CN101381842B - High chromium content ferrite stainless steel and manufacturing method thereof - Google Patents
High chromium content ferrite stainless steel and manufacturing method thereof Download PDFInfo
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Abstract
The invention discloses high chromium ferritic stainless steel and a manufacturing method thereof. The high chromium ferritic stainless steel is characterized in that the high chromium ferritic stainless steel comprises chemical elements according to the following weight percentage: less than or equal to 0.015 percent of C, less than or equal to 0.020 percent of N, less than or equal to 1.0 percent of Si, less than or equal to 1.0 percent of Mn, less than or equal to 0.035 percent of P, less than or equal to 0.010 percent of S, 20 to 25 percent of Cr, 0.30 to 0.50 percent of Cu, less than or equal to 0. 5 percent of Ti and Nb, and the balance being Fe, wherein (Ti/48+Nb/93)/(C/12+N/14) is more than 1.5. The manufacturing method comprises the: 1) a step of continuous casting or die casting, in which raw materials are primarily rolled into steel billets after the die casting; 2) a step of rolling, in which the final rolling temperature of steel plates is between 800 and 950 DEG C, and the gradual cooling is performed after the rolling; 3) a step of continuous annealing, in which the temperature is between 850 and 950 DEG C; 4) a step of the removal of oxide coating; 5) a step of cold rolling; and 6) a step of continuous annealing after the recrystallization. The ferritic stainless steel has the advantages of stronger corrosion resistance, higher plasticity and good deep drawability.
Description
Technical field
The present invention relates to a kind of stainless steel, particularly a kind of ferritic stainless steel.
Background technology
Along with rising violently of metal Ni price, the price of austenitic stainless steel is also constantly soaring thereupon, and the low and ferritic stainless steel that have good solidity to corrosion and a cold formability of cost of development becomes the important topic of present enterprises of producing stainless steel.Ferritic stainless steel does not contain Ni or only contains small amount of N i, cheap, except that having rustless property and anti-general corrosion performance, local corrosion excellent propertys such as the anti-spot corrosion of its burn into of anti-chloride stress cracking the, slit and corrosion resistant, the fields such as electrician's industry, automotive industry, building construction, petrochemical industry and environmental protection of being in have a wide range of applications and vast potential for future development.Traditional ferritic stainless steel enbrittles that transition temperature height, notch sensitivity are big, the postwelding solidity to corrosion descends, easily produce shortcoming such as gauffer in the cold working process, has limited its further broadened application.Adopt modern advanced stainless steel smelting technology, typical impurity element C, N content are reduced significantly, low C, the N that is produced (C+N≤0.04%) ferritic stainless steel is compared with traditional ferritic stainless steel, some weak point on the performance has obtained overcoming significantly and quite satisfactory solution, has shown excellent corrosion resistance, formability and weldability etc.It is outside the pale of civilization to remove ultralow (C+N), also can adopt Ti and Nb to carry out stabilization, and adds different Cr according to the corrosive environment that uses, and adds the solidity to corrosion that Mo and Cu improve ferritic stainless steel simultaneously on demand.But, add Mo and will significantly increase the manufacturing cost of steel.
The available substantially Lankford index of the formability of steel r value represents that the r value is high more, represents that then formability is good more.The method and the IF steel that improve ferritic stainless steel r value are similar.Flourishing in order in end article, to obtain 111}＜112〉orientation, should reduce C, the N content of solid solution in the steel before cold rolling; When adopting refining techniques to reduce C, N content as far as possible, add Nb, Ti and carry out stabilization treatment, and in ingot casting or continuous casting steel billet, obtain higher proportion of equiaxed grain.
In the patent that table 1 is listed, the patent that has has adopted Nb, Ti stabilizing element, or single stableization or bistableization, have in addition add valuable Alloy Elements Mo.Patent US 5512239 and JP 03-002330 remove employing Nb, the Ti bistable is outside the pale of civilization, have also added Mo; Patent US 4374683 has added 0.12%Cu, and adopts the Nb single stableization; Patent JP10017999 has adopted Nb, Ti bistableization; But do not add Cu; 1986051012 of patent JP adopt the Nb single stableization, and have added Cu.
