CN107675090A

CN107675090A - A kind of Brinell hardness 650HBW ranks high-wearing feature steel plate and preparation method thereof

Info

Publication number: CN107675090A
Application number: CN201710834723.5A
Authority: CN
Inventors: 赵培林; 王文生; 刘洪成; 杨旭; 路峰; 武文健; 王金秀; 张明金
Original assignee: Shandong Iron and Steel Group Co Ltd SISG
Current assignee: Shandong Iron and Steel Group Co Ltd SISG
Priority date: 2017-09-15
Filing date: 2017-09-15
Publication date: 2018-02-09
Anticipated expiration: 2037-09-15
Also published as: CN107675090B

Abstract

The invention discloses a kind of Brinell hardness 650HBW grade high-strengths degree wear-resisting steel plate and preparation method thereof, the wear-resisting steel plate chemical composition is by weight percentage：C:0.41~0.50%；Si:≤ 0.25%；Mn:1.0~1.40%；P≤0.02%；S≤0.015%；Cr:0.5~1.2%；Mo:0.1~0.6%；Ti:0.1~0.2%；V:0.10~0.20%；Nb:0~0.07%；Ni:0~0.5%；Al:0.6 1.20%；N:≤ 0.006%；O:≤ 0.0025%；Also meet simultaneously：1.10%≤(Si+Mn)≤1.60%, (Cr+Mo) >=0.80%, 0.15%≤(V+Ti)≤0.3%, remaining is iron Fe and inevitable impurity.The present invention puies forward C content microalloying thinking in use, and adding appropriate Ti, V etc. has the alloying element of precipitation enhancement, using the TiC particles largely separated out, can increase hard phase content in the case of same rigidity to increase substantially wearability.

Description

Brinell hardness 650 HBW-grade high-wear-resistance steel plate and preparation method thereof

Technical Field

The invention relates to a high-wear-resistance steel plate with Brinell hardness reaching above 650HBW and a preparation method thereof, belonging to the technical field of hot-rolled high-strength high-wear-resistance steel plate production.

Background

With the development of national economy, the requirements of the engineering field on the adaptation of used materials to particularly severe working environments are higher and higher. Meanwhile, a series of national policies for environmental protection require vigorous popularization of environmentally friendly materials in projects of various scales. The wear resistance of the engineering material not only reduces the consumption of the material, but also contributes to environmental protection. For engineering wear-resistant materials, the wear amount of equipment determines the service life of the equipment, and finally depends on the wear resistance of the used materials. Therefore, the new materials such as steel with high wear resistance are suitable for the development of the field of the current engineering machinery, are mainly applied to high-value-added mechanical products such as engineering, metallurgy, mining, construction, agriculture, cement production, ports, electric power and the like, and are used for manufacturing bulldozers, loaders, excavators, dump trucks and various mining machines, grab buckets, material piling and taking machines, conveying bent structures and the like, so that the service life is prolonged.

In the case of steel sheets used in large quantities in the engineering field, the wear resistance is mainly determined by the hardness thereof, and the plasticity and toughness indexes of the steel are also one of the important factors affecting the service life of the steel. Generally, the hardness index of steel depends on the content of carbon and alloy in the steel. However, the too high carbon and alloy contents lead to poorer comprehensive properties such as welding performance, fatigue performance, bending performance, forming performance and the like, which limits the wide application of the high-hardness wear-resistant steel in engineering.

In the patent that the Brinell hardness reaches 650HBW, Chinese patent CN102953016A relates to 650HB wear-resistant steel, the invention relates to a wear-resistant steel plate, which comprises the following components in percentage by weight: c: 0.45-0.55%, Si: 0.10-0.35%, Mn 0.20-1.00%, P less than or equal to 0.020%, S less than or equal to 0.010%, Cr: 0.20-1.00%, Mo 0.10-0.80%, Ni 0.50-2.00%, Nb 0.010-0.08%, Ti 0.001-0.060%, Al 0.010-0.10%, B: 0.0005-0.0040%, Mg: 0.001-0.010% of Ca, and simultaneously satisfies the following conditions: the content of (Si + Mn) is less than or equal to 1.10 percent, the content of (Cr + Mo) is more than or equal to 0.80 percent, the content of (Al + Ti) is more than or equal to 0.04 percent and less than or equal to 0.11 percent, and the balance is Fe and inevitable impurities. The preparation method comprises the following steps: smelting, casting and heating the steel billet at the temperature of 1000-1300 ℃, freely rolling, and cooling in air after rolling; quenching at (Ac3-10) ° C- (Ac3+80) ° C, and then tempering at 100-. The hardness of the resulting wear resistant steel sheet is typically 650 HB. Although the hardness reaches 650HB, the C content is higher, which is not beneficial to the ductility and the welding performance, the alloy components including Mg, B, Ca and the like are more, and the cost is obviously increased by more Mo and Ni elements; the design of the above patent components limits the industrial mass production and popularization and application of the wear-resistant steel.

