CN114293094A - 450 MPa-grade vanadium-titanium microalloyed weather-resistant B-shaped steel and production method thereof - Google Patents

Abstract

The invention relates to the technical field of iron and steel production, in particular to a 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel and a production method thereof. Based on the total mass of the 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel, the mass fractions of the chemical components contained in it are: C: 0.06-0.15%, Si: 0.15-0.75%, Mn: 1-1.7%, V: 0.01 to 0.15%, Ti: 0.01 to 0.15%, and the contents of V and Ti satisfy 0.10<[V]+1.86[Ti]−5.88[Ti] ² <0.22. From the above examples and comparative examples, it can be seen that by limiting the reasonable matching relationship of alloy elements in the present invention, the strengthening effect of alloy elements is effectively improved, the alloy cost is significantly reduced, and the overall performance of the material is stably improved.

Description

A kind of 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel and production method thereof

technical field

The invention relates to the technical field of iron and steel production, in particular to a 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel and a production method thereof.

Background technique

The middle beam of the freight car is the main key component of the railway transportation freight car. It is the most stressed and most important part of the vehicle. It is called the backbone of the vehicle, and its strength directly affects the structural performance of the carriage. With the requirements of railway speed increase and weight reduction, the requirements for the middle beam are getting higher and higher. B-shaped steel is a special special steel used to make the middle beam of train cars. With the development of speed-up and heavy-duty railways in my country, there are higher requirements for the performance of B-shaped steel, which not only meets the strength and low temperature impact toughness, but also has strong atmospheric corrosion resistance. Generally, vanadium micro-alloying technology is the main method for B-shaped steel, which improves the strength through the precipitation of vanadium carbonitride, and at the same time adds Cu, Ni and Cr to improve the weathering and corrosion resistance of the steel. Due to the high price of vanadium alloy, its production cost has increased. By using lower-cost titanium elements, rationally optimizing the design of alloy components and smelting production processes, the strengthening effect of vanadium and titanium microalloying elements can be maximized. The development and application of vanadium-titanium composite microalloyed B-beam is of great significance to promoting energy saving and consumption reduction in the iron and steel industry, meeting the requirements of high-speed and heavy-duty leap-forward development of railway transportation, and realizing the upgrading of railway vehicles.

Patent application CN110846578A discloses a high-strength weathering hot-rolled 310 B-beam steel with low surface crack rate and a preparation method thereof. According to the composition characteristics of molten steel, reasonably matching drawing speed, superheat degree, mold water, secondary cold water, and reasonable selection of mold slag and other technical processes to achieve the steel to meet the performance requirements, its chemical composition is: C: 0.13 ~ 0.14%, Si: 0.38% ~ 0.43%, Mn: 1.38% ~ 1.40%, Cr: 0.233 ~ 0.237%, Ni: 0.284 ~ 0.298 %, Cu: 0.265% to 0.316%, V: 0.085 to 0.094%, P≤0.025%, S≤0.015%, and the balance is Fe and inevitable impurities. The B-shaped steel utilizes the vanadium microalloying strengthening effect to improve the strength of the steel and increase the production cost.

The document "Jiang Degang, Zhi Jianguo, Liu Zhencheng. Vanadium-nitrogen microalloying improves the low-temperature impact toughness of high-strength B-beam steel [J], Baotou Steel Technology, 2008, 34(4): 52-55." introduced YQ450NQRl high-strength weather-resistant 310 B-beam steel The design of chemical composition adopts V and N microalloying, which effectively improves the low temperature impact toughness of B-beam. The B-shaped steel relies on the strengthening effect of single vanadium microalloying to improve the strength and toughness, and the production cost is high.

From the above-mentioned prior art, the production of traditional B-shaped steel is mainly based on vanadium microalloying, which improves the strength of steel through the precipitation strengthening effect of vanadium carbonitride, and at the same time improves the weathering and corrosion resistance of steel by adding Cu, Ni and Cr. performance. However, vanadium is a precious metal resource, and the alloy is expensive, which leads to a significant increase in the production cost of B-shaped steel.

SUMMARY OF THE INVENTION

Aiming at the deficiencies in the prior art, the present invention provides a 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel and a production method thereof. The technical scheme of the invention carries out scientific and reasonable optimization design on the alloy composition and smelting production process of 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel, limits the matching relationship of V and Ti content, and maximizes the strengthening effect of microalloying elements. At the same time, the type and distribution of oxides in the steel are optimized, and the comprehensive service performance of the steel is improved. The invention overcomes the problems that the production component system of the hot-rolled B-shaped steel is single at present, that is, it mainly relies on the vanadium microalloying method, which leads to the problems of high alloy element content, low alloy utilization rate and large consumption of precious alloy resources. Reasonable matching of microalloying elements improves the utilization efficiency of alloys, saves alloy resources, and reduces production costs; at the same time, through the regulation of oxides in steel, the adverse effects of titanium microalloying are overcome and product performance is guaranteed.