Chemical ingredients comparison/the wt% of the relevant high corrosion resistance ferritic stainless steel patent of table 1
| Patent name | C | N | Si | Mn | Cr | Ni | Cu | Mo | Ti | Nb |
| ?US?5512239 | ≤0.025 | ≤0.025 | ≤0.10 | ≤1.0 | 17.0-25.0 | ≤0.5 | - | 0.50-2.00 | 10(C+N)-1.0， Al≤0.025 | 10(C+N)-1.0 |
| ?US?4374683 | Unknown | Unknown | Unknown | Unknown | 12.0-25.0 | Unknown | 0.12 | Unknown | - | 0.2-2.0 |
| ?JP?03-002330 | C+N＜0.1 0- | - | Unknown | Unknown | 17-35 | 0.10-4.5 | 0.10-4.5 | 0.05-1.0 | 0.05-1.0 | |
| ?JP?10017999 | ≤0.02 | ≤0.02 | ≤2.0 | ≤0.8 | 10-25 | ≤1.0 | - | - | (Ti/48+Nb/93)/( C/12+N/14)＞1.5 (Ti+Nb)＜0.5％ | |
| ?JP?1986051012 | ?≤0.02 | ≤1.0 | ≤1.0 | 12-25 | - | 0.1-2.0 | - | - | 0.2-2.0 |
Summary of the invention
The objective of the invention is by a kind of high chromium content ferrite stainless steel and manufacture method thereof are provided, improve continous casting sprue dross situation and surface quality of continuously cast slab, reduce continuously cast bloom reconditioning intensity, improve recovery rate of iron, alleviate combustion intensity and smelting cost, make the ferritic stainless steel of producing have stronger corrosion resistance nature, higher plasticity and good deep drawing performance.
Technical scheme of the present invention is: a kind of high chromium content ferrite stainless steel, the chemical element that comprises following weight percent proportioning: C≤0.015, N≤0.020, Si≤1.0, Mn≤1.0, P≤0.035, S≤0.010, Cr:20～25, Cu:0.30～0.50, Ti+Nb≤0.5, and satisfy (Ti/48+Nb/93)/(C/12+N/14)＞1.5, residual element are Fe.
The effect of Cr: Cr is a most important alloying element in the stainless steel, along with the increase of Cr content, stainless steel in the oxidizing acid medium solidity to corrosion, anticorrosion stress-resistant, spot corrosion, crevice corrosion ability are significantly increased in Cl-solution.By guarantee the corrosion resistance nature of exploitation ferritic stainless steel suitable with austenitic stainless steel SUS304, Cr content will be higher than the Cr content among the SUS304 at least in the steel.In addition, in high Cr ferritic stainless steel (Cr＞25%), easily form intermetallic compounds such as α ', σ, χ, not only reduce the erosion resistance of steel, and reduce toughness, plasticity, cold formability and the weldability of steel, so Cr content is unsuitable too high.The Cr content of ferritic stainless steel is limited between 20～25% among the present invention.
The effect of Cu: Cu can improve stainless plasticity and erosion resistance, significantly improves the cold forming capability of ferritic stainless steel.Too much Cu separates out with ε-Cu when annealing easily, causes the decline of cold-forming property and corrosion resistance nature.Therefore, Cu content is limited between 0.3～0.5%.
The effect of Nb, Ti: Nb, Ti and C, N have very strong chemosynthesis, by forming stable (TiNb) (CN) compound, prevent that the Cr concentration that causes owing to the C compound that forms Cr from reducing the corrosion proof decline that causes.Usually, fixedly in the steel C, the required minimized content of N atom should satisfy: (Ti/48+Nb/93)/(C/12+N/14)＞1.5.Nb and Ti act on difference to some extent as the stabilizing element in the steel.The effect of Ti stabilization is by separate out the TiN second phase particle in continuous casting billet solidification processing, owing to fixed the N in the steel, to reduce Cr on the one hand
2N separates out tendency, thereby has improved plasticity, toughness and the corrosion resistance nature of steel, and TiN has increased the ratio of equiax crystal in the continuously cast bloom as the forming core particle on the other hand, thereby improves formability, remaining Ti or with the TiC particle exist or solid solution in steel.The avidity of Nb, Ti and N is greater than Nb, and the avidity of Nb and C is greater than Ti, formed TiN and NbCN to separate out temperature different, TiN separates out in molten steel and can be used as heterogeneous forming core core and promote grain refining, improve proportion of equiaxed grain, thereby improves the processability of the finished product.Grain growth when TiN stops welding, thus mechanical property improved; Surpass the further free N in the fixation weld of the outer remaining Ti of stoicheiometry, thereby improve the intergranular corrosion resistance performance and the mechanical property of weld seam.Nb is the C in the steel fixedly, has avoided M
23C
6Separating out on crystal boundary, thus significantly improve the intergranular corrosion resistance performance; Surpass the content that the outer remaining Nb of stoicheiometry can improve Cr in Passive Film, improve the corrosion resistance nature of steel to a certain extent.Add toughness and processing characteristics that too much Nb and Ti can reduce mother metal and welding joint in the ferritic stainless steel, thereby regulation Nb+Ti≤0.5%.After the present invention adopts Nb, Ti bistableization, C+N only need be controlled at less than 0.035%, can guarantee that corrosion resistance nature reaches the level suitable with austenitic stainless steel SUS304, and need not C+N is reduced to less than 0.015%, thereby alleviate combustion intensity and smelting cost.
