CN105624554A - Steel plate for 70-grade SA671 electric fusion welding pipe with excellent HIC resistance and manufacturing method - Google Patents
Steel plate for 70-grade SA671 electric fusion welding pipe with excellent HIC resistance and manufacturing method Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/28—Normalising
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
Abstract
The invention discloses a steel plate for a 70-grade SA671 electric fusion welding pipe with excellent HIC resistance and a manufacturing method. The steel plate comprises the following chemical components in percentage by weight: 0.09-0.15% of C, 0.15-0.40% of Si, 1.10-1.50% of Mn, 0.05-0.25% of Cu, 0.05-0.40% of Ni, 0.05-0.12% of Mo, 0.005-0.020% of Nb, 0.005-0.030% of V, P not more than 0.008%, S not more than 0.002%, and the balance of Fe and inevitable impurities; and the elements need to satisfy the following relations: when S is not more than 0.002% and not less than 0.0005%, Ca/S is not more than 4.0 and not less than 2.0; and when S is less than 0.0005%, Ca is not more than 0.002%, RMCeq is not more than 575 and not less than 485, and Ceq is not more than 0.43%. The manufactured steel plate is excellent in HIC resistance and SSCC resistance, excellent in high-temperature long-time PWHT resistance, excellent in low-temperature toughness and weldability, strong in manufacturability and lower in production cost.
Description
Technical field
The present invention relates to the steel plate production technology in iron and steel metallurgical industry and the processing and manufacturing technology of middle low temp. electric melting welding pipe, be specifically related to a kind of 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic and manufacture method.
Background technology
SA671 is the relevant room temperature in ASME BPVC ASME and the product specification of low temperature electro-fusion welding pipe, and wherein SA671CC70 and SA571CD70 is its 70 grades of fine grain normal carbon killed steel and 70 grades of fine crystalline carbon silicon manganese killed steel respectively. As classical SA671 steel grade, SA671CC70 and SA671CD70 is widely used abroad. And at home, due to the conventional components system of ASME and GB GB150, GB713 conventional components system between there is the difference in some design concept, therefore, seldom at home relevant industries occur before the two American Standard steel grade.
But, along with the production capacity surplus of recent year Wide and Thick Slab product and oil, complete equipment of chemical equipment manufacture is day by day serious, move towards international market, it is imperative to compete to overseas market. It follows that in recent years at home, adopting the welded tube that U.S.'s ASME standard, European Union's EN standard are ordered goods, if thickness is at SA671CC70 and the SA671CD70 etc. of 8��50mm, its demand is also at rapid increase.
SA671CC70 and the SA671CD70 the two electric smelting welded tube trade mark fine grain normal carbon killed steel SA516Gr.70 in the corresponding steel plate trade mark respectively ASME specification and fine grain carbon silicon manganese killed steel SA537Cl.1. As just boiler vessel steel plate, SA516Gr.70 and SA537Cl.1 in ASME specification is relatively common, Q345R in GB713 is closer to it, and all there is the production capacity of SA516Gr.70 and SA537Cl.1 in domestic main Heavy plate production producer and produces qualification. But, it is equally very fierce in interior product competition that international market includes SA671 electric smelting welded tube, simple by obtaining competitiveness in cost advantage very difficult market in overseas, and the bells and whistles by product quality and product can only be turned to open up a market.
Owing to Service Environment and the use medium of all kinds of electric smelting welded tubes are very different, the requirement of electric smelting welded tube and steel plate used thereof also there is great difference. Such as, containing H2The material failure phenomenon that the electric smelting welded tube used in S corrosive medium environment is susceptible to hydrogen induced cracking (HIC) (hereinafter referred to as HIC), sulfide corrosion cracking (hereinafter referred to as SSCC) is typical characteristic, for this, the adopted steel plate of electric smelting welded tube is just proposed the requirement with good hic resistance, SSCC characteristic by designer. For the wall thickness 70 grades of SA671 electric smelting welded tubes (the steel pipe trade mark respectively SA671CC70 and CD70) at 8��50mm, SA516Gr.70 and the SA537Cl.1 of the respectively 8��50mm of steel plate used by it. The requirement that both steel plates are carried by designer, except meeting in ASME specification except the custom requirements of SA516Gr.70 and SA537Cl.1, also tend to require by following one or more of additional proposition: PWHT characteristic when good hic resistance, anti-SSCC characteristic, low-temperature flexibility, weldability and good high temperature resistance and long.
