Wear-resistant lining plate for vanadium titano-magnetite ball mill and preparation method of wear-resistant lining plate

Abstract

The invention relates to the technical field of wear-resistant metal materials, and particularly discloses a wear-resistant lining plate for a vanadium titano-magnetite ball mill and a preparation method of the wear-resistant lining plate. The lining plate comprises the following chemical components in percentage by mass: 0.35 to 0.45 percent of C, 1.0 to 1.6 percent of Si, 1.2 to 1.8 percent of Mn, 1.5 to 2.2 percent of Cr, 0.8 to 1.2 percent of Mo, 0.04 to 0.10 percent of Ti, 0.15 to 0.25 percent of V, 0.001 to 0.003 percent of B, less than or equal to 0.015 percent of P and S, and the balance of Fe and inevitable impurities. The key point of preparation is a specific multi-step heat treatment process: after austenitizing, isothermal quenching, subzero treatment and high-temperature tempering are sequentially carried out. Through the synergistic effect of vanadium-titanium microalloying and the process, a nanoscale precipitation strengthening phase is formed in steel, so that the lining plate has high hardness and high impact toughness at the same time, the abrasion of vanadium titano-magnetite can be remarkably resisted, the service life is prolonged, and the consumption of per ton of ore is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wear-resistant metal materials in the steel and iron metallurgical industry, and particularly relates to a vanadium-titanium magnetite ball mill wear-resistant lining plate and a preparation method thereof. BACKGROUND

[0002] The information disclosed in this Background section is for the purpose of increasing the understanding of the background of the application and does not necessarily pertain to the prior art that is already known in the art.

[0003] Vanadium-titanium magnetite is a typical refractory ore, which has a complex mineral composition and contains a large amount of high-hardness mineral phases such as ilmenite and titanomagnetite. During the grinding process of the ball mill, the lining plate not only bears the high stress impact of the grinding ball, but also faces the severe cutting, plowing and embedding of these hard mineral particles. At present, the lining plates applied to such working conditions are mostly made of high manganese steel or high chromium cast iron. The high manganese steel relies on work hardening, but the hardening effect is insufficient in the medium-low impact working condition, and plastic deformation and cutting wear are prone to occur. Although the high chromium cast iron has high hardness, it is insufficient in toughness and is prone to brittle fracture or spalling under strong impact. The comprehensive performance of these two materials is difficult to meet the needs of efficient and low-cost grinding of vanadium-titanium magnetite.

[0004] Therefore, it is a technical problem to be solved in the field to develop a lining plate material with high hardness, high toughness, high wear resistance and high impact fatigue resistance to cope with the harsh working conditions of vanadium-titanium magnetite and realize low tonnage consumption and long service life. SUMMARY

[0005] The purpose of the present application is to provide a low-tonnage high-performance wear-resistant lining plate specially used for vanadium-titanium magnetite ball mills. The lining plate realizes the balance between excellent wear resistance and impact toughness through optimized alloy composition design and strict heat treatment process.

[0006] To achieve the above-mentioned purpose, the following technical solutions are adopted in the present application: A wear-resistant lining plate for a vanadium-titanium magnetite ball mill, the chemical composition of the wear-resistant lining plate is as follows in terms of percentage by weight: C: 0.35-0.45%, Si: 1.0-1.6%, Mn: 1.2-1.8%, Cr: 1.5-2.2%, Mo: 0.8-1.2%, V: 0.15-0.25%, Ti: 0.04-0.10%, B: 0.001-0.003%, P and S: ≤0.015%, and the balance is Fe and inevitable impurities.

[0007] A preparation method of the above-mentioned wear-resistant lining plate is realized by the following steps: (1) Smelting and casting: ingredients are prepared according to the following percentages by weight: C: 0.35~0.45%, Si: 1.0~1.6%, Mn: 1.2~1.8%, Cr: 1.5~2.2%, Mo: 0.8~1.2%, Ti: 0.04~0.10%, V: 0.15~0.25%, B: 0.001~0.003%, P, S≤0.015%, the balance being Fe and inevitable impurities, after smelting, ladle refining, vacuum degassing, pouring into ingots or billets; (2) Hot working: the ingots or billets are forged after treatment, and then final forging is performed; (3) Preparing heat treatment: the workpiece after hot working in step (2) is subjected to isothermal annealing treatment to obtain pearlite + ferrite structure; (4) Final heat treatment: the structure obtained in step (3) is austenitized, isothermal quenched, cryogenic treated and tempered to obtain the wear-resistant lining plate.