The effect of C: C is harmful element in ferritic stainless steel.Because Cr content is very high in the alloy, and the solubleness of C thereby is separated out M easily than much lower in the austenite in the ferrite on crystal boundary
23C
6As separating out being higher than more than 800 ℃, how to form at crystal boundary with particulate state, little to the fragility influence: as 600～700 ℃ the time, then manyly on crystal boundary, to separate out, alloy is become fragile with netted.M
23C
6Very fast with netted speed of separating out on crystal boundary, alloy is become fragile, and cause serious grain boundary corrosion because of the poor Cr of crystal boundary.Therefore, for improving the intergranular corrosion resistance performance and the toughness of ferritic stainless steel, must reduce C content or adopt strong C, N compound formation element to be fixed by smelting.
The effect of N: N is as interstitial element, and the solubleness in ferrite is also very low, when alloy Cr content is higher, generates Cr easily
2Therefore N and reduce the corrosion resistance nature and the toughness of ferritic stainless steel, must remove by smelting as far as possible.
The effect of Si: Si can be used as reductor, reductive agent in stainless steel, can improve stainless high-temperature oxidation resistance effectively, but too much Si can cause the plasticity of steel to descend.Regulation Si≤1.0%.
The effect of Mn: Mn is for enlarging the austenitic area element, and excessive Mn can cause duplex structure and make poor processability in ferritic stainless steel.Regulation Mn≤1.0%.
The effect of P, S: P, S are impurity element in steel, reduce the high-temp plastic of steel, in the ferritic stainless steel hot procedure, easily and other factors one work and defective such as cause that the limit is split.In addition, S also can reduce the pitting resistance of ferritic stainless steel.Therefore, should reduce its content as far as possible.
A kind of manufacture method of high chromium content ferrite stainless steel comprises following steps:
(1) according to following chemical element weight percent proportioning smelting molten steel: C≤0.015, N≤0.020, Si≤1.0, Mn≤1.0, P≤0.035, S≤0.010, Cr:20～25, Cu:0.30～0.50, Ti+Nb≤0.5, and satisfy (Ti/48+Nb/93)/(C/12+N/14)＞1.5, residual element are Fe.
(2) continuous casting of molten steel or the die casting after will smelting just rolls into steel billet after the die casting; In the casting process, carry out induction stirring,, cooperate TiN again, the zone of equiaxial crystals ratio is increased to more than 50%, to improve formability as heterogeneous forming core particle by induction stirring at solidification end.For making the finished product obtain the tissue of abundant recrystallize, the microstructure under the necessary refinement as cast condition utilizes TiN can promote the generation of heterogeneous core, blocks the development of column crystal, thereby can reach the purpose of solidified structure miniaturization.
(3) rolling: continuously cast bloom or steel billet are heated to 1050～1100 ℃, are rolled after the insulation, and 800～950 ℃ of steel plate finishing temperatures are rolled the back segmentation and are cooled to 550～750 ℃ of coiling temperatures; Continuously cast bloom or steel billet heat under 1050～1100 ℃ temperature, the single-phase ferritic structure of can obtain uniformly, no obvious alligatoring being grown up.When Heating temperature surpasses the grain coarsening temperature, the NbCN grade in an imperial examination two-phase in the steel will be dissolved, and the disappearance of crystal boundary pinning effect causes crystal grain significantly to be grown up.Do not change owing to do not exist in the hot procedure mutually subsequently, thick tissue can not obtain effective refinement, will influence the final performance of steel.Therefore, Heating temperature must not surpass the grain coarsening temperature.
