CN102925796B - Non-alloyed ultra-low carbon structure cold-rolled sheet and production method thereof - Google Patents

Abstract

The invention relates to the rolling field of automobile steel plates, and in particular relates to a production method of a non-alloyed ultra-low carbon structure cold-rolled sheet. The production method is characterized in that the steel comprises the chemical components by weight percent: 0.0020-0.0060% of C, less than or equal to 0.10% of Si, 0.30-0.80% of Mn, 0.030-0.080% of P, 0.010-0.025% of S, 0.020-0.060% of ALS, 0.0003-0.0005% of Bs and the balance of Fe and unavoidable impurities. Compared with the prior art, the production method has the advantages that 1) niobium-titanium alloy is omitted, and solution strengthening function of C, P and the like is applied, so that the cost is greatly lowered; and 2) the yield strength and the yield strength of ultra-low carbon steel are improved, the ultra-low carbon steel is guaranteed to have good deep drawing performance, and the produced cold-rolled sheet has high strength and good shaping property so as to meet the using aim of the automobile industry.

Description

A kind of no-alloyed Ultra-low carbon is cold-reduced sheet and production method thereof for structure

Technical field

The present invention relates to automotive sheet rolling field, particularly cold-reduced sheet and production method thereof for a kind of no-alloyed Ultra-low carbon structure.

Background technology

In the Ultra-low carbon product of Hyundai Motor steel plate, generally all add appropriate niobium or titanium alloy carrys out C, the N in sublimate steel, improve formed product performance.IF steel is gapless atomic steel, there is low-yield, low yield strength ratio, yield strength≤190MPa, the feature of traditional ultra low-carbon steel be carbon content extremely low≤0.004%, there is very strong deformability, prevent ram-type cracking, require to have good r value and n value simultaneously, to ensure smooth surface after moulding.21st century, world energy sources was supplied with growing tension, and for alleviating the consumption to the energy of automobile, the while does not affect the security requirement of automobile, and the automobile of high-strength light becomes main flow.

European standard EN10268-2006 proposes a series of new requirements to the production technology of autobody sheet, wherein HC220Y trade mark steel requires steel plate in having good super deep drawability, structural part and reinforcing member as automobile will have high-strength impact-resistant, both " high strength and ductility ", require ultra low-carbon steel to there is high yield strength (σ s=220～270MPa), high-tensile (Rm=350～420MPa), deep drawability (r=1.6～2.2, n=0.18～0.25), good ductility (A80 >=34%, A50 >=40%).

Generally adopt and in IF steel, add phosphorus and silicon or manganese, require it to have good mechanical property, and have good anti-secondary processing brittleness, chemical treatment properties and the zinc-plated adaptability of alloying, yield range is very little simultaneously, requires product to have very high stability.General high-strength steel adds niobium titanium alloy when adopting phosphorus as main strengthening element, though there is close technique at home and abroad, implementation has obvious difference, and the unit elongation of the method cannot meet user's demand.

Summary of the invention

The object of this invention is to provide a kind of no-alloyed Ultra-low carbon structure cold-reduced sheet and production method thereof, with the strengthening effect of niobium and titanium in the alternative ultra low-carbon steel of P, make steel plate in thering is good super deep drawability, there is high-strength impact-resistant, meet as the structural part of automobile and the performance requriements of reinforcing member.

For achieving the above object, the present invention realizes by the following technical solutions:

The thin brilliant Ultra-low carbon structure cold-reduced sheet of a kind of no-alloyed, the chemical composition of steel is by weight percentage: C 0.0020%～0.0060%, Si≤0.10%, Mn 0.30%～0.80%, P 0.030%～0.080%, S 0.010%～0.025%, AL _s0.020%～0.060%, Bs 0.0003%～0.0005%, surplus is Fe and inevitable impurity.

The production method of cold-reduced sheet for the thin brilliant Ultra-low carbon structure of above-mentioned a kind of no-alloyed, comprises smelting, continuous casting, hot rolling, cold-rolling pickling, continuous annealing, smooth, and concrete technology parameter is:

1) hot rolling:

Billet heating temperature: 1200～1300 DEG C;

Roughing temperature out: 1050～1150 DEG C;

Finish rolling start rolling temperature: 1050～1150 DEG C;

Hot rolling finishing temperature: 850～930 DEG C;

Coiler plate temperature: 580～620 DEG C;

2) cold rolling: cold rolling draft: 73～87%;

3) continuous annealing: connect and move back 3～4 DEG C/s of temperature rise rate;

Annealing temperature: 820～840 DEG C;

Soaking time: 90～130s;

Slow cooling section temperature: 600～550 DEG C;

Slow cooling speed: 35～50 DEG C/s;

Rapid cooling section temperature: 400～300 DEG C;

Rapid cooling speed: 35～50 DEG C/s;

4) smooth unit elongation: 0.4%～2.0%.

On steel ultra low-carbon steel C≤0.010% basis, increase P content, improve surrender and the tensile strength of ultra low-carbon steel, ensure that it has good deep draw performance simultaneously, by optimizing the carbon content in steel, the intensity of the raising steel such as alloying element Mn, the Si that interpolation can be strengthened is avoided the secondary processing brittleness of steel, simultaneously boron add the secondary processing brittleness that suppresses P.