[0008] Further, the adding order of the components in step (1) is to add ferrotitanium first and then ferrovanadium.

[0009] Further, in step (1), the nitrogen content in the molten steel after vacuum degassing is controlled at 80~150 ppm.

[0010] Further, in step (2), the hot working of the ingots or billets is performed at 1150~1180 ℃, followed by forging; the final forging temperature is 850~900 ℃.

[0011] Further, in step (4), the austenitizing temperature is 900~930 ℃, and the holding time is 1.5~2.0 min / mm.

[0012] Further, in step (4), the isothermal quenching is to rapidly transfer the austenitized workpiece to a salt bath at 280~320 ℃, and keep it isothermal for 60~120 minutes to complete the lower bainite transformation.

[0013] Further, in step (4), the cryogenic treatment temperature is -80 ℃~-120 ℃, and the holding time is 2 h.

[0014] Further, in step (4), the tempering temperature is 500~540 ℃, and the holding time is 2~4 h, and then air cooling to room temperature to obtain the wear-resistant lining plate.

[0015] The beneficial effects of the present application are: (1) The present application forms a large number of dispersed VC, Mo2C carbides in the steel matrix through the "nano precipitation strengthening" mechanism, so that the surface hardness of the liner reaches HRC 60. This hardness is much higher than that of high-abrasive vanadium-titanium magnetite, which can effectively resist cutting and chiseling wear, thereby achieving extremely low wear rate. The strong and tough complex microstructure can effectively absorb and disperse impact energy, greatly delaying the initiation and propagation of fatigue cracks, and improving the service reliability and safety of the liner under long-term vibration and impact working conditions.

[0016] (2) Due to the simultaneous improvement of wear resistance and impact resistance, the liner replacement frequency is sharply reduced, and the service life can reach more than twice that of traditional high manganese steel or high chromium cast iron. This means less downtime and lower liner procurement costs, thereby directly reducing the processing cost per ton of ore. The long service life of the liner directly translates into longer continuous operation time of the ball mill, improving the operation rate and production efficiency of the entire beneficiation production line.

[0017] (3) The multi-step heat treatment process of "isothermal quenching + cryogenic treatment + high temperature tempering" is adopted to realize precise control of the microstructure, and high-performance liners can be stably and repeatedly produced. The melting, ladle refining, vacuum degassing and heat treatment processes used are mature industrial technologies, which are easy to realize large-scale and stable production, and have good industrialization prospects. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a surface hardness, impact toughness and relative wear resistance comparison column chart of examples 1-3 and comparative examples 1 and 2. DETAILED DESCRIPTION

[0019] The present application will be described in detail below with specific examples. The following examples will help those skilled in the art to further understand the present application, but do not limit the present application in any form. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made. These all belong to the protection scope of the present application.

[0020] Example 1 A molten steel with the following chemical composition (wt%): C: 0.40%, Si: 1.3%, Mn: 1.5%, Cr: 1.8%, Mo: 1.0%, Ti: 0.06%, V: 0.2%, B: 0.002%, P: 0.01%, S: 0.008%, and the balance of Fe and unavoidable impurities. After melting, ladle refining and vacuum degassing, titanium-iron alloy is added first, then vanadium-iron alloy is added, and then the ingot is poured; the nitrogen content is controlled to 120 ppm by vacuum degassing.

[0021] Forging: heating to 1160 ℃, initial forging temperature at 1100 ℃, final forging temperature controlled at 880 ℃, slow cooling after forging. Isothermal annealing: after holding at 860 ℃, furnace cooling to 700 ℃ for 4 h, then furnace cooling to 500 ℃ for taking out of the furnace.