Steel billet is de-scaling before roughing, in hot rolling, cooling, coiling process, should avoid Ti and Nb to separate out with the form of C, N compound, and accomplish this point, must control Heating temperature and be lower than 1100 ℃, TiCN, NbCN dissolve when avoiding heating, and promptly the operation of rolling should not exist in steel under the situation of interstitial atom and carries out, to obtain favourable recrystallization texture.Reduce finishing temperature and coiling temperature help obtaining abundant recrystallize in pickling annealing subsequently and contain lower 100}＜011〉ferrite crystal grain of texture component, thereby improve formability.
(4) continuous annealing: 850～950 ℃ of temperature, soaking time 1～1.5min/mm; Steel plate is annealed on the continuous annealing unit, and intensification is identical with other ferritic stainless steels with temperature lowering curve.The separating out of disperse second phase of suppressing recrystallize in the time of should avoiding hot-roll annealing, and this can grow up, control Heating temperature by C, Nization thing and the polymerization of separating out Ti, Nb in the strand process of cooling and makes it not produce to dissolve and realize.
(5) scale removal.
(6) cold rolling: cold roling reduction 60%～75%.
(7) recrystallize continuous annealing: 800～950 ℃ of temperature, soaking time 1～1.5min/mm; During continuous annealing, the annealing temperature of employing is 900～950 ℃, soaking time 1～1.5min/mm.Higher annealing temperature can improve the plasticity and the plastic strain ratio r value of steel.
(8) smooth, smooth can on straightening machine or levelling machine, carrying out, it can not only eliminate the yield phenomenon of steel plate, also can improve the surface quality of steel plate.
Preferably, in the described step (3), steel plate heating back soaking time is 170～220min.
Preferably, in the described step (3), the finishing temperature of steel plate is 850 ℃.
Preferably, in the described step (3), roll the speed of cooling 〉=15 ℃/s of back steel plate.
Preferably, in the described step (5), adopt the method scale removal of pickling or sandblast.During with the acid washing method scale removal, adopt dilute hydrochloric acid, dilute sulphuric acid to carry out pickling, can remove the iron scale of surface of steel plate, guarantee plate surface quality.
Preferably, in the described step (6), cold roling reduction is 75%.
The present invention compared with prior art has following beneficial effect:
1. by Nb and Ti bistable replacement Ti single stableization, significantly improve continous casting sprue dross situation and surface quality of continuously cast slab, reduced continuously cast bloom reconditioning intensity, improved recovery rate of iron; Combustion intensity and smelting cost have also been alleviated simultaneously.
2. control Nb, Ti second approach such as the quantity of particle and size mutually by control hot rolling technology and cold rolled annealed technology, make high chromium content ferrite stainless steel have excellent corrosion resisting performance and cold-forming property concurrently.
3. by improving the Cr content in the ferritic stainless steel, improved the corrosion resistance nature of steel.
4. aspect mechanical property and formability, owing to adopted low-temperature heat, low temperature rolling, low temperature to batch and rational cold rolled annealed system, steel of the present invention has the r value (greater than 1.45) more much higher than Japanese Patent JP10017999, (adopt higher coiling temperature in the JP10017999 patent, the r value only is about 1.0).
5. do not contain valuable alloying elements such as Ni, Mo in the steel of the present invention, have excellent corrosion resisting performance, have good plasticity and formability simultaneously, be applicable to industries such as household electrical appliances, goods, building, the market competitiveness is strong, has bright development prospect.
Description of drawings
Fig. 1 is the metallographic structure after 900 ℃ of annealing of embodiment of the invention B steel.
Fig. 2 is the metallographic structure after 950 ℃ of annealing of embodiment of the invention B steel.
Fig. 3 is Comparative Examples #3 steel of the present invention metallographic structure after 900 ℃ of annealing.
Fig. 4 is Comparative Examples #3 steel of the present invention metallographic structure after 950 ℃ of annealing.
Fig. 5 is bar-shaped TiC precipitated phase electromicroscopic photograph after the Comparative Examples D steel recrystallize of the present invention continuous annealing.
Fig. 6 is spherical TiC precipitated phase electromicroscopic photograph after the Comparative Examples D steel recrystallize of the present invention continuous annealing.
Fig. 7 is (Nb after the embodiment A continuous annealing
0.83Ti
0.17) (N
0.77C
0.05) electromicroscopic photograph of precipitated phase.
Fig. 8 is (Nb after the Embodiment B continuous annealing
0.83Ti
0.17) (N
0.77C
0.05) electromicroscopic photograph of precipitated phase.
