CN105917016B - Ferrite-group stainless steel and its manufacturing method - Google Patents

Ferrite-group stainless steel and its manufacturing method Download PDF

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CN105917016B
CN105917016B CN201580004091.9A CN201580004091A CN105917016B CN 105917016 B CN105917016 B CN 105917016B CN 201580004091 A CN201580004091 A CN 201580004091A CN 105917016 B CN105917016 B CN 105917016B
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annealing
ferrite
value
stainless steel
phase
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CN105917016A (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 Engineering Corp
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NKK Corp
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    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
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Abstract

The present invention provide have sufficient corrosion resistance and formability (elongation and average r value are big, | Δ r | it is small), and the few excellent ferrite-group stainless steel and its manufacturing method of surface property of generation of line defect.Ferrite-group stainless steel of the invention contains C in terms of quality %：0.005~0.05%, Si：0.02~0.50%, Mn：0.05~1.0%, P：0.04% or less, S：0.01% or less, 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 inevitable impurity, and meets V/ (Ti+Nb) >=2.0.

Description

Ferrite-group stainless steel and its manufacturing method
Technical field
The present invention relates to sufficient corrosion resistance and formability and will not generate the line as caused by hot rolling, annealing The excellent ferrite-group stainless steel of the surface property of shape defect and its manufacturing method.
Background technique
Ferrite-group stainless steel is cheap and corrosion resistance excellent, therefore is used in building materials, conveying equipment, household appliances, kitchen The diversified purposes such as utensil, automobile component, application range further continuous enlargement in recent years.In order to be applied to these use On the way, for ferrite-group stainless steel, corrosion resistance is not only needed, it is also necessary to the sufficient formability of regulation shape can be processed into (elongation big (hereinafter, the sufficiently big situation of elongation is known as with ductility), average plastic strain ratio are (hereinafter referred to as average R value) big, r value intra-face anisotropy absolute value (hereinafter referred to as | Δ r |) it is small).In addition, being applied to surface aesthetic In the case where the purposes of property, it is also desirable to which surface property is excellent.
For above content, in patent document 1, a kind of formability and wrinkle properties (ridging are disclosed Resistance) excellent ferrite-group stainless steel, which is characterized in that in terms of quality %, contain C：0.02~0.06%, Si： 1.0% or less, Mn：1.0% or less, P：0.05% or less, S：0.01% or less, Al：0.005% or less, Ti：0.005% with Under, Cr：11~30%, Ni：0.7% hereinafter, and meet 0.06≤(C+N)≤0.12,1≤N/C and 1.5 × 10-3≤(V× N)≤1.5×10-2(the quality % that C, N, V respectively indicate each element).However, not appointing in patent document 1 for anisotropy What is recorded.In addition, it is necessary to carry out so-called coffin annealing (for example, at 860 DEG C 8 hours annealing) after hot rolling.This vanning Annealing processing needs one week or so time until completing if the process comprising heating, cooling down, therefore that there are productivities is low The problem of.
In patent document 2, a kind of processability and the excellent ferrite-group stainless steel of surface property are disclosed, feature exists In containing C in terms of quality %：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 0.00500% steel carries out hot rolling, using box-type furnace or AP production line, (annealing and pickling line, is moved back Fiery pickling lines) continuous oven carry out hot rolled plate annealing in the single-phase temperature range of ferrite, further progress cold rolling and Finish to gauge annealing.However, using box-type furnace, with above-mentioned patent document 1 similarly, the presence of the low problem of productivity. In addition, to elongation, there is no record in patent document 2, but in continuous annealing furnace in the single-phase temperature range of ferrite Carry out hot rolled plate annealing in the case where, annealing temperature it is low therefore recrystallization it is insufficient, in the single-phase temperature range of ferrite into The case where row coffin annealing, reduces compared to elongation.In addition, the ferrite-group stainless steel as patent document 2 under normal circumstances The crystal grain group (field (colony)) with similar crystal orientation can be generated in casting or hot rolling, thus in the presence of | Δ r | The problem of becoming larger.
Advanced technical literature
Patent document
Patent document 1：No. 3584881 bulletins of Japanese Patent No. (Japanese table WO00/60134 public again)
Patent document 2：No. 3581801 bulletins of Japanese Patent No. (Japanese Unexamined Patent Publication 2001-3134)
Summary of the invention
It is an object of the present invention to solve the above subject, provide with sufficient corrosion resistance and formability and will not produce The surface property of the raw line defect as caused by hot rolling, annealing excellent ferrite-group stainless steel and its manufacturing method.
In addition, in the present invention, so-called sufficient corrosion resistance refers to, for completing to grind to surface using #600 sand paper The steel plate that end face portion is sealed afterwards carries out the brine spray cyclic test of the JIS H8502 defined of 3 circulations (with (salt water spray Mist (35 DEG C, 5 mass %NaCl, spraying 2h) → dry (60 DEG C, relative humidity 40%, 4h) → it is wet (50 DEG C, relative humidity >= 95%, 2h)) be 1 test recycled), (=rust area/steel plate is whole for the rust area rate of surface of steel plate in this case Area × 100 [%]) below 25%.
In addition, so-called sufficient formability refers to, the elongation at break in the tension test according to JIS Z 2241 exists It is 25% or more when using along the test film acquired with rolling direction direction at right angle, in the stretching examination according to JIS Z 2241 Test the r that the average r value calculated by following (1) formulas when applying 15% strain is 0.65 or more and is calculated by following (2) formulas (hereinafter referred to as the absolute value of Δ r) (| Δ r |) is 0.30 or less 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, rLTo carry out r value when tension test, r on the direction parallel with rolling directionDFor relative to rolling R value when tension test, r are carried out on the direction that direction is 45 °CFor with carry out stretching examination on rolling direction direction at right angle R value when testing.
