1. A preparation method of rare earth treated low-temperature-resistant steel Q450EWR1 for railway carriages is characterized by comprising the following steps: the method comprises the following steps of (1) heating a continuous casting slab added with rare earth serving as a hot rolling raw material by using a stepping heating furnace, descaling by using high-pressure water, carrying out hot continuous rolling and finish rolling by using an E1R1 roughing mill, an E2R2 roughing mill and a 7-stand, carrying out dense laminar cooling and coiling to finally obtain the high corrosion-resistant steel for the railway carriage;

wherein: heating the casting blank at 11950-1250 ℃, keeping the furnace time at 175-235 min, descaling by high-pressure water, roughly rolling by using an E1R1 and E2R2 rough rolling mill, wherein the initial rolling temperature of rough rolling is not less than 1070 ℃, carrying out 7-frame hot continuous rolling and finish rolling, wherein the initial rolling temperature of finish rolling is not less than 955 ℃, the finish rolling temperature is 860-905 ℃, cooling by adopting a dense laminar flow, the cooling speed is not less than 12 ℃/S, the coiling temperature is 610-660 ℃, and the thickness of the steel strip is not more than 18 mm.

2. The method for preparing the rare earth treated low temperature resistant steel Q450EWR1 for railway carriages as claimed in claim 1, wherein the weight fraction of the hot rolling raw material components is as follows: c: 0.03 to 0.07%, Si: 0.14 to 0.48%, Mn: 0.35-1.50%, P is less than or equal to 0.015%, S is less than or equal to 0.010%, Cu: 0.25-0.55%, Cr: 3.0-5.5%, Ni: 0.10-0.65%, N is less than or equal to 0.003%, O is less than or equal to 0.002%, RE: not less than 0.0015%, and the balance of iron and other inevitable impurities.

3. The method for preparing the rare earth treated low temperature resistant steel Q450EWR1 for railway carriages as claimed in claim 2, wherein the weight fraction of the hot rolling raw material components is as follows: c: 0.05%, Si: 0.28%, Mn: 0.75%, P: 0.012%, S: 0.004%, Cu: 0.35%, Cr: 3.72%, Ni: 0.40%, N: 0.0025%, O: 0.0012 percent, 0.0030 percent of RE and the balance of iron and other inevitable impurities.

4. The method for preparing the rare earth treated low temperature resistant steel Q450EWR1 for railway carriages as claimed in claim 2, wherein the weight fraction of the hot rolling raw material components is as follows: c: 0.04%, Si: 0.31%, Mn: 1.10%, P: 0.011%, S: 0.002%, Cu: 0.42%, Cr: 3.85%, Ni: 0.45%, N: 0.0028%, O: 0.0010 percent, 0.0050 percent of RE and the balance of iron and other inevitable impurities.

Background

Along with the development of national energy transportation, the requirement of high-cold low-temperature energy transportation is increasing day by day, and the development requirements of lightening the self weight of a railway wagon and improving the load capacity require that a steel plate has excellent low-temperature resistance and corrosion resistance, and simultaneously has high strength, high toughness, excellent cold forming performance and welding performance, and the price is relatively stable. The Q450EWR1 high-corrosion-resistance weathering steel is mainly applied to a C80E novel universal open wagon. Compared with Q450NQR1 high-strength weathering steel mainly adopted by C70 type universal open trucks, the yield strength grades are 450MPa, but the-60 ℃ low-temperature impact performance of Q450EWR1 is improved by nearly 30 percent compared with Q450NQR1, thereby meeting the transportation requirements of coal, wood and other materials in alpine regions. The C80E adopts Q450NQR1 low-temperature resistant weathering steel, so that the low-temperature resistance is enhanced, the service life is prolonged, and benefits are created. The load capacity of the C80E universal open wagon is increased by 14.3 percent compared with that of a 70-ton universal open wagon and by 33 percent compared with that of a 60-ton universal open wagon.

Disclosure of Invention

The invention aims to provide a preparation method of rare earth treated low-temperature resistant steel Q450EWR1 for railway carriages, so that the steel plate has excellent low-temperature toughness and the service life of the product is prolonged.

