Preparation method of mining wear-resistant steel US300N hot-rolled round steel

Abstract

The invention discloses a preparation method of mining wear-resistant steel US300N hot-rolled round steel. The preparation method comprises a steelmaking process and a steel rolling process. The hot-rolled round steel comprises the following chemical components in percentage: 0.61 to 0.63 percent of C, 0.70 to 0.75 percent of Mn, 1.75 to 1.85 percent of Si, 0.82 to 0.85 percent of Cr, less than or equal to 0.018 percent of P, less than or equal to 0.010 percent of S, 0.07 to 0.08 percent of Ni, 0.010 to 0.020 percent of Al and the balance of iron and inevitable trace elements. According to the invention, the contents of C, Si and Cr elements are reasonably controlled, the Ni element is added to refine pearlite interlamellar spacing, the size of inclusions and the cleanliness of steel are controlled through a steelmaking process, and the structure transformation and grain size of a hot rolling state are controlled through a steel rolling process, so that the wear-resistant hot-rolled round steel with matched hardness and toughness is obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of material metallurgy, and particularly relates to a preparation method of a mining wear-resistant steel US300N hot-rolled round steel. BACKGROUND

[0002] With the deepening of mining, the requirements for wear-resistant steel materials are increasing. Traditional wear-resistant steel materials often exhibit insufficient wear resistance, short service life and other problems in complex and variable mine environments, which directly affects the efficiency and cost of mining. As a new type of mining wear-resistant steel, US300N has excellent wear resistance, high strength and good toughness, and is very suitable for manufacturing key components of mining machinery. However, how to efficiently prepare high-quality US300N hot-rolled round steel to meet the needs of the mining industry is a technical problem that needs to be solved in the current field of material metallurgy. The present application proposes a new preparation method of a mining wear-resistant steel US300N hot-rolled round steel, aiming to optimize key process parameters such as smelting and rolling to improve the wear resistance and service life of US300N hot-rolled round steel. SUMMARY

[0003] The purpose of the present application is to provide a preparation method of a mining wear-resistant steel US300N hot-rolled round steel, which reasonably controls the content of C, Si and Cr elements and adds Ni element to refine the pearlite interlamellar spacing, controls the inclusion size and cleanliness of the steel through the steelmaking process, and controls the microstructure transformation and grain size of the hot-rolled state through the rolling process, to obtain a wear-resistant hot-rolled round steel with matching hardness and toughness.

[0004] To solve the above technical problems, the present application adopts the following technical scheme:

[0005] The present application provides a preparation method of a mining wear-resistant steel US300N hot-rolled round steel, the steelmaking process is: hot metal pretreatment - converter - LF refining - VD vacuum treatment - continuous casting - slow cooling, the rolling process is: casting blank heating - Ф850mm blooming mill - Ф700mmx3+Ф550mmx4 continuous rolling mill group rolling - sawing - slow cooling - non-destructive testing - inspection - grinding - bundling - warehousing - delivery; the technical parameters controlled in the steelmaking process are:

[0006] S≤0.015% after hot metal pretreatment;

[0007] The converter adopts double slag operation, and the terminal basicity is controlled at 3.5;

[0008] The converter terminal control target C≥0.15%, P≤0.020%;

[0009] VD deep vacuum time≥15min, soft blowing time≥15min;

[0010] Superheat ≤ 30℃, casting speed ≤ 0.62m / min ≤ casting machine speed ≤ 0.66m / min;

[0011] Slow cooling time for billet ≥ 72 hours.

[0012] The technical parameters controlled in the steel rolling process are:

[0013] 1150℃≤rolling temperature≤1180℃;

[0014] 850℃≤Final rolling temperature≤890℃;

[0015] 450℃≤Entry temperature into the slow cooling pit≤500℃;

[0016] Temperature upon exiting the slow cooling pit ≤ 80℃;

[0017] The chemical composition percentage requirements for the hot-rolled round steel are as follows: C: 0.61-0.63%, Mn: 0.70-0.75%, Si: 1.75-1.85%, Cr: 0.82-0.85%, P: ≤0.018%, S: ≤0.010%, Ni: 0.07-0.08%, Al: 0.010-0.020%, with the remainder being iron and unavoidable trace elements.