Fig. 9 is (Nb after the embodiment A continuous annealing
0.83Ti
0.17) (N
0.77C
0.05) the selected diffraction collection of illustrative plates of precipitated phase.
Figure 10 is the polarization curve of embodiment and Comparative Examples.
Figure 11 contrasts synoptic diagram for embodiment steel E and compared steel SUS304 cyclic corrosion result.
Embodiment
The chemical ingredients (wt/%) of comparative example #3, C, D steel and embodiment A, B, E, F, G sees Table 2.Wherein #3 and C, D steel have adopted the Ti single stableization as a comparative example, and embodiment A, B, E, F and G steel adopt Nb, Ti bistableization.
The chemical ingredients of table 2 Comparative Examples and embodiment (wt/%)
| Grade of steel | ?C | ?Si | ?Mn | ?P | ?S | ?Cr | ?Cu | Nb | ?Ti | N |
| #3 | ?0.0034 | ?0.10 | ?0.22 | ?0.008 | ?0.007 | ?20.82 | ?0.36 | -- | ?0.30 | 0.0089 |
| C | ?0.0067 | ?0.19 | ?0.19 | ?0.007 | ?0.006 | ?20.32 | ?0.37 | -- | ?0.19 | 0.012 |
| D | ?0.0072 | ?0.20 | ?0.19 | ?0.007 | ?0.006 | ?20.73 | ?0.38 | -- | ?0.29 | 0.014 |
| A | ?0.0076 | ?0.21 | ?0.21 | ?0.008 | ?0.006 | ?20.52 | ?0.36 | ?0.10 | ?0.19 | 0.016 |
| B | ?0.0066 | ?0.21 | ?0.21 | ?0.008 | ?0.005 | ?20.94 | ?0.38 | ?0.22 | ?0.10 | 0.018 |
| E | ?0.0107 | ?0.32 | ?0.21 | ?0.018 | ?0.001 | ?21.27 | ?0.39 | ?0.21 | ?0.107 | 0.0096 |
| F | ?0.010 | ?0.17 | ?0.20 | ?0.015 | ?0.001 | ?21.13 | ?0.40 | ?0.286 | ?0.10 | 0.009 |
| G | ?0.01 | ?0.14 | ?0.22 | ?0.018 | ?0.003 | ?20.74 | ?0.34 | ?0.19 | ?0.115 | 0.013 |
Embodiment A, B, E, F, G and comparative example #3, C, the different start rolling temperatures of D, finishing temperature, coiling temperature, hot-roll annealing temperature and cold rolled annealed temperature etc. are as shown in table 3 to the influence of invention steel mechanical property.As can be seen from Table 3, reduction finishing temperature, coiling temperature, raising annealing temperature can reduce the yield strength and the tensile strength of steel, improve unit elongation and r value; When adopting higher annealing temperature, can obtain very high unit elongation and r value as more than 900 ℃ during temperature.
Table 3
| Grade of steel | Start rolling temperature | Finishing temperature | Coiling temperature | The hot-roll annealing temperature | The cold rolled continuous annealing temperature | R p0.2 MPa | ?R m?MPa | ?A 50?％ | The n value | The r value |
| A | 1050 | 890 | ?650 | 850 | 900 | 300 | ?440 | ?20.0 | ?0.210 | 1.30 |
| 1050 | 870 | ?650 | 850 | 900 | 300 | ?440 | ?27.5 | ?0.215 | 1.45 | |
| 1050 | 800 | ?650 | 850 | 900 | 270 | ?440 | ?31.0 | ?0.225 | 1.50 | |
| 1050 | 820 | ?550 | 850 | 900 | 310 | ?445 | ?33.0 | ?0.210 | 1.60 | |
| 1050 | 820 | ?600 | 850 | 900 | 305 | ?445 | ?31.0 | ?0.215 | 1.50 | |
| 1050 | 820 | ?700 | 850 | 900 | 310 | ?450 | ?29.0 | ?0.215 | 1.20 | |
| 1050 | 820 | ?750 | 850 | 900 | 310 | ?450 | ?27.0 | ?0.205 | 1.00 | |
