CN116875876A

CN116875876A - Bainite/martensite complex-phase wear-resistant steel and heat treatment method thereof

Info

Publication number: CN116875876A
Application number: CN202211389682.0A
Authority: CN
Inventors: 何德武
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-11-08
Filing date: 2022-11-08
Publication date: 2023-10-13

Abstract

The invention discloses a bainite/martensite composite phase wear-resistant steel and a heat treatment method thereof, and belongs to the technical field of wear-resistant steel. The chemical composition of wear-resistant steel is C 0.45-0.65%, Si 1.5-2.3%, Mn 0.5-1.5%, Cr 1.2-2.7%, Mo0.27-0.55%, V 0.05-0.25%, Ti 0.02- 0.15%, Ni 0.75-1.9%, W 0.75-1.35%, Al 0.01-0.15%, P<0.025%, S<0.015%, O<0.0001%, N<0.0003%, H<0.00001%, the rest is Fe and unavoidable impurities. By combining ingredients and processes, the present invention obtains multi-phase wear-resistant steel with both toughness and wear resistance, which can effectively solve the problem of poor comprehensive performance of existing wear-resistant steel.

Description

Bainite/martensite complex-phase wear-resistant steel and heat treatment method thereof

Technical Field

The invention belongs to the technical field of wear-resistant steel, and particularly relates to bainite/martensite complex-phase wear-resistant steel and a preparation method thereof.

Background

The wear-resistant steel is widely applied to various technical fields with wear-resistant requirements such as mines, metallurgy, engineering machinery, cement, electric power and the like, and relates to wear-resistant parts of various key machines and mechanisms, such as: the abrasion-resistant steel is required to meet extremely high abrasion resistance and extremely good toughness when in use. In the prior art, high manganese steel with wider application range is used, and the initial hardness is low; high chromium cast iron has poor toughness and causes serious equipment accidents once the cast iron fails under impact load; the low alloy steel has poor wear resistance and low working efficiency. Therefore, research on wear-resistant steel with excellent comprehensive properties, namely higher wear resistance and higher toughness is needed.

The patent CN202111076281.5 of 2022, 1 and 4 discloses a preparation method of a precipitation reinforced bainite-martensite multiphase wear-resistant lining plate, which is characterized in that a large amount of micron-sized precipitates are precipitated in multiphase steel by adding carbide forming elements and regulating and controlling a heat treatment process, so that the wear resistance of the material is improved on the basis of not increasing the carbon content, and finally the hardness of the multiphase steel lining plate is HBW426-445 and the impact toughness is 25-35J/cm ² Compared with a carbide-free bainite-martensite complex-phase wear-resistant lining plate, the wear resistance is improved by more than 50%. The preparation method adopted by the invention has higher wear resistance, but has poorer toughness and insufficient comprehensive performance.

Disclosure of Invention

The invention aims to solve the technical problem that the existing wear-resistant steel has poor comprehensive performance.

The technical scheme adopted for solving the technical problems is as follows: the bainite/martensite complex-phase wear-resistant steel comprises the following chemical components in percentage by mass: 0.45-0.65% of C, 1.5-2.3% of Si, 0.5-1.5% of Mn, 1.2-2.7% of Cr, 0.27-0.55% of Mo, 0.05-0.25% of V, 0.02-0.15% of Ti, 0.75-1.9% of Ni, 0.75-1.35% of W, 0.01-0.15% of Al, 0.025% of P, 0.015% of S, 0.0001% of O, 0.0003% of N, 0.00001% of H, and the balance of Fe and unavoidable impurities.

Further, the bainite/martensite complex phase wear resistant steel comprises the following chemical components in percentage by mass: 0.48-0.60% of C, 1.6-2.1% of Si, 0.6-1.2% of Mn, 1.6-2.5% of Cr, 0.35-0.50% of Mo, 0.12-0.22% of V, 0.04-0.12% of Ti, 0.9-1.5% of Ni, 0.85-1.20% of W, 0.03-0.11% of Al, 0.015% of P, 0.01% of S, 0.0001% of O, 0.0003% of N, 0.00001% of H, and the balance of Fe and unavoidable impurities.