Chinese patent CN201310497333.5 discloses a kind of 450MPa level resistance against hydrogen cracking steel heavy plate for pressure vessels and production method thereof, for the boilers and pressure vessel steel plate that tensile strength is 450MPa rank, devising weight percent is C:0.13��0.14%, Si:0.20��0.30%, Mn:0.90��0.95%, the chemical composition of P��0.008% and S��0.001%, devise two benches and adopt the controlled rolling of 2.0 times of thickness, the cooling controlling and rolling controlling process accelerating cooling of 10��12 DEG C/S cooling rate is adopted after rolling, devise off-line normalizing heat treatment technique, the tensile strength finally making steel plate has reached 450��464MPa, intensity rank is on the low side, it is not reaching to the requirement of common SA516Gr.70 and SA537Cl.1 steel plate tensile strength >=485MPa, and this patent is also without the anti-SSCC characteristic relating to steel plate, PWHT characteristic when-62 DEG C of low-temperature flexibilities and high temperature resistance and long.
Chinese patent CN201010572979.1 discloses one and has good hic resistance steels for pressure vessel use Q345R-Z35 special heavy plate and manufacture method thereof, for the boiler vessel GBQ345R-Z35 super-thick steel plate that tensile strength is 490MPa level, devising weight percent is C��0.20%, Si��0.55%, Mn:1.2��1.6%, P��0.025%, S��0.005%, (Nb+V+Ti)��0.10% and the chemical composition of Al >=0.015%, devise two benches and adopt the controlled rolling of 2.0 times of thickness, the cooling controlling and rolling controlling process accelerating cooling of 3��10 DEG C/S cooling rate is adopted after rolling, devise common off-line normalizing heat treatment technique, finally make armor plate strength rank and SA537Cl.1 suitable, and there is good hic resistance characteristic equally, but C in the chemical composition designed by this invention, Si, Mn content is all higher, it is difficult to ensure that the requirement of Ceq��0.43%, its rolling mill practice have employed cooling controlling and rolling controlling process, and when this technique is to the high temperature resistance and long of steel plate, PWHT characteristic has adverse influence.
Chinese patent CN201210055848.5 discloses a kind of resistance against hydrogen cracking steels for pressure vessel use and manufacture method thereof, it is >=Low-carbon High Strength low-alloy the steel plate of 620MPa for tensile strength, devising weight percent is C:0.15��0.25%, Si:0.10��0.30%, Mn:1.00��1.60%, P��0.012%, S��0.002%, Mo:0.35��0.60%, V��0.05%, Ni:0.20��0.80%, the chemical composition of Ca:0.0013��0.0045% and Al:0.002��0.050%, devise the Technology for Heating Processing of quenching+tempering, it is more than 620MPa in order to produce tensile strength, and there is the low-alloy high-strength quenched and tempered steel of good Properties of HIC resistance, but its composition is containing Mo, the composition of the low-alloy high-strength steel of the noble elements such as Ni, can not be used for producing the effective general carbon of SA671 electro-fusion welding or carbon manganese steel plate. in addition, adopting the Technology for Heating Processing of quenching+tempering to produce because of the dual heat treatment of needs, production cost is higher.
Summary of the invention
It is an object of the invention to provide a kind of 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic and manufacture method, it is used for SA516Gr.70 and the SA537Cl.1 steel plate needed for producing 70 grades of SA671 electric smelting welded tubes (the steel pipe trade mark respectively SA671CC70 and SA671CD70) of 8��50mm, this steel plate has good hic resistance characteristic, good anti-SSCC characteristic, low-temperature impact-resistant toughness, good high temperature resistance and long time PWHT (post weld heat treatment) characteristic and good weldability, and its manufacturability is strong, production cost is relatively low.
For reaching above-mentioned purpose, the technical scheme is that
A kind of 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic, its chemical component weight percentage ratio is: C:0.09��0.15%, Si:0.15��0.40%, Mn:1.10��1.50%, Cu:0.05��0.25%, Ni:0.05��0.40%, Mo:0.05��0.12%, Nb:0.005��0.020%, V:0.005��0.030%, P��0.008%, S��0.002%, all the other are Fe and inevitable impurity, and above-mentioned element need to meet following relation:
(1) when 0.0005%��S��0.002%, 2.0��Ca/S��4.0;
As S < 0.0005%, Ca��0.002%;
(2) 485��RMCeq��575, wherein,
RMCeq=720*C+100* (Mn+Si)+35* (Cu+Ni)+500*Nb+260*V+250;
(3) Ceq��0.43%, wherein, Ceq=C+Mn/6+ (Cr+Mo+V)/5+ (Cu+Ni)/15.
