WO2023155447A1

WO2023155447A1 - High wear resistance steel for coal mining and production method therefor

Info

Publication number: WO2023155447A1
Application number: PCT/CN2022/124119
Authority: WO
Inventors: 谯明亮; 翟冬雨; 杨柳; 张媛钰
Original assignee: 南京钢铁股份有限公司
Priority date: 2022-02-15
Filing date: 2022-10-09
Publication date: 2023-08-24
Also published as: CN114525379A

Abstract

A high wear resistance steel for coal mining and a production method therefor. Chemical components and mass percentages are as follows: C: 0.15-0.30 %, Si: 0.20-0.50 %, Mn: 0.90-1.40 %, P ≤ 0.015 %, S ≤ 0.0020 %, Nb: ≤ 0.030 %, V: ≤ 0.020 %, Ti: 0.008-0.015 %, Cr: 0.30-0.90 %, Ni ≤ 0.60 %, Mo: 0.20-0.50 %, Al: 0.025-0.050 %, B: 0.0010-0.0020 %, Mg: 0.0010-0.0018 %, N ≤ 0.0045%, H ≤ 0.0002%, and the balance being Fe and unavoidable impurities. The steel grade of a product is 360-500 HBW, and the thickness specification is 3-180 mm. By means of micro-alloying dispersed particles of a magnesium metallurgy technique, the wear resistance of the product is improved.

Description

High wear resistance steel for coal mining and production method thereof

technical field

The invention belongs to the technical field of iron and steel production, and in particular relates to a high wear resistance steel for coal mining and a production method thereof.

Background technique

Wear-resistant steel is a low-alloy, high-strength, high-wear-resistant martensitic steel, which is widely used in the manufacture of mechanical equipment in the field of coal machinery. The steel plate is required to have high strength and hardness to improve the wear resistance of the steel plate At the same time, it also needs to have good low-temperature toughness and welding performance. Poor low-temperature toughness and welding performance will lead to problems such as easy fracture of the steel plate and poor wear resistance. The quality requirements for products with high strength and high wear resistance are also getting higher and higher.

Due to the high content of alloying elements, martensitic structure will be formed during the cooling process of cast slab and steel plate after heating. Under the action of internal stress, it will crack or form surface microcracks caused by intergranular cracks, which will cause customers to be unable to use normally. According to the characteristics of the product itself, the present invention effectively solves the manufacturing defects of the steel type itself through composition design, improvement of the purity of molten steel, reduction of gas content, heating and heat preservation temperature, etc., satisfies the customer's use requirements, and improves the quality of the product .

Contents of the invention

Purpose of the invention: The purpose of the invention is to provide a high wear-resistant steel for coal mining and its production method. Through the ingenious proportioning of alloying elements and optimization of the production process, the grain size of the product can be effectively reduced and the compactness of the structure can be improved. , improved wear resistance, and through secondary quenching, low temperature tempering and flame cutting methods, delayed cracks are avoided, and the use requirements of high wear resistance steel for coal mining and transportation are realized.

Technical solution: The high wear resistance steel for coal mining of the present invention comprises, by mass percentage: C: 0.15% to 0.30%, Si: 0.20% to 0.50%, Mn: 0.90% to 1.40%, P≤0.015%, S≤0.0020%, Nb: ≤0.030%, V≤0.020%, Ti: 0.008%～0.015%, Cr: 0.30%～0.90%, Ni≤0.60%, Mo: 0.20～0.50%, Al: 0.025%～0.050 %, B: 0.0010% to 0.0020%, Mg: 0.0010% to 0.0018%, N≤0.0045%, H≤0.0002%, and the balance is Fe and unavoidable impurities.

Preferably, by mass percentage: C: 0.15%-0.20%, Si: 0.20%-0.30%, Mn: 0.90%-1.20%, P≤0.013%, S≤0.0015%, Nb:≤0.030%, V≤ 0.020%, Ti: 0.010%～0.015%, Cr: 0.30%～0.90%, Ni≤0.60%, Mo: 0.20～0.50%, Al: 0.025%～0.045%, B: 0.0010%～0.0020%, Mg: 0.0010 %～0.0018%, N≤0.0045%, H≤0.0002%, the balance is Fe and unavoidable impurities.

