CN104884657A - Ferritic stainless steel sheet having excellent anti-bacterial activity, and method for producing same - Google Patents
Ferritic stainless steel sheet having excellent anti-bacterial activity, and method for producing same Download PDFInfo
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- CN104884657A CN104884657A CN201380062495.4A CN201380062495A CN104884657A CN 104884657 A CN104884657 A CN 104884657A CN 201380062495 A CN201380062495 A CN 201380062495A CN 104884657 A CN104884657 A CN 104884657A
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Abstract
The invention discloses a ferritic stainless steel sheet. An first embodiment of the ferritic stainless steel sheet contains 0.1 to 5.0 mass% inclusive of Cu and has a Cu-rich layer on the surface thereof, wherein the maximum concentration of Cu (Cm) in the Cu-rich layer is 10.0 mass% or more and the Fe/Cr ratio at a position at which the maximum concentration of Cu (Cm) is stood at, as observed from the surface of the steel sheet in the thickness direction, is 2.4 or more. A second embodiment of the ferritic stainless steel sheet contains 0.1 to 5.0 mass% inclusive of Cu and has a Cu-rich layer on the surface thereof, wherein the maximum concentration of Cu (Cm) in the Cu-rich layer is 18.0 mass% or more.
Description
Technical field
The present invention relates to the excellent ferrite series stainless steel plate of germ resistance and manufacture method thereof, in more detail, ferrite series stainless steel plate and manufacture method thereof that the optimal seeking of raw and processed materials as health equipment and the buildings building materials etc. such as railing, the first-class axle journal of the fire hose, metal coin (metallic coin), metal vessel, metalic tableware, bathtub, domestic electric appliances, toilet seat, medicine equipment, steam heating uses is related to.
Based on the Japanese patent application laid that on December 26th, 2012 proposes, the application is willing to that the Japanese patent application laid proposed in No. 2012-282843 and on July 17th, 2013 is willing to No. 2013-148950 and advocates its right of priority, quote its content here.
Background technology
Ferrite series stainless steel plate is widely used in the home appliance etc. of galley equipment and microwave oven side plate etc. centered by tank all the time.Recently, consider from clean feel and decorative appearance, angle attractive in appearance, be also used in the interior trim such as medicine equipment and the railing building materials such as hand washing sink.That is, stainless steel plate starts to increase in the use in the unwelcome place of generation of the incidental place of miscellaneous bacteria and miscellaneous bacteria.On the other hand, in recent years, worry that the breeding of such miscellaneous bacteria strengthens the dysgenic tendency of human body, particularly the requirement of the germ resistance of the buildings building materials that the medicine equipment that must clean and galley equipment and many people are assembled is strengthened.Along such trend, require that the ferrite-group stainless steel self that clean position uses has carried out the trial making it have germ resistance at these.
As such trial, such as, can list patent documentation 1 and patent documentation 2 etc.Among them, disclose and adopt in the stacked method being combined with the resin of antiseptic-germicide of stainless surface coated or the method implementing the plating in the base containing antimicrobial component, thus make it have the technology of germ resistance.
In addition, as the method making stainless steel self have germ resistance, patent documentation 3 ~ patent documentation 5 can be listed.In patent documentation 3 and patent documentation 4, adopt alternately treatment with electrolytic method, by applying the current potential of calibration to the ferrite-group stainless steel material containing Cu or austenite stainless steel material, thus make Cu to stripping in electrolytic solution, after this by applying comparatively negative current potential, thus Cu is separated out on the surface of stainless steel, make it have germ resistance thus.
In addition, in patent documentation 5, disclose following method: smooth grinding is carried out to the surface of the ferrite-group stainless steel material containing Cu, austenite stainless steel plate or martensitic stainless steel plate, then implement clean annealing or the pickling of nitre fluoric acid, thus formation makes Cu denseization to the layer of more than 3 quality % on steel top layer.
In addition, recently, germ resistance stainless steel is used in various purposes.Such as, metal coin is considered from the good degree of its processibility and the angle of characteristic of low cost, mostly uses ferrite-group stainless steel.Consider from the angle of economy, the ferrite-group stainless steel of raw materials cost cheapness has profitability.
When ferrite-group stainless steel being applicable to metal coin etc., in order to obtain stamping-out and marking property, sometimes require the softening of this degree of such as below Hv190.Especially, in order to show germ resistance, what the ferrite-group stainless steel containing Cu became problem mostly is the sclerosis produced by solution strengthening or precipitation strength.
Such as, patent documentation 6 discloses the Hv hardness of the ferrite-group stainless steel containing more than 0.66% Cu.Such as, 16.87Cr-0.66Cu is Hv171,13.57Cr-1.08Cu is Hv166.
In addition, as the manufacture method of the ferrite-group stainless steel containing Cu, patent documentation 7 proposes a kind of following technology: about the speed of cooling after hot rolling, be cooled to the coiling temperature of 500 ~ 300 DEG C with 3 DEG C/more than s after hot rolling, thus the Cu existed in hot-rolled sheet bunch is controlled be below 5nm to the maximum, thus avoidance toughness is bad.
But, suggested by patent documentation 1 or patent documentation 2, when by be combined with antiseptic-germicide resin-coated in surface or implement containing antimicrobial component coating, the distinctive surface luster of stainless steel will be lost.Therefore, in the purposes requiring surface luster, commodity value will be lost.Moreover, germ resistance resin film or crack when press working or when using containing the coating of antimicrobial component or defect and easily sustaining damage.In addition, when being exposed to moistening atmosphere, antimicrobial component stripping, appearance degradation, original anti-microbial effect loses simultaneously.
In addition, even if making stainless steel self have in the above-mentioned patent documentation 3 ~ patent documentation 5 of germ resistance, also there is problem.That is, disclosed in patent documentation 3 and patent documentation 4, alternately treatment with electrolytic method makes Cu separate out on stainless surface by electrolysis.Therefore, its shortcoming had is: Cu is easily from steel surfacial spalling, and such as, when with friction surfaces such as metal plug, steel wire scrub-brushes (steelscrubbing brush), the Cu on surface is cut down, thus germ resistance reduces.
In addition, if the present inventor disclose the surface C u concentration of patent documentation 5 to be controlled more than certain value, the prior art that can obtain germ resistance is studied.Consequently, known in these prior aries, the plate width in identical plate face, germ resistance likely produces larger deviation.That is, the anti-bacteria stainless steel that the method for known employing prior art obtains is in its plate face, and the position of existing product having enhanced antibacterial action, also easily exists bad position, and when being supplied to the finished product of endowing antibacterial, yield rate worsens.
So, disclosed stainless steel itself went out the technology of germ resistance or germ resistance easily reduces in the past, otherwise in yield rate remaining deficiency.
In addition, when ferrite series stainless steel plate also requires softening, the control carrying out hardness is needed.There is following problem in the prior art relating to above-mentioned hardness.
In the ferrite-group stainless steel described in patent documentation 6, Cu concentration is 0.66 ~ 1.08%, Hv is less than 190.But the ferrite-group stainless steel described in patent documentation 6 does not meet aftermentioned (a) of the present invention formula, can not tackle the situation also requiring high anti-corrosion except softening.
Patent documentation 7, in order to control to make toughness be improved at below 5nm by Cu bunch, is defined as 3 DEG C/more than s by from after hot rolling to the speed of cooling of batching.But the technology relevant to cold rolling raw-material softening is not open.
As mentioned above, for the ferrite-group stainless steel containing Cu, the technology taking into account germ resistance and softening is not open up to now.
Prior art document
Patent documentation
Patent documentation 1: Japanese Unexamined Patent Publication 5-228202 publication
Patent documentation 2: Japanese Unexamined Patent Publication 6-10191 publication
Patent documentation 3: Japanese Unexamined Patent Publication 8-60302 publication
Patent documentation 4: Japanese Unexamined Patent Publication 8-60303 publication
Patent documentation 5: Japanese Unexamined Patent Publication 11-172380 publication
Patent documentation 6: Japanese Unexamined Patent Publication 2003-213378 publication
Patent documentation 7: No. 2012/108479th, International Publication
Summary of the invention
Invent problem to be solved
Problem of the present invention is: provide a kind of ferrite series stainless steel plate and the manufacture method thereof of taking into account germ resistance and softening.
For solving the means of problem
In order to solve the problem of above-mentioned germ resistance, the present inventor has carried out research with great concentration to the position of product having enhanced antibacterial action in plate face and the difference of bad position.Consequently, following opinion is obtained.
I (), in order to show germ resistance, the Cu peak concentration bottom line of the Cu denseization layer on steel surface needs more than 10 quality %.
