CN105917016A - Ferritic stainless steel and method for producing same - Google Patents

Ferritic stainless steel and method for producing same Download PDF

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Publication number
CN105917016A
CN105917016A CN201580004091.9A CN201580004091A CN105917016A CN 105917016 A CN105917016 A CN 105917016A CN 201580004091 A CN201580004091 A CN 201580004091A CN 105917016 A CN105917016 A CN 105917016A
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annealing
phase
stainless steel
cold
scope
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CN105917016B (en
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吉野正崇
太田裕树
田彩子
松原行宏
水谷映斗
藤泽光幸
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JFE Steel Corp
JFE Engineering Corp
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NKK Corp
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Abstract

Provided are: a ferritic stainless steel which has sufficient corrosion resistance and formability (large elongation and average r value, and small |[delta]r|), while being suppressed in the occurrence of linear streaks and having excellent surface properties; and a method for producing this ferritic stainless steel. A ferritic stainless steel according to the present invention contains, in mass%, 0.005-0.05% of C, 0.02-0.50% of Si, 0.05-1.0% of Mn, 0.04% or less of P, 0.01% or less of S, 15.5-18.0% of Cr, 0.001-0.10% of Al, 0.01-0.06% of N, 0.01-0.25% of V, 0.001-0.020% of Ti and 0.001-0.030% of Nb, with the balance made up of Fe and unavoidable impurities. In addition, this ferritic stainless steel is configured to satisfy V/(Ti+Nb)>=2.0.

Description

Ferrite-group stainless steel and its manufacture method
Technical field
The present invention relates to have sufficient corrosion resistance and formability and will not produce by the line caused by hot rolling, annealing The ferrite-group stainless steel of the surface property excellence of shape defect and its manufacture method.
Background technology
Ferrite-group stainless steel is cheap and corrosion resistance excellent, is therefore used in building materials, conveying equipment, household appliances, kitchen The diversified purposes such as utensil, automobile component, its range of application further continuous enlargement in recent years.Use to be applied to these On the way, for ferrite-group stainless steel, not only need corrosion resistance, in addition it is also necessary to the sufficient formability of regulation shape can be processed into (percentage elongation big (following, situation the biggest for percentage elongation is referred to as have ductility), average plastic strain ratio are (hereinafter referred to as averagely R value) absolute value (hereinafter referred to as | Δ r |) of intra-face anisotropy of big, r value is little).It addition, be applied to surface aesthetic Property purposes in the case of, it is also desirable to surface property is excellent.
For foregoing, in patent documentation 1, disclose a kind of formability and wrinkle properties (ridging Resistance) excellent ferrite-group stainless steel, it is characterised in that in terms of quality %, containing C:0.02～0.06%, Si: Less than 1.0%, below Mn:1.0%, below P:0.05%, below S:0.01%, below Al:0.005%, Ti:0.005% with Under, Cr:11～30%, below Ni:0.7%, and meet 0.06≤(C+N)≤0.12,1≤N/C and 1.5 × 10-3≤(V× N)≤1.5×10-2Quality % of each element (C, N, the V represent respectively).But, patent documentation 1 is not appointed for anisotropy What is recorded.In addition, it is necessary to carry out so-called coffin annealing (such as, the annealing of 8 hours at 860 DEG C) after hot rolling.This vanning If annealing processing comprises heating, the process of cooling, need the time of about one week, therefore to there is productivity ratio low to completing Problem.
In patent documentation 2, disclosing a kind of processability and the ferrite-group stainless steel of surface property excellence, its feature exists In, in terms of quality % containing C:0.01～0.10%, Si:0.05～0.50%, Mn:0.05～1.00%, Ni:0.01～ 0.50%, Cr:10～20%, Mo:0.005～0.50%, Cu:0.01～0.50%, V:0.001～0.50%, Ti:0.001 ～0.50%, Al:0.01～0.20%, Nb:0.001～0.50%, N:0.005～0.050% and B:0.00010～ After the steel of 0.00500% carries out hot rolling, (annealing and pickling line, moves back to use box-type furnace or AP production line Fire pickling lines) continuous oven in the single-phase temperature range of ferrite, carry out hot rolled plate annealing, carry out further cold rolling and Finish to gauge is annealed.But, using in the case of box-type furnace, with above-mentioned patent documentation 1 similarly, the presence of the low problem of productivity ratio. It addition, in patent documentation 2, percentage elongation is not had any record, but in continuous annealing furnace in the single-phase temperature range of ferrite In the case of carrying out hot rolled plate annealing, the low therefore recrystallization of annealing temperature is insufficient, enters with in the single-phase temperature range of ferrite The situation of row coffin annealing is compared percentage elongation and is reduced.It addition, generally ferrite-group stainless steel as patent documentation 2 The crystal grain group (field (colony)) with similar crystal orientation can be generated when casting or hot rolling, thus there is | Δ r | Become big problem.
Look-ahead technique document
Patent documentation
Patent documentation 1: No. 3584881 publications of Japanese Patent No. (Japan's public table WO00/60134 again)
Patent documentation 2: No. 3581801 publications of Japanese Patent No. (Japanese Unexamined Patent Publication 2001-3134)
Summary of the invention
It is an object of the invention to, solve above-mentioned problem, it is provided that there is sufficient corrosion resistance and formability and will not produce The raw ferrite-group stainless steel excellent by the surface property of the line defect caused by hot rolling, annealing and its manufacture method.
Additionally, in the present invention, so-called sufficiently corrosion resistance refers to, for utilizing #600 sand paper to complete surface to grind After by end face portion seal steel plate, carry out 3 circulation JIS H8502 defineds brine spray cyclic test (with (and saline spray Mist (35 DEG C, 5 mass %NaCl, spraying 2h) → be dried (60 DEG C, relative humidity 40%, 4h) → moistening (50 DEG C, relative humidity >= 95%, 2h)) be 1 test circulated), (=rust area/steel plate is overall for the rust area rate of the surface of steel plate in the case of being somebody's turn to do Area × 100 [%]) below 25%.
