CN104264072A

CN104264072A - 600HB (Brinell hardness) grade wear-resistant steel plate and preparation method thereof

Info

Publication number: CN104264072A
Application number: CN201410562198.2A
Authority: CN
Inventors: 赵培林; 杜显彬; 王建军; 王航民; 方金林; 杨旭; 李春传; 郭秀辉; 杜传治; 王金秀; 张明金; 于明杰; 刘莱萌; 路峰
Original assignee: Shandong Iron and Steel Group Co Ltd SISG
Current assignee: Shandong Iron and Steel Group Co Ltd SISG
Priority date: 2014-10-21
Filing date: 2014-10-21
Publication date: 2015-01-07
Anticipated expiration: 2034-10-21
Also published as: CN104264072B

Abstract

The invention discloses a 600HB (Brinell hardness) grade wear-resistant steel plate. The 600HB grade wear-resistant steel plate includes the following chemical components in percentage by weight: 0.33 to 0.40 percent of C (carbon), 0.80 to 1.20 percent of Si (silicon), 1.5 to 2.0 percent of Mn (manganese), 0.02 percent or less of P (phosphorus), 0.015 percent or less of S (sulfur), 0.5 to 1.0 percent of Cr (chromium), 0.2 to 0.5 percent of Mo (molybdenum), 0.1 to 0.2 percent of Ti (titanium), 0.06 to 0.12 percent of V (vanadium), 0 to 0.07 percent of Nb (niobium), 0 to 0.5 percent of Ni (nickel), 0 to 0.1 percent of Al (aluminum), 0.005 percent or less of N (nitrogen), and 0.003 percent or less of O (oxygen), and the balance of iron and unavoidable impurities. The 600HB grade wear-resistant steel plate provided by the invention reaches a Brinell hardness of above 600 HBW, so that the wear-resistant performance is excellent; the Charpy longitudinal impact energy at minus 20 DEG C is above 40 joules, so that the impact toughness is high, and the steel requirements of engineering machinery are satisfied.

Description

600 HB-grade wear-resistant steel plate and preparation method thereof

Technical Field

The invention belongs to the technical field of hot-rolled high-strength steel production, and particularly relates to a wear-resistant steel plate with the hardness reaching 600HB (HBW) level and a preparation method thereof.

Background

At present, the steel with higher requirement on wear resistance in the steel for engineering machinery occupies a larger proportion, and the use requirement and the conditions are very strict. The special-shaped material is mainly applied to high-value-added mechanical products such as engineering, metallurgy, mining, construction, agriculture, cement production, ports and electric power, and specifically comprises a bulldozer, a loader, an excavator, a dump truck, various mining machines, a grab bucket, a stacker-reclaimer, a conveying bent structure and the like, so that the effects of reducing the abrasion loss of equipment and prolonging the service life of the equipment can be achieved.

The wear resistance of the material mainly depends on the integral hardness and a certain amount and size of hard phases dispersed and distributed in the material; some components also have certain requirements with regard to toughness. The higher the hardness of the wear resistant steel, the higher its carbon and alloy content, the poorer the toughness and weldability. Meanwhile, the use performances such as bending performance, forming performance and the like are poor, so that the wide application of the high-hardness wear-resistant steel in engineering is limited.

The existing wear-resistant steels are generally classified into two types, one is high-carbon high-alloy wear-resistant steel, for example, chinese patent CN102703819B relates to a steel with a carbon content of more than 0.6 wt.%, which reduces the toughness and plasticity of wear-resistant steel. In addition, Japanese patent CN1098370 mentions that the chromium content is between 8 and 35 wt.%, and Chinese patent CN102703827B mentions that the manganese content is more than 7 wt.%, and the above patents have very high alloy content. The large carbon and high alloy content seriously deteriorates the welding and processing properties of the wear resistant steel. The other is that by adding a wide variety of alloying elements, excellent mechanical properties can be obtained, but the welding and forming properties are affected. For example, european publication No. EP1563104 discloses a wear-resistant steel sheet having chemical components of C: 0.35-0.8%, Si: 0-2.0%, Mn: 0-2.5%, S: less than or equal to 0.15 percent, Cr: 0-5%, Mo: 0-0.05%, Ni: 0-5%, Cu: 0-1.5%, B: 0-0.02%, Al: 0-2%, Ti: 0-1.1%, N < 0.03%, W: 0-1%, Zr: 0-4%, the wear-resistant steel has wide composition range and complex alloy composition. Patent No. FR2847272 of french application discloses a wear resistant steel whose chemical composition is C: 0.24-0.35%, Si: 0-2%, Mn: 0-2.5%, S: less than or equal to 0.15 percent, Cr: 0-5%, Mo: 0-1%, Ni: 0-5%, Cu: 0-1.5%, B: 0-0.02%, Al: 0-2%, Ti: 0-1.1%, N < 0.03%, W: 0-2%, Zr: 0-2.2%, the carbon content of the wear-resistant steel is relatively low, but the alloy components are complex. Chinese patent CN102199737B relates to 600HB wear-resistant steel, which comprises the following components in percentage by weight: c: 0.41-0.50 wt.%, Si: 0.10-0.60 wt.%, Mn: 0.20-1.20 wt.%, P is less than or equal to 0.050 wt.%, S is less than or equal to 0.030 wt.%, Cr: 0.01-1.50 wt.%, Mo: 0.01-1.00 wt.%, Ni: 0.01-1.50 wt.%, Ti: 0.001-0.10 wt.%, Al: 0.001-0.10 wt.%, RE: 0.001-0.10 wt.%, W: 0.01-1.00 wt.%, B: 0.0005-0.0040 wt.%, Ca: 0.001-0.010 wt.%, and the balance of Fe and inevitable impurities. Although the hardness reaches 600HB, the C content is higher, the plasticity and toughness and the welding performance are not facilitated, the alloy components are more, the cost is obviously increased by more Mo elements, and the difficulty of field industrial mass production is increased by the Al element; 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