In order to achieve the above purpose, one aspect of the present invention provides a 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel, based on the total mass of the 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel, the quality of the chemical components contained in it The fractions are: C: 0.06-0.15%, Si: 0.15-0.75%, Mn: 1-1.7%, P: 0.003-0.02%, S: 0.001-0.015%, Cu: 0.1-0.7%, Ni: 0.1-0.7 %, Cr: 0.1-1%, Mo: 0.0001-0.02%, V: 0.01-0.15%, Ti: 0.01-0.15%, Al: 0.001-0.05%, B: 0.0001-0.002%, O: 0.001-0.01% , N: 0.001～0.03%, the balance is Fe and inevitable impurities;

Among them, the content of V and Ti satisfies the following relationship:

0.10＜[V]+1.86[Ti]－5.88[Ti] ² ＜0.22 Formula (1)

In the formula, [ ] represents the mass fraction of the corresponding element, and the unit is %.

A second aspect of the present invention provides a method for producing a 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel, the method comprising the following steps:

(1) Steelmaking

Smelting desulfurized molten iron and/or scrap steel into molten steel; when the molten steel temperature reaches 1600-1750 ° C, and the molten steel composition reaches C: 0.02-0.08%, P: 0.003-0.02%, S: 0.001-0.025% by mass fraction, the steel;

In the process of tapping, add deoxidizing alloy and slag-forming agent to the ladle;

(2) Refining

The ladle is transported to the refining station for refining; during the refining process, electricity is sent to increase temperature, white slag is desulfurized, and deoxidized and alloyed; according to the composition requirements of 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel, the composition of molten steel is adjusted to reach C: 0.06 by mass fraction ～0.15%, Si: 0.15～0.75%, Mn: 1～1.7%, P: 0.003～0.02%, S: 0.001～0.015%, Cu: 0.1～0.7%, Ni: 0.1～0.7%, Cr: 0.1～ 1%, Mo: 0.0001-0.02%, V: 0.01-0.15%, Ti: 0.01-0.15%, Al: 0.001-0.05%, B: 0.0001-0.002%, O: 0.001-0.01%, N: 0.001-0.03 %, in the process of adjusting the composition, first adjust the mass fraction of V to reach 0.01-0.15%, and then adjust the content of Ti according to the following formula (1) to obtain molten steel with qualified composition,

0.10＜[V]+1.86[Ti]－5.88[Ti] ² ＜0.22 Formula (1)

In the formula, [] represents the mass fraction of the corresponding element, and the unit is %;

(3) Continuous casting

The molten steel with qualified composition is sent to a rectangular continuous casting machine for continuous casting to obtain a continuous casting billet;

(4) Rolling

The continuous casting billet is directly sent to the B-shaped steel rolling unit for rolling, or the continuous casting billet is sent to the B-shaped steel rolling unit for rolling after being heated again; B-shaped steel after hot rolling; B-shaped steel after hot rolling is cooled on a cooling bed to obtain 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel.

The principle and design idea of the technical solution of the present invention are:

Weathering B-shaped steel is used in the manufacture of railway transportation vehicles, which has high requirements on the performance and quality of steel products. On the one hand, it is required to have good comprehensive mechanical properties, that is, sufficiently high strength and low temperature toughness; on the other hand, it has excellent weather resistance and can serve in atmospheric corrosive environments for a long time. At present, vanadium microalloying method is generally used in the production of B-shaped steel, and the strength of steel is improved by the precipitation strengthening effect of vanadium carbonitride. In the composition design, the weathering and corrosion resistance of steel is mainly improved by adding Cu, Ni and Cr, and the adverse effects of non-metallic inclusions on mechanical properties and weathering properties are reduced by refining means. However, vanadium is a precious metal resource, and the alloy is expensive, which leads to a significant increase in the production cost of B-shaped steel. And with the increase of vanadium content, the strengthening contribution rate per unit content decreases, that is, the utilization rate of alloying elements decreases, resulting in waste of precious alloying elements. Titanium microalloying has obvious cost advantages, and the reasonable matching of titanium and vanadium can promote the precipitation strengthening effect and improve the utilization rate of alloying elements. However, because the chemical properties of titanium are more active than that of vanadium, and there are many states of existence in steel, its precipitation behavior is more complicated than that of vanadium, so there are great difficulties in practical application.

In the present invention, a large number of theoretical and experimental studies have been carried out in view of the above problems, and the effective component design scheme and production process of the 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel have been established. The solubility of vanadium in austenite in steel is large, and the precipitation behavior is simple. Most of them are precipitated during the cooling transformation process after hot rolling. In order to achieve sufficient precipitation strengthening effect, it is necessary to greatly increase the amount of vanadium added. The precipitation temperature of titanium is higher than that of vanadium, and a large amount of precipitation begins in the austenite in the high-temperature rolling stage. Since the rolling deformation process of B-shaped steel is more complicated than that of strip, bar and wire products, this makes the precipitation behavior of titanium more complicated. Improper distribution of titanium precipitation during deformation and cooling will adversely affect product performance. The carbonitride precipitates of vanadium and titanium have the same crystal structure type, and the two can dissolve each other to form composite precipitates. In the research process of the present invention, it is found that under the reasonable matching conditions of vanadium and titanium content, the two can play a role of mutual promotion, so that the precipitation process is more stable and uniform, and a better precipitation strengthening effect is exerted. At the same time, it is found that when the vanadium and titanium contents are not matched properly, the precipitation behavior and strengthening effect are weakened, and the expected purpose cannot be achieved, and even the performance of the steel cannot meet the standard requirements or cause waste of alloying elements. The present invention optimizes the effective vanadium and titanium content ranges through a large number of experimental researches, and performs nonlinear regression to obtain the best matching relationship formula of vanadium and titanium content suitable for the performance requirements and production process of 450MPa grade B-shaped steel.