Further, the bainite/martensite complex phase wear resistant steel comprises the following chemical components in percentage by mass: 0.52-0.58% of C, 1.8-2.0% of Si, 0.7-0.9% of Mn, 1.9-2.25% of Cr, 0.39-0.47% of Mo, 0.15-0.2% of V, 0.06-0.1% of Ti, 1.0-1.20% of Ni, 0.95-1.05% of W, 0.05-0.09% of Al, 0.01% of P, 0.005% of S, 0.0001% of O, 0.0003% of N, 0.00001% of H, and the balance of Fe and unavoidable impurities.

The mass ratio of Cr to Mo in the chemical components of the bainite/martensite complex-phase wear-resistant steel is 4.2-4.8:1.

Further, the mass ratio of Cr to Mo is 4.5:1.

The bainite/martensite complex-phase wear-resistant steel comprises 0.25-0.3% of V+Ti by mass percent in chemical components.

The metallographic structure of the bainite/martensite complex-phase wear-resistant steel contains 80-85% of martensite and 15-20% of lower bainite, wherein the martensite is in the shape of short needles and hidden needles.

Further, when the total content of martensite and lower bainite in the metallographic structure of the wear-resistant steel is less than 100%, a trace amount of austenite is also contained.

The bainite/martensite complex phase wear resistant steel is obtained through the steps of electric furnace smelting, external refining, vacuum refining and casting forming, or through the steps of electric furnace smelting, external refining, vacuum refining, continuous casting steel billet and rolling, and then through the steps of normalizing, complete annealing, quenching and tempering.

Further, in the normalizing step, the steel is heated to 40 to 50 ℃ higher than the temperature A3, then heat is preserved for 1 hour every 20mm thick, and then air-cooled to room temperature.

Further, in the above-mentioned complete annealing step, the steel material treated in the normalizing step is heated to 40 to 50 ℃ above the A3 temperature, then is heat-preserved for 1 hour every 20mm thick, and after the heat preservation is finished, is cooled to below the A1 temperature at a cooling rate of 60 ℃/h, and then is air-cooled to room temperature.

Further, in the quenching step, the steel material treated in the complete annealing step is heated to 20-30 ℃ above the temperature A3, then is insulated for 1 hour according to the heat insulation time of every 20mm thickness, is cooled to 85-90 ℃ by quenching oil at the cooling rate of 10-20 ℃ after the heat insulation is finished, and is then air-cooled to 50-60 ℃.

Further, in the tempering step, the steel material treated in the quenching step is subjected to heat preservation for 4 hours at 195-205 ℃ and then is discharged from a furnace for air cooling.

The beneficial effects of the invention are as follows: the bainite/martensite complex-phase wear-resistant steel chemical components and the heat treatment method thereof adopted by the invention regulate the hardness of martensite and bainite by controlling the content of C in a structure; the precipitation of carbide is prevented by controlling the Ni content and the cooling process of heat treatment, cr is controlled to improve the strength and hardness of steel, the hardenability of steel is obviously improved, cr and Ni are utilized to reduce the Ms point of the heat treatment, and during the continuous cooling process of the heat treatment, martensite transformation is pushed to a lower temperature, so that a certain amount of bainite is formed in enough time to obtain a desired bainite/martensite complex phase structure; and meanwhile, the alloy has higher wear resistance by adding W.

The bainite/martensite complex-phase wear-resistant steel is combined with each other through chemical components and processes, so that the bainite/martensite complex-phase wear-resistant steel with both toughness and wear resistance is obtained, and the comprehensive performance is excellent.