The invention aims to provide a 600 HB-grade wear-resistant steel plate, which adopts the concept of microalloying with medium C content, adds proper amount of alloy elements with precipitation strengthening effect such as Ti, V and the like, and utilizes a large amount of precipitated TiC particles to increase the content of hard phase under the condition of the same hardness so as to greatly improve the wear resistance.

In order to achieve the purpose, the invention adopts the technical scheme that:

a600 HB-grade wear-resistant steel plate comprises the following chemical components in percentage by weight: 0.33 to 0.40 percent of C; 0.80 to 1.20 percent of Si; 1.5 to 2.0 percent 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 1.0 percent of Cr; 0.2 to 0.5 percent of Mo; 0.1 to 0.2 percent of Ti; 0.06-0.12% of V; 0 to 0.07 percent of Nb; 0 to 0.5 percent of Ni; al: 0 to 0.1 percent; n is less than or equal to 0.005 percent; o is less than or equal to 0.003 percent; the balance of iron and unavoidable impurities.

The function of elements in the chemical components of the 600HB 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 0.33 to 0.40%.

Silicon: the effect in steel is mainly solid solution strengthening. The higher content of Si can improve the hardenability of steel, and the Si added into the general steel is beneficial to improving the strength and the toughness of the steel. In addition, Si can increase the amount of austenite that reduces the diffusion rate of hydrogen and allows the steel to be tempered at higher temperatures. The non-carbide bainite formed by alloying silicon can reduce the dislocation density in the steel, and can also reduce the diffusion speed of hydrogen atoms in the steel by utilizing a residual austenite film in the non-carbide bainite, thereby improving the delayed fracture resistance of the ultrahigh-strength steel. Therefore, the present invention limits the Si content to 0.8 to 1.2%.

Manganese: the steel has the effects of solid solution strengthening and hardenability improvement, but the segregation tendency of Mn is high, and when the manganese content is high, the steel tends to coarsen crystal grains, the temper embrittlement sensitivity of the steel is increased, and segregation and cracks are easily caused in a cast slab, and the performance of a steel plate is reduced. Therefore, the Mn content is controlled to be 1.5 to 2.0%.

Chromium: chromium can reduce the critical cooling rate and improve the hardenability of steel. 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 chromium content is controlled to be 0.5-1.0%Within the range.

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. The content is controlled within the range of 0.2-0.5%.

Nickel: the critical cooling speed can be reduced and the hardenability of the steel can be improved. The nickel is in the range of 0-0.50%, 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. The content is controlled within the range of 0-0.5%.

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 will generate a large amount of TiN particles, which is not favorable for improving toughness and plasticity, therefore, the content is controlled within the range of 0.1-0.2%.

Aluminum: the content is controlled within the range of 0 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.%.

In a word, the steel grade related by the invention realizes the matching of high strength, high hardness and good plasticity and toughness on the basis of adding a small amount of alloy elements through scientific design of element types and contents, and improves the wear resistance of the steel.

The invention also aims to provide a preparation method of the 600HB wear-resistant steel plate, which comprises the steps of converter smelting, external refining, continuous casting, heating, rolling, accelerated cooling, quenching and tempering;

wherein,

heating: the heating temperature is controlled to be 1200-1250 ℃; a slow temperature rise measure is adopted.

Rolling: the initial rolling temperature of rough rolling is 1060-1150 ℃, and the final rolling temperature is 940-980 ℃; and the cumulative reduction rate of finish rolling is more than 65%, the reduction rate of the last three passes is more than 12%, the initial rolling temperature is 860-900 ℃, and the final rolling temperature is 840-860 ℃.