On the other hand, titanium has a high affinity with oxygen and nitrogen, and it is easy to produce large-sized titanium oxide and nitride during the steel smelting process, which not only reduces the mechanical properties of the steel, but also has an adverse effect on the weathering and corrosion resistance. . Aiming at this problem, the present invention further improves the refining process, controls the fine dispersion distribution of oxides in the steel, and eliminates the adverse effects on the comprehensive performance while ensuring that the titanium element effectively plays a strengthening role. Under the composition design scheme and smelting production process of the present invention, the strengthening effect of alloy elements is effectively improved, the alloy cost is significantly reduced, and the comprehensive performance of the material is stably improved.

The advantages and beneficial effects of the present invention are:

(1) The present invention breaks through the vanadium-based microalloying means of the existing B-shaped steel production technology, adopts a relatively cheap vanadium-titanium composite microalloying scheme, reduces the alloy cost, improves the economic benefit, and is conducive to saving valuable Alloy resources.

(2) The present invention overcomes the difficulty of applying titanium in hot-rolled B-shaped steel, ensures the full and effective exertion of the strengthening effect, improves the utilization rate of alloy elements, solves the long-standing problem in the iron and steel industry, and is conducive to popularization and application in the industry .

(3) The present invention is synergistically improved in terms of alloy composition and smelting production process, while reducing the cost of the alloy, the mechanical properties, weathering and corrosion resistance are improved, and the comprehensive service performance of the material is further improved compared with conventional process products.

Detailed ways

Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, but not to limit the present invention.

The invention provides a 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel. Based on the total mass of the 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel, the mass fraction of the chemical components contained in it is: C: 0.06～ 0.15%, Si: 0.15-0.75%, Mn: 1-1.7%, P: 0.003-0.02%, S: 0.001-0.015%, Cu: 0.1-0.7%, Ni: 0.1-0.7%, Cr: 0.1-1 %, Mo: 0.0001-0.02%, V: 0.01-0.15%, Ti: 0.01-0.15%, Al: 0.001-0.05%, B: 0.0001-0.002%, O: 0.001-0.01%, N: 0.001-0.03% , the remainder is Fe and inevitable impurities;

Among them, the content of V and Ti satisfies the following relationship:

0.10＜[V]+1.86[Ti]－5.88[Ti] ² ＜0.22 Equation (1)

In the formula, [ ] represents the mass fraction of the corresponding element, and the unit is %.

In a preferred embodiment, the number of oxide particles in the B-shaped steel with a size of 0.25-5 μm and containing two or more elements of Al, Ca, Mg, Zr, Ba, and RE is 200-2000/mm ² .

Further preferably, in the oxide particles having a size of 0.25-5 μm and containing two or more elements of Al, Ca, Mg, Zr, Ba, RE, 10-90% of the oxide particles, based on the number of particles, are oxidized The material particles also contain titanium oxide and/or titanium nitride, and the average volume ratio of titanium oxide and/or titanium nitride in the entire particle is <50%, preferably 5-30%, specifically, for example, 12%, 15% %, 16%.

More preferably, the sum of the mass fractions of Ca, Mg, Zr, Ba, and RE elements in the B-shaped steel is 0.001-0.01%, specifically, 0.003%, 0.004%, 0.006%, and 0.01%.

The preferred properties of the 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel are: yield strength ≥450MPa, -40°C impact toughness AK _V ≥47J, and corrosion resistance ≤50% relative to the Q345B standard sample.

The invention also provides a production method of 450MPa grade vanadium-titanium micro-alloying weather-resistant B-shaped steel. The invention adopts vanadium-titanium composite micro-alloying to replace single vanadium micro-alloying, which reduces the production cost of B-shaped steel and can improve the steel quality. comprehensive performance. Specifically, the production method of the 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel comprises the following steps:

(1) Steelmaking

Smelting desulfurized molten iron and/or scrap steel into molten steel; when the molten steel temperature reaches 1600-1750 ° C, and the molten steel composition reaches C: 0.02-0.08%, P: 0.003-0.02%, S: 0.001-0.025% by mass fraction, the steel;

In the process of tapping, add deoxidizing alloy and slag-forming agent to the ladle;