It addition, so-called sufficiently formability refers to, the elongation at break in the tension test according to JIS Z 2241 exists It is more than 25% when using along the test film of the direction collection at a right angle with rolling direction, tries in the stretching according to JIS Z 2241 When testing the strain of applying 15% by following (1) formula calculate average r value be more than 0.65 and by following (2) formula calculating r (absolute value (| Δ r |) of hereinafter referred to as Δ r) is less than 0.30 to the intra-face anisotropy of value.
Average r value=(rL+2×rD+rC)/4 (1)
Δ r=(rL-2 × rD+rC)/2 (2)
Wherein, rLFor carrying out r value during tension test, r on the direction parallel with rolling directionDFor relative to rolling R value when direction is to carry out tension test on the direction of 45 °, rCFor carrying out stretching examination on the direction at a right angle with rolling direction R value when testing.
Being studied to solve problem, it was found that it is for the ferrite-group stainless steel of suitable composition, Steel plate after hot rolling is carried out cold rolling before, anneal within the temperature range of becoming the two-phase of ferritic phase and austenite phase, It is possible to the ferrite-group stainless steel obtaining that there is sufficient corrosion resistance and formability.Additionally, it was found that by fitting above-mentioned When composition of steel in the range of further V, Ti and Nb are specified so that thick Cr carbon will not be separated out during in hot rolling Nitride, and the generation of the line defect of surface of steel plate can be suppressed, its result, not only corrosion resistance and having excellent formability, and And surface property is the most excellent.
The present invention completes based on above discovery, is below its main contents.
[1] a kind of ferrite-group stainless steel, in terms of quality %, containing C:0.005～0.05%, Si:0.02～0.50%, Mn:0.05～1.0%, below P:0.04%, below S:0.01%, Cr:15.5～18.0%, Al:0.001～0.10%, N: 0.01～0.06%, V:0.01～0.25%, Ti:0.001～0.020%, Nb:0.001～0.030%, surplus be Fe and Inevitably impurity, and meet V/ (Ti+Nb) >=2.0.
[2] a kind of ferrite-group stainless steel, in terms of quality %, containing C:0.01～0.05%, Si:0.02～0.50%, Mn:0.2～1.0%, below P:0.04%, below S:0.01%, Cr:16.0～18.0%, Al:0.001～0.10%, N: 0.01～0.06%, V:0.01～0.25%, Ti:0.001～0.015%, Nb:0.001～0.025%, surplus be Fe and Inevitably impurity, and meet V/ (Ti+Nb) >=2.0.
[3] according to the ferrite-group stainless steel described in above-mentioned [1] or [2], wherein, in terms of quality %, possibly together with being selected from One kind or two or more in Cu:0.1～1.0%, Ni:0.1～1.0%, Mo:0.1～0.5%, Co:0.01～0.5%.
[4] according to ferrite-group stainless steel described any one of above-mentioned [1]～[3], wherein, in terms of quality %, also Containing selected from Mg:0.0002～0.0050%, B:0.0002～0.0050%, REM:0.01～0.10%, Ca:0.0002～ One kind or two or more in 0.0020%.
[5] manufacture method of a kind of ferrite-group stainless steel, to having above-mentioned [1] to one-tenth described any one of [4] Hot rolling implemented by the plate slab that is grouped into, followed by keeping 5 seconds～15 minutes move back within the temperature range of 880～1000 DEG C Hot-roll annealing plate made by fire, next implements cold rolling, carries out subsequently keeping 5 seconds～5 within the temperature range of 800～950 DEG C Minute cold-reduced sheet annealing
It should be noted that in this manual, represent that the % of the composition of steel is entirely quality %.
Invention effect
In accordance with the invention it is possible to obtain having sufficient corrosion resistance and formability (percentage elongation and average r value greatly, | Δ R | little) and the ferrite-group stainless steel producing few surface property excellence of line defect.
Detailed description of the invention
Hereinafter, the present invention is described in detail.
Ferrite-group stainless steel is characterised by, in terms of quality %, containing C:0.005～0.05%, Si:0.02～ 0.50%, Mn:0.05～1.0%, below P:0.04%, below S:0.01%, Cr:15.5～18.0%, Al:0.001～ 0.10%, N:0.01～0.06%, V:0.01～0.25%, Ti:0.001～0.020%, Nb:0.001～0.030%, surplus For Fe and inevitable impurity, and meet V/ (Ti+Nb) >=2.0.In the present invention, become the balance being grouped into critically important, The especially balance of V, Ti and Nb is critically important.Make V:0.01～0.25%, Ti:0.001～0.020%, Nb:0.001～ 0.030% and to meet V/ (Ti+Nb) >=2.0 be important important document.By being set to the combination that this one-tenth is grouped into, it is possible to had There is the ferrite-group stainless steel producing few surface property excellence of sufficient corrosion resistance and sufficient formability and line defect.
First, the technology contents of the present invention is described in detail.
Present inventor anneals to not by long hot rolled plate as coffin annealing (batch annealing), but Carried out by the technology using formability that the hot rolled plate annealing of the short time of the high continuous annealing furnace of productivity ratio obtains regulation Research.The problem of the prior art using continuous annealing furnace is, owing to moving back in the single-phase temperature range of ferrite Fire, so not carrying out sufficient recrystallization, it is impossible to obtain sufficient percentage elongation, and field is remaining to cold-reduced sheet annealing, from And | Δ r | is big.Therefore, present inventor considers below scheme: carry out heat in the coexistence region of ferritic phase and austenite phase Roll plate annealing, carry out cold rolling and cold-reduced sheet annealing with usual method subsequently, the most again become ferrite homogeneous structure.