(ii) in addition, the Cu concentration on known steel surface controls to be show the necessary condition of germ resistance, but controls to be not sufficient only according to Cu concentration.That is, according to the evaluation result of the present inventor, even if the Cu peak concentration on steel surface is at more than 10 quality %, also there is the situation that germ resistance is bad.This means except the Cu peak concentration on steel surface, also there is the factor showing germ resistance.In the past, owing to not grasping these factors, thus infer in plate face, the deviation of germ resistance increases.So the present inventor, in order to explore its factor, broadens one's vision further until the one-tenth of steel skin section is grouped into and investigates.Result obtains following opinion: germ resistance and the main component of the Cu denseization layer on steel surface and the existence of Fe, Cr also strongly relevant.Cu in the Cu denseization layer on steel surface is be evaluated as: it is the factor of left and right germ resistance, and its Cu is from steel surface stripping, the cellular activity of bacterium is reduced, thus shows germ resistance.Therefore, it is contemplated that the relation between Fe and Cr being present in Cu periphery in Cu denseization layer produces larger impact to germ resistance.Known in order to stably obtain germ resistance, except the Cu peak concentration of in the past known Cu denseization layer, and then need control Fe/Cr ratio.
(iii) moreover, according to the evaluation result of the present inventor, as long as the Cu peak concentration on known steel surface is at more than 18 quality %, even if not control Fe/Cr ratio, does not see the position that germ resistance is bad yet, thus sufficient germ resistance can be obtained.
In addition, in order to make starting material (steel plate) softening with above-mentioned germ resistance, the present inventor has carried out research with great concentration with regard to the thermal treatment of the ferrite series stainless steel plate containing Cu further on the impact of hardness.Specifically, with regard to Cu solid solution and separate out form and various research has been carried out in the thermal treatment (heating and cooling condition) that has an impact to them, thus obtain following opinion.
A () organizes relatively from hard material and soft material, can see that the precipitation form of Cu has larger difference.In hard material, observe the fine Cu particle of 10 ~ 100nm.On the other hand, in soft material, almost do not see the precipitation of Cu.Although the Cu of soft material is solid-solution in ferrite, the sclerosis increment produced by its solution strengthening is less.Therefore, can think that the major cause of sclerosis results from the precipitation strength of Cu, it is effective for suppressing it to separate out for softening.
In addition, the size of above-mentioned Cu precipitate is nm level, uses the TEM (transmission electron microscope) to the structure observation of tiny area is applicable to carry out structure observation.As test portion adjustment, adopt electrolytic polishing method to be made film test portion, adopt TEM to be amplified to maximum 200,000 times and observe, observe Cu precipitate.
B () makes its softening to be suppressed by the precipitation of Cu, by containing based on the ferrite-group stainless steel of 1.5%Cu, found the effective heat-treat condition of softening (following (b-1), b-2)).In addition, even if the ferrite-group stainless steel of these heat-treat condition Cu:0.3 ~ 1.7 quality % too, be effective to softening.
(b-1) about final annealing, obtain following opinion: by solid solubility temperature being set as 900 ~ 1100 DEG C and being cooled to lower than 500 DEG C, just meet following (a) formula relevant with hardness Hv and realize softening.The solid solubility temperature of 900 ~ 1100 DEG C separates out solid solution again owing to making Cu, thus can think to softening it is effective.In addition, the average cooling rate of 3 DEG C/more than s also suppresses Cu to separate out.
Hv≤40×(Cu-0.3)+135 (a)
In addition, the Cu in formula represents Cu content (quality %).
In contrast, when not meeting above-mentioned (a) formula, in steel with dense observation to Cu precipitate.Even if softening reaches below Hv190, the Cu separated out so also makes solidity to corrosion reduce.
(b-2) about hot-rolled sheet annealing, consider from the angle suppressing Cu to separate out, neither carry out in the mode of continuous annealing with batch annealing, be heated to 800 ~ 1100 DEG C, be then cooled to 400 DEG C with the average cooling rate of 1 DEG C/more than s.Thus, softening can be realized in the scope of above-mentioned (a) formula relevant with hardness meeting the present invention's regulation.
In addition, Cu precipitate given to this invention is in abundant little person is that coarse precipitates that is most of, about 10 ~ 1000nm observes the such degree of a part.On the other hand, in the prior art, although for improving germ resistance and hot properties and control Cu precipitate, its size is almost 10 ~ 1000nm, and it is very high to separate out density.
The present invention obtains based on above opinion, and its content is as described below.
(1) ferrite series stainless steel plate that a kind of germ resistance is excellent, it is characterized in that: in mass %, containing the Cu of 0.1% ~ 5.0%, there is on the surface of stainless steel plate Cu denseization layer, the Cu peak concentration Cm of described Cu denseization layer is more than 10.0 quality %, and the Fe/Cr ratio demonstrating the depth location place apart from surface of steel plate of described Cu peak concentration Cm is more than 2.4.
(2) ferrite series stainless steel plate that germ resistance is excellent, is characterized in that: in mass %, containing the Cu of 0.1% ~ 5.0%, has Cu denseization layer on the surface of stainless steel plate, and the Cu peak concentration Cm of described Cu denseization layer is more than 18.0 quality %.
(3) ferrite series stainless steel plate that the germ resistance according to above-mentioned (1) or (2) is excellent, wherein, the content of described Cu is 0.3 ~ 1.7% in mass %, and the section hardness of steel plate meets following (a) formula in Vickers' hardness scale.
Hv hardness≤40 × (Cu-0.3)+135 (a)
(4) ferrite series stainless steel plate that the germ resistance according to any one of above-mentioned (1) ~ (3) is excellent, wherein, described ferrite series stainless steel plate in mass %, further containing below C:0.050%, Cr:10.0 ~ 30.0%, below Si:2.00%, below P:0.030%, below S:0.010%, below Mn:2.00%, below N:0.050% and below Ni:2.0%, remainder comprises Fe and inevitable impurity.
(5) ferrite series stainless steel plate that the germ resistance according to above-mentioned (4) is excellent, wherein, described ferrite series stainless steel plate in mass %, further containing any one among below Ti:0.50% and below Nb:1.00% or both.
(6) ferrite series stainless steel plate that the germ resistance according to above-mentioned (4) or (5) is excellent, wherein, described ferrite series stainless steel plate in mass %, further containing more than a kind that is selected among below Sn:1.00%, below Mo:1.00%, below Al:1.000%, below Mg:0.010%, below Co:1.000%, below V:0.50%, below Zr:0.10%, below REM:0.100%, below La:0.100%, below B:0.0100% and below Ca:0.010%.
(7) ferrite series stainless steel plate that the germ resistance according to any one of above-mentioned (1) ~ (6) is excellent, wherein, described ferrite series stainless steel plate is used for metal coin.
(8) manufacture method of the ferrite series stainless steel plate that a kind of germ resistance is excellent, it is characterized in that: described manufacture method has hot-rolled process, cold rolling process and final pickling process, the one-tenth that stainless steel plate has according to any one of above-mentioned (1) ~ (6) is grouped into, and described final pickling process has the 2nd pickling process in the acid solution of the hydrofluoric acid aqueous solution of the 1st pickling process in the aqueous sulfuric acid that impregnated in 5.0 ~ 35.0 quality % and the nitric acid that impregnated in containing 1.0 ~ 15.0 quality % and 0.5 ~ 5.0 quality %.
(9) manufacture method of the ferrite series stainless steel plate that the germ resistance according to above-mentioned (8) is excellent, wherein, described hot-rolled process Heating temperature be 1150 ~ 1300 DEG C, finishing temperature carries out under be 800 ~ 1000 DEG C and coiling temperature being the condition of less than 600 DEG C.
(10) manufacture method of the ferrite series stainless steel plate that the germ resistance according to above-mentioned (8) or (9) is excellent, wherein, described manufacture method has hot-rolled sheet annealing operation and final annealing operation further, the one-tenth that described stainless steel plate has according to any one of above-mentioned (3) ~ (6) is grouped into, and described final annealing operation has carries out the operation of annealing with the annealing temperature of 900 ~ 1100 DEG C and be cooled to the operation of 400 DEG C with the average cooling rate of more than 3 DEG C/sec.
(11) manufacture method of the ferrite series stainless steel plate that the germ resistance according to above-mentioned (10) is excellent, wherein, described hot-rolled sheet annealing operation is carried out in the mode of continuous annealing, and described continuous annealing has to be carried out the operation of annealing with the annealing temperature of 800 ~ 1100 DEG C and be then cooled to the operation of 400 DEG C with the average cooling rate of more than 1 DEG C/sec.
The effect of invention
The ferrite series stainless steel plate that germ resistance according to the present invention is excellent and manufacture method thereof, play good germ resistance due to the whole region in plate face, thus can obtain the good germ resistance more than in the past with good yield rate.In addition, according to the preferred mode of the present invention, high denseization of the Cu peak concentration on steel surface can be made to unprecedented degree, better germ resistance can be obtained thus.In addition, by the Cu content of ferrite-group stainless steel is limited in 0.3 ~ 1.7%, the condition of hot-rolled sheet annealing and final annealing is controlled simultaneously, softening can be sought fully.Therefore, softening and excellent antibacterialization can be taken into account.The ferrite series stainless steel plate of the present invention with these features such as can be preferably used as metal coin.