(2) Refining

The ladle is transported to the refining station for refining; during the refining process, electricity is sent to increase temperature, white slag is desulfurized, and deoxidized and alloyed; according to the composition requirements of 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel, the composition of molten steel is adjusted to reach C: 0.06 by mass fraction ～0.15%, Si: 0.15～0.75%, Mn: 1～1.7%, P: 0.003～0.02%, S: 0.001～0.015%, Cu: 0.1～0.7%, Ni: 0.1～0.7%, Cr: 0.1～ 1%, Mo: 0.0001-0.02%, V: 0.01-0.15%, Ti: 0.01-0.15%, Al: 0.001-0.05%, B: 0.0001-0.002%, O: 0.001-0.01%, N: 0.001-0.03 %, in the process of adjusting the composition, first adjust the mass fraction of V to reach 0.01-0.15%, and then adjust the content of Ti according to the following formula (1) to obtain molten steel with qualified composition,

0.10＜[V]+1.86[Ti]－5.88[Ti] ² ＜0.22 Equation (1)

In the formula, [] represents the mass fraction of the corresponding element, and the unit is %;

(3) Continuous casting

The molten steel with qualified composition is sent to a rectangular continuous casting machine for continuous casting to obtain a continuous casting billet;

(4) Rolling

The continuous casting billet is directly sent to the B-shaped steel rolling unit for rolling, or the continuous casting billet is sent to the B-shaped steel rolling unit for rolling after being heated again; B-shaped steel after hot rolling; B-shaped steel after hot rolling is cooled on a cooling bed to obtain 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel.

In the present invention, the deoxidizing alloy may be at least one of silicon, manganese, aluminum, calcium, barium and deoxidizers commonly used in steelmaking.

In the present invention, the slag-forming agent may be at least one of calcium oxide, pre-melted slag and slag-forming agents commonly used in steelmaking.

In a preferred embodiment, in step (1), the mass fractions of Mo and B in molten steel during tapping satisfy Mo: 0.0001-0.02% and B: 0.0001-0.002%.

In a preferred embodiment, in step (2), during the refining process of molten steel, the bottom of the ladle is blown with argon or nitrogen;

In a preferred embodiment, in step (2), the molten steel is further refined by RH or VD.

In a preferred embodiment, in step (2), when the oxygen mass fraction in molten steel reaches 0.001 to 0.01%, adding two or more elements containing Al, Ca, Mg, Zr, Ba, RE Alloy or cored wire. In the present invention, RE refers to a rare earth element, and in a specific embodiment, RE is a rare earth element, including Ce, La, and Y.

In a preferred embodiment, in step (3), the continuous casting of molten steel adopts full protection casting, and the continuous casting process adopts electromagnetic stirring and/or dynamic reduction of the continuous casting billet;

In a preferred embodiment, in step (3), the continuous casting slab is slowly cooled by stacking.

In a preferred embodiment, in step (4), accelerated cooling is performed on the rolling stock between the rolling mill stands and/or after the exit of the finishing mill, and the cooling methods include water cooling and gas mist cooling.

The present invention will be described in detail below by means of examples. In the following examples and comparative examples, the yield strength, impact toughness and corrosion resistance of the B-shaped steel were measured according to the standard YB/T 5182-2006.

Example 1

This example is used to illustrate the 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel and its production method according to the present invention.

The desulfurized molten iron and scrap steel are smelted into molten steel; when the molten steel temperature reaches 1720 ° C and the molten steel composition reaches C: 0.04%, P: 0.008%, S: 0.02% according to the mass fraction, the steel is tapped; during the tapping process, the molten steel is sent to the ladle Silicon manganese and calcium oxide are added to the medium; the ladle is transported to the refining station for refining; during the LF refining process, electricity is sent to raise the temperature, white slag is desulfurized, and deoxidized and alloyed; The content of Ti is adjusted to 0.07%, which satisfies the relational formula (1): [V]+1.86[Ti]－5.88[Ti] ² =0.11; finally, the molten steel with qualified composition is obtained; the qualified molten steel is sent to the rectangular continuous casting machine, continuous casting is carried out to obtain continuous casting billets; the continuous casting billets are reheated and then sent to the B-shaped steel rolling unit for rolling; the starting rolling temperature of the casting billet is 1250 °C, and the final rolling temperature is 900 °C; the hot-rolled B-shaped steel is obtained; The rolled B-shaped steel is cooled on a cooling bed to obtain 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel A1.

The chemical components contained in the 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel A1 are C: 0.1%, Si: 0.15%, Mn: 1.7%, P: 0.008%, S: 0.005%, Cu: 0.4% by mass fraction , Ni: 0.3%, Cr: 0.4%, Mo: 0.004%, V: 0.01%, Ti: 0.07%, Al: 0.05%, B: 0.0006%, O: 0.004%, N: 0.001%, the balance is Fe and inevitable impurities; [V]+1.86[Ti]−5.88[Ti] ² =0.11.

The yield strength of the 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel A1 is 480MPa, the -40°C impact toughness AK _V is 230J, and the corrosion resistance is 25% higher than that of the Q345B standard sample.

Example 2

This example is used to illustrate the 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel and its production method according to the present invention.