That is, by carrying out hot rolling at the ferritic phase of temperature range high temperature more single-phase than ferrite and the coexistence region of austenite phase Plate is annealed, and promotes the recrystallization of ferritic phase.Its result, it is to avoid the ferrite crystal grain being imported into processing strain because of hot rolling is residual Deposit after annealing to cold-reduced sheet, so that the percentage elongation after cold-reduced sheet annealing improves.It addition, annealed by hot rolled plate and from ferrum element When body generates austenite phase mutually, austenite phase generates in the way of having the crystal orientation different from the ferritic phase before annealing, Therefore the field of ferritic phase is destroyed effectively.Therefore, the cold rolled annealed plate after having carried out the annealing of cold rolling and cold-reduced sheet Metal structure in, make the gamma fiber texture (γ-fiber texture) that r value improves grow, and field separated, metal The anisotropy of tissue is relaxed such that it is able to obtain | Δ r | the characteristic of this excellence that diminishes.
It addition, in the case of the coexistence region of ferritic phase and austenite phase carries out hot rolled plate annealing, after hot rolled plate annealing Become ferritic phase and the duplex structure of martensitic phase obtained from austenite phase phase transformation.But, by this is comprised martensite The hot-roll annealing plate of phase carries out cold rolling, and owing to martensitic phase is harder than ferritic phase, therefore the ferritic phase near martensitic phase is excellent First deforming thus roll strain and concentrate, recrystallization position during cold-reduced sheet annealing increases further.When thus, cold-reduced sheet is annealed Recrystallization is promoted further, and the anisotropy of the metal structure after cold-reduced sheet annealing is relaxed further.
But, if learning, in the coexistence region of above-mentioned ferritic phase and austenite phase, the steel of conventional composition being carried out hot rolling Plate is annealed, then can produce the defect (hereinafter referred to as line defect) of the wire along rolling direction after cold-reduced sheet is annealed, thus produce Raw surface property significantly reduces this new problem.
Therefore, present inventor is in order to take into account formability and surface property, to because of in ferritic phase and austenite phase Coexistence region carries out hot rolled plate annealing and produces the reason of line defect and investigated.Its result, learn line defect be because of It is present in the martensitic phase of the notable hard of the steel plate skin section after hot rolled plate annealing and produces.That is, if learning at hot rolled plate There is the martensitic phase of notable hard in the steel plate skin section after annealing, cold rolling middle strain the most later is concentrated in notable hard Martensitic phase and the interface of ferritic phase and produce fine crack, cold-reduced sheet anneal after become line defect.Martensite It is that austenite phase (it is to generate in the hot rolled plate annealing carried out in the coexistence region of ferritic phase and austenite phase) is cold mutually But undergo phase transition during and generate.Find after the hardness of each martensitic crystal grains in having investigated metal structure, most horses Family name's body is calculated as 300～about 400, on the other hand, the notable hard of martensitic phase of a part with Vickers hardness (HV), exceedes HV500, cold rolling in fine crack produce at the interface of martensitic phase and the ferritic phase of this notable hard more than HV500.
Therefore, after hot rolled plate is annealed by present inventor, the martensitic phase of notable hard more than HV500 is given birth to partly The reason become is explained, and conducts in-depth research its solution technology.It is it was found that exist before hot rolled plate is annealed In the case of thick Cr carbonitride, the martensitic phase of notable hard can be generated.This mechanism considers as follows.Anneal at hot rolled plate In, the Cr carbonitride generation solid solution separated out because of hot rolling, thus generate austenite phase.Cr carbon nitridation before hot rolled plate is annealed In the case of thing is thick, it is provided that many to the C quantitative change of austenite phase.Therefore, the week of solid solution is there occurs at thick Cr carbonitride Enclosing, compared with the position of the Cr carbonitride thick with not having solid solution, C concentration uprises partly.From the austenite phase that this C concentration is high, Generate the martensitic phase of notable hard after hot rolled plate is annealed.
Therefore the technology not separating out thick Cr carbonitride when hot rolling is studied by present inventor.Its knot Fruit finds, by composition of steel with V:0.01～0.25%, Ti:0.001～0.020%, Nb:0.001～0.030% and The mode meeting V/ (Ti+Nb) >=2.0 contains V, Ti and Nb, it is possible to the analysis of thick Cr carbonitride when avoiding hot rolling Go out.
That is, find that the Cr carbonitride separated out during hot rolling becomes containing V, Ti and Nb by suitably containing these elements Composite carbon nitride (Cr, V, Ti, Nb) (C, N), small and separate out equably compared with Cr carbonitride, it is possible to suppress thick The generation of Cr carbonitride.
This effect is by manifesting containing appropriate V.The affinity of Ti and Nb and C and N is than Cr's Yu C and N Affinity is strong, is more readily formed carbonitride than Cr.Therefore, in the case of individually containing Ti or Nb, as with Cr carbon nitrogen Ti (C, N) or Nb (C, N) that compound is different separate out, it is impossible to the effect of the generation of the Cr carbonitride being inhibited thick.
On the other hand, V is also the element strong with the affinity of C and N.But, V has formation and Cr, Ti and Nb The composite carbon nitride i.e. tendency of (Cr, V, Ti, Nb) (C, N), the therefore appropriate situation containing V on the basis of Ti and Nb Under, Cr carbonitride separates out as (Cr, V, Ti, Nb) (C, N).Should (Cr, V, Ti, Nb) (C, N) owing to being containing diffusion velocity The precipitate of V, Ti and Nb less than Cr, growth after therefore separating out or coarsening by the diffusion rate controlling of V, Ti and Nb, Precipitation size is more small than conventional Cr carbonitride, it is possible to the generation of the thick carbonitride in suppression hot rolling effectively.
Learn by these effects, when the coexistence region of ferritic phase and austenite phase carries out hot rolled plate annealing, because of thick The generation of the martensitic phase of the notable hard that the solid solution of big Cr carbonitride causes is inhibited, the wire after cold-reduced sheet annealing The generation of defect is greatly decreased.
That is, in order to not annealed by coffin annealing (batch annealing) such long hot rolled plate, but by using The hot rolled plate annealing of the short time of continuous annealing furnace, obtains the formability of regulation in the case of surface property will not be made to reduce, Not only need to carry out the hot rolled plate annealing of short time in the coexistence region of ferritic phase and austenite phase, in addition it is also necessary to be set to suitably Ratio contains the composition of steel of V, Ti and Nb.
