CN104404382B - Exempt from sandblasting direct application weathering steel and production method thereof - Google Patents

Abstract

The invention discloses one and exempt from sandblasting direct application weathering steel and production method thereof, chemical composition and the weight content thereof of this steel are as follows: C:0.04～0.12%, Si:0.20～0.50%, Mn:0.25～0.50%, S: content≤0.008%, P: content≤0.03%, Cu:0.25～0.45%, Cr:0.30～0.60%, Ni:0.20～0.50%, Ti:0.015～0.025, Als: content≤0.03%, remaining is ferrum and inevitable impurity.Production method include converter smelting, refine, continuous casting, heat, roll, control cold, batch and correction step, control cold for section cooling, use leading portion to pull cooling, Cl concentration≤100mg/L in laminar flow recirculated cooling water；Oiler temperature control is 540～560 DEG C；Carrying out smooth with leveling roll, leveling roll surface texturing roughness Rz is 50～100 μm, and RPc is 45～70/cm, and strip steel drafts is 1～4%.Steel good weatherability of the present invention, can remove sandblasting pretreatment operation from and directly application, and coating adhesion is strong, difficult drop-off.

Description

Exempt from sandblasting direct application weathering steel and production method thereof

Technical field

The present invention relates to field of ferrous metallurgy materials, exempt from the direct application of sandblasting in particular to one weather-proof Steel and production method thereof.

Background technology

Steel products under arms time be chronically exposed in air, the moisture that is easily subject in environment, gas The erosion of body, microorganism and ultraviolet etc. and corrode to gradually damaging, add in steel Cu, Ni, It is ferrous materials anticorrosion that the weather-proof element such as Cr, Mo or the steel products to military service carry out paint spraying Two important means.Wherein, the quality of coating quality directly affects the quality of coating performance, right The use value of base material also has a direct impact, and research shows, steel surface pretreatment quality before application It it is the principal element determining coating protective value.

Existing steel, before application, generally need to carry out the surfaces such as sandblasting and process it, wherein sandblasting Operation can remove belt steel surface ferrum oxide cortex, rust and other dirts, improves steel surface coarse Degree, and significant increase coating adhesion and protective value thereof.But, sandblasting pretreatment was producing Journey causes bigger dust pollution, and noise is relatively big, severe exacerbation working environment；Meanwhile, Sandblasting pretreatment operation adds painting cost.

At present, steel surface is exempted from the research in terms of the direct application of sandblasting be concentrated mainly on exempt from spray Sand coating developmental research field, it focuses on the research of application techniques and coating, and the scope of application is subject to One definite limitation, coating quality does not often reach requirement；It addition, CN102691004B discloses The production method of a kind for the treatment of weathering steel for containers without sand blasting or shot blasting, in CN102690937A Also disclose that the production method of a kind of Thin Specs without sand blasting or shot blasting structural steel, these two literary compositions The steel capital offered is by controlling the technological parameter in rolling process, makes steel surface be formed with densification Fe₃O₄It is main scale structure, in forming process, does not falls off and provide certain resistance to Erosion performance, reaches to make steel plate with hope by adjusting finish rolling end breast roller surface roughness Ra Surface roughness meets the coating specification of coating, but it practice, roller surface in the hot rolling By cold and heat succeed each other and High Temperature High Pressure affected, roller surface oxide-film be in growth and abrasion alternation shape State, under extreme condition, oxide-film even can fall off, and therefore, hot roll surface roughness is difficult to Keep and realize accurately controlling, being also coated with a lot of it addition, the Ra wherein disclosed is 0.8～2.4 μm The standard-required of dress occasion is far apart.

Summary of the invention

Present invention aim to provide one to exempt from sandblasting direct application weathering steel and producer thereof Method, this steel good weatherability, sandblasting pretreatment operation can be removed from and directly application, and coating adhesion By force, difficult drop-off.

For achieving the above object, the technical solution used in the present invention is: one exempts from the direct application of sandblasting Weathering steel, chemical composition and the weight percent content thereof of this steel are as follows: C:0.04～0.12%, Si:0.20～0.50%, Mn:0.25～0.50%, S: content≤0.008%, P: content≤ 0.03%, Cu:0.25～0.45%, Cr:0.30～0.60%, Ni:0.20～0.50%, Ti:0.015～ 0.025, Als: content≤0.03%, remaining is ferrum and inevitable impurity.