The desulfurized molten iron is smelted into molten steel; when the molten steel temperature reaches 1690 ° C, the molten steel composition reaches C: 0.02%, P: 0.01%, S: 0.015%, Mo: 0.0001%, B: 0.0001% by mass fraction, tapping; During the tapping process, silicon manganese and calcium oxide are added to the ladle; the ladle is transported to the refining station for refining; during the refining process, electricity is sent to increase the temperature, white slag is desulfurized, and deoxidized and alloyed; in the molten steel refining process, argon is blown at the bottom of the ladle. In the process of adjusting the composition, first adjust the mass fraction of V to reach 0.15%, and then adjust the content of Ti to reach 0.03%, which satisfies the relational formula (1): [V]+1.86[Ti]－5.88[Ti] ² =0.20; When the oxygen mass fraction in the molten steel reaches 0.01%, the alloy cored wire containing Al and Ca is added, and the sum of the mass fractions of Ca, Mg, Zr, Ba, Ce, La, and Y elements in the steel is 0.003%, of which Mg, Zr , Ba, Ce, La and Y elements are residual elements in molten steel; finally, qualified molten steel is obtained; the qualified molten steel is sent to a rectangular continuous casting machine for continuous casting to obtain a continuous casting billet; the continuous casting billet is directly sent into B-shaped steel rolling unit rolling; casting billet rolling temperature of 1200 ° C, final rolling temperature of 850 ° C; obtained hot-rolled B-shaped steel; hot-rolled B-shaped steel cooled on a cooling bed to obtain 450MPa grade vanadium-titanium microalloyed weather resistance B-shaped steel A2.

The chemical composition contained in the 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel A2 is C: 0.06%, Si: 0.36%, Mn: 1.36%, P: 0.016%, S: 0.008%, Cu: 0.2% by mass fraction , Ni: 0.4%, Cr: 0.1%, Mo: 0.0001%, V: 0.15%, Ti: 0.03%, Al: 0.02%, B: 0.0001%, O: 0.007%, N: 0.004%, the balance is Fe and inevitable impurities; [V]+1.86[Ti]−5.88[Ti] ² =0.20.

The number of oxide particles in the steel with a size of 0.25-5 μm and containing Al and Ca elements is 1260/mm ² ; in terms of the number of particles, 55% of the above oxide particles also contain titanium oxide and titanium nitride, and the whole particle The average volume ratio of titanium oxide and titanium nitride in the steel is 15%; the sum of the mass fractions of Ca, Mg, Zr, Ba, and RE elements in the steel is 0.003%.

The yield strength of the 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel A2 is 465MPa, the -40°C impact toughness AK _V is 240J, and the corrosion resistance is 34% higher than that of the Q345B standard sample.

Example 3

This example is used to illustrate the 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel and its production method according to the present invention.

The desulfurized molten iron is smelted into molten steel; when the molten steel temperature reaches 1750 ° C, the molten steel composition reaches C: 0.02%, P: 0.003%, S: 0.005%, Mo: 0.01%, B: 0.0005% by mass fraction, tapping; During the tapping process, aluminum deoxidation and pre-melting slag are added to the ladle; the ladle is transported to the refining station for refining; during the refining process, electricity is sent to raise the temperature, white slag is desulfurized, nitrogen is blown at the bottom of the ladle, and deoxidation alloying is performed; in the process of adjusting the composition , first adjust the mass fraction of V to reach 0.12%, and then adjust the content of Ti to reach 0.01%, which satisfies the relational formula (1): [V]+1.86[Ti]－5.88[Ti] ² =0.138; RH refining the molten steel; When the oxygen mass fraction in the molten steel reaches 0.001%, the alloy containing Mg and Zr is added; finally, the molten steel with qualified composition is obtained; the qualified molten steel is sent to the rectangular continuous casting machine for full protection casting. The continuous casting process adopts electromagnetic stirring to obtain Continuous casting billet; Continuous casting billet is slowly cooled by stacking, and then heated again and sent to the B-shaped steel rolling unit for rolling; the starting rolling temperature of the casting billet is 1100 °C, and the final rolling temperature is 750 °C; Water cooling accelerates cooling; hot-rolled B-shaped steel is obtained; the hot-rolled B-shaped steel is cooled on a cooling bed to obtain 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel A3.

The chemical composition contained in the 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel A3 is C: 0.13%, Si: 0.52%, Mn: 1.56%, P: 0.003%, S: 0.001%, Cu: 0.1% by mass fraction , Ni: 0.7%, Cr: 0.5%, Mo: 0.01%, V: 0.12%, Ti: 0.01%, Al: 0.015%, B: 0.0005%, O: 0.001%, N: 0.025%, the balance is Fe and inevitable impurities; [V]+1.86[Ti]−5.88[Ti] ² =0.138.

The number of oxide particles in the steel ranging from 0.25 to 5 μm and containing Mg and Zr elements is 860/mm ² ; in terms of the number of particles, 74% of the above oxides also contain titanium oxide and titanium nitride, and the whole particle The average volume of titanium oxide and titanium nitride accounts for 16%; the sum of the mass fractions of Ca, Mg, Zr, Ba, and RE elements in the steel is 0.01%.