It is studied to solve project, as a result, it has been found that, for the ferrite-group stainless steel of ingredient appropriate, Before carrying out cold rolling to the steel plate after hot rolling, anneal within the temperature range of becoming the two-phase of ferritic phase and austenite phase, The ferrite-group stainless steel that thus, it is possible to obtain having sufficient corrosion resistance and formability.Additionally, it was found that by being fitted in above-mentioned When composition of steel in the range of further V, Ti and Nb are provided so that coarse Cr carbon will not be precipitated in hot rolling Nitride, and be able to suppress the generation of the line defect of surface of steel plate, as a result, not only corrosion resistance and have excellent formability, and And surface property is also excellent.
It is completed the present invention is based on above discovery, the following are its main contents.
[1] a kind of ferrite-group stainless steel contains C in terms of quality %：0.005~0.05%, Si：0.02~0.50%, Mn：0.05~1.0%, P：0.04% or less, S：0.01% or less, 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 Inevitable impurity, and meet V/ (Ti+Nb) >=2.0.
[2] a kind of ferrite-group stainless steel contains C in terms of quality %：0.01~0.05%, Si：0.02~0.50%, Mn：0.2~1.0%, P：0.04% or less, S：0.01% or less, 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 Inevitable impurity, and meet V/ (Ti+Nb) >=2.0.
[3] ferrite-group stainless steel according to documented by above-mentioned [1] or [2], wherein in terms of quality %, also contain and be selected from Cu：0.1~1.0%, Ni：0.1~1.0%, Mo：0.1~0.5%, Co：It is one kind or two or more in 0.01~0.5%.
[4] ferrite-group stainless steel according to documented by 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~ It is one kind or two or more in 0.0020%.
[5] a kind of manufacturing method of ferrite-group stainless steel, to documented by any one of above-mentioned [1] to [4] at The plate slab that is grouped as implements hot rolling, followed by keeping moving back for 5 seconds~15 minutes within the temperature range of 880~1000 DEG C Hot-roll annealing plate is made in fire, next implements cold rolling, then carries out keeping 5 seconds~5 800~950 DEG C within the temperature range of The cold-reduced sheet annealing of minute
It should be noted that in the present specification, indicating that the % of the ingredient of steel is entirely quality %.
Invention effect
In accordance with the invention it is possible to obtain having sufficient corrosion resistance and formability (elongation and average r value it is big, | Δ R | it is small) and line defect the excellent ferrite-group stainless steel of the few surface property of generation.
Specific embodiment
Hereinafter, the present invention is described in detail.
Ferrite-group stainless steel is characterized in that, in terms of quality %, contains C：0.005~0.05%, Si：0.02~ 0.50%, Mn：0.05~1.0%, P：0.04% or less, S：0.01% or less, 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.It is in the present invention, critically important at the balance being grouped as, The balance of especially V, Ti and Nb are critically important.Make V：0.01~0.25%, Ti：0.001~0.020%, Nb：0.001~ 0.030% and meets V/ (Ti+Nb) >=2.0 and be important important document.By being set as this at the combination being grouped as, can be had The excellent ferrite-group stainless steel of the surface property for having the generation of sufficient corrosion resistance and sufficient formability and line defect few.
Firstly, technology contents of the invention are described in detail.
Present inventor to not annealed by prolonged hot rolled plate as coffin annealing (batch annealing), The technology of formability as defined in being obtained by using the hot rolled plate annealing of the short time of the high continuous annealing furnace of productivity is carried out Research.It is using the project in the prior art of continuous annealing furnace, due to being moved back in the single-phase temperature range of ferrite After fire is unable to get sufficient elongation so not recrystallized adequately, and field remaining is annealed to cold-reduced sheet, from And | Δ r | it is big.Therefore, present inventor considers following scheme：Heat is carried out in ferritic phase and the coexistence region of austenite phase Plate annealing is rolled, cold rolling and cold-reduced sheet annealing are then carried out with usual method, finally become ferrite homogeneous structure again.
That is, by carrying out hot rolling in the ferritic phase of temperature range high temperature more single-phase than ferrite and the coexistence region of austenite phase Plate annealing, promotes the recrystallization of ferritic phase.As a result, avoiding the ferrite crystal grain for being imported into processing strain because of hot rolling residual It deposits to cold-reduced sheet annealing, so that the elongation after making cold-reduced sheet anneal improves.In addition, plain from iron by hot rolled plate annealing When body mutually generates austenite phase, austenite phase is generated in a manner of having the crystal orientation different from the ferritic phase before annealing, Therefore the field of ferritic phase is effectively destroyed.Therefore, the cold rolled annealed plate after having carried out cold rolling and cold-reduced sheet annealing Metal structure in, gamma fiber texture (γ-fiber texture) development for improving r value, and field is separated, metal The anisotropy of tissue is mitigated, so as to obtain | Δ r | become smaller this excellent characteristic.
In addition, in the case where ferritic phase and the coexistence region of austenite phase carry out hot rolled plate annealing, after hot rolled plate annealing Duplex structure as ferritic phase and the martensitic phase obtained from austenite phase phase transformation.However, by including martensite to this The hot-roll annealing plate of phase carries out cold rolling, and since martensitic phase is harder than ferritic phase, the ferritic phase near martensitic phase is excellent First deformation is concentrated to roll strain, and recrystallization position when cold-reduced sheet is annealed further increases.When cold-reduced sheet is annealed as a result, Recrystallization is further promoted, and the anisotropy of the metal structure after cold-reduced sheet annealing is further mitigated.
If carrying out hot rolling to the steel of previous ingredient in the coexistence region of above-mentioned ferritic phase and austenite phase however, learning Plate annealing can then generate the linear defect (hereinafter referred to as line defect) along rolling direction, to produce after cold-reduced sheet annealing Raw surface property significantly reduces this new problem.