Further, the chemical component weight degree of this steel is as follows: C:0.08～0.10%, Si:0.30～0.40%, Mn:0.34～0.40%, S:0.004～0.007%, P:0.009～ 0.010%, Cu:0.35～0.42%, Cr:0.45～0.50%, Ni:0.35～0.50%, Ti:0.020～ 0.022, Als:0.021～0.025%, remaining is ferrum and inevitable impurity.

Further, this steel surface roughness Rz is 20～50 μm, and this steel soluble surface Chloride content is 0～50mg/m²。

Further, the iron scale on this steel surface is three layers of scale structure, and it includes surface Fe₃O₄Top layer, middle Fe/Fe₃O₄Layer, and the Fe being attached directly in steel matrix₃O₄Bottom, Described Fe₃O₄Top layer, Fe/Fe₃O₄Layer and Fe₃O₄The thickness proportion of bottom be 1.8～2.2:2.8～ 3.2:1.

A kind of above-mentioned production method exempting from sandblasting direct application weathering steel, including converter smelting, refine, Continuous casting, heat, roll, control cold, batch and correction step, it is characterised in that: described control is cold is Section cooling, uses leading portion to pull cooling, Cl in laminar flow recirculated cooling water^—Concentration≤100mg/L； Described batching, oiler temperature control is 540～560 DEG C；Described finishing, with leveling roll to coil of strip Carrying out smooth, described leveling roll surface texturing roughness Rz is 50～100 μm, RPc be 45～ 70/cm, formation process strip steel drafts is 1～4%.

Further, in described heating steps, it is 1200～1240 DEG C that slab tapping temperature controls, Control to be 120～150min in stove total time.

Further, described milling step includes that roughing and finish rolling, described roughing outlet temperature are 1020～1040 DEG C, roughing de-scaling passage >=3；Described finish rolling start rolling temperature is 960～1020 DEG C, Finishing temperature is 850～880 DEG C, opens and cools down water between finishing stand, and controlled rolling is the highest surely Constant speed degree >=7m/s.

Further, in described correction step, described leveling roll surface texturing roughness Rz be 80～ 100 μm, RPc is 60～70/cm, and formation process strip steel drafts is 3～4%.

Further, controlling described roughing de-scaling passage is 3～5 times；And control described rolling Highest stabilizing speed is 7～10.5m/s

Hereinafter explanation is analyzed with regard to the chemical composition of the present invention and content thereof and production method:

(1) chemical composition and content thereof

Matrix is played solution strengthening effect as general intensified element by C:C, but C content is too high Time, the toughness of steel declines, and therefore C content is controlled, 0.04～0.12%, to take into account by the present invention The intensity of steel and toughness.

Si:Si plays the effect of solution strengthening in steel, is deoxidant element simultaneously, and Si is when oxidation Cocrystalization compound FeO-Fe is formed with basal body interface at iron scale₂SiO₄, hinder the expansion of Fe ion Dissipate thus the oxidation rate that slows down, reduce iron scale thickness, iron scale attached is significantly greatly increased simultaneously Put forth effort, but when Si content is higher, reduce the toughness of steel, plasticity and ductility, therefore, Under conditions of de-scaling ability meets requirement, Si content is controlled 0.20～0.50% by the present invention.

Mn:Mn is Strengthening and Toughening element important in steel, improves the Fe content in steel, can expand γ District, reduces transition temperature, expands rolling temperature range, promotes crystal grain refinement；Mn oxide with Ferrum oxide dissolves each other completely, has certain Mn content in ferrum oxide cortex, and Mn can increase oxidation The fragility of iron sheet, but its content of consideration based on iron scale integrity should not be the highest, therefore, this Mn content is controlled 0.25～0.50% by invention.

Though P:P can be effectively improved the weather resistance of steel, but it is unfavorable to toughness and the plasticity of steel, Its weatherability can be made up by other weather-proof elements, and therefore, the present invention controls P content≤0.03%.

S: the MnS that in steel, S too high levels produces is mingled with the vertically and horizontally performance of steel can be made to produce substantially Difference, impaired low temperature toughness, and can substantially reduce the weather resistance of steel, therefore, the present invention controls S content≤0.008%.