The yield strength of the 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel A3 is 475MPa, the -40°C impact toughness AK _V is 180J, and the corrosion resistance is 12% higher than that of the Q345B standard sample.

Example 4

This example is used to illustrate the 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel and its production method according to the present invention.

The scrap steel is smelted into molten steel; when the temperature of the molten steel reaches 1690 ° C and the composition of the molten steel reaches C: 0.04%, P: 0.02%, S: 0.025% by mass fraction, the steel is tapped; during the tapping process, silicon is added to the ladle Calcium barium and calcium oxide; the ladle is transported to the refining station for refining; during the refining process, electricity is sent to increase temperature, white slag is desulfurized, and deoxidized and alloyed; in the process of adjusting the composition, the mass fraction of V is first adjusted to 0.08%, and then the content of Ti is adjusted. The content reaches 0.12%, which satisfies the relational formula (1): [V]+1.86[Ti]－5.88[Ti] ² =0.218; VD refining is carried out in molten steel; when the oxygen mass fraction in molten steel reaches 0.007%, Al, Ca, Ba alloy; finally, the molten steel with qualified composition is obtained; the molten steel with qualified composition is sent to the rectangular continuous casting machine for continuous casting to obtain the continuous casting billet; the continuous casting billet is directly sent to the B-shaped steel rolling unit for rolling; the casting billet is rolled The temperature is 1100°C, and the final rolling temperature is 850°C; after the exit of the final rolling mill, the rolling stock is subjected to water-cooling accelerated cooling; the B-shaped steel after hot rolling is obtained; Weathering B-shaped steel A4.

The chemical components contained in the 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel A4 are C: 0.08%, Si: 0.75%, Mn: 1.0%, P: 0.02%, S: 0.012%, Cu: 0.7% by mass fraction , Ni: 0.1%, Cr: 1.0%, Mo: 0.008%, V: 0.08%, Ti: 0.12%, Al: 0.008%, B: 0.002%, O: 0.003%, N: 0.03%, the balance is Fe and inevitable impurities; [V]+1.86[Ti]−5.88[Ti] ² =0.218.

The number of oxide particles in the steel with a size of 0.25 to 5 μm and containing elements of Al, Ca, and Ba is 540/mm ² ; in terms of the number of particles, 76% of the above oxides also contain titanium oxide and titanium nitride. The average volume of titanium oxide and titanium nitride in the particles accounts for 15%; the sum of the mass fractions of Ca, Mg, Zr, Ba, and RE elements in the steel is 0.006%.

The 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel A4 has a yield strength of 490MPa, a -40°C impact toughness AK _V of 240J, and a corrosion resistance of 15% relative to the Q345B standard sample.

Example 5

This example is used to illustrate the 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel and its production method according to the present invention.

The desulfurized molten iron and scrap steel are smelted into molten steel; when the molten steel temperature reaches 1650 ° C and the molten steel composition reaches C: 0.06%, P: 0.012%, S: 0.02% according to the mass fraction, the steel is tapped; during the tapping process, the molten steel is sent to the ladle. Strontium and fluorite are added to the medium; the ladle is transported to the refining station for refining; during the refining process, electricity is sent to increase the temperature, white slag is desulfurized, and deoxidized and alloyed; in the process of adjusting the composition, the mass fraction of V is first adjusted to 0.03%, and then the Ti is adjusted content reaches 0.15%, which satisfies relational formula (1): [V]+1.86[Ti]－5.88[Ti] ² =0.177; when the oxygen mass fraction in molten steel reaches 0.01%, the alloy cored wire containing Ca and Ce is added Finally, get the molten steel with qualified composition; send the qualified molten steel to the rectangular continuous casting machine for continuous casting to obtain the continuous casting billet; after the continuous casting billet is heated again, it is sent to the B-shaped steel rolling unit for rolling; the casting billet is rolled The temperature is 1180°C, and the final rolling temperature is 920°C; the hot-rolled B-shaped steel is obtained; the hot-rolled B-shaped steel is cooled on a cooling bed to obtain a 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel A5.

The chemical components contained in the 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel A5 are C: 0.15%, Si: 0.6%, Mn: 1.25%, P: 0.012%, S: 0.015%, Cu: 0.5% by mass fraction , Ni: 0.2%, Cr: 0.8%, Mo: 0.02%, V: 0.03%, Ti: 0.15%, Al: 0.001%, B: 0.001%, O: 0.01%, N: 0.014%, the balance is Fe and inevitable impurities; [V]+1.86[Ti]−5.88[Ti] ² =0.177.

The number of oxide particles in the steel with a size of 0.25 to 5 μm and containing elements of Ca and Ce is 630/mm ² ; in terms of the number of particles, 70% of the above oxides also include titanium oxide and titanium nitride, and the whole particle The average volume of titanium oxide and titanium nitride accounts for 12%; the sum of the mass fractions of Ca, Mg, Zr, Ba, and RE elements in the steel is 0.004%.

The yield strength of the 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel A5 is 490MPa, the -40°C impact toughness AK _V is 210J, and the corrosion resistance is 21% higher than that of the Q345B standard sample.