In order to solve the technical problems, the invention adopts the following technical scheme:

a preparation method of rare earth treated low-temperature resistant steel Q450EWR1 for railway carriages comprises the following steps: the method comprises the following steps of (1) heating a continuous casting slab added with rare earth serving as a hot rolling raw material by using a stepping heating furnace, descaling by using high-pressure water, carrying out hot continuous rolling and finish rolling by using an E1R1 roughing mill, an E2R2 roughing mill and a 7-stand, carrying out dense laminar cooling and coiling to finally obtain the high corrosion-resistant steel for the railway carriage;

wherein: heating the casting blank at 11950-1250 ℃, keeping the furnace time at 175-235 min, descaling by high-pressure water, roughly rolling by using an E1R1 and E2R2 rough rolling mill, wherein the initial rolling temperature of rough rolling is not less than 1070 ℃, carrying out 7-frame hot continuous rolling and finish rolling, wherein the initial rolling temperature of finish rolling is not less than 955 ℃, the finish rolling temperature is 860-905 ℃, cooling by adopting a dense laminar flow, the cooling speed is not less than 12 ℃/S, the coiling temperature is 610-660 ℃, and the thickness of the steel strip is not more than 18 mm.

Further, the hot rolling raw material comprises the following components in percentage by mass: c: 0.03 to 0.07%, Si: 0.14 to 0.48%, Mn: 0.35-1.50%, P is less than or equal to 0.015%, S is less than or equal to 0.010%, Cu: 0.25-0.55%, Cr: 3.0-5.5%, Ni: 0.10-0.65%, N is less than or equal to 0.003%, O is less than or equal to 0.002%, RE: not less than 0.0015%, and the balance of iron and other inevitable impurities.

Further, the hot rolling raw material comprises the following components in percentage by mass: c: 0.05%, Si: 0.28%, Mn: 0.75%, P: 0.012%, S: 0.004%, Cu: 0.35%, Cr: 3.72%, Ni: 0.40%, N: 0.0025%, O: 0.0012 percent, 0.0030 percent of RE and the balance of iron and other inevitable impurities.

Further, the hot rolling raw material comprises the following components in percentage by mass: c: 0.04%, Si: 0.31%, Mn: 1.10%, P: 0.011%, S: 0.002%, Cu: 0.42%, Cr: 3.85%, Ni: 0.45%, N: 0.0028%, O: 0.0010 percent, 0.0050 percent of RE and the balance of iron and other inevitable impurities.

Compared with the prior art, the invention has the beneficial technical effects that:

rare earth is added into the steel, the content of O, N is low, the high corrosion-resistant steel for the railway carriage is produced by heating, descaling, rough rolling, finish rolling, cooling and coiling the continuous casting slab, and the average impact energy at the low temperature of minus 60 ℃ is more than or equal to 300J when the thickness of the steel strip is less than or equal to 18 mm.

Drawings

The invention is further illustrated in the following description with reference to the drawings.

FIG. 1 shows the microstructure of a steel strip according to example 1 of the present invention.

Detailed Description

The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1

The chemical components of the continuous casting slab are as follows:

table 1 continuous casting billet chemical composition units: is based on

C	Si	Mn	P	S	Cr	Cu	Ni	O	N	RE
											0.05	0.28	0.75	0.012	0.004	3.72	0.35	0.40	0.0012	0.0025	0.0030

Smelting and continuous casting: and (3) carrying out desulfurization pretreatment on molten iron, carrying out decarburization and dephosphorization by adopting a top-bottom combined blown converter, carrying out LF external refining, and carrying out continuous casting.

Heating and rolling: the heating temperature is 1220 ℃, the furnace time is 192min, the rough rolling of an E1R1 and E2R2 rough rolling mill is carried out after high-pressure water descaling, the initial rolling temperature of the rough rolling is 1105 ℃, the 7-stand hot continuous rolling finish rolling is carried out, the initial rolling temperature of the finish rolling is 968 ℃, the finish rolling temperature is 879 ℃, the cooling speed is 16 ℃/S, the coiling temperature is 635 ℃, and the thickness of the steel strip is 10 mm.

TABLE 2 Steel strip Low temperature impact test results

Example 2

The chemical components of the continuous casting slab are as follows:

table 4 continuous casting billet chemical composition units: is based on

C	Si	Mn	P	S	Cr	Cu	Ni	O	N	RE
											0.04	0.31	1.0	0.011	0.002	3.850	0.42	0.45	0.0010	0.0028	0.0050

Smelting and continuous casting: and (3) carrying out desulfurization pretreatment on molten iron, carrying out decarburization and dephosphorization by adopting a top-bottom combined blown converter, carrying out LF external refining, and carrying out continuous casting.

The heating temperature is 1230 ℃, the furnace time is 205min, the rough rolling is carried out by an E1R1 rough rolling mill and an E2R2 rough rolling mill after the high-pressure water descaling, the initial rolling temperature of the rough rolling is 1118 ℃, the 7-stand hot continuous rolling finish rolling is carried out, the initial rolling temperature of the finish rolling is 980 ℃, the final rolling temperature is 882 ℃, the cooling speed is 17 ℃/S, the coiling temperature is 660 ℃, and the thickness of the steel strip is 12 mm.

TABLE 3 Steel strip Low temperature impact test results

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.