Drawings

FIG. 1 is a metallographic structure diagram of a wear-resistant steel prepared in example 1 of the present invention;

FIG. 2 is a metallographic structure diagram of the abrasion-resistant steel prepared in example 2 of the present invention;

FIG. 3 is a metallographic structure diagram of the abrasion-resistant steel prepared in example 3 of the present invention;

FIG. 4 is a metallographic structure diagram of the abrasion resistant steel prepared in example 4 of the present invention;

FIG. 5 is a metallographic structure diagram of the abrasion-resistant steel according to comparative example 1;

FIG. 6 is a metallographic structure diagram of the abrasion resistant steel according to comparative example 2;

FIG. 7 is a metallographic structure diagram of the abrasion resistant steel according to comparative example 3;

FIG. 8 is a metallographic structure diagram of the abrasion resistant steel according to comparative example 4;

FIG. 9 is a metallographic structure diagram of the abrasion resistant steel according to comparative example 5;

FIG. 10 is a metallographic structure diagram of the abrasion-resistant steel according to comparative example 6;

FIG. 11 is a metallographic structure diagram of the abrasion resistant steel according to comparative example 7 of the present invention.

Detailed Description

The technical scheme of the invention can be implemented in the following way.

The bainite/martensite complex-phase wear-resistant steel comprises the following chemical components in percentage by mass: 0.45-0.65% of C, 1.5-2.3% of Si, 0.5-1.5% of Mn, 1.2-2.7% of Cr, 0.27-0.55% of Mo, 0.05-0.25% of V, 0.02-0.15% of Ti, 0.75-1.9% of Ni, 0.75-1.35% of W, 0.01-0.15% of Al, 0.025% of P, 0.015% of S, 0.0001% of O, 0.0003% of N, 0.00001% of H, and the balance of Fe and unavoidable impurities.

Preferably, the bainite/martensite complex-phase wear resistant steel comprises the following chemical components in percentage by mass: 0.48-0.60% of C, 1.6-2.1% of Si, 0.6-1.2% of Mn, 1.6-2.5% of Cr, 0.35-0.50% of Mo, 0.12-0.22% of V, 0.04-0.12% of Ti, 0.9-1.5% of Ni, 0.85-1.20% of W, 0.03-0.11% of Al, 0.015% of P, 0.01% of S, 0.0001% of O, 0.0003% of N, 0.00001% of H, and the balance of Fe and unavoidable impurities.

Preferably, the bainite/martensite complex-phase wear resistant steel comprises the following chemical components in percentage by mass: 0.52-0.58% of C, 1.8-2.0% of Si, 0.7-0.9% of Mn, 1.9-2.25% of Cr, 0.39-0.47% of Mo, 0.15-0.2% of V, 0.06-0.1% of Ti, 1.0-1.20% of Ni, 0.95-1.05% of W, 0.05-0.09% of Al, 0.01% of P, 0.005% of S, 0.0001% of O, 0.0003% of N, 0.00001% of H, and the balance of Fe and unavoidable impurities.

Cr can improve the hardenability of steel and the strength, hardness and wear resistance; mo can obviously improve the hardenability of steel, inhibit the quenching brittleness and improve the tempering stability. The quenching degree can be ensured by the combined action of Cr and Mo, and the mass ratio of Cr to Mo in the chemical components of the bainite/martensite complex-phase wear-resistant steel is 4.2-4.8:1, so that the excellent quenching degree of round steel with the diameter of 60mm can be ensured by the content of Cr and Mo meeting the ratio. When the bainite/martensite complex-phase wear resistant steel with larger size is prepared, in order to ensure the hardenability, the content of Cr and Mo in the chemical components of the bainite/martensite complex-phase wear resistant steel can be increased according to the mass ratio of Cr to Mo of 4.5 to 1 more preferably.

V can refine the crystal grains of the steel and improve the strength and toughness; ti densifies the structure of the steel, refines grains, and reduces the aging sensitivity and brittleness of the steel. In the invention, when V+Ti=0.25-0.3%, the V, ti combination has the best effect and the best economical efficiency. Therefore, the bainite/martensite complex-phase wear resistant steel is preferable, and the mass percentage of V+Ti in the chemical components is 0.25-0.3%.

The bainite/martensite complex-phase wear-resistant steel has the following functions of easy rest chemical components: the content of C is increased, and the yield strength and the tensile strength of the steel are increased, so that the wear resistance of the steel can be improved; si can obviously improve the elastic limit, yield point and tensile strength of steel; mn improves the hardenability of the steel; w further refines the fine grain to a certain extent, and can be combined with C to form WC, so that the wear resistance of the steel is remarkably improved, and the segregation of the steel is aggravated due to the fact that the W content is too high, so that the maximum W content in the steel is limited to be 1.35%; ni can improve the strength of steel and can keep good plasticity and toughness of steel; al is the most effective element for deoxidizing, and a small amount of aluminum in the steel can refine grains and improve impact toughness.