Comparative Example 1

This comparative example is used to illustrate a vanadium-titanium-containing B-shaped steel B1 and its production method.

The desulfurized molten iron and scrap steel are smelted into molten steel; when the molten steel temperature reaches 1700 ° C, and the molten steel composition reaches C: 0.04%, P: 0.01%, S: 0.01% by mass fraction, the steel is tapped; during the tapping process, the molten steel is sent to the ladle. Silicon manganese and calcium oxide are added to the medium; the ladle is transported to the refining station for refining; during the LF refining process, electricity is sent to raise the temperature, white slag is desulfurized, and deoxidized and alloyed; in the process of adjusting the composition, according to the composition of the B-shaped steel B1 containing vanadium and titanium It is required to adjust the content of all alloying elements at the same time; the molten steel obtained by smelting is sent to a rectangular continuous casting machine for continuous casting to obtain a continuous casting billet; the continuous casting billet is reheated and sent to the B-shaped steel rolling unit for rolling; the billet rolling temperature 1250 ℃, finish rolling temperature 900 ℃; obtain B-shaped steel after hot rolling; B-shaped steel after hot rolling is cooled on a cooling bed to obtain B-shaped steel B1 containing vanadium and titanium.

The chemical components contained in the S-shaped steel B1 are C: 0.12%, Si: 0.15%, Mn: 1.57%, P: 0.01%, S: 0.01%, Cu: 0.4%, Ni: 0.3%, Cr: 0.4%, Mo: 0.004%, V: 0.03%, Ti: 0.03%, Al: 0.04%, B: 0.001%, O: 0.005%, N: 0.005%, the balance is Fe and inevitable impurities; [V ]+1.86[Ti]−5.88[Ti] ² =0.08.

The yield strength of the B-shaped steel B1 is 420MPa, the impact toughness AK _V at -40°C is 200J, and the corrosion resistance is 24% higher than that of the Q345B standard sample.

Comparative Example 2

This comparative example is used to illustrate a vanadium-titanium-containing B-shaped steel B2 and its production method.

The desulfurized molten iron and scrap steel are smelted into molten steel; when the molten steel temperature reaches 1720 ° C, and the molten steel composition reaches C: 0.05%, P: 0.005%, S: 0.006% by mass fraction, the steel is tapped; during the tapping process, the molten steel is sent to the ladle. Aluminium and pre-melted slag are added to the medium; the ladle is transported to the refining station for refining; in the LF refining process, electricity is sent to increase temperature, white slag is desulfurized, and deoxidized and alloyed; in the process of adjusting the composition, according to the composition of the vanadium-titanium-containing B-shaped steel B2 It is required to adjust the content of all alloying elements at the same time; the molten steel obtained by smelting is sent to a rectangular continuous casting machine for continuous casting to obtain a continuous casting billet; the continuous casting billet is reheated and sent to the B-shaped steel rolling unit for rolling; the billet rolling temperature 1260 ℃, finish rolling temperature 850 ℃; obtain B-shaped steel after hot rolling; B-shaped steel after hot rolling is cooled on a cooling bed to obtain B-shaped steel B2 containing vanadium and titanium.

The chemical composition contained in the S-shaped steel B2 is C: 0.09%, Si: 0.70%, Mn: 1.2%, P: 0.005%, S: 0.006%, Cu: 0.5%, Ni: 0.3%, Cr: 1.0%, Mo: 0.01%, V: 0.12%, Ti: 0.12%, Al: 0.01%, B: 0.001%, O: 0.003%, N: 0.003%, the balance is Fe and inevitable impurities; [V ]+1.86[Ti]−5.88[Ti] ² =0.26.

The yield strength of the B-shaped steel B2 is 500MPa, the impact toughness AK _V at -40°C is 22J, and the corrosion resistance is 65% higher than that of the Q345B standard sample.

The performance data of the B-shaped steel prepared in the above Examples 1-5 and Comparative Examples 1-2 are shown in Table 1 below.

Table 1

It can be seen from the data in Table 1 above that the S-shaped steels of Examples 1 to 5 of the present invention have good yield strength, impact toughness and corrosion properties, all of which meet the standard requirements. The element content of the B-shaped steel of Comparative Example 1 is lower than the lower limit of the relational formula (1), and the yield strength of the product is lower than 450MPa, which does not meet the standard requirements. The element content of the B-shaped steel of Comparative Example 2 is higher than the upper limit of the relational formula (1), and the yield strength reaches more than 450MPa, but the impact toughness and corrosion resistance are significantly reduced, and the product does not meet the standard requirements.

From the above examples and comparative examples, it can be seen that by limiting the reasonable matching relationship of alloy elements in the present invention, the strengthening effect of alloy elements is effectively improved, the alloy cost is significantly reduced, and the overall performance of the material is stably improved.

The preferred embodiments of the present invention have been described above in detail, however, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, a variety of simple modifications can be made to the technical solutions of the present invention, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be regarded as the content disclosed in the present invention. All belong to the protection scope of the present invention.