| B | 1050 | 915 | ?650 | 850 | 900 | 365 | ?500 | ?23.5 | ?0.200 | 1.45 |
| 1050 | 900 | ?650 | 850 | 900 | 380 | ?500 | ?25.0 | ?0.205 | 1.35 | |
| 1050 | 850 | ?650 | 850 | 900 | 385 | ?505 | ?18.0 | ?0.200 | 1.15 | |
| 1050 | 800 | ?650 | 850 | 900 | 370 | ?500 | ?27.0 | ?0.210 | 1.00 | |
| C | 1050 | 930 | ?650 | 850 | 900 | 345 | ?470 | ?25.0 | ?0.205 | 0.95 |
| 1050 | 900 | ?650 | 850 | 900 | 345 | ?480 | ?29.5 | ?0.205 | 0.95 | |
| 1050 | 800 | ?650 | 850 | 900 | 355 | ?480 | ?26.0 | ?0.210 | 1.20 | |
| #3 | 1050 | 820 | ?650 | 850 | 750 | 345 | ?495 | ?21.0 | ?0.215 | 0.90 |
| 1050 | 820 | ?650 | 850 | 800 | 315 | ?465 | ?36.5 | ?0.250 | 1.45 | |
| 1050 | 820 | ?650 | 850 | 850 | 310 | ?460 | ?39.0 | ?0.250 | 1.65 | |
| 1050 | 820 | ?650 | 850 | 900 | 290 | ?445 | ?36.5 | ?0.240 | 1.70 | |
| 1050 | 820 | ?650 | 850 | 950 | 290 | ?440 | ?38 | ?0.240 | 1.70 | |
| D | 1050 | 820 | ?650 | 850 | 750 | 550 | ?625 | ?11.0 | ?0.105 | 0.50 |
| 1050 | 820 | ?650 | 850 | 800 | 360 | ?480 | ?28.5 | ?0.210 | 1.20 | |
| 1050 | 820 | ?650 | 850 | 850 | 380 | ?495 | ?21.0 | ?0.215 | 1.15 | |
| 1050 | 820 | ?650 | 850 | 900 | 310 | ?480 | ?32.5 | ?0.225 | 1.25 |
| 1050 | 820 | ?650 | 850 | 950 | 355 | ?470 | ?32.0 | ?0.210 | 1.45 | |
| E | 1050 | 820 | ?650 | 850 | 800 | 360 | ?480 | ?28.5 | ?0.210 | 1.20 |
| 1050 | 820 | ?650 | 850 | 850 | 380 | ?495 | ?29.0 | ?0.215 | 1.15 | |
| 1050 | 820 | ?650 | 850 | 900 | 310 | ?480 | ?32.5 | ?0.225 | 1.25 | |
| 1050 | 820 | ?650 | 850 | 950 | 355 | ?470 | ?32.0 | ?0.210 | 1.45 | |
| 1100 | 850 | ?650 | 900 | 900 | 295 | ?445 | ?34.5 | ?0.220 | 1.45 | |
| 1100 | 850 | ?650 | 900 | 950 | 300 | ?450 | ?34.0 | ?0.210 | 1.90 | |
| F | 1100 | 850 | ?650 | 900 | 900 | 295 | ?445 | ?34.5 | ?0.220 | 1.45 |
| 1100 | 850 | ?650 | 900 | 950 | 300 | ?450 | ?34.0 | ?0.210 | 1.90 | |
| G | 1100 | 850 | ?650 | 900 | 900 | 320 | ?505 | ?33.5 | ?0.215 | 1.65 |
| 1100 | 850 | ?650 | 900 | 950 | 355 | ?495 | ?34.0 | ?0.220 | 1.60 |
Embodiment B is seen Fig. 1, Fig. 2, Fig. 3 and Fig. 4 respectively with the metallographic structure behind comparative example #3 cold rolled annealed and the transmission electron microscope photo of precipitated phase.By Fig. 1 to Fig. 4 as can be seen, more than 900 ℃ during annealing temperature, sufficient recrystallize has taken place, grain size is than uniformity.By Fig. 5 and Fig. 6 as can be seen, in the steel of Ti single stableization, precipitated phase is TiN, bar-shaped and globular TiC.
Fig. 7, Fig. 8 are respectively after embodiment A, the B continuous annealing (Nb wherein
0.83Ti
0.17) (N
0.77C
0.05) transmission electron microscope photo of precipitated phase, Fig. 9 is (Nb after the embodiment A continuous annealing
0.83Ti
0.17) (N
0.77C
0.05) the selected diffraction collection of illustrative plates of precipitated phase, this shows, in Nb, Ti bistable steel, except that thick TiN precipitated phase, also there is a large amount of NbCN particles.
