Background technology
Be accompanied by the progress of era development, science and technology, Bridge Design has adopted renewal, more scientific method for designing,Design is overall to large span, the directions such as high percent of pass (large bearing load and bridge deck width), overlength active timeDevelopment, therefore, also more and more higher to the requirement of bridge steel plate. Particularly to the partial component of bridge structure alsoTowards high strength, high tenacity, large thickness direction development. Wherein a kind of bridge main body of steel construction is configured to steelAnchor case, and the consisting of side plate, end plate, support plate, bearing plate, anchor plate, diaphragm plate and add of steel anchor boxStrength plate etc. As the important component part of steel anchor box, anchor plate plays a part crucial, and its Main Function isFixing ground tackle. And along with the development of bridge technology, large-tonnage ground tackle be applied in continuous increase, therefore alsoNeed the anchor plate of large thickness to deepen the fixing of ground tackle.
For the thick bridge steel plate of spy, utilize continuous casting billet generally all only to produce below 130mm thickness beforeSteel plate, if produce the steel plate of thickness more than 160mm, need to adopt to be rolled after molten steel ingot castingMode is carried out. Adopt this ingot ways to produce, and need to adopt heat treatment to improve the high-ductility of steel plateProperty, the effects limit such as the lumber recovery of ingot casting is low, and quality is inhomogeneous, heat treatment cost height thick specification bridge steelThe production of plate and use.
CN101880824A discloses a kind of Q345q special thick bridge steel plate of series and production method thereof, this steelThe maximum ga(u)ge of plate is 130mm, is to adopt ingot casting blank to produce. CN102337456A discloses a kind of thickSpecification bridge steel plate and milling method thereof, adopt continuous casting steel billet production technology to obtain the steel plate of 60-80mm. OnState bridge steel plate that prior art produces not only thickness do not reach requirement, and compression ratio is high, complex process,Production cost is high.
Summary of the invention
The object of this invention is to provide a kind of thickness at 160-190mm, the thick bridge anchor of the spy of low compression ratio pad steelPlate and production method thereof.
Above-mentioned purpose is achieved through the following technical solutions:
The thick bridge anchor of a spy pading plate for low compression ratio, its thickness is 160-190mm, compression ratio is1.58-1.87, its chemical composition is by weight percentage: C:0.14-0.18%, Si:0.33-0.5%,Mn:1.25-1.55%、P:≤0.012%、S:≤0.004%、Nb≤0.03-0.06%、V:0.035-0.055%、Ni:0.35-0.55%, N≤0.008, Als (acid-soluble aluminium): 0.015-0.04%, all the other are Fe and inevitableBe mingled with; Carbon equivalent≤0.45.
The reason of its Design of Chemical Composition is:
C:0.14-0.18%, C is one of element of indispensable raising steel strength, the every increase of carbon content0.1% tensile strength approximately improves 60MPa, and yield limit approximately improves 20-30MPa. Along with the increasing of carbon contentAdd steel grade Fe3C increases, and hardenability also increases, and the tensile strength of steel and yield limit can improve, and plasticityCan decline with toughness index, welding performance variation. This steel grade is as the thick bridge anchor of spy pading plate, not only requirementCertain intensity, and need excellent toughness index and welding performance. This content has not only ensured the strong of steelSpend, and ensured the serviceability of this steel grade, be also applicable to production operation simultaneously.
Si:0.33-0.50%, Si mainly improves steel strength with solution strengthening form, is also the deoxidation unit of steel gradeElement. If but Si content is higher in steel, can cause that reduction of area declines, particularly impact toughness decreased, simultaneouslyAlso unfavorable to the weldability of steel.
Mn:1.25-1.55%, is guaranteeing that aspect the intensity and toughness of steel, Mn is indispensable element. PinTo steel grade of the present invention, Mn mainly, to protect intensity as main, therefore selects Gao Meng.
P :≤0.012%, S :≤0.004%, this is because the P in steel, S content must be controlled at lower scope,Only has smelting clean steel, the combination property of guarantee steel of the present invention.
Nb:0.03-0.06%, superheated susceptivity and the temper brittleness of niobium energy crystal grain thinning and reduction steel, improve strongDegree, but the plasticity of steel and toughness can decline to some extent. In ordinary low-alloy steel, add niobium, can improve Chinese People's Anti-Japanese Military and Political College's gas corruptionAnti-hydrogen, nitrogen, ammonia corrosion ability under erosion and high temperature, niobium also can improve welding performance. In austenitic stainless steelAdd niobium, can prevent intercrystalline corrosion phenomenon.
V:0.035-0.055%, vanadium can enter in iron in endless solid solution, and stops the growth of austenite crystal,Vanadium has the ability of depickling deoxygenation in steel, therefore closely knit containing its section crystallization of steel of vanadium, the effect of vanadium also has in addition,Can improve hardening heat, improve sclerosis energy, when quench hot heating, can prevent its grain growth, help whatThe crystalline structure granular of steel.
Ni:0.35-0.55%, Ni has certain invigoration effect, adds 1% Ni can improve steel strength20MPa. Ni can also improve the toughness, particularly low-temperature flexibility of steel significantly, and steel grade adds Ni no matterThat base material or simulation welding heat affected zone have all been improved low-temperature flexibility significantly, therefore for the thick bridge anchor of spyThe problem that pading plate low-temperature flexibility is poor, has selected nickelic.
N :≤0.008%, steel grade N element is larger for the Toughness of steel plate, has therefore done the limit of the upper limitSystem.