Preferably, by mass percentage: C: 0.20%-0.28%, Si: 0.30%-0.40%, Mn: 1.00%-1.30%, P≤0.015%, S≤0.0020%, Nb: 0.010-0.020%, V ≤0.020%, Ti: 0.010%～0.015%, Cr: 0.50%～0.70%, Ni≤0.60%, Mo: 0.30～0.40%, Al: 0.030%～0.050%, B: 0.0010%～0.0020%, Mg: 0.0010%～0.0018%, N≤0.0045%, H≤0.0002%, the balance is Fe and unavoidable impurities.

Preferably, by mass percentage: C: 0.20%-0.30%, Si: 0.30%-0.50%, Mn: 1.10%-1.40%, P≤0.015%, S≤0.0020%, Nb: 0.020-0.030%, V ≤0.020%, Ti: 0.008%～0.013%, Cr: 0.70%～0.90%, Ni≤0.60%, Mo: 0.40～0.50%, Al: 0.035%～0.050%, B: 0.0010%～0.0020%, Mg: 0.0010%～0.0018%, N≤0.0045%, H≤0.0002%, the balance is Fe and unavoidable impurities.

The present invention also provides a production method of high wear resistance steel for coal mining, comprising the following steps:

S1. Desulfurization and slag removal of molten iron is sent to LF/RH for refining treatment after being smelted in the converter. The RH vacuum treatment time is 10-30 minutes. After the vacuum treatment of molten steel, magnesium-aluminum wire is used for magnesium treatment. Stir statically for 15-20 minutes after the silk is finished;

S2. The molten steel after vacuum treatment is cast, and the electromagnetic stirring process is adopted. After the billet is thermally inspected, it is put into a heating type heat preservation pit for hydrogen expansion;

S3. The heating temperature of the heating furnace is 1150±20°C. The steel plate below 18mm adopts conventional rolling, and the final rolling temperature is ≤930°C. The steel plate with 18mm and above adopts controlled rolling, and the final rolling temperature is ≤900°C;

S4. The steel plate after rolling is quenched and tempered. The initial quenching temperature is set at a heating temperature of 900-920°C, kept for 20-40 minutes, and water-cooled; the secondary quenching temperature is set at a heating temperature of 850-870°C, and kept for 20-30 minutes , water cooling; tempering heating temperature 200 ~ 300 ℃, heat preservation 30 ~ 50min, air cooling;

S5. After quenching and tempering, use an electronic heating pad to heat the steel plate to 120-150°C, and cut it with a burning gun when it comes out of the furnace. After the cutting is completed, cover it with refractory insulation cotton and slowly cool it to room temperature to eliminate the stress caused by cutting;

S6. The divided steel plate is marked according to the performance requirements to obtain a final product.

6. The method for producing high wear-resistant steel for coal mining according to claim 5, characterized in that, in step S1, the molten iron is desulfurized using a KR furnace.

Further, in step S2, the current of the electromagnetic stirring process is 180-280A, the frequency is 6-11A, and the casting speed is 0.6-1.2m/min.

Further, in step S2, the heat preservation temperature of the heat preservation pit is 600-650° C., and the heat preservation time is 30-60 minutes.

Further, in step S5, the starting speed of the cutting is 160-200 mm/min, and the cutting speed is 350-380 mm/min.

Beneficial effect: compared with the prior art, the present invention has the following significant advantages:

(1) The composition design adopts the control of hydrogen element to avoid the cracking induced by stress cracks in the process of stack cooling and slow cooling of martensitic steel. The gap delays the occurrence of cracks; boron can effectively improve the hardenability of the steel plate, adding more boron can combine with nitrogen to form stable BN precipitates; the binding force between Ti and N is much higher than that of B. Therefore, an appropriate amount of Ti element can be added to steel to combine with N to form TiN precipitates, fix N element, make B element free, and increase hardenability. At the same time, nano-scale TiN can refine the grain; The binding force of the steel is extremely strong. When the amount of Ti element added to the steel is large, it is inevitable to form micron-sized TiN inclusions or long TiC inclusions with regular shapes and sharp corners, which are easy to capture H atoms and induce Hydrogen-induced delayed cracks; Nb elements can also combine with N elements to form NbN precipitates, fix N elements, and make B elements free, but its binding force is weaker than that of Ti elements, so reduce the amount of Ti elements added, and at the same time add A small amount of Nb element can achieve the effect of fixing N element; the joint addition of Mo and Nb elements can increase the effectiveness of B element, so you can choose to add Mo element and appropriate amount of Nb element to the steel to fix N element, Make the B element in a free state and play the role of the B element. At the same time, the addition of Mo can improve the hardenability of the steel plate, which is beneficial to the production of martensite and improve the strength of the steel plate; the Al element also has a certain N-fixing effect, but the Al element first Combined with O element in steel to form Al2O3, properly control the content of aluminum to improve product performance and reduce the production of inclusions;