P increases the cold brittleness of the steel, and the phosphorus content of the alloy steel must be low; s, the steel is thermally brittle and is easy to form various sulfide inclusions with other elements, the hot working of the steel is affected, the ductility and toughness of the steel are reduced, and the sulfur content of alloy steel is required to be low; the O and certain elements in the steel form oxide inclusions, so that the mechanical property of the steel is obviously reduced, and the oxygen content in the steel is not more than 10ppm; n obviously reduces the toughness and plasticity of the steel, and the nitrogen content in the steel is not more than 30ppm; h tends to cause hydrogen embrittlement in the steel, and the hydrogen content in the steel of the present invention should not be more than 1ppm.

Preferably, the specific preparation method of the steel comprises the following steps:

a. weighing a certain amount of scrap steel, adding the scrap steel into an electric furnace, and simultaneously adding a slag former with the proportion of 10% of the scrap steel, wherein the slag former is required to have good P removing capability;

b. arc starting smelting, and introducing oxygen for blowing in the smelting process; detecting the temperature of molten steel at the blowing end point, sampling and testing the P content in the molten steel, and carrying out the next step if the P content is less than 0.05%, otherwise, re-slagging and removing P again;

c. pulling out P slag, and making smelting slag into a reduction period; deoxidizing with aluminum rod, and sequentially adding ferrosilicon, ferromanganese and other alloy raw materials according to the molten steel amount, wherein the content of C is controlled to be 0.15-0.2% lower than the target C content;

d. entering an LF furnace, introducing Ar for refining, and adjusting the component C to reach a target component; introducing the mixture into a VD furnace for degassing treatment;

e. continuously casting into billets, and casting into finished products in a casting mode;

f. rolling the billet into a product.

Preferably, the heat treatment method of the bainite/martensite complex phase wear resistant steel comprises the following steps:

in the normalizing process, the steel is heated to 40-50 ℃ above the temperature A3, then is insulated for 1 hour according to the heat insulation time of every 20mm thick, and then is air-cooled to room temperature, so as to refine grains and reduce the band-shaped tissue generated in the rolling process;

in the complete annealing process, heating the steel processed in the normalizing process to 40-50 ℃ above the A3 temperature, preserving heat according to the time of preserving heat for 1h every 20mm thick, cooling to below the A1 temperature at the cooling rate of 60 ℃/h after the heat preservation is finished, then air-cooling to room temperature, refining grains again, eliminating normalizing stress, homogenizing component structures and preparing for quenching;

in the quenching process, heating the steel processed in the complete annealing process to 20-30 ℃ above the A3 temperature, preserving heat for 1h according to the time of preserving heat every 20mm thick, cooling to 85-90 ℃ through quenching oil at the cooling rate of 10-20 ℃ after the heat preservation is finished, and then air-cooling to 50-60 ℃;

in the tempering process, the steel processed in the quenching process is subjected to heat preservation for 4 hours at 195-205 ℃ and then is discharged from a furnace for air cooling, so that tempered martensite is obtained, and the toughness, hardness and wear resistance of the steel are further improved.

The technical scheme and effect of the present invention will be further described by practical examples.

Examples

The invention prepares the bainite/martensite complex phase wear resistant steel by 4 groups of examples 1-4 and 7 groups of comparative examples 1-7 by adopting the chemical components and the heat treatment method thereof.

Examples 1 to 4 and comparative examples 1 to 3 round steel materials having a diameter of 60mm and a length of 60mm were obtained by the steps of electric furnace smelting, external refining, vacuum refining, continuous casting of billets, and rolling, the chemical compositions of examples are shown in Table 1, and the chemical compositions of comparative examples are shown in Table 2.