Accelerated cooling: and (3) carrying out ACC cooling after rolling by a forced cooling process, wherein the start cooling temperature is 820-840 ℃, cooling to 580-630 ℃ and air cooling at the cooling speed of 5-20 ℃/S.

Quenching: the quenching temperature is less than or equal to Ac3+70 ℃, and water cooling is carried out after discharging, which is beneficial to refining the structure and improving the obdurability. 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. The quenching temperature is preferably 860-920 ℃.

Tempering: the tempering temperature is less than 250 ℃, 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 cooling bed cooling, so that the cooling speed can be reduced, and the cracking of the steel plate can be prevented.

In order to save resources and simultaneously meet the requirement of high wear resistance with the hardness of 600HB and have good forming performance, the invention provides the high wear-resistant steel and the manufacturing method thereof.

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

1. the wear-resistant steel plate has simple chemical component design, reduces the content of carbon and alloy by lower C content and adopting Ti and V microalloying thought, has weldability, and is particularly suitable for the application field of engineering machinery needing welding.

2. By adding a large amount of Ti element, the amount of hard phase is increased by utilizing a large amount of precipitated TiC particles, and the wear resistance of the steel plate matrix is improved under the condition of the same hardness.

3. The chemical components and the rolling process are reasonably designed, the process system is relatively loose, and industrial mass production can be stably carried out.

4. The 600 HB-level wear-resistant steel plate produced by the invention has the Brinell hardness of more than 600HBW and excellent wear resistance; the Charpy longitudinal impact energy at the temperature of minus 20 ℃ is more than 40J, the impact toughness is good, and the requirements of steel for engineering machinery are met.

Drawings

FIG. 1 shows the microstructure of a 600 HB-grade wear-resistant steel plate according to example 3 of the present invention, and it can be seen from the figure that the microstructure of the steel plate is mainly martensite.

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.

The chemical compositions of the 600HB grade abrasion resistant steel sheets of examples 1-4 are shown in Table 1.

TABLE 1 chemistry of 600 HB-grade abrasion resistant steel plates of examples 1-4

Example 1

The chemical composition of the 600 HB-grade abrasion-resistant steel plate of this example is shown in Table 1. Smelting in a converter according to chemical components shown in the table 1, casting the smelted components into a continuous casting billet after external refining, and slowly heating the continuous casting billet to 1250 ℃, wherein the initial rolling temperature of rough rolling is 1150 ℃ and the final rolling temperature is 980 ℃; the accumulated reduction rate of finish rolling is 70 percent, the reduction rate of the last three passes is 13 percent, the start rolling temperature of finish rolling is 900 ℃, the finish rolling temperature is 860 ℃, the thickness of the finished steel plate is 8mm, the ACC cooling after rolling selects a forced cooling process, the start cooling temperature is 840 ℃, the ACC cooling is carried out to 630 ℃, the air cooling is carried out at the cooling speed of 20 ℃/S, the quenching heating temperature is Ac3+70 ℃, the ACC cooling is carried out after discharging, the tempering temperature is 200 ℃, and the stacking or cooling bed cooling is carried out after tempering.

Example 2

The chemical composition of the 600 HB-grade abrasion-resistant steel plate of this example is shown in Table 2. Carrying out converter smelting according to chemical components shown in Table 2, carrying out external refining, casting into a continuous casting billet, slowly heating the continuous casting billet to 1220 ℃, wherein the initial rolling temperature of rough rolling is 1130 ℃, and the final rolling temperature is 980 ℃; the accumulated reduction rate of finish rolling is 80%, the reduction rate of the last three passes is 13%, the start rolling temperature of finish rolling is 900 ℃, the finish rolling temperature is 860 ℃, the thickness of the finished steel plate is 12mm, the ACC cooling after rolling selects a forced cooling process, the start cooling temperature is 840 ℃, the ACC cooling is carried out to 630 ℃, the air cooling is carried out at the cooling speed of 20 ℃/S, the quenching heating temperature is 920 ℃, the water cooling is carried out after discharging, the tempering temperature is 190 ℃, and the stacking or cooling bed cooling is carried out after tempering.

Example 3

The chemical composition of the 600 HB-grade abrasion-resistant steel plate of this example is shown in Table 3. Smelting in a converter according to chemical components shown in the table 1, casting the smelted components into a continuous casting billet after external refining, and slowly heating the continuous casting billet to 1200 ℃, wherein the initial rolling temperature of rough rolling is 1060 ℃ and the final rolling temperature is 940 ℃; the accumulated reduction rate of finish rolling is 70 percent, the reduction rate of the last three passes is 13 percent, the start rolling temperature of finish rolling is 860 ℃, the finish rolling temperature is 840 ℃, the thickness of the finished steel plate is 18mm, the ACC cooling after rolling selects a forced cooling process, the start cooling temperature is 820 ℃, the temperature is cooled to 580 ℃, stacking is cooled in air, the cooling speed is 5 ℃/S, the quenching heating temperature is Ac3+30 ℃, the temperature is cooled in water after discharging, the tempering temperature is 200 ℃, and the stacking or cooling bed is cooled after tempering.