Accompanying drawing explanation
Fig. 1 be represent stainless steel of the present invention from surface the figure along an example of the concentration distribution of C, O of depth direction and principal element.
Fig. 2 be represent stainless steel of the present invention from surface the figure along an example of the concentration distribution of the O of depth direction and principal element.
Fig. 3 is the figure representing the relation between evaluating about the Cu peak concentration of embodiments of the invention (the present invention example) and comparative example, Fe/Cr ratio and germ resistance.
Embodiment
Be described in detail with regard to embodiments of the present invention and the excellent ferrite series stainless steel plate of germ resistance and manufacture method thereof below.In addition, as long as no dated especially, the content % of element refers to quality %.
The ferrite series stainless steel plate of the 1st embodiment is in mass %, containing the Cu of 0.1% ~ 5.0%, there is on the surface of stainless steel plate Cu denseization layer, the Cu peak concentration Cm of Cu denseization layer is more than 10.0 quality %, demonstrates the Fe/Cr at the depth location place apart from surface of steel plate of Cu peak concentration Cm than the ferrite series stainless steel plate being more than 2.4.
The ferrite series stainless steel plate of the 2nd embodiment is in mass %, containing the Cu of 0.1% ~ 5.0%, has Cu denseization layer on the surface of stainless steel plate, and the Cu peak concentration Cm of Cu denseization layer is the ferrite series stainless steel plate of more than 18.0 quality %.
The ferrite series stainless steel plate of the 1st embodiment or the 2nd embodiment also in mass %, can contain below C:0.050%, Cr:10.0 ~ 30.0%, below Si:2.00%, below P:0.030%, below S:0.010%, below Mn:2.00%, below N:0.050%, below Ni:2.0% further.
The ferrite series stainless steel plate of the 1st embodiment or the 2nd embodiment also can in mass %, further containing any one among below Ti:0.5% and below Nb:1.00% or both.
The ferrite series stainless steel plate of the 1st embodiment or the 2nd embodiment also can in mass %, further containing more than a kind that is selected among below Sn:1.00%, below Mo:1.00%, below Al:1.000%, below Mg:0.010%, below Co:1.000%, below V:0.50%, below Zr:0.10%, below REM:0.100%, below La:0.100%, below B:0.0100% and below Ca:0.010%.
At this, so-called Cu denseization layer, refers in the top layer of ferrite series stainless steel plate, has the region of the Cu concentration higher than the average Cu concentration in ferrite series stainless steel plate.Specifically, for the ferrite series stainless steel plate of present embodiment, adopt glow discharge optical emission spectrometry (GDS), detect from surface of steel plate to about 800nm degree of depth by pickling process at the element of surface denseization with form the element of oxide compound.The details of detection elements holds rear describing.If measure the concentration distribution of O, Fe, Cr, Si, Mn, Nb, Ti, Al, Cu, then the concentration of Cu, Fe, Cr such as demonstrates the concentration distribution at depth direction as shown in Figure 2.In fig. 2, the Cu concentration ratio degree of depth from surface to degree of depth 30nm is large more than the Cu concentration of 30nm.In fig. 2, if the degree of depth is set as the average Cu concentration of stainless steel plate more than the Cu concentration of 30nm, then the Cu denseization layer in Fig. 2 is the region from surface to degree of depth 30nm.Cu denseization layer can determine in this wise.
In addition, analyze by GDS the Cu concentration obtained to represent by the Cu concentration of the total amount relative to O, Fe, Cr, Si, Mn, Nb, Ti, Al, Cu.In Cu denseization layer, Cu concentration is reached maximum concentration and be set as Cu peak concentration Cm.Moreover, in the present embodiment, the Fe concentration of depth apart from surface of steel plate demonstrating Cu peak concentration Cm is called Fe/Cr ratio with the ratio of Cr concentration.In the example in figure 2, Cu peak concentration Cm is 75.0%, Fe/Cr ratio is 2.9.
O, Fe, Cr, Si, Mn, Nb, Ti, Al, Cu due to for by pickling process at the element of surface denseization with form the element of oxide compound, thus for calculating Cu concentration.
In addition, P, S, N, Ni due to surface denseization that do not produced by pickling process and because forming oxide compound in surface denseization, thus determine not consider when the calculating of Cu concentration.
Ti, Nb, Al are the elements added arbitrarily in present embodiment, but owing to being the element forming oxide compound, thus pay attention to when the calculating of Cu concentration.When not containing these elements, the concentration of these elements is set as 0% and calculate Cu concentration.
In addition, C is pollution element, thus determines, in GDS analyzes after detection, remove C and calculate Cu concentration.
Then, the Cu content with regard to ferrite series stainless steel plate is described.
Cu, in the ferrite series stainless steel plate of present embodiment, is the most important element for improving germ resistance.In the present embodiment, the Cu peak concentration Cm making Cu denseization layer is needed to be more than 10.0%.When steel Cu content lower than 0.1%, even if be suitable for the manufacture method of present embodiment described later, the Cm value of more than 10.0% can not be obtained.Therefore, be 0.1% by the lower limit set of the Cu content of steel.On the other hand, if Cu content is too much, then there is the cracking of strand in the fabrication process, thus the upper limit is set as less than 5.0%.The Cu content of steel is preferably 0.1 ~ 1.7%, most preferably is 0.2 ~ 1.5%.
In the present embodiment, in order to obtain germ resistance, need the strict Elemental redistribution controlling steel top layer.First, the Cu peak concentration Cm needing the Cu denseization layer making steel surface is more than 10.0%.When less than 10.0%, even if meet other regulation, also germ resistance can not be shown.Cu peak concentration Cm is preferably more than 11.0%, and more preferably more than 18.0%.On the other hand, no matter how high Cm is for Cu peak concentration, also can not produce detrimentally affect to germ resistance, and thus its upper limit does not specify.
In addition, the relation of various germ resistance and steel top layer state is studied, found that: need the difference according to Cu peak concentration Cm, suitably control the main component of Cu denseization layer and the existence of Fe, Cr on steel top layer.So, for Cu peak concentration Cm and Fe/Cr ratio, use the figure of Fig. 3 to be further detailed.
Fig. 3 is in the data of test No.1 ~ 551 of table 2 ~ table 15 in aftermentioned embodiment, with near Cu peak concentration Cm:5 ~ 40 quality %, Fe/Cr ratio: the data grid technology near 1 ~ 6 and extracted data carries out drawing obtaining is the figure representing the result that the relation between investigation Cu peak concentration Cm, Fe/Cr ratio and germ resistance evaluation obtains.The drawing point of the white circle in the figure of Fig. 3 represents the example (the present invention's example) that germ resistance is excellent, the drawing point of black circle represents the example (the present invention's example) that germ resistance is excellent especially, and the drawing point of multiplying symbol ("×" symbol) represents the example (comparative example) that germ resistance is bad.
(A) Cu peak concentration Cm more than 10.0% and lower than 18.0% situation (stainless steel plate of the 1st embodiment)
In the ferrite series stainless steel plate of the 1st embodiment, need to make Fe/Cr ratio be more than 2.4.As shown in Figure 3, Fe/Cr than lower than 2.4 time, even if Cu peak concentration Cm is more than 10.0%, also can not show germ resistance.Its reason is also unclear, but according to the presumption of the present inventor, it is generally acknowledged that, by making Fe/Cr than more than 2.4, the bonding of Fe and Cr becomes unstable, and the Cu in Cu denseization layer also becomes unstable.Cu be difficult at normal temperatures to be oxidized compared with Fe, Cr, i.e. the bad element with oxygen bonding.When Fe, Cr play pendulum, owing to removing bonding with the oxygen of Fe or Cr bonding, thus the oxygen amount of Cu periphery increases.Therefore, it is generally acknowledged the bad Cu with oxygen bonding easily with the form of ion from steel surface to stripping water.With the Cu of the form stripping of ion, the cellular activity of bacterium is reduced, thus show germ resistance.Therefore, it is generally acknowledged by making the Fe/Cr on steel top layer than in above-mentioned scope, perhaps as showing germ resistance.Fe/Cr ratio is more preferably 2.6 ~ 9.5, and more preferably 3.0 ~ 9.0.In addition, in order to make Cu peak concentration Cm more than 10.0%, making Fe/Cr than more than 2.4 simultaneously, in the manufacture method of aftermentioned present embodiment, can acid washing conditions be controlled.
