3% of Mn, 1% of Cr, 0.05% of Ni, 0.001% of O, 0.0035% of S, 0.08% of Ti, 0.07% of Al, 0.005% of V, and 0.005% of Nb; [0120] wherein the content of Si and Mn satisfies Si/Mn=7.17; the content of Si and Cr satisfies Si/Cr=2.15; and the content of Ti and Al satisfies Ti+Al=0.15%.

[0121] The only difference between the method for preparing the corrosion-resistant alloy steel bar above and Example 8 is that: in the process of smelting, the mass ratio of ferro-silicon alloy to silicon-manganese alloy is 6.5:1; the mass ratio of ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy and silicon-manganese alloy is 3.6:0.05:0.8:0.05:1; the addition amount of nickel plate is 60 kg; the addition amount of aluminum particles is 180 kg; and the addition amount of silicon-manganese alloy is 500 kg.

Comparative Example 2

[0122] The present application provides a corrosion-resistant alloy steel bar, in percentage by weight, comprising: 0.1% of C, 1.5% of Si, 1.65% of Mn, 1% of Cr, 0.05% of Ni, 0.001% of O, 0.0035% of S, 0.08% of Ti, 0.07% of Al, 0.005% of V, and 0.005% of Nb; [0123] wherein the content of Si and Mn satisfies Si/Mn=0.91; the content of Si and Cr satisfies Si/Cr=1.5; and the content of Ti and Al satisfies Ti+Al=0.15%.

[0124] The only difference between the method for preparing the corrosion-resistant alloy steel bar above and Example 8 is that: in the process of smelting, the mass ratio of ferro-silicon alloy to silicon-manganese alloy is 0.8:1; the mass ratio of ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy and silicon-manganese alloy is 0.6:0.05:0.8:0.05:1; the addition amount of nickel plate is 60 kg; the addition amount of aluminum particles is 180 kg; and the addition amount of silicon-manganese alloy is 2,750 kg.

Comparative Example 3

[0125] The present application provides a corrosion-resistant alloy steel bar, in percentage by weight, comprising: 0.1% of C, 1.5% of Si, 0.3% of Mn, 3% of Cr, 0.05% of Ni, 0.001% of O, 0.0035% of S, 0.08% of Ti, 0.07% of Al, 0.005% of V, and 0.005% of Nb; [0126] wherein the content of Si and Mn satisfies Si/Mn=5; the content of Si and Cr satisfies Si/Cr=0.5; and the content of Ti and Al satisfies Ti+Al=0.15%.

[0127] The only difference between the method for preparing the corrosion-resistant alloy steel bar above and Example 8 is that: in the process of smelting, the mass ratio of ferro-silicon alloy to silicon-manganese alloy is 4.5:1; the mass ratio of ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy and silicon-manganese alloy is 10:0.05:0.8:0.05:1; the addition amount of nickel plate is 60 kg; the addition amount of aluminum particles is 180 kg; and the addition amount of silicon-manganese alloy is 500 kg.

Comparative Example 4

[0128] The present application provides a corrosion-resistant alloy steel bar, in percentage by weight, comprising: 0.1% of C, 1.5% of Si, 0.3% of Mn, 1% of Cr, 0.05% of Ni, 0.001% of O, 0.0035% of S, 0.15% of Ti, 0.07% of Al, 0.005% of V, and 0.005% of Nb; [0129] wherein the content of Si and Mn satisfies Si/Mn=5; the content of Si and Cr satisfies Si/Cr=1.5; and the content of Ti and Al satisfies Ti+Al=0.22%.

[0130] The only difference between the method for preparing the corrosion-resistant alloy steel bar above and Example 8 is that: in the process of smelting, the mass ratio of ferro-silicon alloy to silicon-manganese alloy is 4.5:1; the mass ratio of ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy and silicon-manganese alloy is 3.3:0.05:1.55:0.05:1; the addition amount of nickel plate is 60 kg; the addition amount of aluminum particles is 180 kg; and the addition amount of silicon-manganese alloy is 500 kg.