Further, described 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic, its metallographic structure is: in steel plate upper and lower surface, the thickness range that at least accounts for gross thickness 20%, metallographic structure is based on acicular ferrite and bainite, both reach more than 50% at shared ratio, and do not have obvious banded structure; Metallographic structure in all the other regions of steel plate is carbon manganese steel " normalizing " tissue based on ferrite+pearlite.
Effective steel plate crack length rate CLR��5% of 70 grades of SA671 electro-fusion weldings of the present invention, crack thickness rate CTR��1.5%, crack-sensitivity rate CSR��0.5%; Load not fracture after 80% yield strength load is soaked 720 hours; After the PWHT of 620 DEG C �� 8 hours, still meeting above-mentioned performance requirement.
In present invention formula calculated as below, element meets and represents corresponding element percentage by weight �� 100:
RMCeq=720*C+100* (Mn+S)+35* (Cu+Ni)+500*Nb+260*V+260;
In formula calculated as below, element meets the percentage by weight representing corresponding element:
Ceq=C+Mn/6+ (Cr+Mo+V)/5+ (Cu+Ni)/15.
In the composition design of the present invention:
C, Si, Mn:C, Si, Mn are cheap intensified element, and for ensureing the intensity index of steel plate and the intensity index after the long-time post weld heat treatment of high temperature (PWHT), C, Si, Mn content should be suitably high. But, Properties of HIC resistance, anti-SSCC performance and solderable performance are all had adverse influence by the raising of C, Si, Mn content, and C, Si element is also unfavorable for low-temperature flexibility. Therefore, considering from Properties of HIC resistance, anti-SSCC performance, low-temperature flexibility and solderable performance perspective, C, Si content should control lower as far as possible. From the angle of being easy to production management, C, Si and Mn content also should be able to meet the standard-required of SA516Gr.70 and SA537Cl.1 simultaneously, namely composition bound should meet the common factor of SA516Gr.70 and SA537Cl.1 the two standard-required. In addition, C, Si and Mn content must also consider the impact on metallographic structure required for the present invention, as: under the premise ensureing the intensity index of steel plate and the intensity index after the long-time PWHT of high temperature, suitable minimizing C content, suitably increase Mn, Si content simultaneously, be conducive to being formed under specific heat treatment process conditions required for the present invention want ratio, based on the metallographic structure of acicular ferrite and bainite. More than comprehensive, the present invention designs C:0.09��0.15%, Si:0.15��0.40% and Mn:1.10��1.50%.
Cu:Cu is intensified element, and the increase of Cu content on steel plate Properties of HIC resistance, high temperature resistance and long time PWHT performance have notable forward to affect, but, Cu is precious metal element, and the welding performance of steel plate is brought adverse influence, in ASME relevant criterion, the content of Cu is also done corresponding ceiling restriction. Therefore, in the present invention, Cu content is designed as 0.05��0.25%.
Ni:Ni improves low-temperature flexibility element, meanwhile, when Cu content is higher, keeps the Ni element of enough content to desirably prevent Cu element and brings fragility to deteriorate. But, Ni is also noble element, in ASME relevant criterion, the content of Ni has also been done corresponding ceiling restriction. Additionally, Ni content also should meet SA516Gr.70 and SA537Cl.1 standard-required simultaneously. Therefore, in the present invention, Ni content is 0.05��0.40%.
Mo, Nb, V:Mo, Nb, V are intensified element, during on high temperature resistance and long, PWHT performance has significant forward to affect, but, Mo, Nb, V are precious metal elements, and the welding performance of steel plate is brought adverse influence, in ASME relevant criterion, the content of Mo, V is also done corresponding ceiling restriction. Additionally, Mo, Nb and V content must also meet the standard-required of SA516Gr.70 and SA537Cl.1. Therefore, present invention design: Mo:0.05��0.12%, Nb:0.005��0.020%, V:0.005��0.030%.
S:S is harmful element in steel, and its content increases has significant negative effect to the Properties of HIC resistance of steel, anti-SSCC performance and low-temperature flexibility. For obtaining below good Properties of HIC resistance and-62 DEG C low-temperature flexibility, in the present invention, S content requirement controls below 0.002%.