The microstructure of the 600 HB-grade wear-resistant steel plate of the embodiment 3 is shown in FIG. 1, and it can be seen from FIG. 1 that the microstructure of the steel plate is mainly martensite;

example 4

The chemical composition of the 600 HB-grade abrasion-resistant steel plate of this example is shown in Table 4. Smelting in a converter according to chemical components shown in the table 1, casting the smelted components into a continuous casting billet after external refining, and slowly heating the continuous casting billet to 1210 ℃, wherein the initial rolling temperature of rough rolling is 1110 ℃ and the final rolling temperature is 980 ℃; the accumulated reduction rate of finish rolling is 70 percent, the reduction rate of the last three passes is 13 percent, the start rolling temperature of finish rolling is 900 ℃, the finish rolling temperature is 860 ℃, the thickness of the finished steel plate is 20mm, the ACC cooling after rolling selects a forced cooling process, the start cooling temperature is 840 ℃, the ACC cooling is carried out to 630 ℃, the air cooling is carried out at the cooling speed of 15 ℃/S, the quenching heating temperature is 860 ℃, the ACC cooling is carried out after discharging, the tempering temperature is 180 ℃, and the stacking or cooling bed cooling is carried out after tempering.

Comparative example

The wear resistant steel sheets of comparative examples 1 to 3 were produced by a conventional method using the chemical compositions of the steel grades referred to in table 2.

Table 2 chemical composition of comparative examples 1 to 3 abrasion resistant steel sheets

Performance testing

The wear-resistant steels obtained in comparative examples 1 to 3 were compared with those of the present invention in terms of their properties, and the results are shown in Table 3.

TABLE 3 mechanical Properties of inventive and comparative examples

As can be seen from Table 3, the wear-resistant steel of the examples of the invention has hardness of more than 600HB and Charpy longitudinal impact energy of more than 40J at-20 ℃, and the wear-resistant steel plate related to the invention has excellent mechanical properties. Under the condition that the component system is similar, the hardness of the steel plate is obviously higher than that of the steel of comparative examples 1-2; the hardness of the steel of comparative example 3 is similar to that of the steel sheet according to the present invention, but the wear resistance is lower than that of the steel of this type.

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 4.

TABLE 4 weld performance test results of 600 HB-grade wear-resistant steel plate of inventive example 3

As can be seen from Table 4, the wear-resistant steel plate has no cracks after being welded under the condition of preheating at 170 ℃, 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 test of the wear resistant steel sheet of example 4 of the present invention with the HARDOX600 steel are shown in table 5.

Table 5 results of the wear resistance test of example 4 and comparative steel grade 3.

As can be seen from Table 5, the present invention relates to steel grades having wear resistance comparable to HARDOX600 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 600 HB-grade wear-resistant steel plate is characterized by comprising the following chemical components in percentage by weight: 0.33 to 0.40 percent of C; 0.80 to 1.20 percent of Si; 1.5 to 2.0 percent 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 1.0 percent of Cr; 0.2 to 0.5 percent of Mo; 0.1 to 0.2 percent of Ti; 0.06-0.12% of V; 0 to 0.07 percent of Nb; 0 to 0.5 percent of Ni; al: 0 to 0.1 percent; n is less than or equal to 0.005 percent; o is less than or equal to 0.003 percent; the balance of iron and unavoidable impurities.

2. A preparation method of a 600HB wear-resistant steel plate comprises converter smelting, external refining, continuous casting, heating, rolling, accelerated cooling, quenching and tempering;

wherein, heating: the heating temperature is controlled to be 1200-1250 ℃, and a slow heating method is adopted;

rolling: the initial rolling temperature of rough rolling is 1060-1150 ℃, and the final rolling temperature is 940-980 ℃; the accumulated reduction rate of finish rolling is more than 65%, the reduction rate of the last three passes is more than 12%, the initial rolling temperature is 860-900 ℃, and the final rolling temperature is 840-860 ℃;

accelerated cooling: the ACC after rolling is cooled by a forced cooling process, the opening cooling temperature is 820-840 ℃, the ACC is cooled to 580-630 ℃, and air cooling is carried out at the cooling speed of 5-20 ℃/S;

quenching: quenching temperature is less than or equal to Ac3+70 ℃, and water cooling is carried out after discharging;

tempering: the tempering temperature is less than 250 ℃, and the steel is slowly cooled after being taken out of the furnace.

3. The method according to claim 2, wherein the quenching temperature is 860 to 920 ℃.

4. The method of claim 2, wherein the air cooling is performed by stacking or bed cooling.