[0022] Final heat treatment: Austenitizing: holding at 920 ℃ for 100 minutes; Isothermal quenching: quickly transferred into a 310 ℃ salt bath, holding for 120 minutes; The quenched workpiece was transferred into a -80 ℃ deep cooling box, holding for 2 h; The deep-cooled workpiece was tempered at 510 ℃ for 3.5 h, air cooling to room temperature.

[0023] Example 2 A molten steel with the following chemical composition (wt%): C: 0.37%, Si: 1.1%, Mn: 1.7%, Cr: 2.0%, Mo: 0.9%, Ti: 0.08%, V: 0.18%, B: 0.0015%, P: 0.012%, S: 0.01%, balance Fe and inevitable impurities was prepared. After smelting, ladle refining and vacuum degassing, ferro-titanium was added first, then ferro-vanadium was added, and then the ingot was poured; the nitrogen content was controlled to be 120 ppm by vacuum degassing.

[0024] Forging: heating to 1160 ℃, initial forging temperature at 1100 ℃, final forging temperature controlled at 880 ℃, slow cooling after forging. Isothermal annealing: after holding at 860 ℃, furnace cooling to 700 ℃ for 4 h, then furnace cooling to 500 ℃ for taking out of the furnace.

[0025] Final heat treatment: Austenitizing: holding at 920 ℃ for 100 minutes; Isothermal quenching: quickly transferred into a 310 ℃ salt bath, holding for 120 minutes; The quenched workpiece was transferred into a -80 ℃ deep cooling box, holding for 2 h; The deep-cooled workpiece was tempered at 510 ℃ for 3.5 h, air cooling to room temperature.

[0026] Example 3 A molten steel with the following chemical composition (wt%): C: 0.40%, Si: 1.35%, Mn: 1.55%, Cr: 1.85%, Mo: 1.00%, V: 0.20%, Ti: 0.06%, B: 0.002%, P: 0.014%, S: 0.012%, balance Fe and inevitable impurities was prepared. After smelting, ladle refining and vacuum degassing, ferro-titanium was added first, then ferro-vanadium was added, and then the ingot was poured; the nitrogen content was controlled to be 120 ppm by vacuum degassing.

[0027] Forging: heated to 1160 °C, initial forging temperature at 1100 °C, final forging temperature controlled at 880 °C, slow cooling after forging. Isothermal annealing: after holding at 860 °C, furnace cooling to 700 °C for 4 h, then furnace cooling to 500 °C for taking out of the furnace.

[0028] Final heat treatment: Austenitizing: holding at 910 °C for 110 minutes; Isothermal quenching: quickly transferred into a 290 °C salt bath, holding for 80 minutes; The quenched workpiece was transferred into a -90 °C deep cooling box, holding for 2 h; The deep-cooled workpiece was tempered at 530 °C for 2.5 h, air cooling to room temperature.

[0029] Comparative Example 1: Conventional alloy steel without vanadium-titanium micro-alloying: A molten steel with the following chemical composition (wt%): C: 0.40%, Si: 1.3%, Mn: 1.5%, Cr: 1.8%, Mo: 1.0%, Ti: 0.06%, P: 0.01%, S: 0.008%, the balance being Fe and unavoidable impurities, was prepared. After smelting, ladle refining and vacuum degassing, ferrotitanium was added first, then ferrovanadium was added, and then the ingot was poured. The nitrogen content was controlled to be 120 ppm by vacuum degassing.

[0030] Forging: heated to 1160 °C, initial forging temperature at 1100 °C, final forging temperature controlled at 880 °C, slow cooling after forging. Isothermal annealing: after holding at 860 °C, furnace cooling to 700 °C for 4 h, then furnace cooling to 500 °C for taking out of the furnace.

[0031] Final heat treatment: Austenitizing: holding at 925 °C for 90 minutes; Isothermal quenching: quickly transferred into a 300 °C salt bath, holding for 90 minutes; The quenched workpiece was transferred into a -100 °C deep cooling box, holding for 2 h; The deep-cooled workpiece was tempered at 520 °C for 3 h, air cooling to room temperature.