(B) Cu peak concentration Cm is the situation (stainless steel plate of the 2nd embodiment) of more than 18.0%
In the ferrite series stainless steel plate of the 1st embodiment and the 2nd embodiment, by improving Cu peak concentration Cm, germ resistance is made to be able to further raising.Specifically, as the ferrite series stainless steel plate of the 2nd embodiment, if control more than 18.0% by Cu peak concentration Cm, then germ resistance is able to further raising.Shown by the figure of Fig. 3: when Cu peak concentration Cm higher than the 1st embodiment more than 18.0%, do not need to control especially Fe/Cr ratio.Its reason is also unclear, but according to the presumption of the present inventor, if Cu peak concentration Cm reaches more than 18.0%, then the Cu concentration of the Cu denseization layer on steel top layer increases, and on the other hand, Fe concentration and Cr concentration reduce.Thus, can think that its reason is that the impact of Fe and Cr of Cu denseization layer reduces.Therefore, can infer that, with Fe/Cr than irrelevant, the Cu of Cu denseization layer from steel surface to stripping water with the form of ion, makes the cellular activity of bacterium reduce, thus shows germ resistance.
In addition, in order to make Cu peak concentration Cm more than 18.0%, in the manufacture method of aftermentioned present embodiment, while control acid washing conditions, rolling condition can be controlled.In addition, if exceedingly many at steel top layer Fe, then make the erosion resistance of ferrite series stainless steel plate reduce, thus preferred Fe/Cr is set as less than 10.0.On the other hand, if exceedingly few at steel top layer Fe, then the Cr being present in steel surface is more in easily oxidized state, thus preferred Fe/Cr is set as more than 0.4.Fe/Cr is preferably 0.4 ~ 10.0, and more preferably 0.5 ~ 9.5.
(softening of ferrite series stainless steel plate)
As mentioned above, except the Cu control table by steel surface is revealed except germ resistance, when seeking softening, it is effective that the Cu in final annealing separates out suppression.The actual conditions etc. just seeking the softening of the ferrite series stainless steel plate of the 1st embodiment and the 2nd embodiment is below described.
First, in order to take into account germ resistance and softening, preferably Cu content is set as 0.3 ~ 1.7%.Cu content lower than 0.3% time, due to abundant lower than the solid solubility of Cu, thus occur hardly because Cu separates out the sclerosis caused.On the other hand, when C content is more than 1.7%, even if suppress Cu to separate out, the sclerosis increment produced by the solution strengthening of Cu is comparatively large, is thus often difficult to the softening realizing present embodiment defined.
As the precipitation form of Cu, be also subject to the impact of Cu content etc., but be the granular or bar-shaped of 10 ~ 100nm.For the stainless steel plate of hard, although the size of Cu precipitate has deviation, there is Cu and separate out the larger feature of density.On the other hand, for soft stainless steel plate, it is less that Cu separates out density, and it is also less that it separates out size.Therefore, can think that Cu separates out is the major cause of hardening.In order to understand fully this point, with the stainless steel plate of hard for starting material, under the condition of present embodiment defined, carrying out thermal treatment again, thus the tissue before and after thermal treatment is compared.Consequently, can see following difference: even if same composition, soft material is compared with mechanically resistant material, and Cu separates out density and reduces, and Cu separates out size and also reduces.
In addition, in the control that the Cu for such softening separates out, importantly make Cu solid solution again, in process of cooling, do not make Cu separate out as far as possible.As the factor relevant with it, there are solid solubility temperature and speed of cooling, by manufacturing according to hot-rolled sheet annealing conditions described later and final annealing condition, just make softening be achieved.
The section hardness of the soft stainless steel plate of present embodiment, in Vickers' hardness scale, meets following (a) formula.In addition, (a) formula derives as in the following manner.The figure that to plot with Cu concentration and Vickers' hardness by the measurement result of various Vickers' hardnesses be axle.And the point of drawing is classified according to corrosion proof evaluation result.Consequently, as Vickers' hardness (also referred to as Hv hardness or Hv) below 190, and there is corrosion proof scope, (a) formula can be derived.When not meeting (a) formula, even if Hv is below 190 and soft, also there is deterioration in solidity to corrosion.Can infer that its reason is probably that Cu separates out superfluously.
Hv hardness≤40 × (Cu-0.3)+135 (a)
In addition, " Cu " in (a) formula represents Cu content (quality %).
Then, other chemical composition with regard to the ferrite series stainless steel plate of the 1st embodiment and the 2nd embodiment is described.The essential characteristic of present embodiment is the control of the concentration of element distribution on steel plate top layer as described above.Below record be the steel that can use when even considering the key element beyond solidity to corrosion, processibility and the germ resistancies such as manufacturing become to be grouped into, but when solving problem of the present invention as germ resistance stainless steel plate, its one-tenth is grouped into and is not limited to following composition.
C is the impurity element be inevitably mixed into from melting raw material etc., preferably less, not preset lower limit.If C amount is more than 0.050%, then makes the toughness of steel and cold-workability worsen, thus the upper limit can be set as less than 0.050%.C amount is preferably less than 0.040%, more preferably less than 0.020%.In addition, C is measured and excessively reduces and will bring the increase of manufacturing cost, thus preferred being measured by C is set as more than 0.001%.
Cr, in order to improve solidity to corrosion and high-temperature oxidation, needs interpolation more than 10.0%.On the other hand, if Cr amount is more than 30.0%, then plasticity is likely deteriorated, thus Cr amount can be set as the scope of 10.0 ~ 30.0%.Cr amount is preferably 12.0 ~ 27.0%, most preferably is 13.0 ~ 25.0%.
Si plays a role as deoxidant element, and high-temperature oxidation is improved.In order to obtain this effect, can containing the Si of more than 0.01%.But, if add Si in a large number, then steel plate hardening, thus often make degrade ductility.Therefore, Si content can be set as less than 2.00%.Si amount is preferably 0.01 ~ 1.50%, more preferably 0.10 ~ 1.20%.
P is the element be inevitably mixed into from raw material.P is grain boundary segregation element, if containing too many, then make cold-workability and the toughness deterioration of steel plate, thus P amount can be set as less than 0.030%.
S and P is same, is the element be inevitably mixed into from raw material.S is the element making solidity to corrosion and plasticity deterioration, thus S amount can be set as less than 0.010%.
Mn plays a role as reductor.In addition, Mn can also prevent the embrittlement of grain boundaries because S produces to the segregation of crystal boundary.In order to obtain these effects, can containing the Mn of more than 0.10%.But, if too much, then make the cold-workability of steel plate reduce.Therefore, Mn content can be set as less than 2.00%.Mn amount is preferably 0.10 ~ 1.80%, more preferably 0.12 ~ 1.50%.
About N, if its content increases, then make plasticity deterioration, thus can be set as less than 0.050%.N amount is preferably less than 0.040%, more preferably less than 0.030%.On the other hand, N is measured and excessively reduces and will bring the increase of manufacturing cost, thus preferred being measured by N is set as more than 0.001%.
Ni improves the hot workability of the ferrite series stainless steel plate of present embodiment.In order to obtain this effect, can containing the Ni of more than 0.1%.But if superfluously containing Ni, then ferritic stability reduces, thus Ni amount can be set as less than 2.0%.Ni amount is preferably less than 1.5%, more preferably less than 1.2%.
The ferrite series stainless steel plate of the 1st embodiment and the 2nd embodiment except above-mentioned component element, the impurity also comprising Fe and be inevitably mixed into.
Moreover, in the ferrite series stainless steel plate of the 1st embodiment and the 2nd embodiment, also can contain Ti, Nb optionally composition further.Ti, Nb owing to being carbonitride generting element, because of but improve the element of plasticity.Therefore, can as required containing any one among Ti and Nb or both.In order to the effect of the plasticity that improves, containing the Ti of more than 0.002%, the Nb of more than 0.002% can be contained.But the surplus of Ti, Nb is added the reduction of the deterioration and toughness causing processibility, thus when containing these elements, is preferably set to below Ti:0.50%, below Nb:1.00%.Be more preferably below Ti:0.45%, below Nb:0.95%, be preferably set to below Ti:0.40%, below Nb:0.90% further.
Moreover, in the ferrite series stainless steel plate of the 1st embodiment and the 2nd embodiment, also can contain a kind or element shown below of more than two kinds as required.
Sn is to the effective element of raising solidity to corrosion.In order to obtain this effect, can containing the Sn of more than 0.005%.But if more than 1.00%, then toughness deterioration, is thus set as less than 1.00% by Sn amount.Sn amount is preferably less than 0.60%, more preferably less than 0.50%.
Mo is to the effective element of raising solidity to corrosion.In order to obtain this effect, can containing the Mo of more than 0.002%.But if more than 1.00%, then toughness deterioration, is thus set as less than 1.00% by Mo amount.Mo amount is preferably less than 0.70%, more preferably less than 0.50%.
Al and Mo is same, presents and improves corrosion proof effect.In order to obtain this effect, can containing the Al of more than 0.002%.But, if contained to surplus more than 1.000%, then make manufacturing and processibility reduce.Al amount is preferably less than 0.300%, more preferably less than 0.100%.