Cu:Cu is weather-proof element main in weathering steel, can be effectively improved the weather resistance of steel, Cu joins as alloying element also has solid solution and precipitation strength effect simultaneously in steel, but Cu content Time too high, easily crack when heating or hot rolling, the surface property of deterioration steel, therefore, Cu content is controlled 0.25%～0.45% by the present invention.

Ni: the addition of Ni in steel, its main purpose is to improve the low-temperature flexibility of steel, has simultaneously Effect prevention Cu's is hot-short, but Ni element increases the unevenness of iron scale and basal body interface, goes out In the consideration of iron scale de-scaling, Ni content is controlled 0.20～0.50% by the present invention.

The Match of elemental compositions such as Cr:Cr and Cu in steel use the atmospheric corrosion resistance ability being remarkably improved steel, Additionally, Cr element can be effectively improved the quenching degree of steel, Cr element can be at iron scale and matrix circle Face forms spinel compound, and prevention Fe ion is to external diffusion, but is easily generated during Cr too high levels Fragility, unfavorable to the welding performance of steel, therefore, the present invention Cr content is controlled 0.30～ 0.60%.

Ti:Ti is strong nitride forming element, controls growing up of austenite crystal, improves the weldering of steel Connecing performance and toughness, Ti can be in iron scale and basal body interface segregation, and certain Ti content can drop Low oxidation rate, but chemical combination titanium reduces the quenching degree of steel, and therefore, the present invention is by Ti content control System is 0.015%～0.025%.

Als:Als is the main deoxidant element in steel, and Als too high levels will cause Al oxide Being mingled with increase, reduce the degree of purity of steel, toughness and weather resistance to steel are unfavorable, therefore, and this Bright control Als content≤0.03%.

(2) production method

The present invention, in the section cooling stage, uses leading portion to pull the type of cooling and cools down coil of strip, Make coil of strip reach target coiling temperature in the short period, reduce in the high temperature section time of staying；It addition, Pull cooling and can extend contacting of cooling water and belt steel surface, promotion belt steel surface Fe₃O₄The shape of layer Become；Meanwhile, by controlling Cl in hot-rolling laminar cooling water^—Concentration≤100mg/L, it is ensured that strip steel Soluble chlorine salt content≤the 50mg/m of remained on surface²；Before section cooling, belt steel surface shape Become relatively thin Fe₂O₃Layer, Fe₃O₄Layer and three layers of scale structure of thicker FeO layer composition, FeO thermodynamic instability after temperature is down to less than 570 DEG C, occurs pro-eutectoid reaction and eutectoid anti- Should, reaction equation is as follows:

Pro-eutectoid is reacted:

${\mathrm{Fe}}_{1-x}O\→\frac{x-y}{1-4y}{\mathrm{Fe}}_3{O}_4+\frac{1-4x}{1-4y}{\mathrm{Fe}}_{1-y}O,$

Eutectoid reaction:

4Fe_1-yO→Fe₃O₄+ (1-4y) Fe,

After through relatively low coiling temperature (540～560 DEG C) by strip coiling, cool down at stacking Slow cooling under the conditions of, two above reaction the most fully carry out, at basal body interface separate out elder generation Eutectoid Fe₃O₄Granule ultimately forms complete Fe through outgrowth, merging₃O₄Layer, separates out pro-eutectoid Fe₃O₄After FeO occur eutectoid reaction generate Fe₃O₄The eutectoid structure of+Fe, additionally, due to Coil of strip batch after Hypoxic habitats, the Fe on surface₂O₃Layer will with the Fe ionic reaction to external diffusion Can be to low oxide Fe₃O₄Convert, finally formed by the Fe on surface at belt steel surface₃O₄Top layer, Middle Fe/Fe₃O₄Layer, and the Fe being attached directly in steel matrix₃O₄Three layers of oxygen of bottom composition Change iron sheet structure.

The present invention carries out smooth process after coilcooling to room temperature, first leveling roll is carried out surface Laser roughening processes so that it is surface roughness Rz is 50～100 μm, and RPc is 45～70/cm, And use 1～4% drafts strip steel is carried out smooth, the roughness on leveling roll surface is transferred to Strip steel iron scale surface, by the regulation to leveling roll texturing roughness parameter, and time smooth Use different drafts, belt steel surface iron scale roughness can be adjusted, at transferring rate Under conditions of reaching 50%, belt steel surface roughness is promoted to about 20～50 μm；Steel surface Three layers have good adhesive force between scale structure and steel matrix, in formation process, flat Under the pinning effect of whole roller boss, only occur to come off on a small quantity at boss, other position iron scales Complete and good with steel matrix attachment.