Illustrate it follows that the one-tenth of the ferrite-group stainless steel of the present invention is grouped into.
Hereinafter, unless otherwise defined, % refers to quality %.
C:0.005～0.05%
C has and promotes the generation of austenite phase, makes the two-phase that occurs ferritic phase and austenite phase when hot rolled plate is annealed The effect that temperature range expands.Need containing more than 0.005% to obtain this effect.But, if C measures more than 0.05%, Steel plate hardening thus ductility reduce.Even if it addition, the application present invention, the horse of notable hard also can be generated after hot rolled plate is annealed Family name's body phase, causes the line defect after cold-reduced sheet annealing.Therefore, C amount is set to the scope of 0.005～0.05%.Lower limit is preferably 0.01%, more preferably 0.015%.The upper limit is preferably 0.035%, and more preferably 0.03%, further it is preferably 0.025%.
Si:0.02～0.50%
Si is the element playing deoxidizer effect during steel founding.Need containing more than 0.02% to obtain this effect. But, if Si measures more than 0.50%, then steel plate hardening thus rolling load during hot rolling increase.It addition, after cold-reduced sheet annealing Ductility reduce.Therefore, Si amount is set to the scope of 0.02～0.50%.It is preferably 0.10～the scope of 0.35%.More preferably 0.25～the scope of 0.30%.
Mn:0.05～1.0%
There is in the same manner as Mn with C the generation of promotion austenite phase, make to occur when hot rolled plate is annealed ferritic phase and Ovshinsky The effect that the two-phase temperature range of body phase expands.Need containing more than 0.05% to obtain this effect.But, if Mn amount is super Cross 1.0% then MnS growing amount increase, corrosion resistance reduce.Therefore, Mn amount is set to the scope of 0.05～1.0%.Lower limit is preferably 0.1%, more preferably 0.2%.The upper limit is preferably 0.8%, and more preferably 0.35%, more preferably 0.3%.
Below P:0.04%
P is the element of intercrystalline failure promoting to produce because of cyrystal boundary segregation, and the lowest more good, the upper limit is set to 0.04%. It is preferably less than 0.03%.More preferably less than 0.01%.
Below S:0.01%
S is the element becoming MnS sulfides system's field trash and existing and make ductility, corrosion resistance etc. reduce.Especially exist Content more than 0.01% in the case of these baneful influences significantly produce.Therefore S amount is the lowest more good, and that is measured by S in the present invention is upper Limit is set to 0.01%.More preferably less than 0.007%.More preferably less than 0.005%.
Cr:15.5～18.0%
Cr is the element with the effect forming passivating film at surface of steel plate and make corrosion resistance improve.In order to obtain this effect And needing to make Cr amount is more than 15.5%.But, if Cr measures more than 18.0%, then the generation of austenite phase when hot rolled plate is annealed Become insufficient, it is impossible to obtain the material behavior of regulation.Therefore, Cr amount is set to the scope of 15.5～18.0%.It is preferably 16.0 ～the scope of 18.0%.More preferably 16.0～the scope of 17.0%.
Al:0.001～0.10%
It it is the element playing deoxidizer effect in the same manner as Al with Si.Need to obtain this effect containing 0.001% with On.But, if Al measures more than 0.10%, then Al2O3Increasing Deng Al system field trash, surface property is easily reduced.Therefore, Al amount sets It it is the scope of 0.001～0.10%.It is preferably 0.001～the scope of 0.07%.More preferably 0.001～the scope of 0.05%. More preferably 0.001～the scope of 0.03%.
N:0.01～0.06%
There is in the same manner as N with C, Mn the generation of promotion austenite phase, make to occur when hot rolled plate is annealed ferritic phase and Austria The effect that the two-phase temperature range of family name's body phase expands.Needing to obtain this effect to make N amount is more than 0.01%.But, if N Amount significantly reduces more than 0.06% ductility, and causes corrosion proof reduction because encouraging the precipitation of Cr nitride.Therefore, N Amount is set to the scope of 0.01～0.06%.It is preferably 0.01～the scope of 0.05%.More preferably 0.02～the scope of 0.04%.
V:0.01～0.25%
V is element particularly important in the present invention.V has the feature higher than Cr with the affinity of C and N, by meeting V/ (Ti+Nb) >=2.0, V Yu Cr, Ti and Nb separate out as (Cr, V, Ti, Nb) (C, N) when being incorporated in hot rolling again, thus suppress The precipitation of thick Cr carbonitride.By this effect, the life of the austenite phase that suppression C concentrates superfluously when hot rolled plate is annealed Become, after hot rolled plate is annealed, do not generate the martensitic phase of notable hard, prevent by caused by the generation of fine crack time cold rolling The generation of surface line defect.Need to obtain this effect to make V amount containing more than 0.01%.But, if V amount exceedes 0.25% processability reduces, and causes manufacturing cost to rise.Therefore, V amount is set to the scope of 0.01～0.25%.It is preferably 0.03～the scope of 0.20%.More preferably 0.05～the scope of 0.15%.