Comparative Example 5

[0131] The present application provides a corrosion-resistant alloy steel bar, in percentage by weight, comprising: 0.1% of C, 1.5% of Si, 0.3% of Mn, 1% of Cr, 0.05% of Ni, 0.001% of O, 0.0035% of S, 0.08% of Ti, 0.15% of Al, 0.005% of V, and 0.005% of Nb; [0132] wherein the content of Si and Mn satisfies Si/Mn=5; the content of Si and Cr satisfies Si/Cr=1.5; and the content of Ti and Al satisfies Ti+Al=0.22%.

[0133] The only difference between the method for preparing the corrosion-resistant alloy steel bar above and Example 8 is that: in the process of smelting, the mass ratio of ferro-silicon alloy to silicon-manganese alloy is 4.5:1; the mass ratio of ferro-chromium alloy, ferro-niobium alloy, ferro-titanium alloy, vanadium-nitrogen alloy and silicon-manganese alloy is 3.3:0.05:0.8:0.05:1; the addition amount of nickel plate is 60 kg; the addition amount of aluminum particles is 380 kg; and the addition amount of silicon-manganese alloy is 500 kg.

Test Example 1

[0134] The mechanical properties of the corrosion-resistant alloy steel bars prepared in the Examples and Comparative Examples were tested in accordance with the national standard GB/T228.1-2010, Metal Materials Tensile Test Part 1: Room Temperature Test Method, and the ratio of tensile strength and yield strength (i.e. tensile strength/yield strength) was calculated. The test results were shown in Table 1;

TABLE-US-00001 TABLE 1 Test results of Test Example 1 Mechanical property Ratio of Total tensile elongation strength Yield Tensile Elongation at and Test strength/ strength/ after maximum yield Example MPa MPa fracture/% force/% strength Example 1 468 613 31.8 20.5 1.31 Example 2 481 640 30.6 19.5 1.33 Example 3 495 653 32.5 19.3 1.32 Example 4 468 604 25.3 15.4 1.29 Example 5 456 588 23.8 15.5 1.29 Example 6 430 542 21.7 11.3 1.26 Example 7 435 552 20.5 10.6 1.27 Example 8 435 548 20.5 12.5 1.26 Example 9 445 565 22.5 13.5 1.27 Example 10 448 569 23 13.1 1.27 Comparative 385 443 20.5 10.7 1.15 Example 1 Comparative 370 437 28.5 14.1 1.18 Example 2 Comparative 485 631 8.5 4.6 1.3 Example 3 Comparative 456 575 14.5 6.9 1.26 Example 4 Comparative 365 475 16.5 10.5 1.3 Example 5

[0135] It can be seen from the data in Table 1 that, only when the proportions of various elements meet the conditions of the present application, can the yield strength 430 MPa, elongation after fracture20.5%, ratio of tensile strength and yield strength1.26, and total elongation at maximum force 24 10.6% be guaranteed at the same time, so that the excellent mechanical properties can be obtained under the cases that Mo element needs not to be added in the formula and the content of Cr element is greatly reduced.

Test Example 2

[0136] Zeiss optical microscope was used to observe the structural types of the corrosion-resistant alloy steel bars prepared in the Examples and Comparative Examples under a field of view of 200 times magnification, and the ferrite volume ratio therein was calculated. The test results were shown in Table 2.

Test Example 3

[0137] An electrochemical workstation equipped with a working electrode, a reference electrode, and a counter electrode system was used to test the critical chloride ion concentration value of the passive film rupture on the surface of the corrosion-resistant alloy steel bars prepared in the Examples and Comparative Examples, and the increase multiple of the critical chloride ion concentration value compared with that of the HRB400 type steel bar was calculated. The specific test method was: soaking the test sample in a saturated sodium hydroxide solution for 48 hours, then loading it into the electrochemical workstation and serving as a working electrode; adding 0.01 mol/L of sodium chloride solution into the electrochemical workstation solution every 24 hours, and testing the voltage/current-chloride ion concentration curve; when the current or voltage varies sharply, the corresponding chloride ion concentration value is the critical chloride ion concentration value. The calculation formula is: the increase multiple=critical chloride ion concentration value of corrosion-resistant alloy steel bar/critical chloride ion concentration value of HRB400 steel bar; and the test results were shown in Table 2. The composition ratio of the above HRB400 type steel bar was C: 0.24%, Si: 0.40%, Mn: 1.40%, V: 0.025%, P0.04 and S0.04%.