Compared with prior art, the invention have the advantages that

One, the present invention improves the weather resistance of steel scale on surface by composition of steel design, Wherein, the cooperation of the intensified element such as C, Si, Mn, Cu and Ti ensure that steel grade yield strength reaches More than 400MPa, tensile strength reaches more than 520MPa；The cooperation of the elements such as Cu, Cr, Ni is true Protect the corrosion resisting property of steel grade；The element such as Si, Cr, Ti coordinate hinder Fe ion to external diffusion, Iron scale outer layer is made to generate certain thickness Fe₃O₄Layer；The element cooperations such as Si and Cr improve The adhesive force of iron scale.

Its two, the present invention optimizes rolling mill practice, uses relatively low tapping temperature and relatively short Heat time heating time, reduce Cu element to crystal boundary permeate, reduce point-like scale defect occur several Rate, and according to the temperature and time factor impact on iron scale thickness in oxidation kinetics, use Control the measures such as course of hot rolling temperature, mill speed and unlatching interstand cooling water and be effectively thinned oxygen Change thickness of scale, make iron scale be tightly combined with steel matrix, difficult drop-off.

Its three, the iron scale on steel surface of the present invention is three layers of scale structure, this ferrum oxide Skin is strong with steel matrix adhesion, in the surface roughness transfer process when smooth, and only very small amount Come off, do not fall off in the technical processs such as deformation and welding；And, the present invention is by smooth Process and control Cl in hot-rolling laminar cooling water^—Concentration so that steel surface roughness Rz be 20～ 50 μm, steel soluble surface chloride content is down to 50mg/m²Hereinafter, and then make its surface shape State and coatings system system have the preferable compatibility, and avoid steel soluble surface villaumite to painting Layer performance particularly decay resistance causes damage so that steel of the present invention can remove sandblasting before application from Pretreatment process, is directly used in application, thus dust when decreasing production and noise pollution, change It is apt to working environment, has reduced painting cost, and improve adhesive force and the protective value thereof of coating, It is applicable to rolling stock, container, bridge, the manufacture of electric tower and highway barrier etc., tool There is bigger application value.

Accompanying drawing explanation

Fig. 1 is a kind of leveling roll structural representation after surface laser texturing.

Fig. 2 is smooth front leveling roll and the view exempting from sandblasting direct application weathering steel.

Fig. 3 is that in formation process, leveling roll and the contact condition exempting from sandblasting direct application weathering steel show It is intended to.

Fig. 4 be smooth after exempt from sandblasting direct application weathering steel surface texture schematic diagram.

Fig. 5 is a kind of scale on surface structural representation exempting from sandblasting direct application weathering steel.

Fig. 6 be a kind of exempt from sandblasting direct application weathering steel surface roughness transfer before scanning electricity Mirror photo.

Fig. 7 is the scanning electricity exempting from sandblasting direct application weathering steel surface in Fig. 6 after roughness transfers Mirror photo.

Detailed description of the invention

The present invention is described in further detail with specific embodiment below in conjunction with the accompanying drawings, it is simple to more It is well understood to the present invention, but they do not constitute restriction to the present invention.

Embodiment 1

Produce finished product be 4.5mm thickness specification exempt from sandblasting direct application weathering steel, its technique walks Suddenly include successively: converter smelting, refine, continuous casting, heating, roughing, finish rolling, section cooling, Batch, warehouse-in cooling, smooth and roughness transfer；After refine, molten steel is mainly composed of: C:0.08%, Si:0.30%, Mn:0.34%, S:0.007%, P:0.010%, Cu:0.35%, Cr: 0.50%, Ni:0.35%, Ti:0.020%, Als:0.025%, remaining is ferrum and inevitable Impurity, wherein:

After continuous casting, continuous casting billet surface is mingled with and the defect such as slag inclusion uses mechanical system to remove；

Heating period: controlling slab tapping temperature is 1230 DEG C, is 135min in stove total time；

Rough rolling step: controlling roughing outlet temperature is 1030 DEG C, roughing de-scaling 3 passage；