[0018] Furthermore, the chemical composition percentage requirements for the hot-rolled round steel are as follows: C: 0.61%, Mn: 0.73%, Si: 1.78%, Cr: 0.84%, P: 0.017%, S: 0.007%, Ni: 0.077%, Al: 0.013%, with the remainder being iron and unavoidable trace elements.

[0019] Furthermore, the chemical composition percentage requirements for the hot-rolled round steel are as follows: C: 0.62%, Mn: 0.75%, Si: 1.80%, Cr: 0.85%, P: 0.018%, S: 0.008%, Ni: 0.075%, Al: 0.014%, with the remainder being iron and unavoidable trace elements.

[0020] Furthermore, the chemical composition percentage requirements for the hot-rolled round steel are as follows: C: 0.61%, Mn: 0.73%, Si: 1.79%, Cr: 0.84%, P: 0.017%, S: 0.008%, Ni: 0.074%, Al: 0.013%, with the remainder being iron and unavoidable trace elements.

[0021] Furthermore, the initial rolling temperature is 1162-1168℃.

[0022] Furthermore, the final rolling temperature is 861-866℃.

[0023] Furthermore, the temperature outside the slow-cooling pit is 60-63℃.

[0024] The reasons for limiting the main chemical components of this invention are as follows:

[0025] C: C is the most effective element for improving the strength of steel. Increasing the C content increases the tensile strength and yield strength of the steel, but decreases elongation and impact toughness, reduces corrosion resistance, and causes hardening in the weld heat-affected zone, leading to cold cracking. To ensure good overall performance of the round steel, the C content of the steel in this invention is designed to be 0.61–0.63%.

[0026] Mn: Mn is an important strengthening and toughening element with low cost. As the manganese content increases, the strength of the steel significantly improves, enhancing its processing performance, while the ductile-brittle transition temperature remains almost unchanged. However, excessively high manganese content inhibits ferrite transformation, affecting the yield strength of the steel and hindering the control of the yield-to-tensile ratio. The Mn content of the steel in this invention is designed to be 0.70–0.75%.

[0027] Si: Si can improve the strength of steel. By increasing the Si element, the strength of steel can be improved to a certain extent. However, as the mass percentage of Si increases further, it is easy to cause the formation of martensite in the steel. Therefore, the mass percentage of Si in this invention is controlled at 1.75 to 1.85%.

[0028] Cr: Cr can improve the strength, hardness, and atmospheric corrosion resistance of steel, and the effect is more significant when added with other alloying elements. Chromium can slow down the decomposition rate of austenite, significantly improve the hardenability of steel, and has a secondary hardening effect, but it also increases the steel's tendency to temper brittleness. However, excessive chromium content will reduce the toughness of the base material and the heat-affected zone. The Cr content of the steel in this invention is designed to be 0.82%–0.85%.

[0029] Ni plays a crucial role in steel by stabilizing the austenite structure, improving mechanical properties, and enhancing corrosion resistance. It expands the austenite phase region, forming an infinite solid solution with iron, making it a key element in stabilizing the austenite structure. Ni strengthens ferrite and increases pearlite content, thereby improving strength without significantly reducing toughness. In this invention, the mass percentage of Ni is limited to 0.07–0.08%.

[0030] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0031] In this invention, particular emphasis is placed on the optimization of the hot rolling process. Through experimental research, the optimal hot rolling temperature range and rolling speed were determined. The optimization of these parameters helps to form a fine and uniform grain structure, thereby significantly improving the wear resistance of US300N hot-rolled round steel.

[0032] 1) The rolled microstructure is ferrite + pearlite, which has high strength and toughness and is easy to process into high wear-resistant steel balls.

[0033] 2) Improve the wear resistance of steel balls through reasonable chemical design and solid solution strengthening effect of alloying elements in steel. Detailed Implementation

[0034] The present invention will be further illustrated by specific embodiments below. These embodiments are for illustrative purposes only, and the scope of protection of the present invention is not limited to these embodiments.

[0035] The present invention will now be further described:

[0036] Table 1 is a list of chemical components and weight percentage content of various embodiments of the present invention.

