CN108330398A - A kind of production method of special thick antiacid tank plate - Google Patents

Abstract

A kind of production method of special thick antiacid tank plate, uses process route for converter smelting → LF refining → VD vacuum refinings → molding → Heating Steel Ingots → controlled rolling, control cooling → heat treatment.The chemical composition mass percent of steel is C=0.15 ~ 0.20, Si=0.25~0.50, Mn=1.20~1.35, P≤0.008, S≤0.002, Alt=0.020~0.050, Cr≤0.25, Cu+Ni≤0.5, Ca/S=1.2 ~ 2.0, remaining is Fe and relict element.The 200mm guarantors flaw detection of the method for the present invention production, guarantor's mechanical property, guarantor are antiacid（Hic resistance）Steel product excellent surface quality, I grades of flaw detections are qualified, steel plate end to end sample through Simulated post-weld heat treatment, yield strength surplus capacity is in 40Mpa or more at plate thickness 1/2, tensile strength surplus capacity is in 25~50Mpa, and substantially in 100J or more, steel plate Properties of HIC resistance is excellent for 20 DEG C of impacts.

Description

A kind of production method of special thick antiacid tank plate

Technical field

The invention belongs to smelting iron and steel, rolling and heat treatment technics, and in particular to a kind of special thick antiacid tank plate Production method.

Technical background

Antiacid container steel is mainly used for petrochemical industry and coal chemical industry, mostly refines oil refinery desulfurization and sewage in petrochemical industry It is used in processing equipment.Other are such as oil-gas pipeline（Acid oil gas pipe high-pressure conveys）, electric power（Nuclear power reactor, station boiler） Etc. industries also partly use antiacid steel plate of pressure vessel.In recent years, wet H₂Cause the burn into of pressure vessel and pipeline under S environment Hydrogen induced cracking (HIC) (HIC), H₂The accident rates such as S stress corrosion crackings (SSCC) have the tendency that constantly rising, and wet hydrogen sulfide environment causes The loss that equipment breaks annulus is huge, and the most outstanding corrode is asked in current oil recovery, oil refining, chemical industry, Gas Production One of topic and technical barrier.

Decline with crude quality and equipment enlarging demand, petrochemical industry is for special thick antiacid steels for pressure vessel use Demand will increase year by year, steel plate is constantly increased using thickness, while also proposed the quality requirement being increasingly stringenter to steel plate. With increasing energy input in the world and requiring the upgrading of oil quality, thick antiacid steel plate of pressure vessel demand special in recent years is not It is disconnected to increase.

The antiacid tank plate that China uses at present also needs to ensure steel plate in addition to the requirement that need to meet GB/T 713-2014 After Simulated post-weld heat treatment, the mechanical property at plate thickness 1/2 meets standard requirement, and the Antacid effectiveness of steel plate, which meets design, to be wanted It asks, and low temperature impact properties, field trash, harmful element, gas content etc. is put forward higher requirements.

In composition design, in order to ensure the intensity, low-temperature flexibility and microstructural requirements of material, need to rationally design C, On Si, Mn component base, the content of stringent control harmful element, and using the more first microalloy composite designs of Cu, Cr, Ni.Control Rolling is so that thermoplasticity is become by the reasonable control to METAL HEATING PROCESS system, deformation system and temperature schedule during the rolling process Shape is combined with solid-state phase changes, to obtain tiny grain structure, steel is made to have the new work of rolling of excellent comprehensive mechanical property Skill.It can improve steel tissue crystal grain, improve the intensity and low-temperature toughness of steel plate, at the same can it is energy saving, simplify technique, Alloys producing can be given full play to.Steel plate using ACC carries out acceleration cooling after rolling, and can inhibit crystal grain and grows up, and can promote Make a large amount of disperse educts of alloying element compound, plays refined crystalline strengthening and precipitation enhancement.Normalizing heat treatment can refine crystalline substance Grain, uniform formation eliminate internal flaw and internal stress, so that steel product obtains excellent intensity and toughness group after normalizing It closes.

Invention content

It is an object of the invention to pass through rational composition design, optimization steelmaking process control, using controlled rolling+control The method that cooling+normalizing is combined, produce a kind of guaranteed cost, protect flaw detection, protect it is antiacid（Hic resistance）The thick antiacid container steel of spy of performance Plate.Steel plate is through Simulated post-weld heat treatment, and yield strength surplus capacity is in 40Mpa or more at plate thickness 1/2, and tensile strength surplus capacity is 25 ~50Mpa, substantially in 100J or more, steel plate Properties of HIC resistance is excellent for -20 DEG C of low-temperature impacts.