P:P is harmful element in steel, and its content increases the low-temperature flexibility to steel negative effect, and for obtaining below good-62 DEG C low-temperature flexibility, in the present invention, P content requires to control below 0.008%.
Ca:Ca, as deoxidizer, desulfurizing agent, is to feed among the form of Ca silk addition molten steel, except playing the effect of deoxidation, desulfurization, to also have and MnS sulfides plays spheroidizing, and then can promote the hic resistance of steel, SSCC performance significantly. On the other hand, the deoxidation of Ca, desulfurization product itself are also the non-metallic inclusions in steel, remove if effectively can not float in external refining and casting cycle or discharge and remain in steel, also the hic resistance of steel, SSCC performance can be had a negative impact, therefore, the content of Ca neither more high be conducive to promote the hic resistance of steel, SSCC performance, suitable Ca content according to the height of S content actual in steel, dynamically should be adjusted. In steel, S content is higher, then should add Ca element more and be conducive to the spheroidising of MnS sulfides; In steel, S content is relatively low, then should add Ca less, even not carry out Ca process.
More than comprehensive, control requirement below Ca element is proposed by the present invention: when 0.0005%��S��0.002%, 2.0��Ca/S��4.0; As S < 0.0005%, Ca��0.002%.
It is strength equivalent that the present invention controls 485��RMCeq��575:RMCeq, dimensionless, it it is the peculiar concept that proposes of the present invention, it is used for ensureing employing composition designed by the present invention, explained hereafter steel plate out, after specific PWHT, the tensile strength of steel plate can meet the standard-required of SA516Gr.70 and SA537Cl.1. That is: when 485��RMCeq��575, adopting the steel plate that the Composition And Process designed by the present invention is produced, after the PWHT of 620 DEG C �� 8 hours, the tensile strength of steel plate can meet the standard-required of SA516Gr.70 and SA537Cl.1; Otherwise, then not necessarily disclosure satisfy that.
Ceq: carbon equivalent Ceq is the index of a reflection steel welding performance. It is well known that Ceq is more low, the weldability improving steel plate is more favourable, but the intensity of steel plate is then more unfavorable. Adopting traditional handicraft, 70 grades of effective steel plates of SA671 electro-fusion welding that 50mm is thick, for proof strength, its Ceq generally requires and controls more than 0.43%, but so, brings adverse influence will to the welding performance of steel plate. For ensureing that steel plate has a good welding performance, application claims Ceq��0.43%, wherein: Ceq=C+Mn/6+ (Cr+Mo+V)/5+ (Cu+Ni)/15.
The manufacture method of 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic of the present invention, it comprises the steps:
1) smelt, cast
Undertaken smelting by above-mentioned chemical composition, external refining and continuous casting, wherein, the thickness of blank is more than 4 times of finished steel plate thickness;
2) heating, rolling
Carrying out roughing, controlled rolling after strand heating, in During Controlled Rolling, strand open rolling thickness is not less than 2.0 times of finished steel plate thickness; Start rolling temperature controls at 830��920 DEG C; Finishing temperature control is at 770��830 DEG C; Has at least deflection >=8% of three passages;
3) heat treatment
Normalizing temperature is 880��930 DEG C, and temperature retention time is finished steel plate thickness �� (1��3) minute, finished steel plate thickness unit mm; After normalizing terminates, water-cooled, rate of cooling controls at 5��30 DEG C/sec, and final cooling temperature controls at 560��680 DEG C.
For SA516Gr.70 and the SA537Cl.1 steel plate that the present invention proposes, devise and a kind of produce the smelting of blank, external refining and continuous casting process used by this steel plate, wherein, producing the thickness of blank used by above two steel plate should be more than 4 times of finished steel plate thickness, it is preferable that more than 6 times.
In the rolling mill practice of the present invention, the heating of continuous casting material adopts the heating technique of plain C-Mn steel, rolling then adopts two-phase control rolling technique, first stage adopts the roughing rolling mill practice that plain C-Mn steel is identical, second stage then adopts following controlled rolling process: open rolling thickness should be not less than 2.0 times of finished steel plate thickness, it is preferred to be not less than 2.5 times of finished steel plate thickness; Start rolling temperature should control at 830��920 DEG C, it is preferred to 850��890 DEG C; Finishing temperature control is at 770��830 DEG C, it is preferred to 780��820 DEG C; In second stage, the deflection of three passages is had at least to answer >=8%, it is preferred to have at least deflection >=10% of three passages.