Therefore, it is a trend of development to design chemical components suitable for industrial mass production, increase the content of alloy elements with high wear resistance, and obtain low-alloy wear-resistant steel with excellent performance and good applicability. With the development of society and economy, the low-carbon economy development of the steel industry aims to save resources, save energy and protect the environment. This is an important trend in the development of wear resistant steels. Accordingly, the present invention relates to a high wear-resistant hot-rolled steel sheet having good toughness and welding properties.

Disclosure of Invention

In order to save resources and meet the requirement of high wear resistance of 650HBW on hardness and good forming performance, the invention provides high wear-resistant steel and a preparation method thereof.

The technical scheme of the invention is as follows: a650 HB-grade wear-resistant steel plate comprises the following chemical components in percentage by weight: 0.41 to 0.50 percent of C; si is less than or equal to 0.25 percent; 1.0-1.40% of Mn; p is less than or equal to 0.02 percent; s is less than or equal to 0.015 percent; 0.5 to 1.2 percent of Cr; 0.1 to 0.6 percent of Mo; 0.1 to 0.2 percent of Ti; 0.10 to 0.20 percent of V; 0 to 0.07 percent of Nb; 0 to 0.5 percent of Ni; 0.6 to 1.20 percent of Al; n is less than or equal to 0.006 percent; o is less than or equal to 0.0025 percent; also satisfies at the same time: 1.10 percent to 1.60 percent of (Si + Mn), 0.80 percent to 0.80 percent of (Cr + Mo), 0.15 percent to 0.3 percent of (V + Ti), and the balance of Fe and inevitable impurities.

The function of elements in the chemical components of the 650 HB-grade wear-resistant steel plate related to the invention is as follows:

carbon: the important element for realizing the phase change strengthening in the wear-resistant steel can obviously improve the strength and the hardness of the steel and realize higher wear resistance. However, too high a content of carbon weakens the toughness and weldability of the steel. Therefore, the carbon content is selected to be controlled within the range of 0.41 to 0.55%.

Silicon: the surface quality of the steel plate is affected by the excessive silicon content, and the iron scale on the surface is not easy to remove, so that the service performance of the steel plate is reduced. Silicon solid-soluted in ferrite and austenite increases their hardness and strength, but too high a content of silicon causes a drastic decrease in toughness of the steel. Meanwhile, the affinity of silicon and oxygen is stronger than that of iron, so that low-melting-point silicate is easily generated during welding, the fluidity of slag and molten metal is increased, the quality of a welding seam is influenced, and the content is not easy to be excessive. The content is controlled within 0.25%, and preferably, Si: 0.1 to 0.2 percent.

Manganese: the steel has the effects of solid solution strengthening and hardenability improvement, but the segregation tendency of Mn is high, and when the content of Mn is high, the toughness of the steel plate is reduced due to excessively high Mn; at the same time, the steel tends to coarsen crystal grains, increases the temper embrittlement sensitivity of the steel, and easily causes segregation and cracks in a cast slab, thereby deteriorating the performance of the steel sheet. Therefore, the Mn content is controlled to be 1.2-1.45%.

Chromium: chromium can reduce the critical cooling rate, improve the hardenability of steel and improve the austenite transformation rate. Chromium may form in steel (Fe, Cr)₃C、(Fe，Cr)₇C₃And (Fe, Cr)₂₃C₇And various carbides are added to improve the strength and hardness. The chromium can prevent or slow down the precipitation and aggregation of carbides during tempering, and the tempering stability of the steel can be improved. The content is controlled within the range of 0.5-1.2%.