Mg forms Mg oxide compound and plays a role as reductor in molten steel.In addition, Mg plays a role as the crystallization core of TiN, can fine generation ferritic phase when solidifying.By making solidified structure miniaturization, can prevent from resulting from the surface imperfection of the steel plate of thick solidified structure, and bringing the raising of processibility.Therefore, as required containing Mg.In order to obtain this effect, can containing the Mg of more than 0.001%.But, if contained to surplus more than 0.010%, then make manufacturing and processibility reduce.Mg amount is preferably less than 0.009%, more preferably less than 0.008%.
Co and Mo is same, presents and improves corrosion proof effect.In order to obtain this effect, can containing the Co of more than 0.002%.But, if contained to surplus more than 1.000%, then bring the rising of cost of alloy and the reduction of manufacturing.Co amount is preferably less than 0.400%, more preferably less than 0.200%.
V-arrangement becomes carbonitride, presents the effect improving steel strength.In order to obtain this effect, can containing the V of more than 0.002%.But, if contained to surplus more than 0.50%, then make manufacturing and processibility reduce.V amount is preferably less than 0.20%, more preferably less than 0.10%.
Zr and V is same, forms carbonitride, presents the effect improving steel strength.In order to obtain this effect, can containing the Zr of more than 0.003%.But, if contained to surplus more than 0.10%, then make manufacturing and processibility reduce.Zr amount is preferably less than 0.08%, more preferably less than 0.05%.
REM, La, B, Ca are the elements had an impact to the existing forms of S in steel, can contain as required when improving hot workability.In order to obtain this effect, more than REM:0.003%, more than La:0.002%, more than B:0.0002% and more than Ca:0.002% can be contained.The upper limit of these elements is below REM:0.100%, below La:0.100%, below B:0.0100%, below Ca:0.010%, the preferred upper limit is respectively below REM:0.080%, below La:0.095%, below B:0.0095%, below Ca:0.009%, and preferred scope is respectively below REM:0.050%, below La:0.050%, below B:0.0060%, below Ca:0.007% further.In addition, the said REM of so-called present embodiment, refers to that Sc, Y and ordination number are the element of 58 ~ 71.
The ferrite series stainless steel plate of present embodiment described above preferably can be applicable to the coin purposes requiring germ resistance.In addition, as long as the ferrite series stainless steel plate of the softening of present embodiment, the situation requiring softening in coin purposes further also can be adapted to.
Then, the manufacture method with regard to the ferrite-group stainless steel of present embodiment is described.
In order to manufacture the ferrite-group stainless steel of the 1st embodiment, for the stainless steel with mentioned component composition, carry out hot-rolled process, cold rolling process and final pickling process successively.Here, in final pickling process, carry out impregnated in the 2nd pickling process in the acid solution of the hydrofluoric acid aqueous solution of the 1st pickling process in the aqueous sulfuric acid of 5.0 ~ 35.0 quality % and the nitric acid that impregnated in containing 1.0 ~ 15.0 quality % and 0.5 ~ 5.0 quality %.Impregnated in the 1st pickling process in aqueous sulfuric acid and impregnated in and both can be undertaken by this order containing the 2nd pickling process in the acid solution of nitric acid and hydrofluoric acid aqueous solution, also can be undertaken by contrary order.
In addition, in order to manufacture the ferrite-group stainless steel of the 2nd embodiment, except the manufacturing condition of above-mentioned 1st embodiment, also in hot-rolled process, Heating temperature be 1150 ~ 1300 DEG C, final hot-rolled temperature carries out hot rolling under be 800 ~ 1000 DEG C and coiling temperature being the condition of less than 600 DEG C.
As the reason of the surface of stainless steel plate being carried out to cleanup acid treatment, be in order to remove the oxide skin film that adheres to because of thermal treatment and make Fe and Cr preferentially pickling dissolve and improve surperficial Cu concentration.As such acid, proposed various acid solution in the past.But, present inventor has performed experiment repeatedly, result is distinguished: the situation of the sulfuric acid washing operation (the 1st pickling process) of certain concentration and the nitre fluoric acid pickling process (the 2nd pickling process) of certain concentration that have passed through is compared with using the situation of other acid solution, and the promotion of the efficiency of oxide skin removing and Cu denseization on steel top layer is significantly improved.In addition, in the case, knownly also can obtain other surface property aforesaid, and show germ resistance.According to the manufacture method of the present embodiment based on this opinion, the excellent stainless steel of germ resistance can be obtained effectively.
The acid solution used in pickling needs to be set as following condition.That is, for aqueous sulfuric acid, need concentration to be set in the scope of 5.0 ~ 35.0 quality %.When the concentration of aqueous sulfuric acid is lower than 5.0 quality %, the oxide skin caused because of aqueous acid and the solubilizing reaction of steel carry out hardly, and thus Cu likely can not denseization on surface.On the other hand, if the concentration of aqueous sulfuric acid is more than 35.0 quality %, then the solubilizing reaction caused because of aqueous acid significantly carries out, thus produce because of dissolve cause significantly concavo-convex.The concavo-convex of this degree becomes the striated of product plate or the decorative pattern of plaque-like, thus makes product quality reduce.Therefore, the concentration of aqueous sulfuric acid is preferably 6.0 ~ 34.0 quality %, more preferably 8.0 ~ 33.0 quality %.
For nitre aqueous fluorine acid solution, need concentration of nitric acid to be set as 1.0 ~ 15.0 quality %, hydrofluoric acid concentration is set as 0.5 ~ 5.0 quality %.When concentration of nitric acid is lower than 1.0 quality %, identical with the situation of sulfuric acid, solubilizing reaction carries out hardly, and thus Cu can not denseization on surface.On the other hand, if concentration of nitric acid is more than 15.0 quality %, then solubilizing reaction significantly carries out, thus product quality is reduced.
In addition, for hydrofluoric acid, based on the reason identical with the situation of nitric acid with sulfuric acid, concentration, lower than 0.5 quality % with more than 5.0 quality %, is also not suitable for as concentration of aqueous solution.
Preferred concentration of nitric acid is 1.2 ~ 14.5 quality %, hydrofluoric acid concentration is 0.7 ~ 4.7 quality %, and further preferred concentration of nitric acid is 1.5 ~ 14.0 quality %, hydrofluoric acid concentration is 0.9 ~ 4.5 quality %.
In addition, although the time that be impregnated in by steel plate in these acid solutions will consider Cu peak concentration Cm in Cu denseization layer and other physical property, for aqueous sulfuric acid and nitre aqueous fluorine acid solution, the scope of each comfortable 10 ~ 1000 seconds appropriate selection can be carried out.In addition, for the temperature of each aqueous acid, as long as common condition is just no problem, be not particularly limited.Such as, can carry out the scope of 40 ~ 80 DEG C.
In addition, the feature of the manufacture method of present embodiment is: having found the final pickling by adopting aqueous sulfuric acid and nitre aqueous fluorine acid solution, the physical property on steel top layer can be strict controlled in above-mentioned scope.Therefore, the pickling reversed order of aqueous sulfuric acid and nitre aqueous fluorine acid solution such as also can be made to come.In addition, do not depart from present embodiment ferrite series stainless steel plate physical property scope limit in, beyond the sulfuric acid aqueous solution and nitre aqueous fluorine acid solution, even if carry out the 3rd cleanup acid treatment further, the 4th cleanup acid treatment also has no relations.
Then, be described with regard to hot-rolled process.
The present inventor is studied it, and result is known: by strictly controlling all conditions of hot-rolled process, top layer Cu just at hot rolling stage, denseization occurs.Therefore, known by implementing described final pickling to being in hot rolling the cold-reduced sheet making top layer this state of Cu concentration denseization, just make top layer Cu concentration increase further, thus germ resistance can be made more to improve.
Specifically, known by being 1150 ~ 1300 DEG C in Heating temperature, carrying out hot rolling under finishing temperature to be 800 ~ 1000 DEG C and coiling temperature the be condition of less than 600 DEG C, and then carry out final pickling under the conditions described above, Cu peak concentration Cm just can be made to rise to 18.0%.
In order to increase Cu peak concentration by the final pickling after hot-rolled process, improving the Cu concentration on top layer when importantly hot-rolled sheet manufactures and Cu is existed with solid solution condition.As long as Heating temperature is more than 1150 DEG C, just within the common hold-time, the Cu precipitate solid solution again remained in slightly in slab can be made.But, when more than 1300 DEG C, may surface imperfection etc. be caused because of coarse grains, also waste heat energy.
