CN109023048A - A kind of 460MPa level high-strength quake-proof fire-resistant and weather-resistant steel hot-rolled coil and its production method - Google Patents

Abstract

The present invention provides a kind of 460MPa level high-strength quake-proof fire-resistant and weather-resistant steel hot-rolled coil and its production methods, the fire-resistant and weather-resistant steel, chemical component including following weight percent: carbon 0.045%~0.055%, silicon: 0.2%~0.3%, manganese: 1.6%~1.8%, phosphorus≤0.02%, sulphur≤0.005%, copper: 0.35%~0.40%, chromium: 0.6%~0.8%, nickel: 0.3%~0.4%, niobium: 0.04%~0.05%, titanium: 0.01%~0.02%, molybdenum: 0.2%~0.3%, remaining is iron and inevitable impurity.Fire-resistant and weather-resistant steel hot-rolled coil of the present invention meets corrosion resistance requirement by adding Cu, Cr, Ni element, adds the air-cooled technique of the reasonable controlled rolling of Nb, Mo Match of elemental composition, using ferrite+bainite as target metallographic structure, meets anti-seismic performance and high-temperature behavior requirement.In addition, the present invention by the design of microalloy optimizing components matches reasonable controlled rolling and Controlled cooling process obtains that room temperature, mechanical behavior under high temperature be excellent and the good high-quality fire-resistant and weather-resistant steel of corrosion resistance.

Description

A 460MPa grade high-strength shock-resistant refractory weather-resistant steel hot-rolled coil and its production method

technical field

The invention belongs to the production field of hot-rolled high-strength low-alloy steel, and in particular relates to a 460MPa-level high-strength anti-seismic, refractory, weather-resistant steel hot-rolled coil and a preparation method thereof.

Background technique

With the rise of high-rise, super high-rise, long-span and other structural buildings, steel structures have become one of the main directions for the development of the construction industry, but the fire resistance and corrosion resistance of ordinary steel structures are worse than concrete buildings, and the fire resistance limit of ordinary steel The time is very short, and as the temperature rises, the yield strength of the steel drops significantly, and it basically loses its bearing capacity when it reaches above 600°C. In addition, corrosion is also one of the main reasons for the failure of ordinary steel structure buildings, and ordinary steel structures need to add additional anti-corrosion measures in architectural design. In order to ensure the earthquake resistance, fire resistance and corrosion resistance of steel structure buildings, a lot of related work has been carried out at home and abroad, but mainly the research on the production technology of low-strength hot-rolled medium and thick plates, and the production of high-strength grade refractory and weather-resistant steel hot-rolled coils. Research is rarely reported.

Contents of the invention

In view of the above-mentioned defects in the background technology, the main purpose of the present invention is to provide a 460MPa-level high-strength shock-resistant refractory and weather-resistant steel hot-rolled coil and its production method, which obtains high-strength steel with excellent comprehensive mechanical properties at room temperature, high-temperature mechanical properties, and corrosion resistance. Shock-resistant fire-resistant and weather-resistant steel.

In order to solve the above defects, the technical solution adopted by the present invention is: a 460MPa grade high-strength shock-resistant refractory weather-resistant steel hot-rolled coil and its production method, including the following chemical components in weight percentages:

Carbon 0.045%～0.055%, Silicon: 0.2%～0.3%, Manganese: 1.6%～1.8%, Phosphorus ≤0.02%, Sulfur ≤0.005%, Copper: 0.35%～0.40%, Chromium: 0.6%～0.8%, Nickel Niobium: 0.3% to 0.4%, niobium: 0.04% to 0.05%, titanium: 0.01% to 0.02%, molybdenum: 0.2% to 0.3%, and the rest is iron and unavoidable impurities.

As a further preference, the fire-resistant and weather-resistant steel is a hot-rolled coil of fire-resistant and weather-resistant steel.

As a further preference, the thickness specification of the fire-resistant and weather-resistant steel hot-rolled coil is 6.0 mm to 16.0 mm.