(2) Magnesium metallurgy technology is used to replace calcium treatment technology, and it is applied in high-carbon low-alloy martensitic steel to refine the grain size of the structure and generate simple magnesium-aluminum spinel inclusions instead of calcium-aluminate inclusions , to obtain nano-scale inclusions to improve the wear resistance of the product;

(3) The secondary quenching is adopted, and the cutting process is optimized at the same time, which avoids the influence of the composition on the stress of the steel plate, and avoids the occurrence of cutting cracks.

Description of drawings

FIG. 1 is a metallographic structure diagram of Example 1 of the present invention.

Detailed ways

The technical solution of the present invention will be further described below in conjunction with the accompanying drawings.

Example 1

This embodiment provides a high wear resistance steel for coal mining and its production method. The thickness of the steel plate is 22 mm, and its chemical composition and mass percentage are as follows: C: 0.18%, Si: 0.23%, Mn: 0.99%, P: 0.01: 1%, S: 0.0012%, Nb: 0.009%, V: 0.03%, Ti: 0.013%, Cr: 0.56%, Ni: 0.02%, Mo: 0.39%, Al: 0.036%, B: 0.0017%, Mg: 0.0015%, N: 0.00:33%, H: 0.000:11%, the balance is Fe and unavoidable impurities.

Its manufacturing method comprises the following steps:

S1. The molten iron is desulfurized by the KR furnace. The molten iron is desulfurized and slag-smelted and then sent to the LF/RH for refining treatment. The RH vacuum treatment time is 16 minutes. After the vacuum treatment of the molten steel, the magnesium-aluminum wire is used for magnesium treatment. For iron wire, stir for 18 minutes after wire feeding;

S2. The molten steel after vacuum treatment is cast, using electromagnetic stirring process, current 260A, frequency 9A, casting speed 0.75m/min, after thermal inspection of the billet, it is put into a heating heat preservation pit for hydrogen expansion, heat preservation temperature is 630 degrees, and heat preservation time is 45min ;

S3. The heating temperature of the heating furnace is 1161°C, the steel plate adopts controlled rolling, and the final rolling temperature is 878°C;

S4. The steel plate after rolling is quenched and tempered. The initial quenching temperature is set at a heating temperature of 9.15°C, held for 26 minutes, and water-cooled; the secondary quenching temperature is set at a heating temperature of 865°C, held for 25 minutes, and water-cooled; tempering heating Temperature 280℃, heat preservation 33min, air cooling;

S5. After quenching and tempering, use an electronic heating pad to heat the steel plate to 136°C, and cut it with a combustion gun when it comes out of the furnace. The cutting speed is 180mm/min, and the cutting speed is 360mm/min. To eliminate the stress generated by cutting;

S6. The divided steel plates are marked, put into storage, and delivered according to the performance requirements.

Example 2

This embodiment provides a kind of high wear resistance steel for coal mining and its production method. The thickness of the steel plate is 16 mm, and its chemical composition and mass percentage are as follows: C: 0.27%, Si: 0.31%, Mn: 1.23%, P : 0.013%, S: 0.0011%, Nb: 0.017%, V: 0.0020%, Ti: 0.011%, Cr: 0.59%, Ni: 0.02%, Mo: 0.33%, Al: 0.039%, B: 0.0015%, Mg : 0.0016%, N: 0.0041%, H: 0.00011%, the balance is Fe and unavoidable impurities.