The technical solution of invention：

A kind of production method of special thick antiacid tank plate, uses process route for converter smelting → LF refining → VD vacuum refinings → molding → Heating Steel Ingots → controlled rolling, control cooling → heat treatment, it is characterised in that：The chemical composition mass percent of steel For：C=0.15 ~ 0.20, Si=0.25~0.50, Mn=1.20~1.35, P≤0.008, S≤0.002, Alt=0.020~ 0.050, Cr≤0.25, Cu+Ni≤0.5, Ca/S=1.2 ~ 2.0, remaining is Fe and relict element；It comprises the technical steps that：

（1）Pneumatic steelmaking：Tap C >=0.08, P≤0.008, tapping temperature >=1580 DEG C, and feeding Al lines after stove is no less than 200m, steel Al >=0.020 in water, whole Argon state；

（2）External refining：Molten steel is in the total argon blowing time >=35min of LF stoves, white slag retention time >=15min；The outbound advance of LF stoves The secondary de- P of row, controls P≤0.005；3 average feedings of feeding pure Ca lines 250 ~ 300m, Ca line amount point before LF stoves are outbound, every time It is spaced 30s；Molten steel carries out soft blow argon before going out LF, and the time is more than 5min；VD（RH）Stove is taken out true in total argon blowing time >=30min that stands Sky, vacuum degree 0.5tor hereinafter, the retention time be not less than 15min；Ca 130 ~ 170m of line are fed after the broken sky of molten steel, in steel after having fed Water surface tiles heat preserving agent in time, the soft blow time >=15min；Outbound H≤the 2.0ppm of molten steel；

（3）Molding control：38~42 DEG C of molten steel overheat, cast are noted slowly using high temperature, cryogenic fast injection, and the casting of ingot body is using at the uniform velocity Pour steel, the protection of casting process whole process argon gas；Steel ingot is offline to use 48~72h of insulation cover stacking slow cooling；

（4）Heating：1260~1300 DEG C of Heating Steel Ingots, soaking keeps the temperature 5 ~ 13h until tapping, ensures that Heating Steel Ingots are uniform；

（5）Rolling：I-stage start rolling temperature >=1050 DEG C, 950~980 DEG C of finishing temperature, roughing are rolled at a slow speed using the big pressure of high temperature System, the control of roughing mill speed ensure draught per pass >=40mm after 1.0 ~ 1.5m/s, roughing broadening；Workpiece thickness is set It is set to 1.5 ~ 2.0 times of finished product plate thickness；840 ~ 880 DEG C of II stages start rolling temperature, 800 ~ 840 DEG C of finishing temperature, every time pressure Amount >=35mm adds up reduction ratio >=50%；

（6）Accelerate cooling：780 ~ 800 DEG C of cold temperature, 2 ~ 5 DEG C/s of cooling rate, 680 ~ 720 DEG C of red temperature are opened after rolling；

（7）Stacking slow cooling：It arranges to carry out stacking slow cooling, stacking slow cooling time >=36h into burial pit immediately after steel plate is offline；

（8）Heat treatment：Using normalizing process, 880 ~ 895 DEG C of normalizing temperature, time inside furnace=plate thickness × 1.8 ~ 2.0）min.

Inventive principle and chemical element dosage control mechanism：

C：Carbon often forms carbide in steel alloy with other alloying elements, can be played under room temperature or lower temperature strong Change acts on, and as carbon content increase is susceptible to carbide segregation, causes the hardness of line of segragation difference occur with surrounding tissue, leads Cause HIC corrosion.

Si：When content is higher, the hardness of weld dimensions is unable to control, while Si elements are easily segregated in crystal grain side Boundary can encourage the formation of intercrystalline crack.

Mn：It is solution strengthening element, it is advantageous to the intensity and toughness that improve steel plate, but manganese element is a kind of to be easily segregated Element, in the case where ensureing hardness of steel, content is preferably low.

P：Steel can be caused red crisp in addition to being formed（It is hot-short）Outside the meltable eutectic field trash reduced with plasticity, also to hydrogen atom weight Combination nova process plays inhibiting effect, and metal hydrogenation effect is made to increase, to will also reduce steel in acidity, sulfide hydrogen medium In stability.

S：Sulphur is harmful to the stress corrosion cracking stability of steel.With the increase of sulfur content, the stability of steel is drastically Deteriorate, main cause is the accumulation point that sulphide inculsion is hydrogen, and metal is made to form defective tissue.Sulphur is also absorption hydrogen simultaneously Accelerating agent.Therefore, the reduction, decentralized and nodularization of non-metallic inclusion especially sulfide content can improve steel （Especially high strength steel）Stability in causing metal hydrogenation medium.

Ni：The nickel content for improving low-alloy steel, can reduce it in sulfide hydrogen solution to the resistance of stress corrosion cracking Power, while by its interior suction-operated fining ferrite grains in crystal grain, improving the Low temperature impact toughness of steel.

Cr：They can obtain stable tissue after heat treatment, improve Antacid effectiveness to a certain extent.