As a further preference, the metallographic structure of the refractory and weather-resistant steel hot-rolled coil is ferrite+granular bainite, wherein the volume fraction of ferrite is ≤20%, and the volume fraction of granular bainite is ≥80%.

As a further preference, the weather resistance index of the fire-resistant and weather-resistant steel hot-rolled coil is ≥ 6.5, the yield ratio ≤ 0.83, and the yield strength ≥ 460 MPa.

Another object of the present invention is to provide a method for preparing the above-mentioned fire-resistant and weather-resistant steel, comprising the following steps:

The molten steel is smelted in a converter to obtain a slab, and the weight percentage of the chemical composition of the slab is as follows: carbon 0.045% to 0.055%, silicon: 0.2% to 0.3%, manganese: 1.6% to 1.8%, phosphorus ≤ 0.02%, sulfur ≤ 0.005% %, copper: 0.35% to 0.40%, chromium: 0.6% to 0.8%, nickel: 0.3% to 0.4%, niobium: 0.04% to 0.05%, titanium: 0.01% to 0.02%, molybdenum: 0.2% to 0.3%, The remainder is iron and unavoidable impurities;

The slab is heated, and then subjected to rough rolling and finish rolling to obtain a hot-rolled sheet, and then the hot-rolled sheet is subjected to laminar cooling, and coiled into a hot-rolled coil after cooling.

As a further preference, the temperature of the slab coming out of the furnace is 1180°C-1220°C, and the heating time is 180min-240min.

As a further preference, the rough rolling adopts a 1+5 mode, including rough rolling R1 one-pass rolling and rough rolling R2 five-pass rolling; during the rough rolling process, it is guaranteed that R1 is descaled once and R2 is descaled twice , R2 outlet temperature is 970 ° C ~ 1000 ° C.

As a further preference, the finish rolling adopts 7-stand continuous rolling, the finish rolling temperature is 780°C-820°C, the finish rolling speed is constant, and the steel throwing speed is ≥3.0m/s.

As a further preference, the laminar cooling process adopts a post-stage cooling process, 1 to 3 sets of laminar cooling water are closed, and an air cooling + water cooling process is adopted.

As a further preference, the control range of the coiling temperature is 400°C to 450°C.

The beneficial effects of the present invention are: the fire-resistant and weather-resistant steel of the present invention includes the following chemical components in weight percentage: carbon 0.045%-0.055%, silicon: 0.2%-0.3%, manganese: 1.6%-1.8%, phosphorus≤0.02%, sulfur ≤0.005%, copper: 0.35%~0.40%, chromium: 0.6%~0.8%, nickel: 0.3%~0.4%, niobium: 0.04%~0.05%, titanium: 0.01%~0.02%, molybdenum: 0.2%~0.3 %, the rest is iron and unavoidable impurities. The fire-resistant and weather-resistant steel hot-rolled coils of the present invention meet the corrosion resistance requirements by adding Cu, Cr, and Ni elements, adding Nb, Mo elements to match the reasonable controlled rolling air-cooling process, and taking ferrite + bainite as the target metallographic structure, Meet the requirements of anti-seismic performance and high temperature performance.

In addition, the present invention obtains high-quality fire-resistant and weather-resistant steel with excellent mechanical properties at room temperature and high temperature and good corrosion resistance through optimized design and matching of micro-alloy components, reasonable controlled rolling and controlled cooling process. The fire-resistant and weather-resistant steel of the present invention has yield strength ≥ 460MPa, tensile strength ≥ 570MPa, elongation ≥ 20%, yield strength ratio ≤ 0.83, impact absorption energy at -40°C greater than or equal to 60J, 180°d=2a bending qualified, 600°C heat preservation 3h yield strength ≥ 307MPa, weather resistance index I ≥ 6.5, excellent comprehensive performance.

Description of drawings

Fig. 1 is a schematic diagram of the metallographic structure of a hot-rolled coil of a 460MPa-grade high-strength anti-shock, fire-resistant and weather-resistant steel according to an embodiment of the present invention.