The present invention, after blank rolls into steel plate, adopts the Technology for Heating Processing accelerating cooling after normalizing, in order to further crystal grain thinning, reduce banded structure, acicular ferrite and bainite proportion controlled in the scope that the present invention needs. Particularly as follows: normalizing temperature is 880��930 DEG C, it is preferred to 900��910 DEG C; Temperature retention time is finished steel plate thickness �� (1��3) minute, finished steel plate thickness unit mm, it is preferred to finished steel plate thickness �� (1.2��2) minute. After steel plate goes out normalizing furnace, it is possible to carrying out the cooling of the acceleration after normalizing by the mode sprayed water or spray, its rate of cooling should control within the scope of 5��30 DEG C/sec, it is preferred within 8��20 DEG C/sec of scopes; Final cooling temperature should control at 560��680 DEG C, it is preferred to 610��650 DEG C. Wherein, final cooling temperature is the temperature value utilized in the steel plate thickness calculated with mathematical model on 1/4 position.
Process through above-mentioned manufacturing process, the metallographic structure obtaining steel is by steel plate: in steel plate upper and lower surface, the thickness range that accounts for gross thickness at least 20%, in its metallographic structure, ratio shared by acicular ferrite and bainite reaches more than 50%, and does not have obvious banded structure in this thickness range. Metallographic structure in all the other thickness areas of steel plate is then traditional carbon manganese steel " normalizing " tissue based on ferrite+pearlite.
Compared with the normalized steel metallographic structure that traditional " ferrite+pearlite " is master, the metallographic structure of the present invention defining the isolation zone of a rare banded structure, rare " hydrogen trap " in surface of steel plate, the thickness range that accounts for gross thickness at least 20%, the retardance hydrion effect to steel plate center " intrusion " can be played, thus being substantially improved the Properties of HIC resistance of steel; And in the metallographic structure of the present invention, acicular ferrite and the ratio shared by bainite are higher, are conducive under the premise of equal carbon equivalent, improve tensile strength and the yield strength of steel.
Present invention mentioned component design and processes requires SA516Gr.70 and the SA537Cl.1 steel plate produced, every product attribute of this steel plate except accord with SA516Gr.70 and SA537Cl.1 custom requirements except, following multinomial additional properties needed for also meeting electric smelting welded tube SA671CC70 and SA671CD70:
(1) good hic resistance characteristic, it is desirable to after soaking 96 hours according to the solution A in NACETM0248, crack length rate CLR��5%, crack thickness rate CTR��1.5%, crack-sensitivity rate CSR��0.5% etc.;
(2) good anti-SSCC characteristic, it is desirable to according to the solution A in NACETM0177, adopts B method, loads 80% yield strength load, not fracture after soaking 720 hours;
(3) requirement of good low-temperature impact toughness ,-62 DEG C of low temperature Charpy-V impact powers are on average not less than 27J;
(4) PWHT characteristic during good high temperature resistance and long, it is desirable to after the PWHT (post weld heat treatment) of 620 DEG C �� 8 hours, the traditional performance of steel plate and Properties of HIC resistance, anti-SSCC performance remain to meet aforementioned claim.
Beneficial effects of the present invention:
The present invention devises 70 grades of effective SA516Gr.70 and SA537Cl.1 steel plates of SA671 electro-fusion welding, this steel plate decapacitation meets in ASME specification outside the basic demand of common SA516Gr.70 and SA537Cl.1 properties of product, also there is good hic resistance characteristic, good anti-SSCC characteristic, good low-temperature toughness, good weldability.
Steel plate of the present invention is after the PWHT (post weld heat treatment) of 620 DEG C �� 8 hours, and the traditional performance of steel plate and Properties of HIC resistance, anti-SSCC performance, low-temperature impact toughness remain to meet aforementioned claim, have PWHT characteristic during good high temperature resistance and long; Also there is good manufacturability and relatively low production cost, particularly accelerated cooling process after Technology for Heating Processing of the present invention employing normalizing, but reached the effect of quenching+tempering technique.
Accompanying drawing explanation
Fig. 1 is the metallographic structure photo in the embodiment of the present invention 1 on the 4mm thickness position of 36mm steel plate distance surface.