Ti:0.001～0.020%, Nb:0.001～0.030%, V/ (Ti+Nb) >=2.0
Ti and Nb, in the same manner as V, is the element higher than Cr with the affinity of C and N, with V in the case of steel contains V And Cr generates (Cr, V, Ti, Nb) (C, N), the effect of precipitation of thick Cr carbonitride when there is suppression hot rolling.In order to Obtain this effect and need the Ti containing more than the 0.001% and Nb of more than 0.001%, and meet V/ (Ti+Nb) >= 2.0.But, if Ti amount more than 0.020% or Nb measure more than 0.030%, then during hot rolling be not separate out (Cr, V, Ti, Nb) (C, N) Ti (C, N) and Nb (C, N), the effect of the Cr carbonitride that therefore cannot be inhibited thick but are individually separated out, it is impossible to Obtain the surface property of regulation.Therefore, Ti amount be set to 0.001～0.020%, Nb amount be set to the scope of 0.001～0.030%. Ti amount preferably 0.001～the scope of 0.015%.More preferably 0.003～the scope of 0.010%.Nb amount be preferably 0.001～ The scope of 0.025%.More preferably 0.005～the scope of 0.020%.In the case of V/ (Ti+Nb) is less than 2.0, in order to generate Composite carbon nitride and the V that needs is not enough, therefore Ti, Nb and V separately become carbide or nitride and generate, Therefore the generation of thick Cr carbonitride cannot be adequately suppressed.Therefore, V/ (Ti+Nb) is set to more than 2.0.It is preferably 3.0 Above.More preferably more than 4.0.On the other hand, if V/ (Ti+Nb) is more than 30.0, though then V, Ti and Nb containing for regulation Amount also will not be consumed by the formation of composite carbon nitride, and the V amount existed with solid solution condition in parent phase increases, and therefore produces by steel The reduction of the percentage elongation caused by the hardening of plate.Therefore, the upper limit of V/ (Ti+Nb) is preferably 30.0.
Surplus is Fe and inevitable impurity.
The effect that can obtain the present invention it is grouped into by above one-tenth, but for improving manufacturing or material further The purpose of characteristic can contain elements below.
In Cu:0.1～1.0%, Ni:0.1～1.0%, Mo:0.1～0.5%, Co:0.01～0.5% a kind or Two or more
Cu and Ni is all to improve corrosion proof element, and it is effective for especially containing in the case of requiring high corrosion-resistant 's.It addition, Cu and Ni has the generation of promotion austenite phase, makes to occur when hot rolled plate is annealed ferritic phase and austenite phase Two-phase temperature range expand effect.These effects become notable in the case of Cu and Ni contains more than 0.1% respectively. But, if Cu content is more than 1.0%, hot-workability reduces thus undesirable.Therefore, in the case of containing Cu it is set to Less than 1.0%.It is preferably 0.2～the scope of 0.8%.More preferably 0.3～the scope of 0.5%.If Ni content is more than 1.0%, Processability reduces thus undesirable.Therefore it is set to less than 1.0% in the case of containing Ni.It is preferably 0.1～0.6% Scope.More preferably 0.1～the scope of 0.3%.
Mo is the element making corrosion resistance improve, and it is effective for especially containing in the case of requiring high corrosion-resistant.This effect Fruit becomes notable when containing more than 0.1%.But, if Mo content is more than 0.5%, the austenite phase when hot rolled plate is annealed Generation becomes insufficient, it is impossible to obtain the material behavior of regulation thus undesirable.Therefore, in the case of containing Mo, it is set to 0.1 ～less than 0.5%.It is preferably 0.1～the scope of 0.3%.
Co is the element making toughness improve.This effect is obtained by the Co containing more than 0.01%.On the other hand, if Co Amount can make processability reduce more than 0.5%.Therefore, it is set to less than 0.5% in the case of containing Co.It is preferably 0.01 ～the scope of 0.2%.
Selected from Mg:0.0002～0.0050%, B:0.0002～0.0050%, REM:0.01～0.10%, Ca:0.0002 ～one kind or two or more in 0.0020%
Mg:0.0002～0.0050%
Mg is the element with the effect making hot-workability improve.Need to obtain this effect containing 0.0002% with On.But, if Mg measures more than 0.0050%, surface quality reduces.Therefore, it is set to 0.0002 in the case of containing Mg ～the scope of 0.0050%.It is preferably 0.0005～the scope of 0.0035%.More preferably 0.0005～the scope of 0.0020%.
B:0.0002～0.0050%
B is for preventing the brittle effective element of low temperature secondary operations.Need to obtain this effect containing More than 0.0002%.But, if B measures more than 0.0050%, hot-workability reduces.Therefore, set in the case of containing B It it is the scope of 0.0002～0.0050%.It is preferably 0.0005～the scope of 0.0035%.More preferably 0.0005～ The scope of 0.0020%.
REM:0.01～0.10%
REM is the element making oxidative resistance improve, and the oxide scale film especially with suppression weld part is formed so that welding Connect the effect that the corrosion resistance in portion improves.Need containing more than 0.01% to obtain this effect.But, if containing having more than The manufacturings such as 0.10% pickling when cold-reduced sheet can be made to anneal reduce.It addition, REM is expensive element, if excessively containing Manufacturing cost then can be caused to increase thus undesirable.Therefore, it is set to 0.01～the model of 0.10% in the case of containing REM Enclose.
Ca:0.0002～0.0020%
Ca is to have for preventing the nozzle caused by the crystallization of the Ti system field trash easily produced when casting continuously inaccessible The composition of effect.Need containing more than 0.0002% to obtain this effect.But, if Ca measures more than 0.0020%, generate CaS and make corrosion resistance reduce.Therefore, it is set to 0.0002～the scope of 0.0020% in the case of containing Ca.It is preferably 0.0005～the scope of 0.0015%.More preferably 0.0005～the scope of 0.0010%.
Next the manufacture method of the ferrite-group stainless steel of the present invention is illustrated.
The ferrite-group stainless steel of the present invention obtains in the following way: implement the steel plate with mentioned component composition Hot rolling, makes hot rolling followed by the hot rolled plate annealing keeping 5 seconds～15 minutes within the temperature range of 880～1000 DEG C Annealed sheet, next implements cold rolling, carries out keeping 5 seconds～the cold-reduced sheet of 5 minutes subsequently within the temperature range of 800～950 DEG C Annealing.
First, melt being grouped into the molten steel constituted by above-mentioned one-tenth by the known method such as converter, electric furnace, vacuum melting furnace Casting, makes steel raw material (plate by continuous casting process or ingot casting-cogging method (ingoting-blooming method) Base).This slab is heated 1～24 hour at 1100～1250 DEG C and carries out hot rolling again and make hot rolled plate, or do not add Heat but make hot rolled plate so that as-cast condition directly carries out hot rolling.