Its manufacturing method comprises the following steps:

S1. The molten iron is desulfurized by the KR furnace. The molten iron is desulfurized and the slag is sent to the converter for smelting and then sent to the LF/RH for refining treatment. The RH vacuum treatment time is 20 minutes. After the vacuum treatment of the molten steel, the magnesium-aluminum wire is used for magnesium treatment. For iron wire, stir for 18 minutes after wire feeding;

S2. The molten steel after vacuum treatment is cast, using electromagnetic stirring process, current 200A, frequency 10A, casting speed 1.1m/min, after thermal inspection of the billet, it is put into a heating heat preservation pit for hydrogen expansion, heat preservation temperature is 640 degrees, and heat preservation time is 36min ;

S3. The heating temperature of the heating furnace is 1168°C, and the steel plate is conventionally rolled;

S4. The steel plate after rolling is quenched and tempered. The initial quenching temperature is set at a heating temperature of 915°C, held for 35 minutes, and water-cooled; the secondary quenching temperature is set at a heating temperature of 855°C, held for 26 minutes, and water-cooled; the tempering heating temperature is 230°C ℃, heat preservation for 41min, air cooling;

S5. After quenching and tempering, use an electronic heating pad to heat the steel plate to 130°C, and cut it with a combustion gun when it comes out of the furnace. The cutting speed is 190mm/min, and the cutting speed is 370mm/min. To eliminate the stress generated by cutting;

Example 3

This embodiment provides a kind of high wear resistance steel for coal mining and its production method. The thickness of the steel plate is 90 mm, and its chemical composition and mass percentage are as follows: C: 0.29%, Si: 0.41%, Mn: 1.36%, P : 0.009%, S: 0.0008%, Nb: 0.029%, V: 0.0030%, Ti: 0.012%, Cr: 0.79%, Ni: 0.03%, Mo: 0.47%, Al: 0.043%, B: 0.00170%, Mg : 0.0016%, N: 0.0040%, H: 0.00010%, the balance is Fe and unavoidable impurities.

Its manufacturing method comprises the following steps:

S1. The molten iron is desulfurized by the KR furnace. The molten iron is desulfurized and slag-smelted and then sent to the LF/RH for refining treatment. The RH vacuum treatment time is 17 minutes. After the vacuum treatment of the molten steel, the magnesium-aluminum wire is used for magnesium treatment. For iron wire, stir for 19 minutes after wire feeding;

S2. The molten steel after vacuum treatment is casted, using electromagnetic stirring process, current 260A, frequency 6A, casting speed 0.65m/min, after thermal inspection of the billet, it is put into a heating heat preservation pit for hydrogen expansion, heat preservation temperature is 610 degrees, and heat preservation time is 55min ;

S3. The heating temperature of the heating furnace is 1135°C, the steel plate adopts controlled rolling, and the final rolling temperature is 770°C;

S4. The steel plate after rolling is quenched and tempered. The initial quenching temperature is set at a heating temperature of 905°C, held for 35 minutes, and water-cooled; the secondary quenching temperature is set at a heating temperature of 855°C, held for 28 minutes, and water-cooled; the tempering heating temperature is 220°C ℃, heat preservation for 45min, air cooling;

S5. After quenching and tempering, heat the steel plate to 121°C with an electronic heating pad, and cut it with a combustion gun when it comes out of the furnace. The cutting speed is 165mm/min, and the cutting speed is 360mm/min. To eliminate the stress generated by cutting;

Example mechanical properties:

According to the characteristics of the product, in-depth research from the composition design of the steel plate has reduced the production of large-scale inclusions. For the first time, magnesium metallurgy technology has been used to obtain nano-scale inclusions and effectively refine the grain size of the structure. Through the austenitization temperature The optimization of the structure refines the grain size of the structure. Through the refinement of the purity of molten steel and the grain size, the wear resistance of the high-strength martensitic structure steel is improved. The optimization process of the secondary quenching is used to refine the grain size of the structure. grains, eliminate the structural stress, solve the occurrence of delayed cracks in high-strength martensitic steel, and improve the high wear resistance of the product in coal mining.