Aluminum: the content is controlled within the range of 0.02-0.20 wt.%. Because aluminum also has the function of inhibiting the formation of carbides, the aluminum can be used for inhibiting the precipitation of the carbides, so that carbon is combined with V and Ti in later ferrite to precipitate a large amount of second phase particles such as TiC, VC and the like, the wear resistance of the steel is improved, and the Al is controlled within the range of 0.6-1.20%;

molybdenum: can improve hardenability, refine crystal grains and improve strength and toughness. Molybdenum exists in a solid solution phase and a carbide phase in steel, and therefore, the molybdenum-containing steel has both the effects of solid solution strengthening and carbide dispersion strengthening. Molybdenum is an element that reduces temper brittleness and can improve temper stability. Preferably, the concentration is controlled within the range of 0.2 to 0.4%.

Nickel: the critical cooling speed can be reduced and the hardenability of the steel can be improved. The nickel is in the range of 0-2.50%, can be mutually dissolved with iron in any proportion, improves the low-temperature toughness of the steel by thinning ferrite grains, and has the effect of obviously reducing the cold-brittleness transition temperature. For high grade and high low temperature toughness wear resistant steel, nickel is a very beneficial additive element. However, since the content is too high, the scale on the surface of the steel sheet is hard to be peeled off, and the cost is significantly increased, the content needs to be controlled. Preferably, the concentration is controlled within the range of 0.2 to 0.4%.

Titanium: is one of strong carbide forming elements, and forms fine TiC particles with carbon, thereby having precipitation strengthening effect and improving strength on one hand; in addition, the precipitated fine and dispersed TiC particles can be used as a hard phase, so that the wear resistance of the steel is obviously improved. The TiC particles are fine and distributed in the grain boundary. Too high Ti content is not favorable for improving toughness and plasticity, so that the content of Ti is controlled within 0.1-0.2%.

Vanadium: is one of the newly formed elements of strong carbide, forms fine VC particles with carbon, has precipitation strengthening effect on one hand, and improves the strength; in addition, the separated fine dispersed VC particles obviously improve the strength of the steel. In addition, VC particles can be used as ferrite nucleation particles to refine the structure. Therefore, the concentration is controlled to be in the range of 0.1 to 0.2%.

Aluminum: the content is controlled within the range of 0.001 to 0.10 wt.%. The nitrogen in the aluminum and the steel can form fine and insoluble AlN particles to refine the microstructure. Aluminum not only acts as a deoxidizer but also promotes the formation of metastable austenite. The aluminum can inhibit and delay the carbide decomposition of the super-cooled austenite, and improve the toughness.

Phosphorus and sulfur: in wear resistant steel, sulphur and phosphorus are harmful elements, their contents are strictly controlled, and the steel grade to which the invention relates has a phosphorus content of less than 0.02 wt.% and a sulphur content of less than 0.01 wt.%.

The steel plate with the Brinell hardness of more than 650HBW, provided by the invention, realizes high strength and high hardness on the basis of adding a proper amount of alloy elements through scientific design of element types and contents, improves the wear resistance of the steel, and ensures that the steel plate has good matching of plasticity and toughness.

The invention relates to a preparation method of a 650 HBW-grade abrasion-resistant steel plate with Brinell hardness, which comprises the working procedures of converter smelting, external refining, continuous casting, heating, rolling, cooling, quenching, tempering and the like; wherein,

1) in the heating step, the heating temperature is controlled to be 1230-1280 ℃; a slow temperature rise measure is adopted.

2) In the rolling process, the initial rolling temperature of rough rolling is 1100-1200 ℃, and the final rolling temperature is 900-960 ℃; the accumulated reduction rate of finish rolling is more than 60%, the reduction rate of the last three passes is more than 10%, the initial rolling temperature is 850-900 ℃, and the final rolling temperature is 800-830 ℃.

3) In the accelerated cooling step: and (3) carrying out ACC cooling after rolling by adopting a forced cooling process, wherein the opening temperature is 800-830 ℃, cooling to 500-560 ℃ and air cooling at the cooling speed of 5-20 ℃/S.

4) Heat treatment after rolling:

quenching: the quenching temperature is controlled to be (Ac3+20) ° C- (Ac3+80) ° C, and water cooling is performed after the steel is taken out of the furnace, so that the structure is favorably refined, and the toughness is improved. The steel contains higher carbon and a certain amount of alloy elements such as Si, Mn, Cr, Mo, Ni and the like, and needs to be fully dissolved at high temperature, but the temperature is not high enough to prevent austenite grains from excessively growing and the surface of a steel billet from being seriously oxidized; cr, Mo, etc. can improve the hardenability of the steel sheet, so that a high-thickness steel sheet can be produced under the water-cooling condition. Therefore, the quenching temperature is selected to be 850-900 ℃.