The polarization curve of embodiment A, B and Comparative Examples C, D, #3, JFE443CT, SUS304 and spot corrosion disruptive potential and chemical ingredients relation are seen Figure 10 and table 4 respectively.
Table 4 pitting potential E
p(V) with the relation of chemical ingredients
| Specimen coding | E P1 | E P2 | E P3 | Mean value E P | Chemical ingredients |
| 3-1 | 0.634 | 0.797 | 0.72 | C+N＝123ppm Ti＝0.3％ | |
| 3-2 | 0.541 | 0.58 | 0.56 | ||
| 3-4 | 0.515 | 0.456 | 0.49 | ||
| A1 | 0.4 | 0.518 | 0.46 | C+N＝236ppm Ti＝0.19％，Nb＝0.10％ | |
| A12 | 0.416 | 0.469 | 0.44 |
| B1 | 0.426 | 0.501 | 0.46 | C+N＝246ppm Ti＝0.10％，Nb＝0.20％ | |
| B12 | 0.64 | 0.491 | 0.57 | ||
| C1 | 0.4 | 0.263 | 0.285 | 0.32 | C+N＝187ppm Ti＝0.19％ |
| C12 | 0.318 | 0.552 | 0.525 | 0.47 | |
| D1 | 0.423 | 0.432 | 0.43 | C+N＝212ppm Ti＝0.29 | |
| D12 | 0.303 | 0.3 | 0.3 | ||
| JFE443CT | 0.328 | 0.212 | 0.27 | C+N＝203ppm Ti＝0.3％ | |
| SUS304 | 0.303 | 0.296 | 0.30 |
Specimen codings different in the table 4 are represented different hot resume, first digit or letter representation grade of steel, 3-1,3-2 represent Comparative Examples #3 steel through 950 ℃, 900 ℃, 800 ℃ rolling samples of different finishing temperatures with 3-4, and cold rolling and continuous annealing process subsequently is then identical.First letter representation embodiment A, B and Comparative Examples C, D among A1, A12, B1, B12, C1, C12, D1 and the D12, numeral " 1 " and " 12 " expression coiling temperature is all 650 ℃, but hot-roll annealing technology difference, the former represents cover annealing, the latter represents continuous annealing, and cold rolled continuous annealing technology subsequently is identical.
By Figure 10 and table 4 as can be seen, the size of spot corrosion disruptive potential is pressed JFE443CT, SUS304, and D, C, A, B, the #3 order increases successively, and anti-pitting attack ability of this explanation embodiment is better than the JFE443CT material object; From chemical ingredients, the #3 steel is compared with the D component steel with JFE443CT, other alloying element contents much at one, but the former C+N content lower (123ppm), pitting potential is the highest, and the C+N content that this explanation reduces in the ferritic stainless steel helps improving its corrosion-resistant ability.When A and B component steel employing Nb+Ti stable compositionization, when promptly substituting part Ti with 0.10-0.20%Nb, even C+N content is up to 236ppm and 246ppm, it is low but only adopt the JFE443CT and the D component steel of Ti single stableization that its pitting potential also is higher than SUS304 and C+N content, and Nb content is high more, pitting potential is high more, this explanation Nb can improve the pitting potential of ferritic stainless steel, and the pitting resistance of Nb, Ti bistable ferritic stainless steel is better than the ferritic stainless steel of Ti single stableization.
Figure 11 is embodiment steel E and compared steel SUS304 cyclic corrosion result.Test sample is the #600 glazed surface, and each test period is as follows: spray salt (5%NaCl, 35 ℃, 2 hours) → do (60 ℃, 4 hours) → wet (40 ℃, 2 hours), test 30 cycles altogether.As can be seen, SUS304 is after 30 periodic tests, and there is the corrosion spot in the part, show and corrode, and institute's invention steel does not also corrode basically.Therefore, the corrosion resistance nature of steel of the present invention slightly is better than SUS304.
Claims (7)
1. high chromium content ferrite stainless steel, it is characterized in that: the chemical element that comprises following weight percent proportioning: C≤0.015, N≤0.020, Si≤1.0, Mn≤1.0, P≤0.035, S≤0.010, Cr:20.52～25, Cu:0.34～0.50, Ti+Nb≤0.5, and satisfy (Ti/48+Nb/93)/(C/12+N/14)＞1.5, residual element are Fe.