Detailed ways

The present invention provides a 460MPa grade high-strength shock-resistant refractory and weather-resistant steel hot-rolled coil and a production method thereof, thereby obtaining a refractory and weather-resistant steel with excellent comprehensive properties such as excellent shock resistance, fire resistance, and weather resistance.

In order to solve the above problems, the main ideas of the embodiments of the present invention are:

A 460MPa grade high-strength shock-resistant refractory and weather-resistant steel hot-rolled coil, including the following chemical components in weight percentages:

Carbon 0.045%～0.055%, Silicon: 0.2%～0.3%, Manganese: 1.6%～1.8%, Phosphorus ≤0.02%, Sulfur ≤0.005%, Copper: 0.35%～0.40%, Chromium: 0.6%～0.8%, Nickel Niobium: 0.3% to 0.4%, niobium: 0.04% to 0.05%, titanium: 0.01% to 0.02%, molybdenum: 0.2% to 0.3%, and the rest is iron and unavoidable impurities.

Among them, C (carbon) element is one of the most effective strengthening elements in steel, and it is also the cheapest chemical element, but C can significantly reduce the plasticity and toughness of steel, and the higher the carbon content, the worse the welding performance. Therefore, the C content ranges from 0.045% to 0.055%.

Si (silicon) element has a strong solid solution strengthening effect, which can significantly increase the tensile strength of steel, and slightly increase the yield strength of steel, but the plastic toughness has decreased. The use of Si in combination with other elements such as Cu, Cr, and P can improve the weather resistance of steel. Higher Si content is conducive to refining α-Fe0OH, thereby reducing the overall corrosion rate of steel. Therefore, the Si content is 0.2% to 0.3%. .

The solid solution strengthening effect of Mn (manganese) element is obvious, and the strength can be effectively improved under room temperature and high temperature conditions, and the Mn content is 1.6% to 1.8%.

P (phosphorus) element is the main strengthening element in steel, and at the same time, it is an element that improves the weather resistance of steel. On the one hand, P has a strong solid solution strengthening effect, on the other hand, P element can significantly improve the atmospheric corrosion resistance of steel as an anode depolarizer, but the presence of P in steel will deteriorate the toughness of steel, especially severely reduce the corrosion resistance of steel. Excellent low temperature impact toughness, so the P element is ≤0.02%.

S (sulfur) elements are easy to form MnS inclusions with Mn elements and deteriorate the mechanical properties of steel. In high-strength wear-resistant steels, the S content should be as low as possible to prevent microcracks from initiating at the MnS inclusions. The upper limit of the S content in the present invention 0.005%.

Cu (copper) is the earliest discovered alloying element resistant to atmospheric corrosion. When a certain amount of Cu element is added to the steel, it has better weather resistance than ordinary carbon steel no matter in the rural atmosphere, industrial atmosphere or marine atmosphere. The simultaneous presence of Cu and P elements can also form various compound salts, which become the core of FeOOH crystallization, reduce the ion channel and anode area through the refinement of the inner rust layer, reduce the formation of Fe ₃ O ₄ , and reduce the conductivity of the inner rust layer sex. However, Cu element is very easy to cause "copper brittleness" and seriously affects the surface quality of the strip steel. Considering comprehensively, the content of Cu element is controlled at 0.35% to 0.40%.

Cr (chromium) element can effectively improve the corrosion resistance of steel. When Cr and Cu are added to steel at the same time, the effect is particularly obvious. The increase of Cr content is conducive to the refinement of α-FeOOH. When the α-FeOOH at the rust layer and metal interface When the Cr content exceeds 5%, it can effectively suppress corrosive ions. In addition, Cr element can significantly improve the strength, hardness and wear resistance of steel, and increase the hardenability of steel, but at the same time it can also reduce the plasticity and toughness of steel. Considering that the content of Cr element in steel is controlled at 0.6% to 0.8% %.

Ni (nickel) is a relatively stable element. The addition of Ni can change the self-corrosion potential of steel to the positive direction, increasing the stability of the steel. In addition, the addition of Ni is mainly to form a Cu-Ni alloy with Cu to prevent corrosion. For the occurrence of "copper embrittlement", the control range of Ni content is comprehensively considered to be 0.3% to 0.4%.