Therefore, present inventor's formability and surface property in order to balance, to because in ferritic phase and austenite phase The reason of carrying out hot rolled plate annealing in coexistence region and generating line defect is investigated.As a result, learn line defect be because It is present in the martensitic phase of the significant hard of the steel plate surface section after hot rolled plate is annealed and generates.If that is, learning in hot rolled plate There are the martensitic phases of significant hard for steel plate surface section after annealing, then strain is concentrated in significant hard in cold rolling later Martensitic phase and ferritic phase interface and generate fine crack, cold-reduced sheet annealing after become line defect.Martensite It is mutually austenite phase (it is generated in the hot rolled plate annealing carried out in ferritic phase and the coexistence region of austenite phase) cold But it undergoes phase transition and generates during.It is found after the hardness for having investigated each martensitic crystal grains in metal structure, most horses Family name's body is mutually calculated as 300~400 or so with Vickers hardness (HV), and in contrast, the significant hard of a part of martensitic phase is more than HV500, fine crack in cold rolling are more than that the martensitic phase of the significant hard of HV500 and the interface of ferritic phase generate at this.
Therefore, present inventor locally gives birth to the martensitic phase for the significant hard for after hot rolled plate annealing being more than HV500 At the reason of illustrated, and technology is solved to it and is had made intensive studies.Itself as a result, it has been found that, hot rolled plate anneal before exist In the case where coarse Cr carbonitride, the martensitic phase of significant hard can be generated.The mechanism considers as follows.It anneals in hot rolled plate In, the Cr carbonitride being precipitated by hot rolling is dissolved, and thus generates austenite phase.Cr carbon nitridation before hot rolled plate annealing In the case that object is coarse, the C quantitative change for being supplied to austenite phase is more.Therefore, the week being dissolved in coarse Cr carbonitride It encloses, C concentration is locally got higher compared with the position of the coarse Cr carbonitride of no solid solution.From the highly concentrated austenite phase of the C, Generate the martensitic phase of the significant hard after hot rolled plate annealing.
Therefore present inventor studies the technology that coarse Cr carbonitride is not precipitated in hot rolling.It is tied Fruit discovery, by composition of steel with V：0.01~0.25%, Ti：0.001~0.020%, Nb：0.001~0.030% and The mode for meeting V/ (Ti+Nb) >=2.0 contains V, Ti and Nb, can be avoided the analysis of coarse Cr carbonitride when hot rolling Out.
That is, discovery, by suitably containing these elements, the Cr carbonitride that when hot rolling is precipitated, which becomes, contains V, Ti and Nb Compound carbonitride (Cr, V, Ti, Nb) (C, N), it is small compared with Cr carbonitride and be equably precipitated, be able to suppress coarse Cr carbonitride generation.
This effect containing suitable V by showing.The affinity ratio Cr's and C and N of Ti and Nb and C and N Affinity is strong, and carbonitride is more readily formed than Cr.Therefore, individually contain Ti Nb in the case where, as with Cr carbon nitrogen The different Ti of compound (C, N) or Nb (C, N) is precipitated, and is unable to get the effect of the generation for the Cr carbonitride for inhibiting coarse.
On the other hand, V is also the element strong with the affinity of C and N.It is formed and Cr, Ti and Nb however, V has Compound carbonitride be (Cr, V, Ti, Nb) (C, N) tendency, therefore on the basis of Ti and Nb in right amount contain V the case where Under, Cr carbonitride is precipitated as (Cr, V, Ti, Nb) (C, N).(Cr, V, Ti, Nb) (C, N) is somebody's turn to do due to being containing diffusion velocity The precipitate of V, Ti and the Nb smaller than Cr, thus be precipitated after growth or coarsening by V, Ti and Nb diffusion rate controlling, Precipitation size is more small than previous Cr carbonitride, can effectively inhibit the generation of the coarse carbonitride in hot rolling.
It learns through these effects, when carrying out hot rolled plate annealing in ferritic phase and the coexistence region of austenite phase, because thick The generation of the martensitic phase of significant hard caused by the solid solution of big Cr carbonitride is inhibited, the threadiness after cold-reduced sheet annealing The generation of defect is greatly decreased.
That is, in order not to by prolonged hot rolled plate annealing as coffin annealing (batch annealing), but by using The hot rolled plate of the short time of continuous annealing furnace is annealed, and obtains defined formability in the case where surface property will not be made to reduce, It not only needs to carry out the hot rolled plate annealing of short time in ferritic phase and the coexistence region of austenite phase, it is also necessary to be set as with suitable Ratio contains the composition of steel of V, Ti and Nb.
Next, being illustrated to ferrite-group stainless steel of the invention at being grouped as.
Hereinafter, unless otherwise defined, % refers to quality %.
C：0.005~0.05%
C has the generation for promoting austenite phase, makes the two-phase of ferritic phase and austenite phase occur when hot rolled plate is annealed The widened effect of temperature range.In order to obtain the effect and need containing 0.005% or more.However, if C amount is more than 0.05% Steel plate hardening reduces to ductility.In addition, even if with the application of the invention, the horse of significant hard can be generated after hot rolled plate annealing Family name's body phase, the line defect after causing cold-reduced sheet to be annealed.Therefore, C amount is set as 0.005~0.05% range.Lower limit is preferably 0.01%, more preferably 0.015%.The upper limit is preferably 0.035%, more preferably 0.03%, still more preferably for 0.025%.
Si：0.02~0.50%
Si is the element for playing the role of deoxidier when steel founding.In order to obtain the effect and need containing 0.02% or more. However, rolling load when steel plate hardening is to hot rolling increases if Si amount is more than 0.50%.In addition, after cold-reduced sheet annealing Ductility reduce.Therefore, Si amount is set as 0.02~0.50% range.Preferably 0.10~0.35% range.More preferably 0.25~0.30% range.