Then, the scope with regard to finishing temperature and coiling temperature is described.When adopting the manufacturing process of hot-rolled sheet in the past to manufacture the ferrite series stainless steel plate of present embodiment, the Cu contained in steel generates when cooling with the form of Cu precipitate.Therefore, the Cu amount of solid solution in steel reduces.On the other hand, finishing temperature when finding out by being manufactured by hot-rolled sheet is set as 800 ~ 1000 DEG C, and use the common equipment such as water spray, cooling hot-rolled plate faster, and batch below 600 DEG C, Cu precipitate just can not generate.The known hot-rolled stainless steel plate obtained like this adopts common pickling also can become the high cold-reduced sheet of Cu concentration, and then the known pickling by afore mentioned rules, by becoming top layer, there is the ferrite series stainless steel plate that Cu peak concentration Cm is the high density Cu unprecedented so far of more than 18.0%.
Its reason is also unclear, but according to the presumption of the present inventor, can think as follows.When the heating of plate blank of 1150 ~ 1300 DEG C, Fe and Cr of easily oxidation is by preferential oxidation compared with Cu.Therefore, due to immediately below oxide skin, do not have oxidized Cu left behind, thus surface C u concentration also raises.Moreover, final hot-rolled temperature is set as 800 ~ 1000 DEG C, and batches below 600 DEG C, pass through Cu precipitate temperature province in the short period of time thus, thus Cu precipitation is suppressed.Therefore, surface C u concentration can be manufactured high and there is no the hot-rolled stainless steel plate of Cu precipitate.
In addition, although as long as steel billet temperature is below 600 DEG C, the Cu velocity of diffusion in steel is just slack-off, the generation of Cu precipitate is suppressed, if but keep for a long time, then Cu precipitate is generated, thus preferably after final hot rolling, carry out water filling batch, and then water-cooled is carried out to coiled material.
In hot-rolled process, preferred condition is Heating temperature respectively: more than 1200 DEG C, finishing temperature: more than 800 DEG C, coiling temperature: less than 600 DEG C, most preferred condition is Heating temperature respectively: 1250 ~ 1300 DEG C, finishing temperature: 900 ~ 1000 DEG C, coiling temperature: less than 500 DEG C.
In addition, under the condition of the stainless steel plate with germ resistance of the above-mentioned present embodiment final annealing operation after cold rolling, by annealing in 900 ~ 1100 DEG C, be cooled to 400 DEG C with the average cooling rate of more than 3 DEG C/sec, just can below softening to the hardness of present embodiment defined.
Solid solubility temperature (final annealing temperature) is as long as more than the temperature that can make Cu solid solution, and the impact produced hardness is just few.So, in order to grasp the impact of solid solubility temperature on hardness, in the scope of 700 ~ 1100 DEG C, under all temps, carrying out solution treatment (final annealing), then carried out water-cooled.Consequently, under the solid solubility temperature more than 900 DEG C, hardness does not almost change, and it is lower than Hv10 on the impact of hardness.
In addition, by average cooling rate when cooling after solution treatment is set as more than 3 DEG C/sec, just becomes the Hv hardness meeting following (a) formula of present embodiment defined, thus its softening can be made.
Hv hardness≤40 × (Cu-0.3)+135 (a)
In order to grasp the impact of average cooling rate on hardness, carry out solution treatment at 900 ~ 1100 DEG C after, cool with various method of cooling.Result is known: by being cooled to cooling termination temperature described later with the average cooling rate of more than 3 DEG C/sec, just make its softening.The average cooling rate of more than 3 DEG C/sec can adopt the common equipment such as blowing gas to control.In addition, high speed of cooling, more has the tendency suppressing Cu to separate out, thus more effective to softening.Therefore, the not special restriction of the upper limit of average cooling rate, can consider the performance of used cooling apparatus etc. and in addition suitable decision.
In cooling after solution treatment, cooling termination temperature is set as less than 400 DEG C.
In order to grasp the impact of cooling termination temperature on hardness, after carrying out solution treatment at 900 ~ 1100 DEG C, controlling to all temps with the speed of cooling of average more than 3 DEG C/sec cooling, then carrying out naturally cooling (average cooling rate is lower than 3 DEG C/sec).Consequently, when being set as the cooling termination temperature of less than 400 DEG C, can softening to the Hv hardness meeting above-mentioned (a) formula of present embodiment defined.
On the other hand, cooling termination temperature, 500 ~ 700 DEG C time, has confirmed obvious hardening.In the test film of this hardening, observe the Cu precipitate of 10 ~ 100nm.Therefore, the temperature province of 500 ~ 700 DEG C is commonly considered as the nose temperature province (nosetemperature range) that Cu separates out, and quickly move through this Cu and separates out nose temperature province namely to strengthen speed of cooling to softening be effective.
As mentioned above, in the final annealing operation of present embodiment, preferred condition is Heating temperature (final annealing temperature): 910 ~ 1080 DEG C, cooling end temp: less than 390 DEG C, average cooling rate: more than 3.2 DEG C/sec, and most preferred condition is Heating temperature respectively: 920 ~ 1060 DEG C, cooling end temp: less than 380 DEG C, average cooling rate: more than 3.5 DEG C/sec.
In order to softening, the hot-rolled sheet annealing conditions further after regulation hot rolling, concerning suppression Cu separates out, is preferred mode.
By regulation hot-rolled sheet annealing conditions, the size of Cu precipitate is in the final annealing as rear operation, and just may be controlled to can the size of solid solution.In addition, hot-rolled sheet annealing is not with batch annealing but carries out in the mode of continuous annealing, is heated to 800 ~ 1100 DEG C, is then cooled to 400 DEG C with the average cooling rate of 1 DEG C/more than s.
When Heating temperature is lower than 800 DEG C, recrystallize is also insufficient, and on the other hand when more than 1100 DEG C, coarse grains, thus produces detrimentally affect to manufacturing after this.In addition, in order to suppress Cu to separate out, cooling termination temperature is set as 400 DEG C.When the average cooling rate for less than 1 DEG C/sec, Cu precipitate coarsening, in final annealing after this, can not make the solid solution fully of Cu precipitate.
In hot-rolled sheet annealing operation, preferred condition is Heating temperature respectively: 810 ~ 1090 DEG C, cooling temperature: less than 390 DEG C, average cooling rate: more than 1.1 DEG C/sec, and most preferred condition is Heating temperature respectively: 820 ~ 1080 DEG C, cooling temperature: less than 380 DEG C, average cooling rate: more than 1.2 DEG C/sec.
As indicated above, the ferrite series stainless steel plate excellent according to the germ resistance of the 1st embodiment and the 2nd embodiment and manufacture method thereof, can whole region in plate face and play good germ resistance, and the good germ resistance more than in the past can be obtained with good yield rate.In addition, according to ferrite series stainless steel plate and the manufacture method thereof of the 2nd embodiment, high denseization of the Cu peak concentration on steel surface can be made to unprecedented degree, better germ resistance can be obtained thus.In addition, in order to take into account germ resistance and softening, the Cu content of the ferrite-group stainless steel containing Cu is preferably 0.3 ~ 1.7%.
Embodiment
(embodiment 1)
Adopt vacuum melting to carry out melting to the steel of composition as shown in table 1A and table 1B, under the final hot-rolled temperature of the Heating temperatures of 1100 ~ 1350 DEG C and 700 ~ 1020 DEG C, carry out hot rolling, batch under the coiling temperature of 400 ~ 700 DEG C.Then, carry out keeping at 980 DEG C in an atmosphere the hot-rolled sheet in 10 seconds to anneal, then carry out common pickling.Then, implement cold rolling and implement final annealing, thus making the cold-reduced sheet that thickness of slab is 1.0 ~ 1.3mm.After this, in the sulfuric acid of 40 ~ 80 DEG C and nitre fluoric acid, carry out pickling, thus produce ferrite series stainless steel plate.In addition, in table 1A and table 1B, the hurdle being labeled as "-" represents and does not add this element, does not thus measure.
For the ferrite series stainless steel plate obtained, carry out following evaluation.In addition, in the present embodiment, in order to be confirmed whether to show good germ resistance in whole plate face, enlisting the services of the plate width that creates a difference in germ resistance and evaluating.That is, for the arbitrfary point of the length direction of each steel plate, cut out the square test film of many 50mm in the mode of enlisting the services of plate width.Then, these all test films are evaluated.
(mensuration of surface composition concentration)
For above-mentioned test film, glow discharge optical emission spectrometry (GDS) is adopted to measure from surperficial C, O, Fe, Cr, Si, Mn, Nb, Ti, Al, Cu concentration distribution to about 800nm of steel respectively.Cu, Fe, Cr concentration in Cu denseization layer just as shown in the example of fig. 1, changes at depth direction.Then, removing C and calculating concentration distribution again, then such the changing at depth direction of example as shown in Figure 2, distinguish defining Cu denseization layer at stainless steel surface.In addition, the Cu peak concentration of Cu denseization layer is set as Cm.Moreover, also obtain the Fe/Cr ratio obtained by the Fe concentration of the depth that can obtain Cu peak concentration Cm and the ratio of Cr concentration.