Nb (niobium) element has significant fine-grain strengthening and moderate precipitation strengthening effect. Nb element can effectively control the size of prior austenite, refine bainite grains, and achieve fine-grain strengthening effect; Nb in austenite Deformation-induced precipitation and precipitation in ferrite can both play a certain role in precipitation strengthening, and the second phase precipitation of Nb has high thermal stability, which can not only improve the strength at room temperature, but also help to improve the strength at high temperature. , the Nb element content is 0.04% to 0.05%.

Ti (titanium) is a strong carbide forming element. It has a strong binding force with C and S in steel. The affinity between Ti and S is greater than that between Fe and S. Titanium sulfide is preferentially formed in Ti-containing steel to inhibit FeS. The formation of steel reduces the hot brittleness of steel. The carbides formed by Ti and C have extremely strong binding force and are extremely stable. When the heating temperature reaches above 1000°C, TiC begins to dissolve, and a large amount of TiC can be precipitated in the subsequent hot rolling and coiling process, which plays a significant role in precipitation. Strengthening effect, but the fine-grain strengthening effect of Ti is limited, comprehensively considering that the content of Ti element in the present invention is 0.01%-0.02%.

Mo (molybdenum) is the most effective alloying element to improve the high temperature strength of steel. It is an essential alloying element in refractory steel. Mo has three strengthening mechanisms in refractory steel: solid solution strengthening, precipitation strengthening and promoting bainite transformation. Play a role. The element radius of Mo is larger than that of Fe, and the Mo element mainly existing in the form of solid solution can significantly strengthen the ferrite matrix, and the Mo element content is 0.2% to 0.3%. The embodiment of the present invention adopts a low Mo composition design, realizes ferrite + bainite structure through controlled rolling and controlled cooling process, replaces solid solution strengthening of Mo element with bainite structure dislocation strengthening, and reduces microalloy cost.

In the embodiment of the present invention, hot-rolled refractory and weather-resistant steel coils can be prepared through conventional hot continuous rolling production lines, and the thickness specification can be 6.0 mm to 16.0 mm. For example, it includes the following steps: after molten steel is smelted in a converter, a slab containing the above-mentioned chemical composition is obtained; the slab is heated, and then a hot-rolled sheet is obtained through rough rolling and finish rolling, and then the hot-rolled sheet is subjected to laminar flow After cooling, it is coiled into hot-rolled coils.

The embodiment of the present invention precisely regulates the volume fraction of ferrite and bainite through the matching design of finishing rolling temperature, steel throwing speed and cooling mode, and satisfies the requirements of yield ratio and high-temperature mechanical properties at the same time.

Furthermore, the preparation method of the embodiment of the present invention adopts low-temperature controlled rolling to give full play to the fine-grain strengthening effect of Nb. The temperature control range of the slab out of the furnace is 1180°C to 1220°C, the R2 outlet temperature is 970°C to 1000°C, and the final rolling temperature is 780℃～820℃.

Further, in order to accurately control the volume fraction of ferrite, constant-speed rolling can be used in the finishing rolling process, and different steel throwing speeds can be set for different thickness specifications. The steel throwing speed is ≥ 3.0m/s. According to different steel throwing speeds, different numbers of front-end headers are closed to control the residence time of the steel plate in the ferrite phase region, and then control the ferrite volume fraction.

Further, the post-stage cooling process is used to control the cooling process, 1 to 3 groups of laminar cooling water are closed, and the air-cooling + water-cooling process is used to control the ferrite volume fraction, and then control the yield ratio.

Furthermore, the preparation method of the embodiment of the present invention adopts low-temperature coiling, and the coiling temperature is precisely controlled by adjusting the laminar cooling water, for example, the coiling temperature is set in the bainite transformation phase region, and the control range is 400°C to 450°C to ensure a large amount of bainite structure.