Tempering: the tempering temperature is less than 300 ℃, and the steel is slowly cooled after being taken out of the furnace. The elements Cr, Mo and the like can improve the tempering stability, ensure that the steel plate has higher strength and hardness and simultaneously has excellent plasticity and toughness.

And the air cooling adopts stacking or slow cooling pit cooling, so that the cooling speed can be reduced, and the steel plate can be prevented from cracking.

Compared with the prior art, the invention has the following remarkable advantages and effects:

1. the chemical composition design is simple, and the proper C content is selected and the Ti and V microalloying thought is adopted, so that the wear-resistant steel plate has higher weldability;

2. the ferrite structure is purified by adopting Al with proper content, the early precipitation of carbide is delayed, so that the later-stage carbon can be fully combined with Ti, V and the like, the Al replaces Si, and the surface quality of the steel plate is improved.

3. By adding a large amount of V and Ti elements and utilizing a large amount of separated VC and TiC particles, the quantity of hard phases is increased, and the strength and the wear resistance of the steel plate matrix are obviously improved.

4. The chemical components and the rolling process are reasonable in design, the process window is wide, and industrial mass production can be stably carried out.

5. The element design of the invention needs to satisfy the conditions of 1.10 percent to (Si + Mn) 1.60 percent, 0.80 percent to (Cr + Mo), and 0.3 percent to (V + Ti), and the technical effect of the invention can be achieved only when the conditions are satisfied. For example, the 650HB wear-resistant steel plate produced by the invention has the Brinell hardness of more than 650HBW and excellent wear resistance; the longitudinal Charpy impact energy is more than 34J at the temperature of minus 20 ℃, the impact toughness is good, and the requirements of high-end steel for engineering machinery are met.

Drawings

FIG. 1 is a microstructure diagram of a 650 HB-grade wear-resistant steel plate according to example 3 of the present invention, from which it can be seen that the microstructure of the steel plate is mainly a structure such as tempered martensite;

FIG. 2 is a microstructure of fine second phase precipitates such as TiC in example 2.

Detailed Description

The present invention will be described below with reference to specific examples. It should be noted that the examples are only for illustrating the present invention and do not represent the scope of the present invention, and that other people having insubstantial modifications and adaptations made according to the present invention still belong to the scope of the present invention.

Example 1

The chemical composition of the 650HB wear-resistant steel plate of the invention is shown in Table 1. Smelting in a converter according to chemical components shown in Table 1, casting into a continuous casting billet after refining, heating the continuous casting billet to 1280 ℃, rolling at 1160 ℃, forming the thickness of a finished steel plate to be 20mm, air-cooling after rolling, quenching at the heating temperature of Ac3+70 ℃, tempering at the temperature of 300 ℃, and stacking or cooling in a slow cooling pit after tempering.

TABLE 1 chemical composition of 650HB grade abrasion resistant steel plate of example 1

Example 2

The implementation mode is the same as that of the embodiment 1, wherein the heating temperature is 1250 ℃, the initial rolling temperature is 1140 ℃, the thickness of the finished steel plate is 16mm, the quenching heating temperature is Ac3+50 ℃, the tempering temperature is 200 ℃, and the steel plate is stacked or cooled in a slow cooling pit after being tempered. The microstructure of fine second phase precipitates such as TiC in example 2 is shown in FIG. 2. As can be seen from FIG. 2, the TiC particles, which form fine particles with carbon, are distributed in the grain boundary and can be used as a hard phase, thereby obviously improving the wear resistance of the steel.

TABLE 2 chemical composition of 650HB grade abrasion resistant steel plate of example 2

Example 3

The implementation mode is the same as that of example 1, wherein the heating temperature is 1240 ℃, the initial rolling temperature is 1130 ℃, the thickness of the finished steel plate is 12mm, the quenching heating temperature is Ac3+40 ℃, the tempering temperature is 180 ℃, and the steel plate is stacked or cooled in a slow cooling pit after being tempered. The microstructure is shown in FIG. 1, and it is understood that the microstructure of the steel sheet is mainly a structure such as tempered martensite.