Mn：0.05~1.0%
Mn has the generation for promoting austenite phase in the same manner as C, makes ferritic phase and Ovshinsky occur when hot rolled plate is annealed The widened effect of two-phase temperature range of body phase.In order to obtain the effect and need containing 0.05% or more.However, if Mn amount is super Cross 1.0% then MnS production quantity increase, corrosion resistance reduce.Therefore, Mn amount is set as 0.05~1.0% range.Lower limit is preferably 0.1%, more preferably 0.2%.The upper limit is preferably 0.8%, and more preferably 0.35%, further preferably 0.3%.
P：0.04% or less
P is the element for promoting the intercrystalline failure generated by cyrystal boundary segregation, therefore more lower better, and the upper limit is set as 0.04%. Preferably 0.03% or less.More preferably 0.01% or less.
S：0.01% or less
S is the reduced elements such as to become MnS sulfides system's field trash and there is and make ductility, corrosion resistance.Especially exist Content be more than in the case where 0.01% these baneful influences significantly generate.Therefore the lower S amount the better, by the upper of S amount in the present invention Limit is set as 0.01%.More preferably 0.007% or less.Further preferably 0.005% or less.
Cr：15.5~18.0%
Cr is the element for having the effect of forming passivating film in surface of steel plate and improving corrosion resistance.The effect in order to obtain And it needs that Cr amount is made to be 15.5% or more.However, if Cr amount is more than 18.0%, the generation of austenite phase in hot rolled plate annealing It becomes inadequate, is unable to get defined material property.Therefore, Cr amount is set as 15.5~18.0% range.Preferably 16.0 ~18.0% range.More preferably 16.0~17.0% range.
Al：0.001~0.10%
Al is the element for playing the role of deoxidier in the same manner as Si.In order to obtain the effect and need containing 0.001% with On.However, if Al amount is more than 0.10%, Al2O3Equal Al system field trash increases, and surface property is easily reduced.Therefore, Al amount is set For 0.001~0.10% range.Preferably 0.001~0.07% range.More preferably 0.001~0.05% range. Further preferably 0.001~0.03% range.
N：0.01~0.06%
N has the generation for promoting austenite phase in the same manner as C, Mn, makes ferritic phase and Austria occur when hot rolled plate is annealed The widened effect of two-phase temperature range of family name's body phase.The effect and needing makes N amount be 0.01% or more in order to obtain.However, if N More than 0.06% ductility of amount significantly reduces, and leads to corrosion proof reduction because of the precipitation of growth encourage Cr nitride.Therefore, N Amount is set as 0.01~0.06% range.Preferably 0.01~0.05% range.More preferably 0.02~0.04% range.
V：0.01~0.25%
V is element particularly important in the present invention.V has the feature with the affinity ratio Cr high of C and N, passes through satisfaction V/ (Ti+Nb) >=2.0, V is compound with Cr, Ti and Nb and is precipitated in hot rolling as (Cr, V, Ti, Nb) (C, N), to inhibit The precipitation of coarse Cr carbonitride.By the effect, the life for the austenite phase for inhibiting C to be excessively concentrated in hot rolled plate annealing At the martensitic phase of significant hard not being generated after hot rolled plate annealing, caused by the generation of fine crack when preventing as cold rolling Surface line defect generation.The effect and needing makes V amount contain 0.01% or more in order to obtain.However, if V amount is more than 0.25% processability reduces, and manufacturing cost is caused to rise.Therefore, V amount is set as 0.01~0.25% range.Preferably 0.03~0.20% range.More preferably 0.05~0.15% range.
Ti：0.001~0.020%, Nb：0.001~0.030%, V/ (Ti+Nb) >=2.0
Ti and Nb are the elements with the affinity of C and N ratio Cr high in the same manner as V, in the case where steel contains V with V And Cr generates (Cr, V, Ti, Nb) (C, N), has the effect of the precipitation of coarse Cr carbonitride when inhibiting hot rolling.In order to Obtain the effect and need the Nb containing 0.001% or more Ti and 0.001% or more, and meet V/ (Ti+Nb) >= 2.0.However, if it is more than 0.030% that Ti amount, which is more than 0.020% or Nb amount, when hot rolling be not be precipitated (Cr, V, Ti, Nb) (C, N Ti (C, N) and Nb (C, N) is precipitated) but individually, therefore is unable to get the effect for the Cr carbonitride for inhibiting coarse, it can not Obtain defined surface property.Therefore, Ti amount is set as the range that 0.001~0.020%, Nb amount is set as 0.001~0.030%. Ti amount is preferably 0.001~0.015% range.More preferably 0.003~0.010% range.Nb amount preferably 0.001~ 0.025% range.More preferably 0.005~0.020% range.In the case that V/ (Ti+Nb) is less than 2.0, in order to generate Compound carbonitride and the V that needs is insufficient, therefore Ti, Nb and V separately become carbide or nitride and generate, Therefore inhibit the generation of coarse Cr carbonitride with being unable to fully.Therefore, V/ (Ti+Nb) is set as 2.0 or more.Preferably 3.0 More than.More preferably 4.0 or more.On the other hand, if V/ (Ti+Nb) is more than 30.0, even if V, Ti and Nb are defined contain Amount will not be consumed by the formation of compound carbonitride, be increased in parent phase with V amount existing for solid solution condition, therefore be generated by steel The reduction of 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.
By above at being grouped as available effect of the invention, but for further increasing manufacturing or material The purpose of characteristic can contain element below.