In summary, the embodiment of the present invention obtains comprehensive mechanical properties at room temperature, high temperature mechanical High-strength, shock-resistant, fire-resistant and weather-resistant steel with excellent performance and corrosion resistance.

Relying on the national key research and development plan "Research on the Stabilized Production and Application of 460MPa Anti-seismic, Corrosion-resistant and Fire-resistant Steel Plates and Section Steels (2017YFB0304703)", the present invention aims to provide a hot-rolled coil with excellent comprehensive properties such as excellent shock resistance, fire resistance, and weather resistance. its preparation method.

In order to make the above and other objects, features, and advantages of the present invention more comprehensible, the following examples are given to illustrate the fire-resistant and weather-resistant steel hot-rolled coils of the present invention and the preparation method thereof.

The design of the 460MPa high-strength shock-resistant, refractory and weather-resistant steel hot-rolled coil in the embodiment of the present invention is as follows: the production process is: continuous casting slab heating→rough descaling→fixed width press→rough rolling→flying shear→finish descaling→finish rolling → Laminar cooling → Coiling. The chemical composition of the above-mentioned slabs is shown in Table 1.

In addition, the temperature of the slab out of the furnace is 1180°C~1220°C, and the heating time is 180min~240min; the rough rolling adopts the 1+5 mode, that is, the rough rolling R1 is rolled in one pass, and the rough rolling R2 is rolled in five passes. Guaranteed one descaling of R1, two descaling of R2, the outlet temperature of R2 is 970℃～1000℃; Steel speed ≥ 3.0m/s; controlled cooling process adopts post cooling process, closes 1 to 3 groups of laminar cooling water, controls ferrite volume fraction ≤ 20% by air cooling + water cooling process, coiling temperature control range is 400 ℃ ~450°C, to ensure that more than 80% bainite structure is obtained, and by accurately controlling the volume fraction of ferrite structure and bainite structure, the yield ratio of hot-rolled coils is guaranteed to be ≤0.83.

Table 1

Wherein, slab heating and rough rolling process parameters are as shown in Table 2 in the embodiment of the present invention:

Table 2

Finish rolling and cooling process parameters are shown in Table 3 in the embodiment of the present invention:

table 3

The mechanical properties ((longitudinal sample)) of the fire-resistant and weather-resistant steel provided by the embodiments of the present invention are shown in Table 4. The room temperature tensile properties, bending properties, impact properties and high-temperature performance inspections are respectively implemented in the standard "GB/T228.1 Metal Material Tensile Tensile Test Part 1: Room Temperature Test Method", "GB/T232 Metal Material Bending Test Method", "GB/T229 Metal Material Charpy Pendulum Impact Test Method", "GB/T228.2 Metal Material Tensile Test Part 2 Part: High Temperature Test Methods".

Table 4

Fig. 1 is a schematic diagram of the metallographic structure of a 460MPa-grade high-strength shock-resistant refractory and weather-resistant steel hot-rolled coil prepared in Example 1 of the present invention.

The above-mentioned technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

The fire-resistant and weather-resistant steel hot-rolled coils of the present invention meet the corrosion resistance requirements by adding Cu, Cr, and Ni elements, adding Nb, Mo elements to match the reasonable controlled rolling air-cooling process, and taking ferrite + bainite as the target metallographic structure, Meet the requirements of anti-seismic performance and high temperature performance.