Test Example 4

[0138] The chlorine salt corrosion resistance of the corrosion-resistant alloy steel bars prepared in the Examples and Comparative Examples was tested respectively, and the increase multiple of the chlorine salt corrosion resistance compared thereof compared with that of the HRB400 type steel bar was calculated. The specific test method was: the 100 mm long ends of the alloy corrosion-resistant steel bar of various Examples and Comparative Examples were cut off, and the test sample with a diameter of 8 mm was obtained by turning it with a lathe; the test sample was put into the corrosion solution at a temperature of 35 C. and a humidity of 80% for salt spray corrosion test. The corrosion solution for testing is a sodium chloride solution with a chloride salt concentration of 5 wt %, and a pH value of 7.0, the testing time was 14 days, and the weight of the test samples before and after corrosion was measured using an electron microscope balance. The calculation formula is: increase multiple=weight variation value of corrosion-resistant alloy steel bar before and after corrosion/weight variation value of HRB400 type steel bar before and after corrosion. The test results were shown in Table 2. The composition ratio of the above HRB400 type steel bar was C: 0.24%, Si: 0.40%, Mn: 1.40%, V: 0.025%, P0.04% and S0.04%.

TABLE-US-00002 TABLE 2 Test results of Test Examples 2-4 Increase Increase multiples of multiples chloride salt of critical corrosion chloride ion resistance Proportion concentration compared Microstructure of value compared with Number type Ferrite/% with HRB400 HRB400 Example 1 Ferrite + 53 4.5 6.6 Pearlite Example 2 Ferrite + 55 4.2 7.5 Pearlite Example 3 Ferrite + 58 4.8 8.2 Pearlite Example 4 Ferrite + 63 3.3 3.7 Pearlite Example 5 Ferrite + 65 3 4.9 Pearlite Example 6 Ferrite + 73 2.4 2.7 Pearlite Example 7 Ferrite + 70 2.2 3.2 Pearlite Example 8 Ferrite + 68 2.1 3.3 Pearlite Example 9 Ferrite + 68 2.2 3.5 Pearlite Example Ferrite + 65 2.7 3.4 10 Pearlite Comparative Ferrite + 75 2.1 5 Example 1 Pearlite Comparative Ferrite + 80 1.1 3 Example 2 Pearlite Comparative Ferrite + 33 2.5 4.5 Example 3 Pearlite + Bainite Comparative Ferrite + 40 3 5.6 Example 4 Pearlite Comparative Ferrite + 85 3 7 Example 5 Pearlite

[0139] It can be seen from the results in Table 2 above that in the corrosion-resistant alloy steel bars of the present application, the proportion of ferrite in the microstructure type reaches 53% to 73%. Compared with HRB400, the critical chloride ion concentration value was increased to 2.1 times and more, the chlorine salt corrosion resistance was improved to 2.7 times and more, and the comprehensive performance was significantly improved.

[0140] It can be concluded from the data in Table 1 and Table 2 that both the mechanical properties and corrosion resistance can be obtained under the composition ratio of the present application, and the comprehensive performance is remarkable. In addition, there is no Mo element in the composition ratio of the present application and the content of Cr element was greatly reduced, and the cost was significantly reduced.

[0141] Obviously, the above examples are merely examples made for clear description, rather limiting the embodiments. For those of ordinary skill in the art, other different forms of variations or modifications can also be made on the basis of the above-mentioned description. All embodiments are not necessary to be and cannot be exhaustively listed herein. In addition, obvious variations or modifications derived therefrom all fall within the scope of protection of the present application.