Utilize hot rolling low temperature coiling technique to avoid the formation of FePTi, prevent its destruction to stampability and high-elongation, avoided, because of two-phase particle, the inhibition of crystal boundary is improved to unit elongation by pure carbon element no-alloyed simultaneously, adjusting cold-rolling process soaking temperature makes product have { the 111} texture of higher strong punching press up to 820 degree above, utilize high polishing draft to obtain high tensile strength and yield strength, to ensure plasticity and the shock resistance of steel simultaneously.

Compared with prior art, the invention has the beneficial effects as follows:

1) cancel adding of niobium titanium alloy, the solution strengthening effects such as application C, P, and adopt the ultra low-carbon steel of high Mn as main component, P and Mn element are distributed with the effect of crystal grain thinning at grain boundaries, adjusting process makes refined crystalline strengthening, greatly reduces costs, and effect stability.

2) improve surrender and the tensile strength of ultra low-carbon steel, ensured that it has good deep draw performance simultaneously, produced and there is the forming property that high intensity has had again, met the application target of automotive industry.

Brief description of the drawings

Fig. 1 is continuous annealing process figure of the present invention;

Fig. 2 is cold-rolled products metallograph of the present invention.

Embodiment

Below in conjunction with embodiment, the present invention is further described:

The thin brilliant Ultra-low carbon structure cold-reduced sheet of a kind of no-alloyed of the present invention, the chemical composition of steel is by weight percentage: C 0.0020%～0.0060%, Si≤0.10%, Mn 0.30%～0.80%, P 0.030%～0.080%, S 0.010%～0.025%, AL _s0.020%～0.060%, Bs 0.0003%～0.0005%, surplus is Fe and inevitable impurity.Wherein Bs is acid-soluble boron.

A production method for cold-reduced sheet for the thin brilliant Ultra-low carbon structure of no-alloyed, comprises smelting, continuous casting, hot rolling, cold-rolling pickling, continuous annealing, smooth, and its concrete technology parameter is:

1) hot rolling:

Billet heating temperature: 1200～1300 DEG C;

Roughing temperature out: 1050～1150 DEG C;

Finish rolling start rolling temperature: 1050～1150 DEG C;

Hot rolling finishing temperature: 850～930 DEG C;

Coiler plate temperature: 580～620 DEG C;

2) cold rolling: cold rolling draft: 73～87%;

3) see Fig. 1, continuous annealing process figure of the present invention: connect and move back 3～4 DEG C/s of temperature rise rate;

Annealing temperature: 820～840 DEG C;

Soaking time: 90～130s;

Slow cooling section temperature: 600～550 DEG C;

Slow cooling speed: 35～50 DEG C/s;

Rapid cooling section temperature: 400～300 DEG C;

Rapid cooling speed: 35～50 DEG C/s;

4) smooth unit elongation: 0.4%～2.0%.

Seeing Fig. 2, is cold-rolled products metallograph of the present invention, and cold-rolled products performance test effect of the present invention is in table 1:

Table 1

Unit elongation A 50	Yield strength	Tensile strength	R is average	N is average
					40～45	222～260	350～370	1.89～2.1	0.19～0.22

The present invention has met high yield strength (σ s=220～270MPa), the tensile strength (350～420MPa) of the ultra low-carbon steel for automobile structure and reinforcing member of European EN10268-2006 standard completely, deep drawability (r=1.6～2.2, n=0.18～0.25), the requirement of good ductility (δ >=34%).

Owing to not adding the alloy such as Nb or Ti in steel, there is no precipitation strength, C, Mn, P, the N of Main Basis exist in steel with the form of solid solution, make product there is very high intensity, produce and there is the forming property that high intensity has had again, can meet the thin brilliant Ultra-low carbon structural steel of no-alloyed of the super deep-draw needs of automotive industry.

Claims (1)

1. the production method of the thin brilliant Ultra-low carbon structure use cold-reduced sheet of no-alloyed, it is characterized in that, the chemical composition of steel is by weight percentage: C0.0020%～0.0060%, Si≤0.10%, Mn0.30%～0.80%, P0.030%～0.080%, S0.010%～0.025%, AL _s0.020%～0.060%, Bs0.0003%～0.0005%, surplus is Fe and inevitable impurity;

Its production method comprises smelting, continuous casting, hot rolling, cold-rolling pickling, continuous annealing, smooth, and its concrete technology parameter is:

1) hot rolling:

Billet heating temperature: 1200～1300 DEG C;

Roughing temperature out: 1050～1150 DEG C;

Finish rolling start rolling temperature: 1050～1150 DEG C;

Hot rolling finishing temperature: 850～930 DEG C;

Coiler plate temperature: 580～620 DEG C;

2) cold rolling: cold rolling draft: 73～87%;

3) continuous annealing: connect and move back 3～4 DEG C/s of temperature rise rate;

Annealing temperature: 820～840 DEG C;

Soaking time: 90～130s;

Slow cooling section temperature: 600～550 DEG C;

Slow cooling speed: 35～50 DEG C/s;

Rapid cooling section temperature: 400～300 DEG C;

Rapid cooling speed: 35～50 DEG C/s;

4) smooth unit elongation: 0.4%～2.0%.

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