In addition, the present invention obtains high-quality fire-resistant and weather-resistant steel with excellent mechanical properties at room temperature and high temperature and good corrosion resistance through optimized design and matching of micro-alloy components, reasonable controlled rolling and controlled cooling process. The fire-resistant and weather-resistant steel of the present invention has upper yield strength ≥ 460MPa, tensile strength ≥ 570MPa, elongation ≥ 20%, yield strength ratio ≤ 0.83, impact absorption energy at -40°C greater than or equal to 60J, 180°d=2a bending qualified, 600°C 3h heat preservation yield strength ≥ 307MPa, weather resistance index I ≥ 6.5, excellent comprehensive performance.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A 460MPa grade high-strength anti-shock refractory and weather-resistant steel hot-rolled coil, characterized in that: it includes the following chemical components in weight percentage: Carbon 0.045%～0.055%, Silicon: 0.2%～0.3%, Manganese: 1.6%～1.8%, Phosphorus ≤0.02%, Sulfur ≤0.005%, Copper: 0.35%～0.40%, Chromium: 0.6%～0.8%, Nickel Niobium: 0.3% to 0.4%, niobium: 0.04% to 0.05%, titanium: 0.01% to 0.02%, molybdenum: 0.2% to 0.3%, and the rest is iron and unavoidable impurities. 2. The 460MPa-grade high-strength earthquake-resistant refractory and weather-resistant steel hot-rolled coil according to claim 1, characterized in that: the thickness specification of the fire-resistant and weather-resistant steel hot-rolled coil is 6.0 mm to 16.0 mm. 3. The 460MPa grade high-strength shock-resistant refractory and weather-resistant steel hot-rolled coil according to claim 1, characterized in that: the metallographic structure of the fire-resistant and weather-resistant steel hot-rolled coil is ferrite+granular bainite, wherein Fe The volume fraction of ferrite is ≤20%, and the volume fraction of granular bainite is ≥80%. 4. The 460MPa-grade high-strength shock-resistant refractory and weather-resistant steel hot-rolled coil according to claim 1, characterized in that: the weather resistance index of the fire-resistant and weather-resistant steel hot-rolled coil is ≥6.5, and the yield ratio is ≤0.83. 5. The preparation method of the 460MPa grade high-strength shock-resistant refractory and weather-resistant steel hot-rolled coil as described in any one of claims 1-4, characterized in that: comprising the steps of: The molten steel is smelted in a converter to obtain a slab, and the weight percentage of the chemical composition of the slab is as follows: carbon 0.045% to 0.055%, silicon: 0.2% to 0.3%, manganese: 1.6% to 1.8%, phosphorus ≤ 0.02%, sulfur ≤ 0.005% %, copper: 0.35% to 0.40%, chromium: 0.6% to 0.8%, nickel: 0.3% to 0.4%, niobium: 0.04% to 0.05%, titanium: 0.01% to 0.02%, molybdenum: 0.2% to 0.3%, The remainder is iron and unavoidable impurities; The slab is heated, and then subjected to rough rolling and finish rolling to obtain a hot-rolled sheet, and then the hot-rolled sheet is subjected to laminar cooling, and coiled into a hot-rolled coil after cooling. 6. The method for preparing 460MPa grade high-strength earthquake-resistant refractory and weather-resistant steel hot-rolled coils according to claim 5, characterized in that: the temperature of the slab coming out of the furnace is 1180°C-1220°C, and the heating time is 180min-240min. 7. The method for preparing hot-rolled coils of 460MPa high-strength earthquake-resistant, refractory and weather-resistant steel according to claim 5, characterized in that: the rough rolling adopts a 1+5 mode, including rough rolling R1 one-pass rolling and rough rolling R2 five Pass rolling; during the rough rolling process, ensure that R1 descales once, R2 descales twice, and the outlet temperature of R2 is 970 ° C ~ 1000 ° C. 8. According to claim 5, the preparation method of 460MPa-grade high-strength shock-resistant, refractory and weather-resistant steel hot-rolled coils is characterized in that: the finishing rolling adopts 7-stand continuous rolling, the finishing rolling temperature is 780°C-820°C, finishing The rolling speed is constant, and the steel throwing speed is ≥3.0m/s. 9. According to claim 5, the preparation method of 460MPa grade high-strength shock-resistant, refractory and weather-resistant steel hot-rolled coils is characterized in that: the laminar flow cooling process adopts a post-stage cooling process, and 1 to 3 groups of laminar flow cooling water are closed. Air cooling + water cooling process. 10. The method for preparing 460MPa-grade high-strength shock-resistant, refractory, and weather-resistant steel hot-rolled coils according to claim 5, characterized in that: the control range of the coiling temperature is 400°C-450°C.