Detailed description of the invention
Below in conjunction with embodiment and accompanying drawing, the present invention will be further described.
Embodiment 1
Certain project is manufacture the SA671CC70 electric smelting welded tube of 36mm wall thickness, needs 36mm thickness SA516Gr.70 steel plate, and another project is manufacture the SA671CD70 electric smelting welded tube that wall thickness is 12mm, then need 12mm thickness SA537Cl.1 steel plate. The steel plate of the two specification except requiring carbon equivalent Ceq��0.43%, other specific requirements such as table 1.
In the present embodiment, the chemical composition of actual blank is as shown in table 2, and concrete fabrication process parameters is as shown in table 3, and detailed process is as follows:
Above-mentioned sotck thinkness is 250mm, has exceeded 6 times with the ratio of finished steel plate thickness; The heating of this blank adopts the heating technique of plain C-Mn steel, and rolling then adopts two-phase control rolling technique. Wherein, first stage adopts the roughing rolling mill practice that plain C-Mn steel is identical, second stage then adopts following controlled rolling process: the open rolling thickness of 36mm steel plate is 90mm, start rolling temperature is 860 DEG C, finishing temperature control is at 810 DEG C, finally roll into the rolled plate of 36mm, and period has the deflection of 3 continuous passages to exceed 10%; The open rolling thickness of 12mm steel plate is 40mm, and start rolling temperature is 880 DEG C, and finishing temperature control, at 785 DEG C, finally rolls into the rolled plate of 12mm, and period has the deflection of 3 passages to exceed 10%.
36mm and the 12mm steel plate that above-mentioned blank rolls into accelerates the technique of cooling and carries out heat treatment after adopting normalizing, wherein: the normalizing temperature of 36mm steel plate is 900 DEG C, temperature retention time is 48 minutes; After steel plate goes out normalizing furnace, carrying out the cooling of the acceleration after normalizing, its rate of cooling 15 DEG C/sec by spray mode, final cooling temperature (utilizes with the temperature value on 1/4 position in the steel plate thickness that mathematical model calculates) as 630 DEG C; The normalizing temperature of 12mm steel plate is 900 DEG C, and temperature retention time is 20 minutes; After steel plate goes out normalizing furnace, carrying out the cooling of the acceleration after normalizing, its rate of cooling 30 DEG C/sec by spray mode, final cooling temperature (utilizes with the temperature value on 1/4 position in the steel plate thickness that mathematical model calculates) as 610 DEG C.
After above-mentioned Technology for Heating Processing processes, 36mm steel plate is in the thickness range of steel plate, upper and lower surface respectively about 8mm, ratio shared by acicular ferrite and bainite has all reached more than 50%, and does not have obvious banded structure in this thickness range, and its metallographic structure is as shown in Figure 1.
Above-mentioned 36mmSA516Gr.70 steel plate and 12mm thickness SA537Cl.1 steel plate have carried out mechanical performance detection according to ASME relevant criterion, specifically, HIC tests, require, according to after the solution A immersion in NACETM0248 96 hours, to detect crack length rate CLR, crack thickness rate CTR, crack-sensitivity rate CSR etc.; SSCC tests, it is desirable to according to the solution A in NACETM0177, adopts B method, loads 80% yield strength load, soak 720 hours; PWHT characteristic during high temperature resistance and long, it is desirable to after the PWHT (post weld heat treatment) of 620 DEG C �� 8 hours, the performance of detection steel plate. Result shows that properties has all reached predeterminated target, and concrete testing result is as shown in table 4.
Embodiment 2
Certain project is manufacture the SA671CD70 electric smelting welded tube that wall thickness is 50mm, then need 50mm thickness SA537Cl.1 steel plate. Steel plate except requiring carbon equivalent Ceq��0.43%, other specific requirements such as table 1.
In the present embodiment, the chemical composition of actual blank is as shown in table 2, and concrete fabrication process parameters is as shown in table 3, and other are with embodiment 1.
After thermally treated PROCESS FOR TREATMENT, 50mm steel plate is in the thickness range of steel plate, upper and lower surface respectively about 10mm, ratio shared by acicular ferrite and bainite has all reached more than 50%, and does not have obvious banded structure in this thickness range, and its metallographic structure is similar to Fig. 1.
The present embodiment 50mmSA537Cl.1 steel plate has carried out mechanical performance detection according to ASME relevant criterion, and specifically with embodiment 1, testing result is as shown in table 4.