[0032] Comparative Example 2: The same composition steel with conventional heat treatment: The molten steel is prepared with the following chemical composition (wt%): C: 0.40%, Si: 1.3%, Mn: 1.5%, Cr: 1.8%, Mo: 1.0%, Ti: 0.06%, V: 0.2%, B: 0.002%, P: 0.01%, S: 0.008%, and the balance of Fe and inevitable impurities. After smelting, ladle refining and vacuum degassing, ferro-titanium is added first, then ferro-vanadium, and then the ingot is poured; the nitrogen content is controlled to 120 ppm by vacuum degassing.

[0033] Forging: heated to 1160 °C, starting forging temperature at 1100 °C, and final forging temperature controlled at 880 °C, slow cooling after forging. Isothermal annealing: after holding at 860 °C, furnace cooling to 700 °C for 4 h, and then furnace cooling to 500 °C for discharge.

[0034] Final heat treatment: Austenitizing: holding at 925 °C for 90 min; Tempering at 520 °C for 3 h after quenching, and air cooling to room temperature.

[0035] Comparative Example 1 and Example 1: the fundamental role of vanadium-titanium micro-alloying and innovative heat treatment is demonstrated. Without V and Ti, the material has neither fine-grain strengthening nor nano-precipitation strengthening, and only conventional strength and poor wear resistance can be obtained, which cannot meet the requirements of harsh working conditions.

[0036] Comparative Example 2 and Example 1: under the same composition, the decisive influence of the innovative heat treatment process is demonstrated. Although conventional quenching and tempering can obtain high hardness, the microstructure is single, the internal stress is high, the residual austenite is unstable, which leads to serious lack of toughness and easy brittle fracture. At the same time, the nano-precipitation strengthening effect is insufficient, and the wear resistance is low.

[0037] Table 1 Chemical composition of examples and comparative examples (wt%)

Claims

1. A wear-resistant liner for a vanadium-titanium magnetite ball mill, characterized in that, Its chemical composition by weight percentage is as follows: C: 0.35~0.45%, Si: 1.0~1.6%, Mn: 1.2~1.8%, Cr: 1.5~2.2%, Mo: 0.8~1.2%, Ti: 0.04~0.10%, V: 0.15~0.25%, B: 0.001~0.003%, P, S≤0.015%, with the balance being Fe and unavoidable impurities.

2. A method for preparing the wear-resistant liner according to claim 1, characterized in that, The following steps are adopted: (1) Smelting and casting: The ingredients are prepared according to the composition described in claim 1, and after smelting, ladle refining and vacuum degassing, they are cast into steel ingots or billets; (2) Hot working: After processing the steel ingot or billet, it is forged and then the final forging is carried out; (3) Preliminary heat treatment: The workpiece after hot working in step (2) is subjected to isothermal annealing to obtain a pearlite + ferrite structure; (4) Final heat treatment: The microstructure obtained in step (3) is austenitized, isothermal quenched, cryogenically treated and tempered to obtain wear-resistant lining plate.

3. The preparation method according to claim 2, characterized in that, The ingredients are added in the following order: first titanium-iron alloy, then vanadium-iron alloy.

4. The preparation method according to claim 2, characterized in that, In step (1), after vacuum degassing, the nitrogen content in the molten steel is controlled at 80~150 ppm.

5. The preparation method according to claim 2, characterized in that, The hot working described in step (2) involves treating the steel ingot or billet at 1150~1180 ℃.

6. The preparation method according to claim 2, characterized in that, The final forging temperature is 850~900 ℃.

7. The preparation method according to claim 2, characterized in that, The austenitizing temperature in step (4) is 900~930 ℃, and the holding time is 1.5~2.0 min / mm.

8. The preparation method according to claim 2, characterized in that, The isothermal quenching described in step (4) involves rapidly transferring the austenitized workpiece to a salt bath at 280~320 ℃ and isothermally holding it for 60~120 minutes to complete the lower bainite transformation.

9. The preparation method according to claim 2, characterized in that, The cryogenic treatment temperature in step (4) is -80℃ to -120℃, and the holding time is 2 hours.

10. The preparation method according to claim 2, characterized in that, The tempering temperature in step (4) is 500~540℃, and the temperature is maintained for 2~4 hours. Then, the material is air-cooled to room temperature to obtain the wear-resistant lining plate.

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