The finish rolling stage: controlling finish rolling start rolling temperature is 1020 DEG C, and finishing temperature is 870 DEG C, opens Finish rolling F1～F3 interstand cooling water, roll highest stabilizing speed 7.8m/s；

The section cooling stage: section cooling mode uses leading portion to pull cooling, laminar flow recirculated cooling water Water quality Cl^—Concentration controls as 65mg/L；

Batch and cooling stage: controlling coiling temperature is 550 DEG C, by steel coil transportation to steel after batching Item pool, allows coil of strip carry out stacking Slow cooling；

Finishing stage: carry out smooth to coil of strip, as it is shown in figure 1, smooth leveling roll 1 used passes through After surface laser frosting treatment, its surface texturing roughness Rz is 80 μm, and RPc is 65/cm； As shown in figs. 2 to 4, in formation process, under the pinning effect of the boss 1-1 of leveling roll, steel The iron scale 3 on matrix 2 surface only occurs to come off on a small quantity at boss 1-1 transfer, other positions Iron scale 3 complete and adhere to well with steel matrix 2；Formation process strip steel drafts is 2%, Final production obtains exempting from sandblasting direct application weathering steel.

Through inspection, it is as follows that gained exempts from sandblasting direct application weathering steel performance indications: yield strength is 415MPa, tensile strength is 545MPa, and percentage elongation is 35%；The iron scale thickness on surface is 6～8.5 μm, as it is shown in figure 5, this iron scale 3 is three layers of scale structure, including surface Fe₃O₄Top layer 3-1, middle Fe/Fe₃O₄Layer 3-2, and be attached directly in steel matrix 2 Fe₃O₄Bottom 3-3, Fe₃O₄Top layer 3-1, Fe/Fe₃O₄Layer 3-2 and Fe₃O₄The thickness of bottom 3-3 Ratio is 2:3:1；Steel surface more smooth (as shown in Figure 6) before roughness transfers, is unfavorable for Application, and after roughness transfers, surface roughness is greatly improved, and iron scale surface is thick Rugosity Rz reaches 40 μm (as shown in Figure 7), can exempt from sandblasting pretreatment in coating process；It addition, The top layer soluble chlorine salinity of steel is 18mg/m²。

Embodiment 2

Produce finished product be 2.0mm thickness specification exempt from sandblasting direct application weathering steel, its technique walks Suddenly include successively: converter smelting, refine, continuous casting, heating, roughing, finish rolling, section cooling, Batch, warehouse-in cooling, smooth and roughness transfer；After refine, molten steel is mainly composed of: C:0.10%, Si:0.40%, Mn:0.40%, S:0.004%, P:0.009%, Cu:0.42%, Cr: 0.45%, Ni:0.35%, Ti:0.022%, Als:0.021%, remaining is that ferrum is with inevitable Impurity, wherein:

After continuous casting, continuous casting billet surface is mingled with and the defect such as slag inclusion uses mechanical system to remove；

Heating period: controlling slab tapping temperature is 1235 DEG C, is 135min in stove total time；

Rough rolling step: controlling roughing outlet temperature is 1035 DEG C, roughing de-scaling 3 passage；

The finish rolling stage: controlling finish rolling start rolling temperature is 960 DEG C, and finishing temperature is 870 DEG C, opens Finish rolling F1～F3 interstand cooling water, rolling highest stabilizing speed is 10.5m/s；

The section cooling stage: section cooling mode uses leading portion to pull cooling, laminar flow recirculated cooling water Water quality Cl^—Concentration controls as 50mg/L；

Batch and cooling stage: controlling coiling temperature is 540 DEG C, by steel coil transportation to steel after batching Item pool, allows coil of strip carry out stacking Slow cooling；

Finishing stage: carry out smooth to coil of strip, smooth leveling roll used is at surface laser texturing After reason, its surface texturing roughness Rz is 100 μm, and RPc is 70/cm, formation process band Steel drafts is 4%.

Through inspection, it is as follows that gained exempts from sandblasting direct application weathering steel performance indications: yield strength is 435MPa, tensile strength is 560MPa, and percentage elongation is 32%；The iron scale thickness on surface is 6～7.5 μm, this iron scale is three layers of scale structure, including the Fe on surface₃O₄Top layer, Middle Fe/Fe₃O₄Layer, and the Fe being attached directly in steel matrix₃O₄Bottom, Fe₃O₄Top layer, Fe/Fe₃O₄Layer and Fe₃O₄The thickness proportion of bottom is 1.8:2.8:1, this iron scale surface roughness Rz is 25 μm, and top layer soluble chlorine salinity is 12mg/m², coating process can be exempted from sandblasting Pretreatment.