It follows that carry out hot rolling.In winding, preferably coiling temperature is set to more than 500 DEG C less than 850 DEG C.If winding Temperature less than 500 DEG C then winding after recrystallization insufficient thus exist cold-reduced sheet annealing after ductility reduce situation, thus Undesirable.If being wound at a temperature of more than 850 DEG C, particle diameter becomes big, exists and produces surface deterioration when punch process Situation.Therefore, coiling temperature is preferably the scope of 500～850 DEG C.
Afterwards, carry out protecting at a temperature of become ferritic phase and austenite phase 880～1000 DEG C of coexistence region temperature Hold the hot rolled plate annealing of 5 seconds～15 minutes.
Hot rolled plate annealing is the surface property and formability and important operation specified to make the present invention obtain.In heat Roll in the case of plate annealing temperature is less than 880 DEG C and cannot produce sufficient recrystallization, and owing to becoming ferrite monophase field, because of The situation of the effect of the present invention that this existence cannot be obtained by coexistence region annealing and manifest.But, if annealing temperature exceedes 1000 DEG C of solid solutions that then can promote carbide.Therefore encourage C concentration in austenite phase, generate notable after hot rolled plate is annealed The martensitic phase of hard, it is impossible to obtain the surface property of regulation.
If it addition, hot-roll annealing temperature is more than 1000 DEG C, then the growing amount of austenite phase reduces.Therefore, at hot rolled plate The amount of the martensitic phase generated after annealing reduces, it is impossible to fully obtain by the metal comprising ferritic phase and martensitic phase The anisotropy of the metal structure rolling strain ferritic phase concentration near martensitic phase when tissue carries out cold rolling and realize Alleviation effects, thus | the Δ r | of regulation cannot be obtained.
In the case of annealing time was less than 5 seconds, also cannot fully produce Ovshinsky even if carrying out annealing with the temperature of regulation The generation of body phase and the recrystallization of ferritic phase, therefore cannot obtain desired formability.On the other hand, if annealing time exceedes The part of 15 minutes then (Cr, V, Ti, Nb) (C, N) occurs solid solution to encourage C concentration in austenite phase, because of with above-mentioned together The mechanism of sample and the surface property of regulation cannot be obtained.
If it addition, annealing time was more than 15 minutes, then produce excessive C (it is to martensitic phase because of above-mentioned mechanism After hot rolled plate is annealed, austenite phase undergoes phase transition and generates) in concentration.This martensitic phase decomposes when cold-reduced sheet is annealed For carbide and ferritic phase, if but C concentration amount is excessive, and martensitic phase is changed to the ferritic phase containing a large amount of carbides.By In the few ferrite crystal grain of carbide in this becomes crystal grain after cold-reduced sheet is annealed and on crystal boundary and crystal grain and on crystal boundary The mixed grain tissue of the too much ferrite crystal grain of carbide.In the case of becoming this metal structure, the crystal grain that carbide is few The grain many with carbide produces difference of hardness, and therefore deformation strain concentrates on both interfaces of crystal grain, easily with the carbon on crystal boundary Compound is that starting point produces big space (void), makes ductility reduce.
Therefore, hot rolled plate annealing keeps 5 seconds～15 minutes at a temperature of 880～1000 DEG C.Be preferably, 900～ Keep 15 seconds～15 minutes at a temperature of 1000 DEG C.More preferably, keep 15 seconds～3 minutes at a temperature of 900～1000 DEG C.
It follows that carry out cold rolling and cold-reduced sheet annealing.Implement pickling as required and make product.
About cold rolling, from the viewpoint of formability and shape correction, preferably reduction ratio with more than 50% is carried out.Separately Outward, in the present invention, it is also possible to by cold rolling-annealing be repeated twice above, it is also possible to by cold rolling make thickness of slab 200 μm with Under stainless steel foil.
Cold-reduced sheet about cold-reduced sheet is annealed, and keeps at a temperature of 800～950 DEG C to obtain good formability 5 seconds～5 minutes.
Cold-reduced sheet annealing is to make the ferritic phase formed in hot rolled plate is annealed become with the duplex structure of martensitic phase The important operation for ferrite homogeneous structure.In the case of cold-reduced sheet annealing temperature is less than 800 DEG C, recrystallization cannot be abundant Produce thus the ductility of regulation and average r value cannot be obtained.On the other hand, in the cold-reduced sheet annealing temperature feelings more than 950 DEG C Under condition, the composition of steel of the two-phase temperature range becoming ferritic phase and austenite phase in this temperature generates after cold-reduced sheet is annealed Martensitic phase, therefore steel plate hardening and cannot obtain regulation ductility.Even it addition, this temperature becomes the single-phase temperature of ferrite The composition of steel of degree scope, also can cause the glossiness of steel plate to reduce, therefore from surface quality because of the notable coarsening of crystal grain Viewpoint is set out undesirable.In the case of annealing time was less than 5 seconds, even if with the annealing temperature of regulation, tying again of ferritic phase Crystalline substance also cannot produce fully, therefore cannot obtain the ductility of regulation and average r value.If annealing time was more than 5 minutes, then brilliant The notable coarsening of grain, the glossiness of steel plate reduces, therefore undesirable from the viewpoint of surface quality.Therefore, cold-reduced sheet annealing It is set in the range of 800～950 DEG C keep 5 seconds～5 minutes.It is preferably, keeps 15 seconds～3 points at 850 DEG C～900 DEG C Clock.BA annealing (bright annealing (bright annealing)) can also be carried out to further seek for glossiness.
Additionally, in order to make surface property improve further, it is also possible to implement grinding, grinding etc..
Embodiment 1
Hereinafter, the present invention is explained by embodiment.