Embodiment 3
Certain project is manufacture the SA671CC70 electric smelting welded tube that wall thickness is 8mm, then need 8mm thickness SA516Gr.70 steel plate. Steel plate except requiring carbon equivalent Ceq��0.43%, other specific requirements such as table 1.
In the present embodiment, the chemical composition of actual blank is as shown in table 2, and concrete fabrication process parameters is as shown in table 3, and other are with embodiment 1.
After thermally treated PROCESS FOR TREATMENT, 8mm steel plate is in the thickness range of steel plate, upper and lower surface respectively about 1.6mm, ratio shared by acicular ferrite and bainite has all reached more than 50%, and does not have obvious banded structure in this thickness range, and its metallographic structure is similar to Fig. 1.
The present embodiment 8mm thickness SA516Gr.70 steel plate has carried out mechanical performance detection according to ASME relevant criterion, and specifically with embodiment 1, testing result is as shown in table 4. .
Embodiment 4
Certain project is manufacture the SA671CD70 electric smelting welded tube that wall thickness is 8mm, then need 8mm thickness SA537Cl.1 steel plate. Steel plate except requiring carbon equivalent Ceq��0.43%, other specific requirements such as table 1.
In the present embodiment, the chemical composition of actual blank is as shown in table 2, and concrete fabrication process parameters is as shown in table 3, and other are with embodiment 1.
After thermally treated PROCESS FOR TREATMENT, 8mm steel plate is in the thickness range of steel plate, upper and lower surface respectively about 1.6mm, ratio shared by acicular ferrite and bainite has all reached more than 50%, and does not have obvious banded structure in this thickness range, and its metallographic structure is similar to Fig. 1.
The present embodiment 8mm thickness SA537Cl.1 steel plate has carried out mechanical performance detection according to ASME relevant criterion, and specifically with embodiment 1, testing result is as shown in table 4.
Embodiment 5
Certain project is manufacture the SA671CC70 electric smelting welded tube that wall thickness is 50mm, then need 6mm thickness SA516Gr.70 steel plate. Steel plate except requiring carbon equivalent Ceq��0.43%, other specific requirements such as table 1.
In the present embodiment, the chemical composition of actual blank is as shown in table 2, and concrete fabrication process parameters is as shown in table 3, and other are with embodiment 1.
After thermally treated PROCESS FOR TREATMENT, 50mm steel plate is in the thickness range of steel plate, upper and lower surface respectively about 10mm, ratio shared by acicular ferrite and bainite has all reached more than 50%, and does not have obvious banded structure in this thickness range, and its metallographic structure is similar to Fig. 1.
The present embodiment 50mm thickness SA516Gr.70 steel plate has carried out mechanical performance detection according to ASME relevant criterion, and specifically with embodiment 1, testing result is as shown in table 4.
As shown in Table 4, SA516Gr.70 and SA537Cl.1 steel plate prepared by the present invention, its properties has all reached the predeterminated target of table 1, specifically: except according with the custom requirements of SA516Gr.70 and SA537Cl.1, also meet electric smelting welded tube SA671CC70 and SA671CD70 and met following multinomial additional properties:
(1) good hic resistance characteristic, it is desirable to after soaking 96 hours according to the solution A in NACETM0248, crack length rate CLR��5%, crack thickness rate CTR��1.5%, crack-sensitivity rate CSR��0.5% etc.;
(2) good anti-SSCC characteristic, it is desirable to according to the solution A in NACETM0177, adopts B method, loads 80% yield strength load, not fracture after soaking 720 hours;
(3) requirement of good low-temperature impact toughness ,-62 DEG C of low temperature Charpy-V impact powers are on average not less than 27J;
(4) PWHT characteristic during good high temperature resistance and long, it is desirable to after the PWHT (post weld heat treatment) of 620 DEG C �� 8 hours, the traditional performance of steel plate and Properties of HIC resistance, anti-SSCC performance remain to meet aforementioned claim.
Claims (14)
1. 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic, its chemical component weight percentage ratio is: C:0.09��0.15%, Si:0.15��0.40%, Mn:1.10��1.50%, Cu:0.05��0.25%, Ni:0.05��0.40%, Mo:0.05��0.12%, Nb:0.005��0.020%, V:0.005��0.030%, P��0.008%, S��0.002%, all the other are Fe and inevitable impurity, and above-mentioned element need to meet following relation simultaneously:
1) when 0.0005%��S��0.002%, 2.0��Ca/S��4.0;
As S < 0.0005%, Ca��0.002%;
2) 485��RMCeq��575, wherein,
RMCeq=720*C+100* (Mn+Si)+35* (Cu+Ni)+500*Nb+260*V+250;
3) Ceq��0.43%, wherein, Ceq=C+Mn/6+ (Cr+Mo+V)/5+ (Cu+Ni)/15.