Table 1 chemical composition of examples

Composition of the components	Example 1	Example 2	Example 3	Example 4
					C％	0.47	0.50	0.53	0.56
Si％	1.55	1.64	1.88	1.91
					Mn％	1.26	0.99	0.81	0.75
Cr％	1.45	1.75	1.98	2.02
					Mo％	0.29	0.36	0.42	0.44
Ni％	0.82	1.22	1.05	1.18
					W％	0.76	0.89	1.02	1.05
Al％	0.024	0.036	0.057	0.062
					V％	0.08	0.13	0.19	0.18
Ti％	0.022	0.037	0.069	0.078
					P％	0.021	0.012	0.007	0.008
S％	0.011	0.008	<0.001	<0.001
					O％	<0.0001	<0.0001	<0.0001	<0.0001
N％	<0.0003	<0.0003	<0.0003	<0.0003
					H％	<0.00001	<0.00001	<0.00001	<0.00001

Table 2 chemical composition of comparative example

Composition of the components	Comparative example 1	Comparative example 2	Comparative example 3	Comparative example 4	Comparative example 5	Comparative example 6	Comparative example 7
								C％	0.44	0.52	0.53	0.56	0.56	0.56	0.56
Si％	1.45	1.91	1.97	1.91	1.91	1.91	1.91
								Mn％	0.81	0.83	0.88	0.75	0.75	0.75	0.75
Cr％	0.99	1.84	2.02	2.02	2.02	2.02	2.02
								Mo％	0.39	0.41	0.43	0.44	0.44	0.44	0.44
Ni％	1.07	0.25	1.08	1.18	1.18	1.18	1.18
								W％	1.02	1.01	0.1	1.05	1.05	1.05	1.05
Al％	0.035	0.058	0.054	0.062	0.062	0.062	0.062
								V％	0.17	0.11	0.16	0.18	0.18	0.18	0.18
Ti％	0.04	0.05	0.09	0.078	0.078	0.078	0.078
								P％	0.006	0.007	0.007	0.008	0.008	0.008	0.008
S％	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
								O％	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001	<0.0001
N％	<0.0003	<0.0003	<0.0003	<0.0003	<0.0003	<0.0003	<0.0003
								H％	<0.00001	<0.00001	<0.00001	<0.00001	<0.00001	<0.00001	<0.00001

The transformation points of the steel materials of the hypoeutectoid steels of examples 1 to 4 and comparative examples 1 to 7 were determined according to the Andruse transformation point formula of the steel, and the results are shown in tables 3 and 4, respectively.

Table 3 example phase transition point temperature

Temperature (temperature)	Example 1	Example 2	Example 3	Example 4
					A3	855℃	857℃	877℃	880℃
A1	775℃	785℃	791℃	792℃
					Ms	235℃	203℃	218℃	203℃

Table 4 comparative example phase transition point temperature

Temperature (temperature)

Comparative example 1

Comparative example 2

Comparative example 3

Comparative example 4

Comparative example 5

Comparative example 6

Comparative example 7

A3

824℃

883℃

866℃

880℃

A1

732℃

803℃

783℃

792℃

Ms

292℃

242℃

221℃

203℃

And heating by adopting a box-type resistance furnace, and performing heat treatment on round steel products with phi 60mm and length 60mm obtained in examples 1-4 and comparative examples 1-7 to obtain the bainite/martensite complex phase wear-resistant steel. In the complete annealing process, after the heat preservation is finished, furnace cooling is carried out at a cooling rate of 60 ℃/h until the temperature is lower than the temperature A1, and then air cooling is carried out until the temperature is room temperature; in the quenching process, K1498 isothermal graded quenching oil or water is adopted as a quenching cooling medium, the cooling medium is heated to 85 ℃ before quenching, the workpiece is taken out from the cooling medium for air cooling after being cooled to 85 ℃, and the workpiece is immediately tempered after being air cooled to 50-60 ℃. The specific heat treatment process parameters are shown in table 5.

TABLE 5 heat treatment process parameters

Physical properties of the bainitic/martensitic complex-phase wear-resistant steels prepared in examples 1 to 4 and comparative examples 1 to 7 were examined, and the results are shown in Table 6.