By 50kg small size vacuum smelting furnace, the rustless steel with the chemical composition shown in table 1 is carried out founding.By these steel After base is with 1150 DEG C of heating 1h, implements hot rolling and make the thick hot rolled plate of 3.5mm.It follows that these hot rolled plates are remembered with table 2 After the condition carried implements hot rolled plate annealing, surface is carried out blasting treatment and descales based on pickling.Pickling refers to, in temperature After spending 80 DEG C, 20 mass % sulfuric acid solutions impregnating 120 seconds, be made up of 15 mass % nitric acid and 3 mass % Fluohydric acid .s The mixed acid solution that temperature is 55 DEG C impregnates 60 seconds.Further, 0.7mm thickness is made and with the bar described in table 2 by cold rolling Part carries out cold-reduced sheet annealing, subsequently by water temperature 80 DEG C, 18 mass %Na2SO4With 25C/dm in aqueous solution2Condition carry out Cathodic pickling and in water temperature 50 DEG C, 10 mass %HNO3With 30C/dm in aqueous solution2The cathodic pickling that carries out of condition and Carry out the process that descales, obtain cold-rolling pickling annealed sheet.
Thus obtained cold-rolling pickling annealed sheet is carried out following evaluation.
(1) surface property evaluation
After cold-reduced sheet annealing, measure every 1m2The number of the line defect of a length of more than 5mm present in steel plate.Will be The line defect that cold rolled annealed plate surface confirms is at every 1m2Steel plate is at 5 below situation be set to qualified, will be more than 5 at Situation be set to defective.
(2) evaluation of ductility
JIS 13B tension test sheet is gathered along the direction at a right angle with rolling direction from cold-rolling pickling annealed sheet, according to JIS Z2241 carries out tension test, measures elongation at break, and it is qualified the situation that elongation at break is more than 25% to be set to (zero), the elongation at break situation less than 25% is set to defective (×).
(3) average r value and the evaluation of | Δ r |
From cold-rolling pickling annealed sheet edge parallel relative to rolling direction (L direction), (D direction) at 45 ° and (C at a right angle Direction) direction gather JIS 13B tension test sheet, carry out the tension test according to JIS Z2241 until reach strain 15% and interrupt, measure the r value of all directions and calculate average r value (=(rL+2rD+rC)/4) and the intra-face anisotropy of r value (Δ r=(rL-2rD+rC)/2) absolute value (| Δ r |).Here, rL、rD、rCIt is L direction, D direction and the r in C direction respectively Value.About average r value, be set to qualified (zero) by more than 0.65, by be set to less than 0.65 defective (×).About | Δ r |, will Less than 0.30 is set to qualified (zero), will be more than 0.30 defective (×).
(4) corrosion proof evaluation
The test film of 60mm × 100mm is gathered, after completing to grind to surface by #600 sand paper from cold-rolling pickling annealed sheet End face portion is sealed and makes test film, for the brine spray cyclic test of JIS H 8502 defined.Brine spray Cyclic test is with brine spray (35 DEG C, 5%NaCl, spraying 2h) → be dried (60 DEG C, relative humidity 40%, 4h) → moistening (50 DEG C, relative humidity >=95%, 2h) are that 1 circulation carries out 3 circulations.To the brine spray circulation implementing 3 circulations Test film surface shooting photo after test, by the rust area on graphical analysis determination test sheet surface, according to rust area With the ratio of test film entire area calculate rust area rate ((rust area in test film/test film entire area) × 100 [%]).About rust area rate, it is set to corrosion resistance the most excellent and qualified (◎) by less than 10%, will be more than 10% and be Less than 25% is set to qualified (zero), will be set to more than 25% defective (×)
Evaluation result is shown in table 2 in the lump with hot rolled plate annealing and cold rolled annealed condition.
[table 1]
[table 2]
Underscore represents not within the scope of the invention.
In example No.1 meeting the scope of the present invention～23,33～46,52～63, confirm after cold-reduced sheet annealing Line defect be every 1m2In be at 5 below, obtained good surface property.It addition, elongation at break be 25% with Upper, average r value is more than 0.65, | Δ r | is less than 0.30, has obtained good formability.It addition, about corrosion resistance, in reality The rust area rate having executed the test film surface after the brine spray cyclic test of 3 circulations is less than 25%, has obtained good Good characteristic.
Especially in steel L, M, N and the BM (No.17,18,19,52,61) containing Cu, Ni and Mo, brine spray Rust area rate after cyclic test is less than 10%, and corrosion resistance improves further.
On the other hand, the content at V is less than the scope of the present invention and is unsatisfactory for the comparative example of V/ (Ti+Nb) >=2.0 In comparative example No.26 beyond the scope of this invention for No.24 and Ti and Nb, the amount of precipitation of (Cr, V, Ti, Nb) (C, N) is not Foot, therefore the immobilization of solid solution C, the N in hot rolled plate annealing is insufficient, and its result generates notable hard after hot rolled plate annealing Martensitic phase, produces line defect after cold-reduced sheet annealing in a large number.
In the comparative example No.25 that the content of V is beyond the scope of this invention, although obtained regulation average r value and | Δ r |, but because making steel plate hardening containing excessive V, thus fail to obtain the ductility of regulation.
Cr content less than the scope of the present invention comparative example No.27 in, although obtained regulation surface property and Ductility, average r value and | Δ r |, but owing to Cr content is not enough, therefore do not obtain the corrosion resistance of regulation.
In Cr content exceedes the comparative example No.28 of the scope of the present invention, although obtained sufficient corrosion resistance, but due to Superfluously containing Cr so do not generate austenite phase when hot rolled plate anneal, thus fail to obtain the ductility specified, average r value with And | Δ r |.
In the comparative example No.29 that C amount is beyond the scope of this invention, although V, Ti and Nb measure in the scope of the present invention In, but the C in steel is not as (Cr, V, Ti, Nb) (C, N), and by immobilization the most fully, remaining has solid solution C, therefore in heat Generate the martensitic phase of notable hard after rolling plate annealing, do not obtain the surface property of regulation.Further, since solid solution C amount increases, institute Significantly rise with armor plate strength, do not obtain the ductility of regulation.
On the other hand, in the C amount comparative example No.30 less than the scope of the present invention, austenite phase steady realized based on C Fixedization is the most insufficient, does not therefore generate an adequate amount of austenite phase in the annealing of the hot rolled plate in coexistence region, thus is advised Fixed average r value and | Δ r |.