In addition, Fig. 2 is the example of steel of the present invention, and Cu peak concentration Cm is 75.0%.In addition, the Fe/Cr ratio calculated by the densitometer of Fe and Cr of the position that can obtain Cu peak concentration Cm is 2.9.
(evaluation of germ resistance)
The evaluation of germ resistance is carried out according to ISO 22196.For above-mentioned test film, be coated with the confession examination bacterium liquid of 1 milliliter respectively, at 25 DEG C, leave standstill 36 hours, then wiping bacterium liquid, and it is shaken out in diluent.The liquid that shakes out of specified amount is poured into (pour) in measurement substratum, carries out the cultivation of 24 hours at 35 DEG C, then antibacterial activity value is measured.By the steel with excellent antibacterial that the propagation that the steel of anti-microbial activity value more than 2.0 is evaluated as bacterium is suppressed, in the germ resistance evaluation in table, be expressed as " B " (Good: good).In addition, when anti-microbial activity value is more than 4.0, be evaluated as the steel with germ resistance excellent especially, in the germ resistance evaluation in table, be expressed as " A " (Excellent: excellent).When anti-microbial activity value lower than 2.0, be evaluated as the steel of germ resistance difference, in the germ resistance evaluation in table, be expressed as " C " (Bad: poor).
In addition, in table, for each steel, just recite its numerical value seriatim, but in the test film measured, recite the test film that germ resistance is minimum in germ resistance is evaluated, for the result of surface composition concentration, represent the measurement result of the test film that germ resistance is minimum.This is because in the test film of the plate width of each steel, as long as the anti-microbial activity value of the minimum test film of germ resistance is more than 2.0, just can say has germ resistance at the whole plate mask of these steel.
Evaluation result is as shown in table 2 ~ 14.Table 2 ~ 7 (test No.1 ~ 276) be use nitre fluoric acid as the first pickle solution, use sulfuric acid as the second pickle solution and carry out pickling with this order time evaluation result.In addition, table 8 ~ 14 (test No.277 ~ 551) be exchange pickling order and the first pickle solution is set as sulfuric acid, the second pickle solution is set as nitre fluoric acid and carries out pickling with this order time evaluation result.In addition, in table 2 ~ 14, the hurdle being labeled as "-" represents and does not carry out this process.
About the steel plate adopting the present invention of the method manufacture of present embodiment example namely to test No.1 ~ 180, No.277 ~ 456, anti-microbial activity value after its cultivation is more than 2.0, show stable germ resistance (germ resistance is evaluated as " B ", the drawing point for the white circle in Fig. 3).
Moreover, about test No.181 ~ 206 adopting the manufacture method meeting the hot-rolled condition specified by the method for present embodiment to manufacture, No.457 ~ 481, its maximum Cu concentration C m is more than 18%, show germ resistance (germ resistance is evaluated as " A ", the drawing point for the black circle in Fig. 3) excellent especially.
On the other hand, about the steel plate adopting the comparative example departing from the condition manufacture of the acid washing conditions specified by the method for present embodiment namely to test No.207 ~ 276, No.482 ~ 551, its anti-microbial activity value is lower than 2.0 (germ resistance is evaluated as " C ", the drawing point for the multiplying symbol ("×" symbol) in Fig. 3).Especially, about test No.207 ~ 221 and the steel plate testing No.497 ~ 511, as cleanup acid treatment, owing to only having carried out the process of nitre fluoric acid, thus maximum Cu concentration C m is lower than 10%, and compared with example of the present invention, germ resistance reduces.
(embodiment 2)
Then, in order to confirm the softening effect of present embodiment, when showing 1A, showing the manufacture of a part of steel grade of 1B, the condition of hot-rolled sheet annealing operation and final annealing operation is changed to the condition shown in table 15.
In addition, in example 2, implement under hot-rolled process, cold rolling process, the condition of final pickling process in the scope of present embodiment.
For each steel plate after manufacture, carry out resolving surface hardness and corrosion proof evaluation.In addition, section hardness adopts following method to measure.Select arbitrarily 5 positions at thickness of slab immediate vicinity, implement Vickers hardnes test at the position of this selection, its mean value is set as the measured value of section hardness.Solidity to corrosion, according to JIS Z2371, carries out the test of being sprayed continuously 72 hours by the 5%NaOH solution of 308K, observes its shape Condition that gets rusty.
Evaluation result is as shown in Table 15.
In the example not meeting the preferred final annealing condition of present embodiment, obtain the result that section Hv hardness more than 190 or meets (a) formula.
On the other hand, adopt the present invention of present embodiment preferred final annealing condition manufacture example namely test No.552,555,556,559,560,563,564,567,568,571,572,575,576,579,580, the Hv hardness of the steel plate of 583 below 190, and meets (a) formula.Consequently, compared with the example departing from the preferred manufacturing condition of present embodiment with other, the result that the obviously less thus solidity to corrosion of getting rusty obtaining point-like improves more.From this result: as long as the preferred manufacturing condition of present embodiment, just can produce and such as also can be applicable to as the coin steel plate of situation requiring softening and high anti-corrosion.
Table 1A (quality %)
Steel No. | Cu | C | Cr | Si | P | S | Mn | N | Ni | Ti | Nb | Other |
1 | 0.1 | 0.002 | 11 | 0.20 | 0.002 | 0.005 | 0.15 | 0.010 | - | - | 0.35 | |
2 | 0.1 | 0.01 | 13 | 0.70 | 0.020 | 0.005 | 0.15 | 0.010 | - | - | 0.35 | |
3 | 0.1 | 0.01 | 14 | 0.20 | 0.020 | 0.005 | 0.15 | 0.010 | 0.2 | - | - | |
4 | 0.1 | 0.006 | 15 | 0.30 | 0.015 | 0.001 | 1.40 | 0.010 | - | 0.50 | - | |
5 | 0.1 | 0.005 | 15.5 | 0.20 | 0.030 | 0.010 | 1.45 | 0.010 | - | 0.13 | 0.30 | |
6 | 0.1 | 0.01 | 16 | 0.20 | 0.020 | 0.005 | 1.50 | 0.010 | 0.2 | - | - | |
7 | 0.1 | 0.008 | 16.5 | 0.20 | 0.030 | 0.005 | 0.15 | 0.040 | - | 0.10 | 0.32 | Sn:0.02 |
8 | 0.1 | 0.001 | 17 | 0.20 | 0.020 | 0.005 | 0.15 | 0.001 | - | 0.20 | 0.35 | Al:0.050 |
9 | 0.1 | 0.01 | 17.5 | 0.20 | 0.020 | 0.005 | 0.15 | 0.010 | - | 0.30 | 0.28 | Co:0.20 |
10 | 0.1 | 0.011 | 23 | 0.1 | 0.03 | 0.010 | 0.15 | 0.010 | - | 0.40 | - | Mg:0.007 |
A | 0.3 | 0.005 | 12.0 | 0.01 | 0.010 | 0.001 | 0.10 | 0.010 | 0.2 | - | 0.30 | |
B | 0.3 | 0.002 | 13.8 | 0.10 | 0.005 | 0.010 | 1.00 | 0.050 | - | - | 1.00 | |
C | 0.3 | 0.010 | 15.8 | 0.30 | 0.002 | 0.005 | 0.40 | 0.001 | - | 0.50 | - | |
D | 0.3 | 0.006 | 17.4 | 0.20 | 0.020 | 0.005 | 0.15 | 0.010 | - | 0.10 | 0.35 | |
E | 0.3 | 0.006 | 16.5 | 0.20 | 0.020 | 0.005 | 0.15 | 0.010 | - | - | 0.35 | |
F | 0.3 | 0.006 | 16.6 | 0.20 | 0.020 | 0.005 | 0.15 | 0.010 | 0.2 | 0.10 | - | |
G | 0.3 | 0.010 | 20.4 | 0.70 | 0.022 | 0.010 | 1.40 | 0.040 | - | 0.20 | - | |
H | 0.3 | 0.010 | 21.5 | 0.20 | 0.020 | 0.006 | 1.45 | 0.040 | - | 0.28 | 0.30 | |
I | 0.3 | 0.050 | 24.6 | 0.30 | 0.002 | 0.010 | 1.50 | 0.040 | - | 0.50 | - | |
J | 0.3 | 0.006 | 17.4 | 0.20 | 0.020 | 0.005 | 0.15 | 0.010 | - | - | 0.32 | Sn:0.30 |
K | 0.3 | 0.006 | 16.5 | 0.20 | 0.020 | 0.005 | 0.15 | 0.010 | - | 0.10 | 0.35 | Mo:0.12 |
L | 0.3 | 0.006 | 17.4 | 0.20 | 0.015 | 0.005 | 0.15 | 0.010 | 0.2 | - | 0.28 | REM:0.022 |