TABLE 3 chemical composition of 650HB grade abrasion resistant steel plate of example 3

Example 4

The implementation mode is the same as that of example 1, wherein the heating temperature is 1210 ℃, the initial rolling temperature is 1120 ℃, the thickness of the finished steel plate is 10mm, the quenching heating temperature is Ac3+20 ℃, the tempering temperature is 170 ℃, and the steel plate is stacked or cooled in a slow cooling pit after being tempered.

Table 4 chemical composition of 650HB grade abrasion resistant steel plate of example 4

TABLE 5 comparative examples are of the steel grades referred to in the prior patents

Performance testing

The mechanical properties of the inventive wear resistant steel and the comparative steel are shown in table 6.

TABLE 6 mechanical Properties of inventive and comparative steels

As is clear from Table 6, the wear-resistant steels according to the examples of the present invention have hardness of 650HB or more and Charpy longitudinal impact energy of 34J or more at-20 ℃ and are excellent in mechanical properties. The hardness of the steel plate is obviously higher than that of comparative steel 2; the hardness of the comparative steel 1 is similar to that of the steel plate related to the invention, but the wear resistance is lower than that of the comparative steel, and the impact energy is lower.

The wear-resistant steel plate of example 3 of the invention was subjected to an oblique Y groove weld crack test, and the test results are shown in table 7.

TABLE 7 weld performance test results of 650 HB-grade wear-resistant steel plates of inventive example 3

As can be seen from Table 7, the wear-resistant steel plate has no cracks after being welded under the condition of preheating at 180 ℃, and the steel plate has better welding performance.

The abrasion resistance test was performed on an ML-100 abrasive abrasion tester using the same test conditions. The results of the wear tests on the wear resistant steel sheet of the invention example 4 and comparative steel 1 are shown in table 8.

Table 8 results of the wear resistance test of example 4 and comparative steel grade 1.

As can be seen from Table 7, the present invention relates to a steel grade having a slightly higher wear resistance than the comparative steel.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. The high-strength wear-resistant steel plate with the Brinell hardness of 650HBW is characterized by comprising the following chemical components in percentage by weight: 0.41 to 0.50 percent of C; si is less than or equal to 0.25 percent; 1.0-1.40% of Mn; p is less than or equal to 0.02 percent; s is less than or equal to 0.015 percent; 0.5 to 1.2 percent of Cr; 0.1 to 0.6 percent of Mo; 0.1 to 0.2 percent of Ti; 0.10 to 0.20 percent of V; 0 to 0.07 percent of Nb; 0 to 0.5 percent of Ni; 0.6 to 1.20 percent of Al; n is less than or equal to 0.006 percent; o is less than or equal to 0.0025 percent; also satisfies at the same time: 1.10 percent to 1.60 percent of (Si + Mn), 0.80 percent to 0.80 percent of (Cr + Mo), 0.15 percent to 0.3 percent of (V + Ti), and the balance of Fe and inevitable impurities.

2. The method of making a brinell hardness 650HBW grade abrasion resistant steel plate of claim 1, said method comprising converter smelting, external refining, continuous casting, heating, rolling, cooling, quenching and tempering;

wherein,

1) in the heating step: the heating temperature is controlled to be 1230-1280 ℃; adopting a slow temperature rise measure;

2) in the rolling process: the initial rolling temperature of rough rolling is 1100-1200 ℃, and the final rolling temperature is 900-960 ℃; the accumulated reduction rate of finish rolling is more than 60 percent, the reduction rate of the last three passes is more than 10 percent, the initial rolling temperature is 850-900 ℃, and the final rolling temperature is 800-830 ℃;

3) in the cooling step: the ACC after rolling is cooled by a strong cooling process, the opening temperature is 800-830 ℃, the ACC is cooled to 500-560 ℃ for air cooling, and the cooling speed is 5-20 ℃/S;

4) heat treatment after rolling:

quenching: controlling the quenching temperature to be (Ac3+20) ° C- (Ac3+80) ° C, and performing water cooling after discharging;

tempering: the tempering temperature is less than 300 ℃, and the steel is cooled in air after being taken out of the furnace.

3. The method according to claim 2, wherein the quenching temperature is 850 to 900 ℃.

4. The method of claim 2, wherein the air cooling is performed by using a stack or a buffer cooling pit.