Claims

A high wear-resistant steel for coal mining, characterized in that it comprises: C: 0.15% to 0.30%, Si: 0.20% to 0.50%, Mn: 0.90% to 1.40%, P≤0.015%. S≤0.0020%, Nb: ≤0.030%, V≤0.020%, Ti: 0.008%～0.015%, Cr: 0.30%～0.90%, Ni≤0.60%, Mo: 0.20～0.50%, Al: 0.025%～0.050 %, B: 0.0010% to 0.0020%, Mg: 0.0010% to 0.0018%, N≤0.0045%, H≤0.0002%, and the balance is Fe and unavoidable impurities.
The high wear resistance steel for coal mining according to claim 1, characterized in that, by mass percentage, it comprises: C: 0.15% to 0.20%, Si: 0.20% to 0.30%, Mn: 0.90% to 1.20%, P≤0.013%, S≤0.0015%, Nb: ≤0.030%, V≤0.020%, Ti: 0.010%～0.015%, Cr: 0.30%～0.90%, Ni≤0.60%, Mo: 0.20～0.50%, Al : 0.025% to 0.045%, B: 0.0010% to 0.0020%, Mg: 0.0010% to 0.0018%, N≤0.0045%, H≤0.0002%, and the balance is Fe and unavoidable impurities.
The high wear resistance steel for coal mining according to claim 1, characterized in that, by mass percentage, it comprises: C: 0.20% to 0.28%, Si: 0.30% to 0.40%, Mn: 1.00% to 1.30%, P≤0.015%, S≤0.0020%, Nb: 0.010～0.020%, V≤0.020%, Ti: 0.010%～0.015%, Cr: 0.50%～0.70%, Ni≤0.60%, Mo: 0.30～0.40%, Al: 0.030% to 0.050%, B: 0.0010% to 0.0020%, Mg: 0.0010% to 0.0018%, N≤0.0045%, H≤0.0002%, and the balance is Fe and unavoidable impurities.
The high wear resistance steel for coal mining according to claim 1, characterized in that, by mass percentage, it comprises: C: 0.20% to 0.30%, Si: 0.30% to 0.50%, Mn: 1.10% to 1.40%, P≤0.015%, S≤0.0020%, Nb: 0.020～0.030%, V≤0.020%, Ti: 0.008%～0.013%, Cr: 0.70%～0.90%, Ni≤0.60%, Mo: 0.40～0.50%, Al: 0.035% to 0.050%, B: 0.0010% to 0.0020%, Mg: 0.0010% to 0.0018%, N≤0.0045%, H≤0.0002%, and the balance is Fe and unavoidable impurities.
A method for producing high wear-resistant steel for coal mining according to any one of claims 1-4, characterized in that it comprises the steps of:

S1. Desulfurization and slag removal of molten iron is sent to LF/RH for refining treatment after being smelted in the converter. The RH vacuum treatment time is 10-30 minutes. After the vacuum treatment of molten steel, magnesium-aluminum wire is used for magnesium treatment. Stir statically for 15-20 minutes after the silk is finished;

S2. The molten steel after vacuum treatment is cast, and the electromagnetic stirring process is adopted. After the billet is thermally inspected, it is put into a heating type heat preservation pit for hydrogen expansion;

S3. The heating temperature of the heating furnace is 1150±20°C. The steel plate below 18mm adopts conventional rolling, and the final rolling temperature is ≤930°C. The steel plate with 18mm and above adopts controlled rolling, and the final rolling temperature is ≤900°C;

S4. The steel plate after rolling is quenched and tempered. The initial quenching temperature is set at a heating temperature of 900-920°C, kept for 20-40 minutes, and water-cooled; the secondary quenching temperature is set at a heating temperature of 850-870°C, and kept for 20-30 minutes , water cooling; tempering heating temperature 200 ~ 300 ℃, heat preservation 30 ~ 50min, air cooling;

S5. After quenching and tempering, use an electronic heating pad to heat the steel plate to 120-150°C, and cut it with a burning gun when it comes out of the furnace. After the cutting is completed, cover it with refractory insulation cotton and slowly cool it to room temperature to eliminate the stress caused by cutting;

S6. The divided steel plate is marked according to the performance requirements to obtain a final product.
The production method of high wear resistance steel for coal mining according to claim 5, characterized in that, in step S1, the molten iron is desulfurized using a KR furnace.
The production method of high wear-resistant steel for coal mining according to claim 5, characterized in that, in step S2, the current of the electromagnetic stirring process is 180-280A, the frequency is 6-11A, and the casting speed is 0.6 ~1.2m/min.
The production method of high wear resistance steel for coal mining according to claim 5, characterized in that, in step S2, the heat preservation temperature of the heat preservation pit is 600-650°C, and the heat preservation time is 30-60 minutes.
The production method of high wear-resistant steel for coal mining according to claim 5, characterized in that, in step S5, the starting speed of the cutting is 160-200 mm/min, and the cutting speed is 350-380 mm/min.