V/ (Ti+Nb) less than the scope of the present invention comparative example No.31 and No.32 in, during hot rolling (Cr, V, Ti, Nb) precipitation of (C, N) insufficient, therefore separates out substantial amounts of thick Cr carbonitride, generates notable hard after hot rolled plate annealing The martensitic phase of matter, therefore produces line defect after cold-reduced sheet is annealed in a large number, does not obtains the surface property of regulation.
No.47 and No.64 is that V/ (Ti+Nb) compares the scope of the invention less than the scope of the present invention and hot-roll annealing temperature High comparative example.Owing to V/ (Ti+Nb) is less than the scope of the present invention, therefore encourage with the thick carbide separated out during hot rolling Solid solution and the C that the produces concentration in austenite phase, after hot rolled plate is annealed, generate the martensitic phase of notable hard, the most greatly Amount produces line defect, does not obtains the surface property of regulation.Further, since hot-roll annealing temperature is higher than the scope of the invention, because of The amount of the austenite phase generated in this annealing reduces, and the amount of the martensitic phase generated after hot rolled plate annealing reduces, and therefore cannot obtain The anisotropy alleviation effects of metal structure realized to cold rolling after utilizing, does not obtains | the Δ r | of regulation.
No.48 and No.65 is that V/ (Ti+Nb) is less than the scope of the present invention and hot-roll annealing temperature than present invention model Enclose low comparative example.Although V/ (Ti+Nb) is less than the scope of the present invention, but hot-roll annealing temperature becomes the single-phase temperature of ferrite Scope thus do not generate austenite phase, the line defect therefore caused almost without the generation of the martensitic phase because of notable hard Generation, obtained good surface property.But, owing to hot-roll annealing temperature is lower than the scope of the invention, therefore do not produce Sufficiently recrystallization, and after hot rolled plate is annealed, do not generate martensitic phase thus do not obtain the ductility of regulation, average r value and |Δr|。
No.66 is the comparison that V/ (Ti+Nb) is longer than the scope of the invention less than the scope of the present invention and hot rolled plate annealing time Example.Therefore, dense in austenite phase of the C excessively producing the solid solution with the thick carbide separated out during hot rolling and produce Contracting, its result, generate the martensitic phase of notable hard after hot rolled plate annealing, produce line defect the most in a large number and specified Surface property.It addition, the metal structure after cold-reduced sheet annealing becomes the ferrum too much by the carbide in crystal grain and on crystal boundary The mixed grain tissue of the ferrite crystal grain composition that carbide in ferritic crystal grain and crystal grain and on crystal boundary is few, therefore in stretching change During shape, the interface at both crystal grain produces strain concentration locally, does not obtains the ductility of regulation.
No.67 is the comparison that V/ (Ti+Nb) is lower than the scope of the invention less than the scope of the present invention and cold-reduced sheet annealing temperature Example.Owing to V/ (Ti+Nb) is less than the scope of the present invention, produces line defect the most in a large number and do not obtain the surface property of regulation. Further, since cold-reduced sheet annealing temperature is lower than the scope of the invention, recrystallization when therefore cold-reduced sheet is annealed is insufficient and remaining has Worked structure time cold rolling, does not therefore obtain the ductility of regulation and average r value.
No.68 is the comparison that V/ (Ti+Nb) is higher than the scope of the invention less than the scope of the present invention and cold-reduced sheet annealing temperature Example.Owing to V/ (Ti+Nb) is less than the scope of the present invention, therefore produces substantial amounts of line defect and do not obtain the superficiality of regulation Energy.Further, since cold-reduced sheet annealing temperature is higher than the scope of the invention, therefore become the two-phase temperature in ferritic phase and austenite phase The annealing carried out in the range of degree, thus again generate austenite phase, after cold-reduced sheet is annealed, become martensitic phase, therefore steel plate mutually Notable hardening, does not obtains the ductility of regulation.
Industrial applicibility
Ferrite-group stainless steel obtained by the present invention is particularly suitable for application to the stamping product based on drawing, wants Ask the application of the purposes such as kitchen appliance, tableware of high surface aesthetics.

Claims (5)

1. a ferrite-group stainless steel, in terms of quality %, containing C:0.005～0.05%, Si:0.02～0.50%, Mn: 0.05～1.0%, below P:0.04%, below S:0.01%, Cr:15.5～18.0%, Al:0.001～0.10%, N:0.01 ～0.06%, V:0.01～0.25%, Ti:0.001～0.020%, Nb:0.001～0.030%, surplus is Fe and can not The impurity avoided, and meet V/ (Ti+Nb) >=2.0.
2. a ferrite-group stainless steel, in terms of quality %, containing C:0.01～0.05%, Si:0.02～0.50%, Mn:0.2 ～1.0%, below P:0.04%, below S:0.01%, Cr:16.0～18.0%, Al:0.001～0.10%, N:0.01～ 0.06%, V:0.01～0.25%, Ti:0.001～0.015%, Nb:0.001～0.025%, surplus is Fe and can not keep away The impurity exempted from, and meet V/ (Ti+Nb) >=2.0.
Ferrite-group stainless steel the most according to claim 1 and 2, wherein, in terms of quality %, possibly together with selected from Cu:0.1～ 1.0%, one kind or two or more in Ni:0.1～1.0%, Mo:0.1～0.5%, Co:0.01～0.5%.
4. according to the ferrite-group stainless steel according to any one of claims 1 to 3, wherein, in terms of quality %, possibly together with being selected from In Mg:0.0002～0.0050%, B:0.0002～0.0050%, REM:0.01～0.10%, Ca:0.0002～0.0020% One kind or two or more.
5. a manufacture method for ferrite-group stainless steel, is grouped into the one-tenth having according to any one of Claims 1-4 Hot rolling implemented by plate slab, makes followed by the annealing kept 5 seconds～15 minutes within the temperature range of 880～1000 DEG C Next hot-roll annealing plate, implements cold rolling, carries out keeping 5 seconds～5 minutes cold subsequently within the temperature range of 800～950 DEG C Roll plate annealing.
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