CN103757540A

CN103757540A - Export S355J2 titanium-added steel plate and production method thereof

Info

Publication number: CN103757540A
Application number: CN201410008540.4A
Authority: CN
Inventors: 刘源; 李新玲; 王若刚; 应传涛; 陈华; 杨军; 刘立强; 张坤; 罗志华
Original assignee: Angang Steel Co Ltd
Current assignee: Angang Steel Co Ltd
Priority date: 2014-01-09
Filing date: 2014-01-09
Publication date: 2014-04-30

Abstract

The invention provides an export S355J2 titanium-added steel plate and a production method thereof. The export S355J2 titanium-added steel plate contains the following chemical ingredients by wt%: not more than 0.16% of C, 0.25-0.45% of Si, 1.0-1.4% of Mn, not more than 0.02% of P, not more than 0.004% of S, 0.05-0.06% of Ti, not more than 0.40 of CEV, and the balance of ion and inevitable impurities. Total heating time of continuous casting billet heating is not less than 9min/cm, the highest heating temperature is 1220 DEG C, soaking temperature is not more than 1200 DEG C, and soaking zone in-furnace time is more than 90min; the first stage start rolling temperature is not more than 1140 DEG C, and total reduction rate is more than 60%; the second stage start rolling temperature is 950 DEG C, finial rolling temperature is less than 900 DEG C, and deformation rate is controlled to 50%-60%; stacking temperature is not less than 400 DEG C, and stacking time is not less than 16h. The production technology provided by the invention has short technological process, and is low in production cost, suitable for large-batch production and beneficial for increasing export volume; product ingredients and product performance of the steel plate completely meet the requirements of European standard EN10020, Reh of the steel plate is up to 386MPa, Rm of the steel plate is up to 522MPa, A value of the steel plate is 28%, and average impact value of the steel plate at -20 DEG C is up to 172J.

Description

A kind of outlet S355J2 adds titanium steel plate and production method thereof

Technical field

The invention belongs to technical field of ferrous metallurgy, relate in particular to and a kind ofly for the S355J2 exporting, add titanium steel plate and production method thereof.

Background technology

According to the definition of 3.2.1 alloy steel in Europe superscript EN10020-" definition of Steel Grade and division ", it is steel alloy that B content exceedes 0.0008% steel grade, and it is preferential in national policy, to stipulate that steel alloy can be enjoyed 13% export tax rebate.Along with in recent years, steel industry production and operation are absorbed in lasting predicament, and domestic each producer, all in the new benefit growth point of exploitation of trying one's best, has been invested sight containing in the exploitation of B steel one after another.At steel grade, add B element, can realize smoothly the object of export tax rebate.But due to a series of impacts that added B to cause, can use and bring certain quality risk to user.It is embodied in:

1, in welding process, very easily crack.

The crack-sensitivity formula of steel products is:

Pcm＝C+Si/30+(Mn+Cu+Cr)/20+Ni/60+Mo/15+V/10+5B

By above-mentioned formula, can find out, B is 5 times of C to the influence power of crackle, 150 times of Si, and 100 times of Mn, that is to say, once after having added B in steel, crackle probability of occurrence will increase greatly.

2, containing the poor toughness of B steel, impact property fluctuation is larger.

B becomes precipitation or netted separating out at steel grade along crystal boundary, makes the toughness drop of steel, forms " boron is crisp ", and due to the crisp existence of boron, its low-temperature flexibility is worse, and while using in cold district, steel, when being subject to surging force, very easily rupture.

3, for avoiding, can worsen containing B rigidity, add in B steel B elemental range and design extremely narrowly, process window is young, if produce in batches, causes smelting procedure Efficiency Decreasing.

In the steel of some important use, as according to the standard of U.S.'s pipe line steel, boron is forbidden being added in pipe line steel.Domestic iron and steel enterprises, in the contract of supply boron-containing steel, has also also clearly marked the clause of " can not be used for large-scale load assembly and like " mostly, is also to have taken into full account the quality risk that B adds.