Selected from Cu：0.1~1.0%, Ni：0.1~1.0%, Mo：0.1~0.5%, Co：1 kind in 0.01~0.5% or Two or more
Cu and Ni is to improve corrosion proof element, and it is effective for especially containing in the case where requiring high corrosion-resistant 's.In addition, Cu and Ni has the generation for promoting austenite phase, makes ferritic phase and austenite phase occur when hot rolled plate is annealed The widened effect of two-phase temperature range.These effects become significant in the case where Cu and Ni contain 0.1% or more respectively. However, hot-workability reduces to undesirable if Cu content is more than 1.0%.Therefore, it is set in the case where containing Cu 1.0% or less.Preferably 0.2~0.8% range.More preferably 0.3~0.5% range.If Ni content is more than 1.0% Processability reduces to undesirable.Therefore 1.0% or less is set in the case where containing Ni.Preferably 0.1~0.6% Range.More preferably 0.1~0.3% range.
Mo is the element for improving corrosion resistance, and it is effective for especially containing in the case where requiring high corrosion-resistant.The effect Fruit becomes significant when containing 0.1% or more.However, if Mo content is more than 0.5% when hot rolled plate is annealed austenite phase Generation becomes inadequate, and is unable to get defined material property to undesirable.Therefore, 0.1 is set as in the case where containing Mo ~0.5% or less.Preferably 0.1~0.3% range.
Co is the element for improving toughness.The effect is obtained and the Co containing 0.01% or more.On the other hand, if Co Amount can be such that processability reduces more than 0.5%.Therefore, 0.5% or less is set in the case where containing Co.Preferably 0.01 ~0.2% range.
Selected from Mg：0.0002~0.0050%, B：0.0002~0.0050%, REM：0.01~0.10%, Ca：0.0002 It is one kind or two or more in~0.0020%
Mg：0.0002~0.0050%
Mg is the element for having the effect of improving hot-workability.In order to obtain the effect and need containing 0.0002% with On.However, surface quality reduces if Mg amount is more than 0.0050%.Therefore, 0.0002 is set in the case where containing Mg ~0.0050% range.Preferably 0.0005~0.0035% range.More preferably 0.0005~0.0020% range.
B：0.0002~0.0050%
B is for preventing the effective element of low temperature secondary operation embrittlement.In order to obtain the effect and need containing 0.0002% or more.However, hot-workability reduces if B amount is more than 0.0050%.Therefore, it is set in the case where containing B For 0.0002~0.0050% range.Preferably 0.0005~0.0035% range.More preferably 0.0005~ 0.0020% range.
REM：0.01~0.10%
REM is the element for improving oxidative resistance, and especially there is the oxide scale film for inhibiting weld part to be formed to make to weld The effect that the corrosion resistance of socket part improves.In order to obtain the effect and need containing 0.01% or more.However, if containing having more than The manufacturings such as 0.10% pickling when cold-reduced sheet can be made to anneal reduce.In addition, REM is expensive element, if excessively containing It then will lead to manufacturing cost to increase to undesirable.Therefore, 0.01~0.10% model is set to containing REM It encloses.
Ca：0.0002~0.0020%
Ca is that have for preventing the nozzle as caused by the crystallization for the Ti system field trash being easy to produce when continuously casting from occluding The ingredient of effect.In order to obtain the effect and need containing 0.0002% or more.However, being generated if Ca amount is more than 0.0020% CaS and reduce corrosion resistance.Therefore, 0.0002~0.0020% range is set to containing Ca.Preferably 0.0005~0.0015% range.More preferably 0.0005~0.0010% range.
Next the manufacturing method of ferrite-group stainless steel of the invention is illustrated.
Ferrite-group stainless steel of the invention obtains in the following way：The steel plate formed with mentioned component is implemented Hot rolling anneals followed by the hot rolled plate kept within the temperature range of 880~1000 DEG C 5 seconds~15 minutes and hot rolling is made Next annealed sheet implements cold rolling, then carry out keeping 5 seconds~5 minutes cold-reduced sheets within the temperature range of 800~950 DEG C Annealing.
Firstly, by being melted by above-mentioned at being grouped as the molten steel constituted method as well known to converter, electric furnace, vacuum melting furnace etc. Casting, is made steel raw material (plate by continuous casting process or ingot casting-cogging method (ingoting-blooming method) Base).The slab is heated 1~24 hour at 1100~1250 DEG C and carries out hot rolling again and hot rolled plate is made, or without adding Heat but with as-cast condition directly carries out hot rolling and hot rolled plate is made.
Next, carrying out hot rolling.In winding, coiling temperature is preferably set as 500 DEG C or more 850 DEG C or less.If winding Temperature lower than 500 DEG C then wind after recrystallization it is insufficient to there are cold-reduced sheet annealing after ductility reduce the case where, thus It is undesirable.If more than 850 DEG C at a temperature of be wound if partial size become larger, exist and generate surface deterioration in punch process Situation.Therefore, coiling temperature is preferably 500~850 DEG C of range.
Later, carry out become 880~1000 DEG C of coexistence region temperature of ferritic phase and austenite phase at a temperature of protect Hold hot rolled plate annealing in 5 seconds~15 minutes.
Hot rolled plate annealing be in order to make the present invention obtain as defined in surface property and formability and important process.In heat Sufficient recrystallization can not be generated in the case where rolling plate annealing temperature lower than 880 DEG C, and due to becoming ferrite monophase field, because There is the case where being unable to get the effect of the invention shown using coexistence region annealing in this.However, if annealing temperature is more than 1000 DEG C of solid solutions that can then promote carbide.Therefore concentration of the C into austenite phase is encouraged, is generated after hot rolled plate annealing significant The martensitic phase of hard is unable to get defined surface property.