2. 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic according to claim 1, it is characterized in that, the metallographic structure of described 70 grades of effective steel plates of SA671 electro-fusion welding: in steel plate upper and lower surface, the thickness range that at least accounts for gross thickness 20%, in its metallographic structure, the ratio shared by acicular ferrite and bainite reaches more than 50%, and does not have obvious banded structure; Metallographic structure in all the other regions of steel plate is carbon manganese steel " normalizing " tissue based on ferrite+pearlite.
3. 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic according to claim 1 and 2, it is characterized in that, effective steel plate crack length rate CLR��5% of described 70 grades of SA671 electro-fusion weldings, crack thickness rate CTR��1.5%, crack-sensitivity rate CSR��0.5%; Load not fracture after 80% yield strength load is soaked 720 hours; After the PWHT of 620 DEG C �� 8 hours, still meeting above-mentioned performance requirement.
4. the manufacture method of the 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic as described in any one of claim 1-3, it comprises the steps:
1) smelt, cast
Undertaken smelting by chemical composition described in claim 1, external refining and continuous casting, wherein, the thickness of blank is more than 4 times of finished steel plate thickness;
2) hot rolling
Carrying out roughing, controlled rolling after strand heating, in During Controlled Rolling, strand open rolling thickness is not less than 2.0 times of finished steel plate thickness; Start rolling temperature is 830��920 DEG C; Finishing temperature is 770��830 DEG C, has at least deflection >=8% of three passages;
3) heat treatment
Normalizing temperature is 880��930 DEG C, and temperature retention time is finished steel plate thickness �� (1��3) minute, finished steel plate thickness unit mm; After normalizing terminates, water-cooled, rate of cooling is 5��30 DEG C/sec, and final cooling temperature is 560��680 DEG C.
5. the manufacture method of 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic according to claim 4, it is characterised in that step 1) in, the thickness of blank is more than 6 times of finished steel plate thickness.
6. the manufacture method of 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic according to claim 4, it is characterised in that step 2) in, strand open rolling thickness is not less than 2.5 times of finished product thickness.
7. the manufacture method of 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic according to claim 4, it is characterised in that step 2) in, start rolling temperature is 850��890 DEG C.
8. the manufacture method of 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic according to claim 4, it is characterised in that step 2) in, finishing temperature is 780��820 DEG C.
9. the manufacture method of 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic according to claim 4, it is characterised in that step 2) in, control process has at least deflection >=10% of three passages.
10. the manufacture method of 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic according to claim 4, it is characterised in that step 3) in, normalizing temperature is 900��910 DEG C; Temperature retention time is finished steel plate thickness �� (1.2��2) minute, finished steel plate thickness unit mm.
11. the manufacture method of 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic according to claim 4, it is characterised in that step 3) in, rate of cooling is 8��20 DEG C/sec.
12. the manufacture method of 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic according to claim 4, it is characterised in that step 3) in, final cooling temperature is 620��650 DEG C.
13. the manufacture method of the 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic according to any one of claim 4-12, it is characterized in that, the metallographic structure of described 70 grades of effective steel plates of SA671 electro-fusion welding: in steel plate upper and lower surface, the thickness range that at least accounts for gross thickness 20%, in its metallographic structure, the ratio shared by acicular ferrite and bainite reaches more than 50%, and does not have obvious banded structure; Metallographic structure in all the other regions of steel plate is carbon manganese steel " normalizing " tissue based on ferrite+pearlite.
14. the manufacture method of the 70 grades of effective steel plates of SA671 electro-fusion welding with good hic resistance characteristic according to any one of claim 4-13, it is characterized in that, effective steel plate crack length rate CLR��5% of described 70 grades of SA671 electro-fusion weldings, crack thickness rate CTR��1.5%, crack-sensitivity rate CSR��0.5%; Load not fracture after 80% yield strength load is soaked 720 hours; After the PWHT of 620 DEG C �� 8 hours, still meeting above-mentioned performance requirement.
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