TABLE 6 physical Property detection results

	HRC surface	HRC surface 15mm	HRC core	Impact absorption energy (20 ℃ C.) KV ₂
					Example 1	56.7	56.4	56.3	39/35/36
Example 2	59.2	59.3	59.2	32/38/33
					Example 3	61.3	61.6	61.6	42/44/44
Example 4	62.1	61.9	61.8	47/43/43
					Comparative example 1	53.9	52.2	50.4	35/39/33
Comparative example 2	63.5	63.4	63.2	7/8/8
					Comparative example 3	61.4	61.4	61.2	43/45/47
Comparative example 4	61.2	61.5	60.5	26/29/28
					Comparative example 5	57.6	57.9	57.1	23/24/22
Comparative example 6	56.8	56.7	56.5	15/16/17
					Comparative example 7	52.2	52.0	51.8	51/56/57

Wear resistance tests were performed on the bainitic/martensitic complex-phase wear-resistant steels prepared in examples 1 to 4 and comparative examples 1 to 7.

Test equipment and test sample: the ML-10 abrasive wear testing machine of the wear testing machine; abrasive corundum sandpaper (200 #); weighing: a one thousandth electronic balance; samples the bainitic/martensitic complex phase wear-resistant steels prepared in examples 1 to 4 and comparative examples 1 to 3 were processed to 20 g.+ -. 0.1g and then subjected to wear resistance test, and the results are shown in Table 7.

TABLE 7 abrasion resistance test results

	Time	Initial weight	Final weight	Wear amount
					Example 1	2h	20.076	16.456	3.62
Example 2	2h	19.984	17.323	2.661
					Example 3	2h	19.993	18.861	1.069
Example 4	2h	19.926	18.773	1.053
					Comparative example 1	2h	20.067	14.259	5.808
Comparative example 2	2h	19.916	18.904	1.012
					Comparative example 3	2h	19.978	16.613	3.365
Comparative example 4	2h	19.634	17.859	1.775
					Comparative example 5	2h	20.663	16.626	4.037
Comparative example 6	2h	19.987	15.522	4.465
					Comparative example 7	2h	19.838	12.076	7.762

As can be seen from examples 1 to 4, the components and the heat treatment process of examples 1 to 4 all adopt the technical scheme of the invention, and the physical properties and the wear resistance of the finally prepared bainite/martensite complex phase wear resistant steel are equivalent, wherein the component proportion adopted in examples 3 to 4 is the most preferable component proportion of the invention, and the finally prepared bainite/martensite complex phase wear resistant steel has the most excellent physical properties and wear resistance, so that the bainite/martensite complex phase wear resistant steel prepared by the technical scheme of the invention has excellent comprehensive properties.

As is clear from comparative examples 1 to 3, in comparative example 1, the wear-resistant steel prepared finally has low hardness and poor wear resistance due to the lower contents of C, cr and Si; in the comparative example 2, the lower Ni content is adopted, the adopted quenching cooling medium is water, and the cooling rate is higher, so that the prepared wear-resistant steel has high hardness and wear resistance, but has poor toughness, and has no practical application significance; the W added in comparative example 3 was extremely low, and the physical properties of the finally obtained wear-resistant steel were comparable to those of examples 1 to 4, but the wear resistance was greatly lowered and the overall properties were poor. The composition ratios of comparative examples 4 to 7 were the same as in example 4, but the mechanical properties and wear resistance index were reduced under different heat treatment process parameters.

The metallographic structure diagrams of examples 1 to 4 and comparative examples 1 to 7 are shown in FIGS. 1 to 11, respectively, and it is understood that the metallographic structures of examples 1 to 4 and comparative example 3 are substantially identical with each other by the same heat treatment process, and the obtained metallographic structures are lower bainite+martensite+very little retained austenite, and the martensite is in the form of short needles and hidden needles, wherein the martensite accounts for about 83% and the lower bainite accounts for about 15%. With the change of the heat treatment process parameters, metallographic structures are in different forms, and undissolved ferrite exists in the quenching structure in the comparative example 1 under lower normalizing stability; comparative example 2 has a fully martensitic structure due to an excessively high cooling rate; comparative example 4 had a relatively coarse structure and a large amount of retained austenite due to an excessively high heat treatment temperature.