Claims (10)

1. a 450MPa grade vanadium-titanium microalloying weathering B-shaped steel, is characterized in that, with the total mass of the described 450MPa grade vanadium-titanium microalloying weathering B-shaped steel as a benchmark, the mass fraction of the chemical composition it comprises is: C: 0.06-0.15%, Si: 0.15-0.75%, Mn: 1-1.7%, P: 0.003-0.02%, S: 0.001-0.015%, Cu: 0.1-0.7%, Ni: 0.1-0.7%, Cr: 0.1 ～1%, Mo: 0.0001～0.02%, V: 0.01～0.15%, Ti: 0.01～0.15%, Al: 0.001～0.05%, B: 0.0001～0.002%, O: 0.001～0.01%, N: 0.001～ 0.03%, the balance is Fe and inevitable impurities; Among them, the content of V and Ti satisfies the following relationship: 0.10＜[V]+1.86[Ti]－5.88[Ti] ² ＜0.22 Formula (1) In the formula, [ ] represents the mass fraction of the corresponding element, and the unit is %. 2. 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel according to claim 1, characterized in that, the size of the B-shaped steel is 0.25～5 μm and contains two kinds of Al, Ca, Mg, Zr, Ba, RE or The number of oxide particles of two or more elements is 200 to 2000 particles/mm ² . 3. The 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel according to claim 2, wherein the size is 0.25-5 μm and contains two or more of Al, Ca, Mg, Zr, Ba, RE In the oxide particles of the element, 10-90% of the oxide particles further contain titanium oxide and/or titanium nitride based on the number of particles, and the average volume ratio of titanium oxide and/or titanium nitride in the whole particle <50%. 4. The 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel according to claim 2 or 3, wherein the sum of the mass fractions of Ca, Mg, Zr, Ba, RE elements in the B-shaped steel is 0.001-0.01%. 5. a production method of 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel, is characterized in that, the method comprises the following steps: (1) Steelmaking Smelting desulfurized molten iron and/or scrap steel into molten steel; when the molten steel temperature reaches 1600-1750 ° C, and the molten steel composition reaches C: 0.02-0.08%, P: 0.003-0.02%, S: 0.001-0.025% by mass fraction, the steel; In the process of tapping, add deoxidizing alloy and slag-forming agent to the ladle; (2) Refining The ladle is transported to the refining station for refining; during the refining process, electricity is sent to increase temperature, white slag is desulfurized, and deoxidized and alloyed; according to the composition requirements of 450MPa grade vanadium-titanium microalloyed weather-resistant B-shaped steel, the composition of molten steel is adjusted to reach C: 0.06 by mass fraction ～0.15%, Si: 0.15～0.75%, Mn: 1～1.7%, P: 0.003～0.02%, S: 0.001～0.015%, Cu: 0.1～0.7%, Ni: 0.1～0.7%, Cr: 0.1～ 1%, Mo: 0.0001-0.02%, V: 0.01-0.15%, Ti: 0.01-0.15%, Al: 0.001-0.05%, B: 0.0001-0.002%, O: 0.001-0.01%, N: 0.001-0.03 %, in the process of adjusting the composition, first adjust the mass fraction of V to reach 0.01-0.15%, and then adjust the content of Ti according to the following formula (1) to obtain molten steel with qualified composition, 0.10＜[V]+1.86[Ti]－5.88[Ti] ² ＜0.22 Formula (1) In the formula, [] represents the mass fraction of the corresponding element, and the unit is %; (3) Continuous casting The molten steel with qualified composition is sent to a rectangular continuous casting machine for continuous casting to obtain a continuous casting billet; (4) Rolling The continuous casting billet is directly sent to the B-shaped steel rolling unit for rolling, or the continuous casting billet is sent to the B-shaped steel rolling unit for rolling after being heated again; B-shaped steel after hot rolling; B-shaped steel after hot rolling is cooled on a cooling bed to obtain 450MPa grade vanadium-titanium microalloyed weathering B-shaped steel. 6 . The production method according to claim 5 , wherein, in step (1), the mass fractions of Mo and B in molten steel during tapping satisfy Mo: 0.0001-0.02% and B: 0.0001-0.002%. 7 . 7. production method according to claim 5, is characterized in that, in step (2), in molten steel refining process, ladle bottom blows argon or nitrogen; Preferably, in step (2), the molten steel is further refined by RH or VD. 8. The production method according to claim 5 or 7, characterized in that, in step (2), when the oxygen mass fraction in molten steel reaches 0.001 to 0.01%, adding Al, Ca, Mg, Zr, Ba, Alloy or cored wire of two or more elements in RE. 9. production method according to claim 5 is characterized in that, in step (3), the continuous casting of molten steel adopts full protection casting, and the continuous casting process adopts electromagnetic stirring and/or continuous casting billet dynamic reduction; Preferably, in step (3), the continuous casting slab is slowly cooled by stacking. 10. The production method according to claim 5, characterized in that, in step (4), accelerated cooling is performed on the rolling stock between the rolling mill stands and/or after the exit of the finishing mill, and the cooling methods include water cooling and gas mist cooling .