[0037] Tables 2 and 3 are lists of steelmaking and rolling process control parameters for each embodiment of the present invention. Table 4 lists the inclusion dimensions for each embodiment; Table 5 lists the mechanical properties of hot-rolled round steel for each embodiment.

[0038] Table 1. Chemical composition and weight percentage (%) of each example.

[0039]

[0040]

[0041] Table 2 Main parameters of steelmaking process for each embodiment

[0042]

[0043] Table 3 Rolling process parameters for each embodiment

[0044]

[0045] Table 4. Inclusion dimensions of each embodiment

[0046] Embodiments Class A Class B Class C Class D 1 1.0 1.0 0.5 1.0 2 1.5 1.0 0.5 1.0 3 1.5 1.0 0.5 1.0

[0047] Table 5 Mechanical properties of hot-rolled round steel in each embodiment.

[0048]

[0049] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing US300N hot-rolled round steel for mining applications, comprising the following steelmaking process: hot metal pretreatment—converter—LF refining—VD vacuum treatment—continuous casting—slow cooling; and the following rolling process: billet heating—850mm billet mill—700mm×3+550mm×4 continuous rolling mill—sawing—slow cooling—non-destructive testing—inspection—grinding—bundling—warehousing—shipping; characterized in that... The technical parameters controlled in the steelmaking process are: After pretreatment, the sulfur content of the molten iron is ≤0.015%. The converter adopts a dual-slag operation, and the final alkalinity is controlled at 3.5; The converter's final control targets are C ≥ 0.15% and P ≤ 0.020%. VD deep vacuum time ≥15min, soft blowing time ≥15min; Superheat ≤ 30℃, casting speed ≤ 0.62m / min ≤ casting machine speed ≤ 0.66m / min; Slow cooling time for billet ≥ 72 hours. The technical parameters controlled in the steel rolling process are: 1150℃≤rolling temperature≤1180℃; 850℃≤Final rolling temperature≤890℃; 450℃≤Entry temperature into the slow cooling pit≤500℃; Temperature upon exiting the slow cooling pit ≤ 80℃; The chemical composition percentage requirements for the hot-rolled round steel are as follows: C: 0.61-0.63%, Mn: 0.70-0.75%, Si: 1.75-1.85%, Cr: 0.82-0.85%, P: ≤0.018%, S: ≤0.010%, Ni: 0.07-0.08%, Al: 0.010-0.020%, with the remainder being iron and unavoidable trace elements.

2. The method for preparing US300N hot-rolled round steel for mining wear resistance according to claim 1, characterized in that, The chemical composition percentage requirement for the hot-rolled round steel is: C: 0.61%, Mn: 0.73%, Si: 1.78%, Cr: 0.84%, P: 0.017%, S: 0.007%, Ni: 0.077%, Al: 0.013%, with the remainder being iron and unavoidable trace elements.

3. The method for preparing US300N hot-rolled round steel for mining wear resistance according to claim 1, characterized in that, The chemical composition percentage requirements for the hot-rolled round steel are as follows: C: 0.62%, Mn: 0.75%, Si: 1.80%, Cr: 0.85%, P: 0.018%, S: 0.008%, Ni: 0.075%, Al: 0.014%, with the remainder being iron and unavoidable trace elements.

4. The method for preparing US300N hot-rolled round steel for mining wear resistance according to claim 1, characterized in that, The chemical composition percentage requirement for the hot-rolled round steel is: C: 0.61%, Mn: 0.73%, Si: 1.79%, Cr: 0.84%, P: 0.017%, S: 0.008%, Ni: 0.074%, Al: 0.013%, with the remainder being iron and unavoidable trace elements.

5. The method for preparing US300N hot-rolled round steel for mining wear resistance according to claim 1, characterized in that, The initial rolling temperature is 1162-1168℃.

6. The method for preparing US300N hot-rolled round steel for mining wear resistance according to claim 1, characterized in that, The final rolling temperature is 861-866℃.

7. The method for preparing US300N hot-rolled round steel for mining wear resistance according to claim 1, characterized in that, The temperature after exiting the slow cooling pit is 60-63℃.

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