In addition, the production quantity of austenite phase is reduced if hot-roll annealing temperature is more than 1000 DEG C.Therefore, in hot rolled plate The amount of the martensitic phase generated after annealing is reduced, and is unable to fully obtain by the metal comprising ferritic phase and martensitic phase Rolling strains the ferritic phase concentration near martensitic phase and the anisotropy of the metal structure of realization when organizing to carry out cold rolling Alleviation effects, thus as defined in being unable to get | Δ r |.
In the case where annealing time was less than 5 seconds, it is unable to fully generate Ovshinsky being annealed with defined temperature The generation of body phase and the recrystallization of ferritic phase, therefore it is unable to get desired formability.On the other hand, if annealing time is more than 15 minutes then (Cr, V, Ti, Nb) (C, N) a part occur solid solution and encourage concentration of the C into austenite phase, because with it is above-mentioned together The mechanism of sample and be unable to get defined surface property.
In addition, if annealing time is more than 15 minutes, excessive C is generated because of above-mentioned mechanism, and to martensitic phase, (it is Austenite phase undergoes phase transition and generates after hot rolled plate annealing) in concentration.The martensitic phase is decomposed when cold-reduced sheet is annealed For carbide and ferritic phase, but if C concentration measure it is excessive if martensitic traoformation turn to the ferritic phase containing a large amount of carbide.By This becomes after cold-reduced sheet annealing in the carbide in crystal grain and on crystal boundary few ferrite crystal grain and crystal grain and on crystal boundary The excessive ferrite crystal grain of carbide mixed grain tissue.In the case where becoming this metal structure, the few crystal grain of carbide Difference of hardness is generated with the grain more than carbide, therefore deformation strain concentrates on the interface of the crystal grain of the two, is easy with the carbon on crystal boundary Compound is that starting point generates big gap (void), reduces ductility.
Therefore, hot rolled plate annealing 880~1000 DEG C at a temperature of keep 5 seconds~15 minutes.Preferably, 900~ It is kept for 15 seconds~15 minutes at a temperature of 1000 DEG C.More preferably, 900~1000 DEG C at a temperature of keep 15 seconds~3 minutes.
Next, carrying out cold rolling and cold-reduced sheet annealing.Implement pickling as needed and product is made.
About cold rolling, preferably carried out from the viewpoint of formability and shape correction with 50% or more reduction ratio.Separately Outside, in the present invention, cold rolling-annealing can also be repeated twice it is above, can also be made up of cold rolling 200 μm of plate thickness with Under stainless steel foil.
About cold-reduced sheet cold-reduced sheet anneal, in order to obtain good formability and 800~950 DEG C at a temperature of keep 5 seconds~5 minutes.
Cold-reduced sheet annealing be in order to make the duplex structure of ferritic phase and martensitic phase formed in hot rolled plate annealing at The important process for ferrite homogeneous structure.In the case where cold-reduced sheet annealing temperature is lower than 800 DEG C, recrystallization is unable to fully It generates to be unable to get defined ductility and average r value.On the other hand, in the feelings that cold-reduced sheet annealing temperature is more than 950 DEG C Under condition, generated after cold-reduced sheet annealing in the composition of steel that the temperature becomes the two-phase temperature range of ferritic phase and austenite phase Martensitic phase, thus steel plate hardening and be unable to get defined ductility.Even in addition, the temperature becomes the single-phase temperature of ferrite The composition of steel for spending range, also can cause the glossiness of steel plate to reduce because of the significant coarsening of crystal grain, therefore from surface quality Viewpoint is set out undesirable.In the case where annealing time was less than 5 seconds, even if ferritic phase is tied again with defined annealing temperature Crystalline substance generates with being also unable to fully, therefore is unable to get defined ductility and average r value.It is brilliant if annealing time is more than 5 minutes The glossiness of the significant coarsening of grain, steel plate reduces, therefore undesirable from the viewpoint of surface quality.Therefore, cold-reduced sheet is annealed It is set as being kept for 5 seconds~5 minutes in the range of 800~950 DEG C.Preferably, 15 seconds~3 points are kept at 850 DEG C~900 DEG C Clock.BA annealing (bright annealing (bright annealing)) can also be carried out in order to further seek for glossiness.
In addition, grinding, grinding etc. also can be implemented in order to further increase surface property.
Embodiment 1
Hereinafter, explaining the present invention in detail by embodiment.
Founding is carried out to the stainless steel with chemical composition shown in table 1 by 50kg small size vacuum smelting furnace.By these steel After base is with 1150 DEG C of heating 1h, implements hot rolling and the hot rolled plate of 3.5mm thickness is made.Next, being remembered to these hot rolled plates with table 2 After the condition of load implements hot rolled plate annealing, blasting treatment is carried out to surface and is descaled based on pickling.Pickling refers to, in temperature After being impregnated 120 seconds in 80 DEG C of degree, 20 mass % sulfuric acid solutions, what is be made of 15 mass % nitric acid and 3 mass % hydrofluoric acid It is impregnated 60 seconds in the mixed acid solution that 55 DEG C of temperature.Further, that 0.7mm is made by cold rolling is thick and with item documented by table 2 Part carries out cold-reduced sheet annealing, then by 80 DEG C of water temperature, 18 mass %Na2SO4With 25C/dm in aqueous solution2Condition carry out Cathodic pickling and in 50 DEG C of water temperature, 10 mass %HNO3With 30C/dm in aqueous solution2Condition carry out cathodic pickling and The processing that descales is carried out, cold-rolling pickling annealed sheet is obtained.
Thus obtained cold-rolling pickling annealed sheet is conducted the following evaluation.
(1) surface property is evaluated
After cold-reduced sheet annealing, every 1m is measured2Length present in steel plate is the number of the line defect of 5mm or more.It will be The line defect that cold rolled annealed plate surface confirms is in every 1m2It is set as qualified in steel plate for the situation at 5 under, will be more than at 5 The case where be set as unqualified.