2. the manufacture method of a high chromium content ferrite stainless steel as claimed in claim 1 is characterized in that comprising following steps:
(1) according to following chemical element weight percent proportioning smelting molten steel: C≤0.015, N≤0.020, Si≤1.0, Mn≤1.0, P≤0.035, S≤0.010, Cr:20.52～25, Cu:0.34～0.50, Ti+Nb≤0.5, and satisfy (Ti/48+Nb/93)/(C/12+N/14)＞1.5, residual element are Fe;
(2) continuous casting or die casting just roll into steel billet after the die casting;
(3) rolling: continuously cast bloom or steel billet are heated to 1050～1100 ℃, are rolled after the insulation, and 800 ℃～950 ℃ of steel plate finishing temperatures are rolled the back segmentation and are cooled to 550～750 ℃ of coiling temperatures;
(4) continuous annealing: 850～950 ℃ of temperature, soaking time 1～1.5min/mm;
(5) scale removal;
(6) cold rolling: cold roling reduction 60%～75%;
(7) recrystallize continuous annealing: 800～950 ℃ of temperature, soaking time 1～1.5min/mm;
(8) smooth.
3. the manufacture method of high chromium content ferrite stainless steel as claimed in claim 2 is characterized in that, in the described step (3), steel plate heating back soaking time is 170～200min.
4. the manufacture method of high chromium content ferrite stainless steel as claimed in claim 2 is characterized in that, in the described step (3), the finishing temperature of steel plate is 850 ℃.
5. the manufacture method of high chromium content ferrite stainless steel as claimed in claim 2 is characterized in that, in the described step (3), rolls the speed of cooling 〉=15 ℃/s of back steel plate.
6. the manufacture method of high chromium content ferrite stainless steel as claimed in claim 2 is characterized in that, in the described step (5), adopts the method scale removal of pickling or sandblast.
7. the manufacture method of high chromium content ferrite stainless steel as claimed in claim 2 is characterized in that, in the described step (6), cold roling reduction is 75%.
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| CN102234738B (en) * | 2010-04-28 | 2013-10-16 | 宝山钢铁股份有限公司 | Ferrite stainless steel for buildings and preparation method thereof |
| CN103506381A (en) * | 2012-06-28 | 2014-01-15 | 宝钢不锈钢有限公司 | Rolling method for solving surface wrinkling problem of ferritic stainless steel |
| CN103741053B (en) * | 2013-12-26 | 2018-04-10 | 宝钢不锈钢有限公司 | A kind of ferritic stainless steel and its manufacture method with excellent polishing performance |
| WO2015122523A1 (en) * | 2014-02-17 | 2015-08-20 | 新日鉄住金マテリアルズ株式会社 | Stainless steel foil and method for manufacturing same |
| CN106319370B (en) * | 2015-06-19 | 2019-08-16 | 宝钢不锈钢有限公司 | With excellent plasticity and high-intensitive middle chrome ferritic stainless steel and its manufacturing method |
| WO2017030148A1 (en) * | 2015-08-19 | 2017-02-23 | 新日鉄住金マテリアルズ株式会社 | Stainless steel foil |
| WO2017135240A1 (en) * | 2016-02-02 | 2017-08-10 | 日新製鋼株式会社 | HOT ROLLED Nb-CONTAINING FERRITIC STAINLESS STEEL SHEET AND METHOD FOR PRODUCING SAME, AND COLD ROLLED Nb-CONTAINING FERRITIC STAINLESS STEEL SHEET AND METHOD FOR PRODUCING SAME |
| CN107653367A (en) * | 2016-07-25 | 2018-02-02 | 宝钢特钢有限公司 | The manufacture method of electrothermal tube corrosion resistant alloy cold-rolled strip |
| CN112647026B (en) * | 2020-12-25 | 2022-06-14 | 中北大学 | Method for preparing high-chromium and high-molybdenum ferritic stainless steel |
| CN114150115B (en) * | 2021-11-09 | 2023-06-16 | 山西太钢不锈钢股份有限公司 | Annealing method of high-chromium super ferrite stainless steel plate with intergranular corrosion resistance |
| CN114150124B (en) * | 2021-12-09 | 2023-04-11 | 山西太钢不锈钢股份有限公司 | Annealing and pickling process method for high-chromium-nickel stainless steel cold-rolled steel strip |
| CN114749485B (en) * | 2022-04-13 | 2024-05-03 | 山西太钢不锈钢股份有限公司 | Hot continuous rolling method for high-chromium ferromolybdenum stainless steel |
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