In fact, except B element, the definition of 3.2.1 alloy steel in Europe superscript EN10020-" definition of Steel Grade and division ", Ti content exceedes 0.05% steel also referred to as steel alloy, can enjoy equally in national policy 13% export tax rebate preferential.And Ti be metallurgical academia generally acknowledge in steel, produce refined crystalline strengthening and precipitation strength and improve the beneficial element of steel strength.

Summary of the invention

Object of the present invention is intended to overcome above-mentioned defect, provides a kind of technical process short, and production cost is low, is applicable to producing in enormous quantities, and the outlet S355J2 that product composition and performance meet Europe superscript EN10020 requirement completely adds titanium steel plate and production method thereof.

For this reason, the solution that the present invention takes is:

A kind of outlet S355J2 adds titanium steel plate, and its chemical composition wt% content is: C≤0.16%, Si 0.25-0.45%, Mn 1.0-1.4%, P≤0.02%, S≤0.004%, Ti 0.05-0.06%, and CEV≤0.40, all the other are iron and inevitable impurity.

Composition is the basic determinative of rigidity energy, and technique adjustment is just for obtaining best over-all properties or outstanding a certain performance.According to outlet is added to the requirement of titanium S355J2 steel plate composition and performance, and consider the needs of follow-up export tax rebate, therefore adopt above Composition Design.

C:C≤0.16%, carbon plays solution strengthening and proposes high-intensity effect, but too high levels can reduce weldability, affects HAZ toughness.

Mn:1.0%-1.4%, manganese is weak carbide forming element.And can change ferritic nucleation and growth, by precipitation strength and dispersion-strengthened, further crystal grain thinning improves steel plate toughness when keeping intensity.

Ti:0.05-0.06%, titanium plays refined crystalline strengthening and precipitation strength in steel, but cost of alloy is higher, and consider the needs of follow-up export tax rebate.

Export the production method that S355J2 adds titanium steel plate, it is characterized in that, reduce Heating temperature, keep the austenite crystal miniaturization before rolling; Adopt two-part controlled rolling, by one-phase recrystallization zone repeated deformation, make austenite crystal miniaturization; Two-stage is strengthened the accumulation draught in austenite non-recrystallization district, increases boundary or grain area and the deformation bands area of austenite unit volume; Its concrete grammar is:

1, continuously cast bloom heating: total heat-up time >=9min/cm, maximum heating temperature l220 ℃, soaking temperature≤l200 ℃, soaking zone time inside furnace > 90min;

2, controlled rolling: one-phase start rolling temperature≤l140 ℃, accumulative total draft > 60%; 950 ℃ of two-stage start rolling temperatures, 900 ℃ of finishing temperature <, deformation rate is controlled at 50%-60%;

3, stacking slow cooling: stacking temperature >=400 ℃, time >=16h.

Beneficial effect of the present invention is:

The present invention has overcome the defect containing B steel, has the technological process of production short, the feature that production cost is low, be particularly suitable for producing in enormous quantities, be conducive to the amount of increasing export, its product composition and performance meet Europe superscript EN10020 requirement completely, have improved the safe application performance of steel plate.The S355J2 that the present invention produces adds titanium steel plate mechanical properties test result and is respectively: Reh reaches 386MPa, and Rm reaches 522MPa, and A value is that 28% ,-20 ℃ of impact values on average reach 172J, and all mechanical performance indexs are all much larger than standard gauge definite value.

Embodiment

Embodiment 1:

Steel trade mark S355J2, thickness of strand is 280mm, mill product thickness is 40mm.

Chemical composition wt% content is: C:0.14%, Si:0.30%, Mn:1.1%, Ti:0.055%, P:0.01%, S:0.003%, all the other are iron and inevitable trace impurity.

The technological process of production is: rectify-stacking slow cooling-cutting-inspection-finished product of the cooling-Re of continuously cast bloom-heating-dephosphorization-controlled rolling-control.