Embodiment 3

Produce finished product be 2.0mm thickness specification exempt from sandblasting direct application weathering steel, its technique walks Suddenly include successively: converter smelting, refine, continuous casting, heating, roughing, finish rolling, section cooling, Batch, warehouse-in cooling, smooth and roughness transfer；After refine, molten steel is mainly composed of: C:0.04%, Si:0.50%, Mn:0.25%, S:0.008%, P:0.03%, Cu:0.25%, Cr:0.3%, Ni:0.5%, Ti:0.015%, Als:0.03%, remaining is ferrum and inevitable impurity, its In:

After continuous casting, continuous casting billet surface is mingled with and the defect such as slag inclusion uses mechanical system to remove；

Heating period: controlling slab tapping temperature is 1200 DEG C, is 150min in stove total time；

Rough rolling step: controlling roughing outlet temperature is 1040 DEG C, roughing de-scaling 4 passage；

The finish rolling stage: controlling finish rolling start rolling temperature is 1000 DEG C, and finishing temperature is 880 DEG C, opens Finish rolling F1～F3 interstand cooling water, roll highest stabilizing speed 7m/s；

The section cooling stage: section cooling mode uses leading portion to pull cooling, laminar flow recirculated cooling water Water quality Cl^—Concentration controls as 100mg/L；

Batch and cooling stage: controlling coiling temperature is 560 DEG C, by steel coil transportation to steel after batching Item pool, allows coil of strip carry out stacking Slow cooling；

Finishing stage: carry out smooth to coil of strip, smooth leveling roll used is at surface laser texturing After reason, its surface texturing roughness Rz is 50 μm, and RPc is 45/cm, formation process strip steel Drafts is 1%.

Through inspection, it is as follows that gained exempts from sandblasting direct application weathering steel performance indications: yield strength is 410MPa, tensile strength is 540MPa, and percentage elongation is 36%；The iron scale thickness on surface is 6～9 μm, this iron scale is three layers of scale structure, including the Fe on surface₃O₄Top layer, in Between Fe/Fe₃O₄Layer, and the Fe being attached directly in steel matrix₃O₄Bottom, Fe₃O₄Top layer, Fe/Fe₃O₄ Layer and Fe₃O₄The thickness proportion of bottom is 2.2:3:1, and this iron scale surface roughness Rz is 20 μm, top layer soluble chlorine salinity is 50mg/m², coating process can be exempted from sandblasting and locate in advance Reason.

Embodiment 4

Produce finished product be 4.5mm thickness specification exempt from sandblasting direct application weathering steel, its technique walks Suddenly include successively: converter smelting, refine, continuous casting, heating, roughing, finish rolling, section cooling, Batch, warehouse-in cooling, smooth and roughness transfer；After refine, molten steel is mainly composed of: C:0.12%, Si:0.30%, Mn:0.34%, S:0.007%, P:0.010%, Cu:0.35%, Cr: 0.50%, Ni:0.35%, Ti:0.020%, Als:0.025%, remaining is ferrum and inevitable Impurity, wherein:

After continuous casting, continuous casting billet surface is mingled with and the defect such as slag inclusion uses mechanical system to remove；

Heating period: controlling slab tapping temperature is 1240 DEG C, is 120min in stove total time；

Rough rolling step: controlling roughing outlet temperature is 1020 DEG C, roughing de-scaling 5 passage；

The finish rolling stage: controlling finish rolling start rolling temperature is 980 DEG C, and finishing temperature is 850 DEG C, opens Finish rolling F1～F3 interstand cooling water, roll highest stabilizing speed 8m/s；

The section cooling stage: section cooling mode uses leading portion to pull cooling, laminar flow recirculated cooling water Water quality Cl^—Concentration controls as 40mg/L；

Batch and cooling stage: controlling coiling temperature is 545 DEG C, by steel coil transportation to steel after batching Item pool, allows coil of strip carry out stacking Slow cooling；

Finishing stage: carry out smooth to coil of strip, smooth leveling roll used is at surface laser texturing After reason, its surface texturing roughness Rz is 60 μm, and RPc is 50/cm, formation process strip steel Drafts is 3%.