(2) evaluation of ductility
JIS 13B tension test sheet is acquired from cold-rolling pickling annealed sheet along with rolling direction direction at right angle, according to JIS Z2241 carries out tension test, measures elongation at break, and the situation that elongation at break is 25% or more is set as qualified (zero), the case where by elongation at break less than 25%, is set as unqualified (×).
(3) average r value and | Δ r | evaluation
From cold-rolling pickling annealed sheet along relative to rolling direction parallel (direction L), (direction D) at 45 ° and at right angle (C Direction) direction acquire 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 r value intra-face anisotropy (Δ r=(rL-2rD+rC)/2) absolute value (| Δ r |).Here, rL、rD、rCIt is the r in the direction L, the direction D and the direction C respectively Value.About average r value, it is set as qualified (zero) by 0.65 or more, unqualified (×) will be set as less than 0.65.About | Δ r |, it will 0.30 or less is set as qualified (zero), will be more than 0.30 is unqualified (×).
(4) corrosion proof evaluation
From the test film of cold-rolling pickling annealed sheet acquisition 60mm × 100mm, after completing grinding to surface by #600 sand paper End face portion is sealed and makes test film, the brine spray cyclic test for 8502 defined of JIS H.Brine spray Cyclic test is moistened with brine spray (35 DEG C, 5%NaCl, spraying 2h) → dry (60 DEG C, relative humidity 40%, 4h) → (50 DEG C, relative humidity >=95%, 2h) is 1 circulation and progress 3 recycle.To the brine spray circulation for implementing 3 circulations Test film surface after test shoots photo, by the rust area on image analysis measurement test piece surface, according to rust area Calculated with the ratio of test film entire area rust area rate ((rust area/test film entire area in test film) × 100 [%]).About rust area rate, it is especially excellent and qualified (◎) that corrosion resistance is set as by 10% or less, will be more than 10% and be 25% or less is set as qualified (zero), will be more than 25% to be set as unqualified (×)
Evaluation result and hot rolled plate are annealed and cold rolled annealed condition is shown in table 2 together.
[table 1]
[table 2]
Underscore indicates not within the scope of the invention.
In example No.1~23 for meeting the scope of the present invention, 33~46,52~63, confirmed after cold-reduced sheet annealing Line defect be every 1m2In at 5 hereinafter, having obtained good surface property.In addition, elongation at break be 25% with Upper, average r value is 0.65 or more, | Δ r | it is 0.30 hereinafter, having obtained good formability.In addition, about corrosion resistance, in reality The rust area rate on the test film surface after having applied the brine spray cyclic test of 3 circulations is 25% hereinafter, having obtained good Good characteristic.
Especially in steel L, M, N and BM (No.17,18,19,52,61) containing Cu, Ni and Mo, brine spray Rust area rate after cyclic test is 10% hereinafter, corrosion resistance further increases.
On the other hand, it is lower than the scope of the present invention in the content of V and is unsatisfactory for the comparative example of V/ (Ti+Nb) >=2.0 In comparative example No.26 No.24 and Ti and Nb beyond the scope of this invention, the amount of precipitation of (Cr, V, Ti, Nb) (C, N) is not Foot, therefore the immobilization of solid solution C, N in hot rolled plate annealing are insufficient, as a result, generating significant hard after hot rolled plate annealing Martensitic phase largely generates line defect after cold-reduced sheet annealing.
In the content of V comparative example No.25 beyond the scope of this invention, although obtained defined average r value and | Δ r |, but make steel plate hardening because containing excessive V, therefore fail to obtain defined ductility.
Cr content lower than the scope of the present invention comparative example No.27 in, although obtained defined surface property and Ductility, average r value and | Δ r |, but since Cr content is insufficient, do not obtain defined corrosion resistance.
In the comparative example No.28 that Cr content is more than the scope of the present invention, although having obtained sufficient corrosion resistance, due to Excessively contain Cr so not generating austenite phase in hot rolled plate annealing, thus fail to obtain defined ductility, average r value with And | Δ r |.
In C amount comparative example No.29 beyond the scope of this invention, although V, Ti and Nb amount are in the scope of the present invention It is interior, but the C in steel be not used as (Cr, V, Ti, Nb) (C, N) by all fully immobilizations and remaining has solid solution C, therefore in heat The martensitic phase for generating significant hard after plate is annealed is rolled, does not obtain defined surface property.In addition, since solid solution C amount increases, institute It is significantly risen with armor plate strength, does not obtain defined ductility.
On the other hand, in comparative example No.30 of the C amount lower than the scope of the present invention, based on the steady of the C austenite phase realized Fixedization is simultaneously insufficient, therefore does not generate an adequate amount of austenite phase in the hot rolled plate annealing in coexistence region, to not advised Fixed average r value and | Δ r |.
In V/ (Ti+Nb) comparative example No.31 and No.32 lower than the scope of the present invention, when hot rolling (Cr, V, Ti, Nb) the precipitation of (C, N) and insufficient, therefore a large amount of coarse Cr carbonitride is precipitated, it is generated after hot rolled plate annealing significant hard The martensitic phase of matter, therefore line defect is largely generated after cold-reduced sheet annealing, defined surface property is not obtained.
No.47 and No.64 is V/ (Ti+Nb) lower than the scope of the present invention and hot-roll annealing temperature compares the scope of the invention High comparative example.Since V/ (Ti+Nb) is lower than the scope of the present invention, the coarse carbide being precipitated when encouraging with hot rolling Solid solution and the concentration of the C that generates into austenite phase, the martensitic phase of significant hard is generated after hot rolled plate annealing, therefore big Amount generates line defect, does not obtain defined surface property.In addition, since hot-roll annealing temperature is higher than the scope of the invention, because The amount of the austenite phase generated in this annealing is reduced, and the amount of the martensitic phase generated after hot rolled plate annealing is reduced, therefore can not be obtained Cold rolling after to utilization and the anisotropy alleviation effects of metal structure realized, do not obtain as defined in | Δ r |.