Take low-temperature heat system, reduce Heating temperature, avoid high temperature to burn steel and cause grain coarsening, keep the austenite crystal miniaturization before rolling.Adopt two-stage control rolling, form as much as possible ferrite transformation core, effectively refinement ferrite crystal grain.By one-phase recrystallization zone repeated deformation, make austenite crystal miniaturization; Two-stage is strengthened the accumulation draught in austenite non-recrystallization district, increases boundary or grain area and the deformation bands area of austenite unit volume, improves steel plate obdurability.

Continuously cast bloom total heat-up time of 9min/cm, maximum heating temperature is controlled at l220 ℃, soaking temperature l120 ℃, soaking zone time inside furnace 100min.

One-phase adopts and depresses greatly, start rolling temperature l110 ℃, and each pass deformation is controlled at 15-25%, accumulative total draft 70%, finishing temperature is controlled at 960 ℃.Subordinate phase start rolling temperature is controlled at 950 ℃, 870 ℃ of finishing temperatures, and deformation rate is controlled at 60%.

Stacking slow cooling after steel plate hot aligning, 470 ℃ of stacking temperature, time 20h.

Embodiment 2:

Steel trade mark S355J2, thickness of strand is 240mm, mill product thickness is 20mm.

Chemical composition wt% content is: C:0.16%, Si:0.25%, Mn:1.4%, Ti:0.059%, P:0.016%, S:0.002%, all the other are iron and inevitable trace impurity.

Continuously cast bloom total heat-up time of 9.4min/cm, maximum heating temperature is controlled at l220 ℃, soaking temperature l180 ℃, soaking zone time inside furnace 95min.

One-phase adopts and depresses greatly, start rolling temperature l140 ℃, and each pass deformation is controlled at 18-23%, accumulative total draft 65%, finishing temperature is controlled at 1080 ℃.Subordinate phase start rolling temperature is controlled at 950 ℃, 860 ℃ of finishing temperatures, and deformation rate is controlled at 54%.MPa

Stacking slow cooling after steel plate hot aligning, 500 ℃ of stacking temperature, time 23h.

The mechanical properties test result of embodiment steel plate is as shown in the table.

Note: standard-required steel plate thickness 16-40mm mechanical performance index is: Reh >=335 MPa, 630 MPa >=Rm >=470 MPa, A >=21%, impact >=34 J.

As can be seen from the above table, the outlet of producing by above composition and technological design adds titanium S355J2 steel plate and meets standard needs completely, and has improved safe application performance, enjoys policy of tax refunds on export goods simultaneously.

Claims

1. an outlet S355J2 adds titanium steel plate, it is characterized in that, its chemical composition wt% content is: C≤0.16%, Si 0.25-0.45%, Mn 1.0-1.4%, P≤0.02%, S≤0.004%, Ti 0.05-0.06%, and CEV≤0.40, all the other are iron and inevitable impurity.

2. export as claimed in claim 1 the production method that S355J2 adds titanium steel plate, it is characterized in that, reduce Heating temperature, keep the austenite crystal miniaturization before rolling; Adopt two-part controlled rolling, by one-phase recrystallization zone repeated deformation, make austenite crystal miniaturization; Two-stage is strengthened the accumulation draught in austenite non-recrystallization district, increases boundary or grain area and the deformation bands area of austenite unit volume; Its concrete grammar is:

(1), continuously cast bloom heating: total heat-up time >=9min/cm, maximum heating temperature l220 ℃, soaking temperature≤l200 ℃, soaking zone time inside furnace > 90min;

(2), controlled rolling: one-phase start rolling temperature≤l140 ℃, accumulative total draft > 60%; 950 ℃ of two-stage start rolling temperatures, 900 ℃ of finishing temperature <, deformation rate is controlled at 50%-60%;

(3), stacking slow cooling: stacking temperature >=400 ℃, time >=16h.