Als:0.015-0.04%, crystal grain thinning, plays invigoration effect.
Carbon equivalent ce V=C+Mn/6+ (Cr+Mo+V)/5+ (Ni+Cu)/15 :≤0.45, for ensureing the weldering of steel plateConnect performance, its chemical composition should ensure that CEV is as far as possible little, should adopt low-carbon (LC) design.
The production method that the thick bridge anchor of described spy pading plate is further provided, the method comprises converter smelting, LFStove becomes base, hot rolling for the first time, hot rolling for the second time, the several steps of slow cooling with the refining of RH stove, continuous casting, wherein:
The heating-up temperature of hot rolling is for the first time 1250-1280 DEG C, and the rate of heat addition is that 9-12min/cm (refers to every heating1cm base needs 9-12min), adopt the fast speed rolling of the thick continuous casting steel billet low temperature of 300mm, rolling temperature is 1050DEG C, rolling pass is 4-6 passage, and rolling mode adopts axial rolling on earth, and being rolled into thickness is 220-250mmSlab;
The heating-up temperature of hot rolling is for the second time 1250-1280 DEG C, and the rate of heat addition is 8-11min/cm, adopts second orderSection rolling: one-phase rolling starts temperature≤1050 DEG C, and passage is depressed more than 20mm/ road, is rolled into thickThe slab that degree is 200-230mm, object is to adopt low temperature to depress greatly fast and makes the abundant fragmentation of crystal grain and transmitTo slab heart portion; Two-stage rolling starts temperature between 920-940 DEG C, two-stage accumulative total passage 5-7 time,Being rolled into thickness is 160-190mm finished steel plate, and the object of two-stage rolling is further crystal grain thinning,Improve toughness and intensity.
Employing air cooling after two-stage rolling completes.
Preferably, in the time carrying out the refining of RH stove, controlling the Fruit storage time is not less than 15 minutes.
Although the special thick bridge steel plate of the Q345q of the present invention and CN101880824A series is same grade of steel, identicalInstitutional framework. But the maximum steel plate thickness of CN101880824A is 130mm, be to adopt ingot casting blank rawProduce, with maximum ga(u)ge 190mm of the present invention and adopt the thick continuous casting steel billet of 300mm to produce to exist thickness andThe huge difference of rolling compression ratio; CN101880824A and the present invention simultaneously also exists technological process notWith, the former is TMCP+ Technology for Heating Processing, and the present invention does not adopt Technology for Heating Processing, but adopt twiceSlab hot rolling technology, technique of the present invention is simpler, and flow process is shorter.
The invention has the beneficial effects as follows:
Compared with prior art, the present invention can provide a kind of thickness at 160-190mm, and compression ratio is at 1.58-1.87Bridge anchor pading plate. Indices has reached yield strength >=360MPa, and tensile strength >=500MPa prolongsStretch rate >=25% ,-20 DEG C of ballistic work >=160J, one-level flaw detection is simultaneously qualified, simultaneously Z-direction stretching section shrinkageRate can reach Z25 rank, and-40 DEG C of Charpy-V impact powers (v-notch) are more than 100J.
Secondly, the production technology of bridge anchor pading plate provided by the invention is simple, and cost is low.
Embodiment 1-6
The thick bridge anchor of a spy pading plate for low compression ratio, its thickness is 160-190mm, compression ratio is1.58-1.87, its chemical composition is C:0.14-0.18%, Si:0.33-0.5%, Mn by weight percentage:1.25-1.55%、P:≤0.012%、S:≤0.004%、Nb≤0.03-0.06%、V:0.035-0.055%、Ni:0.35-0.55%, N≤0.008, Als:0.015-0.04%, all the other are Fe and are inevitably mingled with;Carbon equivalent≤0.45.
The production method of the thick bridge anchor of the spy pading plate of described low compression ratio comprises converter smelting, LF stove and RHStove refining, continuous casting become base, hot rolling for the first time, hot rolling for the second time, the several steps of slow cooling, wherein:
In the time carrying out the refining of RH stove, controlling the Fruit storage time is not less than 15 minutes; In the steel billet makingO, N, H, P, S are controlled at below 250ppm, and non-metallic inclusion (A, B, C, D) is comprehensive≤2.5 grades, chemical composition according to following control: C:0.14-0.18%, Si:0.33-0.5%, Mn:1.25-1.55%,P:≤0.012%、S:≤0.004%、Nb≤0.03-0.06%、V:0.035-0.055%、Ni:0.35-0.55%、N≤0.008, Als:0.015-0.04%, all the other are Fe and are inevitably mingled with, and obtain internal soundness good,The slab of high purity;
The heating-up temperature of hot rolling is for the first time 1250-1280 DEG C, and the rate of heat addition is 9-12min/cm, adoptsThe fast speed rolling of the thick continuous casting steel billet low temperature of 300mm, rolling temperature is 1050 DEG C, rolling pass is 4-6 passage,Rolling mode adopts axial rolling on earth, is rolled into the slab that thickness is 220-250mm;
The heating-up temperature of hot rolling is for the second time 1250-1280 DEG C, and the rate of heat addition is 8-11min/cm, adopts second orderSection rolling, one-phase rolling starts temperature≤1050 DEG C, and passage is depressed more than 20mm/ road, is rolled into thickDegree is the slab of 200-230mm, and two-stage rolling starts temperature between 920-940 DEG C, two-stage accumulative totalPassage 5-7 time, being rolled into thickness is 160-190mm finished steel plate.
The value list (wt%) of table 1 various embodiments of the present invention and comparative example