Claims

1. The bainite/martensite complex-phase wear-resistant steel is characterized by comprising the following chemical components in percentage by mass: 0.45-0.65% of C, 1.5-2.3% of Si, 0.5-1.5% of Mn, 1.2-2.7% of Cr, 0.27-0.55% of Mo, 0.05-0.25% of V, 0.02-0.15% of Ti, 0.75-1.9% of Ni, 0.75-1.35% of W, 0.01-0.15% of Al, 0.025% of P, 0.015% of S, 0.0001% of O, 0.0003% of N, 0.00001% of H, and the balance of Fe and unavoidable impurities.

2. The bainite/martensite multiphase wear resistant steel according to claim 1, is characterized in that the chemical components thereof are as follows in mass percent: 0.48-0.60% of C, 1.6-2.1% of Si, 0.6-1.2% of Mn, 1.6-2.5% of Cr, 0.35-0.50% of Mo, 0.12-0.22% of V, 0.04-0.12% of Ti, 0.9-1.5% of Ni, 0.85-1.20% of W, 0.03-0.11% of Al, 0.015% of P, 0.01% of S, 0.0001% of O, 0.0003% of N, 0.00001% of H, and the balance of Fe and unavoidable impurities.

3. The bainite/martensite multiphase wear resistant steel according to claim 1, is characterized in that the chemical components thereof are as follows in mass percent: 0.52-0.58% of C, 1.8-2.0% of Si, 0.7-0.9% of Mn, 1.9-2.25% of Cr, 0.39-0.47% of Mo, 0.15-0.2% of V, 0.06-0.1% of Ti, 1.0-1.20% of Ni, 0.95-1.05% of W, 0.05-0.09% of Al, 0.01% of P, 0.005% of S, 0.0001% of O, 0.0003% of N, 0.00001% of H, and the balance of Fe and unavoidable impurities.

4. A bainite/martensite complex phase wear resistant steel according to any of claims 1 to 3, characterised in that: the mass ratio of Cr to Mo in the chemical components is 4.2-4.8:1; the mass percentage of V+Ti is 0.25-0.3%.

5. A bainite/martensite complex phase wear resistant steel according to any of claims 1 to 3, characterised in that: the metallographic structure of the wear-resistant steel contains 80-85% of martensite and 15-20% of lower bainite, wherein the martensite is short needles and hidden needles.

6. A method for producing a bainitic/martensitic, multiphase, wear resistant steel according to any one of claims 1 to 5, characterized in that: the bainite/martensite complex phase wear resistant steel is obtained through the working procedures of electric furnace smelting, external refining, vacuum refining and casting forming, or through the working procedures of electric furnace smelting, external refining, vacuum refining, continuous casting of steel billets and rolling.

7. The method for preparing the bainite/martensite complex phase wear resistant steel according to claim 6, characterized in that: in the normalizing process, the steel is heated to 40-50 ℃ above the temperature of A3, then is insulated for 1 hour according to the heat insulation time of every 20mm, and then is cooled to room temperature.

8. The method for preparing the bainite/martensite complex phase wear resistant steel according to claim 6, characterized in that: in the complete annealing process, the steel processed in the normalizing process is heated to 40-50 ℃ above the A3 temperature, then is insulated for 1 hour according to the thickness of 20mm, is cooled to below the A1 temperature at the cooling rate of 60 ℃ per hour after the insulation is finished, and is then air-cooled to room temperature.

9. The method for preparing the bainite/martensite complex phase wear resistant steel according to claim 6, characterized in that: in the quenching process, the steel treated in the complete annealing process is heated to 20-30 ℃ above the A3 temperature, then is insulated for 1h according to the heat insulation time of every 20mm, is cooled to 85-90 ℃ through quenching oil at the cooling rate of 10-20 ℃ after the heat insulation is finished, and is then air-cooled to 50-60 ℃.

10. The method for preparing the bainite/martensite complex phase wear resistant steel according to claim 6, characterized in that: in the tempering process, the steel processed in the quenching process is discharged from a furnace for air cooling after heat preservation for 4 hours at 195-205 ℃.