Through inspection, it is as follows that gained exempts from sandblasting direct application weathering steel performance indications: yield strength is 445MPa, tensile strength is 570MPa, and percentage elongation is 30%；The iron scale thickness on surface is 6～8 μm, this iron scale is three layers of scale structure, including the Fe on surface₃O₄Top layer, in Between Fe/Fe₃O₄Layer, and the Fe being attached directly in steel matrix₃O₄Bottom, Fe₃O₄Top layer, Fe/Fe₃O₄ Layer and Fe₃O₄The thickness proportion of bottom is 2:3.2:1, and this iron scale surface roughness Rz is 50 μm, top layer soluble chlorine salinity is 0mg/m², coating process can be exempted from sandblasting pretreatment.

Claims (8)

1. exempt from sandblasting direct application weathering steel for one kind, it is characterised in that: the chemical composition of this steel and Its weight percent content is as follows: C:0.04～0.12%, Si:0.20～0.50%, Mn: 0.25～0.50%, S: content≤0.008%, P: content≤0.03%, Cu:0.25～0.45%, Cr:0.30～0.60%, Ni:0.20～0.50%, Ti:0.015～0.025, Als: content≤ 0.03%, remaining is ferrum and inevitable impurity；This steel surface roughness Rz be 20～ 50 μm, and this steel soluble surface chloride content is 0～50mg/m²。

Exempt from sandblasting direct application weathering steel the most according to claim 1, it is characterised in that: The chemical component weight degree of this steel is as follows: C:0.08～0.10%, Si:0.30～ 0.40%, Mn:0.34～0.40%, S:0.004～0.007%, P:0.009～0.010%, Cu:0.35～0.42%, Cr:0.45～0.50%, Ni:0.35～0.50%, Ti:0.020～ 0.022, Als:0.021～0.025%, remaining is ferrum and inevitable impurity.

The most according to claim 1 or claim 2 exempting from sandblasting direct application weathering steel, its feature exists In: the iron scale on this steel surface is three layers of scale structure, and it includes the Fe on surface₃O₄ Top layer, middle Fe/Fe₃O₄Layer, and the Fe being attached directly in steel matrix₃O₄Bottom, described Fe₃O₄Top layer, Fe/Fe₃O₄Layer and Fe₃O₄The thickness proportion of bottom is 1.8～2.2:2.8～3.2:1.

4. exempt from a production method for sandblasting direct application weathering steel described in claim 1, bag Include converter smelting, refine, continuous casting, heat, roll, control cold, batch and correction step, its It is characterised by: described control is cold for section cooling, uses leading portion to pull cooling, laminar flow circulating cooling Cl in water^—Concentration≤100mg/L；Described batching, oiler temperature control is 540～560 DEG C； Described finishing, carries out smooth with leveling roll to coil of strip, described leveling roll surface texturing roughness Rz is 50～100 μm, and RPc is 45～70/cm, formation process strip steel drafts be 1～ 4%.

Exempt from the production method of sandblasting direct application weathering steel the most according to claim 4, its Being characterised by: in described heating steps, it is 1200～1240 DEG C that slab tapping temperature controls, Control to be 120～150min in stove total time.

6. according to claim 4 or 5, exempt from the production method of sandblasting direct application weathering steel, It is characterized in that: described milling step includes that roughing and finish rolling, described roughing outlet temperature are 1020～1040 DEG C, roughing de-scaling passage >=3；Described finish rolling start rolling temperature is 960～1020 DEG C, Finishing temperature is 850～880 DEG C, opens and cools down water between finishing stand, and controlled rolling is the highest Stabilized speed >=7m/s.

7. according to claim 4 or 5, exempt from the production method of sandblasting direct application weathering steel, It is characterized in that: in described correction step, described leveling roll surface texturing roughness Rz be 80～ 100 μm, RPc is 60～70/cm, and formation process strip steel drafts is 3～4%.

Exempt from the production method of sandblasting direct application weathering steel the most according to claim 6, its It is characterised by: controlling described roughing de-scaling passage is 3～5 times；And it is the highest to control described rolling Stabilized speed is 7～10.5m/s.