Cu：Copper can accelerate the recombination velocity of hydrogen atom, and then reduce the activity of hydrogen, improve material in acid medium Corrosion resistance.

Beneficial effects of the present invention：By selecting steel ingot to ensure compression ratio, each harmful element is strictly controlled on ingredient Content ensures the cleanliness factor of steel by LF+VD furnace outer refining process；Make the crystalline substance of steel using controlled rolling and controlled cooling+normalizing heat treatment Granularity reaches 10~11 grades, and obtains ideal organization type.By effective implementation of above-mentioned measure, it is successfully produced out 200mm thickness guarantor flaw detection, guarantor's mechanical property, guarantor are antiacid（Hic resistance）The steel heavy plate for pressure vessels Q345R of performance（R-HIC）Steel.This hair The bright whole process by being heat-treated from converter smelting to steel plate strictly presses the execution of above-mentioned production technology, obtains the matter in kind of product It is excellent to measure properties：Q345R（R-HIC）Control of deleterious element is stringent in the ingredient of steel, and steel plate sample is through simulating at postwelding heat It manages, the yield strength surplus capacity at plate thickness 1/2 is in 20~40MPa, and tensile strength surplus capacity is in 30~50MPa, -20 DEG C of low temperature Impact value is in 100J or more, and performance is stable, surplus is big, and steel plate Properties of HIC resistance is excellent, fully meets standard and design is wanted It asks.

Specific implementation mode

With reference to embodiment, the present invention will be further described.

A kind of production method of special thick antiacid tank plate, uses process route for converter smelting → LF refining → VD vacuum Refining → molding → Heating Steel Ingots → controlled rolling, control cooling → heat treatment, it is characterised in that：The chemical composition quality hundred of steel Point ratio is：C=0.15 ~ 0.20, Si=0.25~0.50, Mn=1.20~1.35, P≤0.008, S≤0.002, Alt=0.020~ 0.050, Cr≤0.25, Cu+Ni≤0.5, Ca/S=1.2 ~ 2.0, remaining is Fe and relict element.

It comprises the technical steps that：

（1）Pneumatic steelmaking：Tap C=0.09, P=0.006, tapping temperature：1620 DEG C, Al lines are fed after stove must not be less than 200m, Al >=0.020 in molten steel is asked, whole Argon state is kept；

（2）External refining：Molten steel is in the total argon blowing time of LF stoves 45 minutes, white slag retention time 16min.Two are carried out before LF stoves are outbound Secondary de- P controls P=0.004%；The 3 average feedings of pure Ca lines 270m, Ca line amount point are fed according to Alt contents before LF stoves are outbound, often Minor tick 30s；Molten steel carries out soft blow argon operation, soft argon blowing time 8min before going out LF；VD（RH）Stove controls：It is advised according to molten steel temperature drop Rule determines VD（RH）Stove processing time, it is desirable that VD（RH）Stove vacuumizes, vacuum degree 0.4tor in total argon blowing time 35min that stands, and protects Hold time 18min；150 meters of pure Ca lines are fed after molten steel is broken empty, are tiled in time heat preserving agent in molten steel surface after having fed, the soft blow time 18min, soft blow process forbid it is quick-fried blow, situations such as molten steel is exposed.Molten steel goes out hydrogen of standing firm, [H]=0.9ppm.

（3）Molding control：40 DEG C of molten steel overheat, the control of ingot body casting rate is uniform, and liquid level steadily rises, and casting process is whole It is protected using argon gas.Insulation cover stacking slow cooling 60h is used after steel ingot is offline.

（4）Heating：1260~1300 DEG C of Heating Steel Ingots temperature, steel ingot soaking keeps the temperature 10h until tapping, ensures Heating Steel Ingots Uniformly.

（5）Rolling：I-stage start rolling temperature >=1050 DEG C, 950~980 DEG C of finishing temperature；Steel plate rolling requires roughing to use The big pressure of high temperature rolls at a slow speed, and the control of roughing mill speed ensures draught per pass >=40mm after 1.3m/s, roughing broadening； Workpiece thickness is set as 350mm；850 DEG C of II stages start rolling temperature, 830 DEG C of finishing temperature, draught per pass >=35mm are tired out Count reduction ratio >=50%；

（6）Accelerate cooling：780 ~ 800 DEG C of cold temperature, 3.5 DEG C/s of cooling rate, 690 ~ 700 DEG C of red temperature are opened after rolling；

（7）It arranges to carry out stacking slow cooling, stacking slow cooling time 42h into burial pit immediately after steel plate is offline；

（8）Heat treatment：Using normalizing process, normalizing temperature：880~895℃；Time inside furnace 360min；

The embodiment Q345R tested according to the above method（R-HIC）Finished steel, chemical composition are as shown in table 1.Steel plate sample end to end The results are shown in Table 2 for mechanics properties testing after Simulated post-weld heat treatment, and the quasi- post weld heat treatment technique of sample mold is in table 2 590 DEG C × 14h, T is steel plate thickness in table.It is antiacid（Hic resistance）Performance test results are as shown in table 3.In table 3：CLR is that crackle is long Degree rate, CTR are crack thickness rate, and CSR is crack-sensitivity rate.