M | 0.3 | 0.006 | 16.5 | 0.20 | 0.030 | 0.005 | 0.15 | 0.010 | - | 0.20 | - | B:0.0010 |
N | 0.3 | 0.006 | 16.6 | 0.20 | 0.020 | 0.005 | 0.15 | 0.010 | - | - | - | |
0 | 1.2 | 0.005 | 12.0 | 0.01 | 0.030 | 0.001 | 0.10 | 0.010 | - | - | 0.36 | |
P | 1.2 | 0.002 | 13.8 | 0.10 | 0.020 | 0.010 | 1.00 | 0.040 | - | - | 1.00 | |
Q | 1.2 | 0.010 | 14.6 | 0.30 | 0.020 | 0.005 | 0.40 | 0.001 | - | 0.50 | - | |
R | 1.2 | 0.006 | 17.4 | 0.20 | 0.020 | 0.005 | 0.15 | 0.010 | - | 0.13 | 0.35 | |
S | 1.2 | 0.006 | 16.5 | 0.20 | 0.020 | 0.005 | 0.15 | 0.010 | 0.2 | - | 0.35 | |
T | 1.2 | 0.006 | 16.6 | 0.20 | 0.020 | 0.005 | 0.15 | 0.010 | - | 0.10 | - | |
U | 1.2 | 0.010 | 20.4 | 0.70 | 0.010 | 0.010 | 0.90 | 0.040 | - | 0.20 | - | |
V | 1.2 | 0.010 | 21.5 | 0.20 | 0.010 | 0.006 | 1.40 | 0.030 | - | 0.30 | 0.70 | |
W | 1.2 | 0.010 | 24.4 | 2.00 | 0.010 | 0.002 | 1.45 | 0.001 | - | 0.40 | 1.00 | |
X | 1.2 | 0.050 | 24.5 | 0.30 | 0.005 | 0.010 | 1.50 | 0.040 | - | 0.50 | - | |
Y | 1.2 | 0.006 | 16.1 | 0.20 | 0.020 | 0.005 | 0.15 | 0.010 | 0.2 | - | 0.32 | Sn:0.07 |
Z | 1.2 | 0.006 | 17.4 | 0.20 | 0.020 | 0.005 | 0.15 | 0.010 | - | 0.10 | 0.35 | La:0.050 |
AA | 1.2 | 0.006 | 16.5 | 0.20 | 0.020 | 0.005 | 0.15 | 0.010 | - | - | 0.28 | V:0.10 |
AB | 1.2 | 0.006 | 17.6 | 0.20 | 0.020 | 0.005 | 0.15 | 0.010 | - | 0.20 | - | Mo:0.50 |
AC | 1.2 | 0.006 | 16.4 | 0.20 | 0.020 | 0.005 | 0.15 | 0.010 | 0.2 | - | - | |
AD | 1.5 | 0.005 | 12.0 | 0.01 | 0.005 | 0.001 | 0.10 | 0.010 | - | - | 0.36 |
Table 2
Table 3
Table 4
Table 5
Table 6
Table 7
Table 8
Table 9
Table 10
Table 11
Table 12
Table 13
Table 14
Table 15
Table 16
Utilizability in industry
The ferrite series stainless steel plate of present embodiment can whole region in plate face and play good germ resistance.In addition, softening and excellent germ resistance can be taken into account.Therefore, the ferrite series stainless steel plate of present embodiment is preferably used as the starting material of health equipment and the buildings building materials etc. such as railing, the first-class axle journal of the fire hose, metal coin, metal vessel, metalic tableware, bathtub, domestic electric appliances, toilet seat, medicine equipment, steam heating.
Claims (11)
1. the ferrite series stainless steel plate that germ resistance is excellent, is characterized in that:
In mass %, containing the Cu of 0.1% ~ 5.0%,
Have Cu denseization layer on the surface of stainless steel plate, the Cu peak concentration Cm of described Cu denseization layer is more than 10.0 quality %, and the Fe/Cr ratio demonstrating the depth location place apart from surface of steel plate of described Cu peak concentration Cm is more than 2.4.
2. the ferrite series stainless steel plate that germ resistance is excellent, is characterized in that:
In mass %, containing the Cu of 0.1% ~ 5.0%,
Have Cu denseization layer on the surface of stainless steel plate, the Cu peak concentration Cm of described Cu denseization layer is more than 18.0 quality %.
3. the ferrite series stainless steel plate that germ resistance according to claim 1 and 2 is excellent, wherein, the content of described Cu is 0.3 ~ 1.7% in mass %, and the section hardness of steel plate meets following (a) formula in Vickers' hardness scale;
Hv hardness≤40 × (Cu-0.3)+135 (a).
4. the ferrite series stainless steel plate that the germ resistance according to any one of claims 1 to 3 is excellent, wherein, described ferrite series stainless steel plate in mass %, further containing below C:0.050%, Cr:10.0 ~ 30.0%, below Si:2.00%, below P:0.030%, below S:0.010%, below Mn:2.00%, below N:0.050% and below Ni:2.0%, remainder comprises Fe and inevitable impurity.
5. the ferrite series stainless steel plate that germ resistance according to claim 4 is excellent, wherein, described ferrite series stainless steel plate in mass %, further containing any one among below Ti:0.50% and below Nb:1.00% or both.
6. the ferrite series stainless steel plate that the germ resistance according to claim 4 or 5 is excellent, wherein, described ferrite series stainless steel plate in mass %, further containing more than a kind that is selected among below Sn:1.00%, below Mo:1.00%, below Al:1.000%, below Mg:0.010%, below Co:1.000%, below V:0.50%, below Zr:0.10%, below REM:0.100%, below La:0.100%, below B:0.0100% and below Ca:0.010%.
7. the ferrite series stainless steel plate that the germ resistance according to any one of claim 1 ~ 6 is excellent, wherein, described ferrite series stainless steel plate is used for metal coin.
8. a manufacture method for the ferrite series stainless steel plate that germ resistance is excellent, is characterized in that:
Described manufacture method has hot-rolled process, cold rolling process and final pickling process,
The one-tenth that stainless steel plate has according to any one of claim 1 ~ 6 is grouped into,
Described final pickling process has the 2nd pickling process in the acid solution of the hydrofluoric acid aqueous solution of the 1st pickling process in the aqueous sulfuric acid that impregnated in 5.0 ~ 35.0 quality % and the nitric acid that impregnated in containing 1.0 ~ 15.0 quality % and 0.5 ~ 5.0 quality %.
9. the manufacture method of the ferrite series stainless steel plate that germ resistance according to claim 8 is excellent, wherein, described hot-rolled process Heating temperature be 1150 ~ 1300 DEG C, finishing temperature carries out under be 800 ~ 1000 DEG C and coiling temperature being the condition of less than 600 DEG C.
10. the manufacture method of the ferrite series stainless steel plate that germ resistance is according to claim 8 or claim 9 excellent, wherein,
Described manufacture method has hot-rolled sheet annealing operation and final annealing operation further,
The one-tenth that described stainless steel plate has according to any one of claim 3 ~ 6 is grouped into,
Described final annealing operation has carries out the operation of annealing with the annealing temperature of 900 ~ 1100 DEG C and is cooled to the operation of 400 DEG C with the average cooling rate of more than 3 DEG C/sec.
The manufacture method of the ferrite series stainless steel plate that 11. germ resistancies according to claim 10 are excellent, wherein, described hot-rolled sheet annealing operation is carried out in the mode of continuous annealing, and described continuous annealing has to be carried out the operation of annealing with the annealing temperature of 800 ~ 1100 DEG C and be then cooled to the operation of 400 DEG C with the average cooling rate of more than 1 DEG C/sec.
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JP2013148950A JP6240423B2 (en) | 2012-12-26 | 2013-07-17 | Ferritic stainless steel sheet with excellent antibacterial properties and method for producing the same |
PCT/JP2013/083205 WO2014103722A1 (en) | 2012-12-26 | 2013-12-11 | Ferritic stainless steel sheet having excellent anti-bacterial activity, and method for producing same |
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CN114364822A (en) * | 2020-01-21 | 2022-04-15 | 日铁不锈钢株式会社 | Stainless steel material having antibacterial and antiviral properties and method for producing same |
CN114364822B (en) * | 2020-01-21 | 2023-02-28 | 日铁不锈钢株式会社 | Stainless steel material with antibacterial and antiviral properties and manufacturing method thereof |
CN114867879A (en) * | 2020-04-15 | 2022-08-05 | 日铁不锈钢株式会社 | Ferritic stainless steel material and method for producing same |
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JP2014141735A (en) | 2014-08-07 |
KR101762046B1 (en) | 2017-07-26 |
WO2014103722A1 (en) | 2014-07-03 |
KR20150083457A (en) | 2015-07-17 |
JP6240423B2 (en) | 2017-11-29 |
TW201428111A (en) | 2014-07-16 |
IN2015DN03729A (en) | 2015-09-18 |
TWI503421B (en) | 2015-10-11 |
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