No.48 and No.65 is V/ (Ti+Nb) lower than the scope of the present invention and hot-roll annealing temperature is than model of the present invention Enclose low comparative example.Although V/ (Ti+Nb) is lower than the scope of the present invention, hot-roll annealing temperature becomes the single-phase temperature of ferrite Range is not to generating austenite phase, therefore almost without the line defect because of caused by the generation of the martensitic phase of significant hard Generation, obtained good surface property.However, not generated since hot-roll annealing temperature is lower than the scope of the invention Adequately recrystallization, and after hot rolled plate annealing do not generate martensitic phase to do not obtain defined ductility, average r value and |Δr|。
No.66 is V/ (Ti+Nb) lower than the scope of the present invention and the comparison longer than the scope of the invention of hot rolled plate annealing time Example.Therefore, the solid solution for the coarse carbide being precipitated when excessively generating with hot rolling and the C that generates is dense into austenite phase Contracting as a result, generating the martensitic phase of significant hard after hot rolled plate annealing, therefore largely generates line defect and is not provided Surface property.In addition, the metal structure after cold-reduced sheet annealing becomes the iron excessive by the carbide in crystal grain and on crystal boundary The mixed grain tissue of the few ferrite crystal grain composition of carbide in ferritic crystal grain and crystal grain and on crystal boundary, therefore become stretching It is concentrated when shape in the strain that the interface of the crystal grain of the two generates part, does not obtain defined ductility.
No.67 is V/ (Ti+Nb) lower than the scope of the present invention and the comparison lower than the scope of the invention of cold-reduced sheet annealing temperature Example.It is a large amount of to generate line defect and do not obtain defined surface property since V/ (Ti+Nb) is lower than the scope of the present invention. In addition, since cold-reduced sheet annealing temperature is lower than the scope of the invention, recrystallization when cold-reduced sheet is annealed is insufficient and remaining to be had Worked structure when cold rolling, therefore defined ductility and average r value are not obtained.
No.68 is V/ (Ti+Nb) lower than the scope of the present invention and the comparison higher than the scope of the invention of cold-reduced sheet annealing temperature Example.Since V/ (Ti+Nb) is lower than the scope of the present invention, generates a large amount of line defect and do not obtain defined superficiality Energy.In addition, becoming the two-phase temperature in ferritic phase and austenite phase since cold-reduced sheet annealing temperature is higher than the scope of the invention The annealing carried out in range is spent, to generate austenite phase again, mutually becomes martensitic phase, therefore steel plate after cold-reduced sheet annealing Significant hardening does not obtain defined ductility.
Industrial applicibility
The obtained ferrite-group stainless steel of the present invention is particularly suitable for application to stamping product based on drawing, wants Ask the application of the purposes such as kitchen appliance, tableware of high surface aesthetics.

Claims (6)

1. a kind of ferrite-group stainless steel contains C in terms of quality %：0.015~0.035%, Si：0.02~0.50%, Mn： 0.05~1.0%, P：0.04% or less, S：0.01% or less, 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,
Elongation at break on rolling direction direction at right angle be 25% or more, in the tension test according to JIS Z 2241 The average r value calculated by following (1) formulas the when strain of middle application 15% is 0.65 or more and by the Δ r of following (2) formulas calculating Absolute value | Δ r | be 0.30 hereinafter,
Average r value=(rL+2×rD+rC)/4 (1)
Δ r=(rL-2×rD+rC)/2 (2)
Wherein, rLTo carry out r value when tension test, r on the direction parallel with rolling directionDFor relative to rolling direction To carry out r value when tension test, r on 45 ° of directionsCFor when with tension test is carried out on rolling direction direction at right angle R value.
2. a kind of ferrite-group stainless steel contains C in terms of quality %：0.01~0.05%, Si：0.02~0.50%, Mn：0.2 ~1.0%, P：0.04% or less, S：0.01% or less, 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,
Elongation at break on rolling direction direction at right angle be 25% or more, in the tension test according to JIS Z 2241 The average r value calculated by following (1) formulas the when strain of middle application 15% is 0.65 or more and by the Δ r of following (2) formulas calculating Absolute value | Δ r | be 0.30 hereinafter,
Average r value=(rL+2×rD+rC)/4 (1)
Δ r=(rL-2×rD+rC)/2 (2)
Wherein, rLTo carry out r value when tension test, r on the direction parallel with rolling directionDFor relative to rolling direction To carry out r value when tension test, r on 45 ° of directionsCFor when with tension test is carried out on rolling direction direction at right angle R value.
3. ferrite-group stainless steel according to claim 1 or 2, wherein in terms of quality %, the content of the C is 0.015 ~0.035%, and also containing selected from Cu：0.1~1.0%, Ni：0.1~1.0%, Mo：0.1~0.5%, Co：0.01~ It is one kind or two or more in 0.5%.
4. ferrite-group stainless steel according to claim 1 or 2, 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：1 in 0.0002~0.0020% Kind or two or more.
5. ferrite-group stainless steel according to claim 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：1 kind in 0.0002~0.0020% or 2 kinds More than.
6. a kind of manufacturing method of ferrite-group stainless steel is that ferrite described in any one of claims 1 to 5 is stainless The manufacturing method of steel implements hot rolling to plate slab, followed by the holding 5 seconds~15 within the temperature range of 880~1000 DEG C Minute annealing hot-roll annealing plate is made, next implement cold rolling, then carry out protecting within the temperature range of 800~950 DEG C Hold cold-reduced sheet annealing in 5 seconds~5 minutes.
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