1 embodiment chemical composition of table（wt.%）

2 embodiment mechanics properties testing result of table

3 embodiment of table is antiacid（Hic resistance）Performance test results

Sample carries out HIC experiments by GB/T8650 standards：25 DEG C of test temperature, testing liquid are solution A, H₂S is passed through to full With, initial pH=2.74, pH=3.91 when off-test, test period 96h.Every group of sample detection faces are carried out after the test Amplify 100 times of observations after metallurgical polishing under the microscope, does not find any crackle.

Guarantor produced by the invention flaw detection, protect mechanical property, protect it is antiacid（Hic resistance）The 200mm thickness Q345R (R-HIC) of performance Steel plate, product surface quality is excellent, outer inspection qualification rate 100%, I grades of flaw detection qualification rates 100%, properties percent of pass 100%.Steel plate Sample is through Simulated post-weld heat treatment end to end, and yield strength surplus capacity exists in 40Mpa or more, tensile strength surplus capacity at plate thickness 1/2 25~50Mpa, substantially in 100J or more, steel plate Properties of HIC resistance is excellent for -20 DEG C of impacts.To sum up, Q345R (R-HIC) product is complete Meet the associated specifications of China GB/T713-2014 and antiacid container steel.

Claims (1)

1. a kind of production method of special thick antiacid tank plate, uses process route for converter smelting → LF refining → VD vacuum fines Refining → molding → Heating Steel Ingots → controlled rolling, control cooling → heat treatment, it is characterised in that：The chemical composition quality percentage of steel Than for：C=0.15 ~ 0.20, Si=0.25~0.50, Mn=1.20~1.35, P≤0.008, S≤0.002, Alt=0.020~ 0.050, Cr≤0.25, Cu+Ni≤0.5, Ca/S=1.2 ~ 2.0, remaining is Fe and relict element；It comprises the technical steps that：

（1）Pneumatic steelmaking：Tap C >=0.08, P≤0.008, tapping temperature >=1580 DEG C, and feeding Al lines after stove is no less than 200m, steel Al >=0.020 in water, whole Argon state；

（2）External refining：Molten steel is in the total argon blowing time >=35min of LF stoves, white slag retention time >=15min；The outbound advance of LF stoves The secondary de- P of row, controls P≤0.005；3 average feedings of feeding pure Ca lines 250 ~ 300m, Ca line amount point before LF stoves are outbound, every time It is spaced 30s；Molten steel carries out soft blow argon before going out LF, and the time is more than 5min；VD（RH）Stove is taken out true in total argon blowing time >=30min that stands Sky, vacuum degree 0.5tor hereinafter, the retention time be not less than 15min；Ca 130 ~ 170m of line are fed after the broken sky of molten steel, in steel after having fed Water surface tiles heat preserving agent in time, the soft blow time >=15min；Outbound H≤the 2.0ppm of molten steel；

（3）Molding control：38~42 DEG C of molten steel overheat, cast are noted slowly using high temperature, cryogenic fast injection, and the casting of ingot body is using at the uniform velocity Pour steel, the protection of casting process whole process argon gas；Steel ingot is offline to use 48~72h of insulation cover stacking slow cooling；

（4）Heating：1260~1300 DEG C of Heating Steel Ingots, soaking keeps the temperature 5 ~ 13h until tapping, ensures that Heating Steel Ingots are uniform；

（5）Rolling：I-stage start rolling temperature >=1050 DEG C, 950~980 DEG C of finishing temperature, roughing are rolled at a slow speed using the big pressure of high temperature System, the control of roughing mill speed ensure draught per pass >=40mm after 1.0 ~ 1.5m/s, roughing broadening；Workpiece thickness is set It is set to 1.5 ~ 2.0 times of finished product plate thickness；840 ~ 880 DEG C of II stages start rolling temperature, 800 ~ 840 DEG C of finishing temperature, every time pressure Amount >=35mm adds up reduction ratio >=50%；

（6）Accelerate cooling：780 ~ 800 DEG C of cold temperature, 2 ~ 5 DEG C/s of cooling rate, 680 ~ 720 DEG C of red temperature are opened after rolling；

（7）Stacking slow cooling：It arranges to carry out stacking slow cooling, stacking slow cooling time >=36h into burial pit immediately after steel plate is offline；

（8）Heat treatment：Using normalizing process, 880 ~ 895 DEG C of normalizing temperature, time inside furnace=plate thickness × 1.8 ~ 2.0）min.