CN101684542A - Duplex stainless steel with pitting corrosion resistance and favourable cold temperature flexibility and manufacturing method thereof - Google Patents
Duplex stainless steel with pitting corrosion resistance and favourable cold temperature flexibility and manufacturing method thereof Download PDFInfo
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Abstract
The invention discloses a duplex stainless steel with pitting corrosion resistance and favourable cold temperature flexibility and a manufacturing method thereof. The duplex stainless steel comprisesthe following components in mass percentage: 0.01-0.10% of C, 0.2-1.0% of Si, more than 0% and less than 1.5% of Mn, 20.0-22.0% of Cr, 1.8-4.0% of Ni, 0.08-0.2% of N, more than 0% and less than 0.5% of Mo, less than or equal to 1.0% of one or more than one of W and Cu and the balance Fe and inevitable impurities. The invention controls Mn content below 1.5% until zero and simultaneously adjusts the content of elements of N, Ni and the like to ensure that steel has high strength, favourable corrosion resistance and favourable impact toughness at room temperature and low temperature when steel contains no or small amount of noble element Mo; meanwhile, the duplex stainless steel has low cost and small hot working difficulty, can be largely applied in the fields of buildings along the coast,petrochemical industry and the like and can replace 304 austenitic stainless steel of which the nickel content is above 8% at room temperature and lower temperature.
Description
Technical field
The present invention relates to duplex stainless steel and manufacture method thereof, the duplex stainless steel and the manufacture method thereof of especially a kind of pitting corrosion resistance and excellent in low temperature toughness.
Background technology
Duplex stainless steel is made up of ferrite and austenite two-phase, and wherein every phase ratio is no less than 30%.Because the feature of two-phase structure makes duplex stainless steel have the advantage of ferritic stainless steel and austenitic stainless steel concurrently, with the ferritic stainless steel ratio, its toughness height, brittle transition temperature are low, intergranular corrosion resistance and good welding performance.Ferritic steel thermal conductivity height, advantage that the coefficient of expansion is little have been kept simultaneously.Its yield strength is compared with austenitic stainless steel and is significantly improved, and anti-chloride stress cracking corrosion cracking ability has the excellent anti-pitting and the ability of crevice corrosion simultaneously apparently higher than the austenitic stainless steel of 300 series.
Nineteen sixty-eight the stainless steel precision sweetening process--the invention of argon oxygen decarburization (AOD) makes the generation of a series of new type of stainless steel become possibility.One of many progress that AOD brought are the interpolations of alloying element nitrogen.Duplex stainless steel adds nitrogen can make the toughness of heat affected zone under the welded condition and the performance that erosion resistance approaches matrix metal, and nitrogen has also reduced the formation speed of phase between poisonous metal.Nitrogenous duplex stainless steel is called as s-generation duplex stainless steel.The 2205th, the representative steel grade of s-generation dual phase steel also is widely used in a plurality of fields such as offshore oil platform, chemical industry, papermaking.
Economical diphase stainless steel refers in particular to a class Cr content below 22%, and nickel content is low, and the while does not contain molybdenum, tungsten or only contains the duplex stainless steel of a spot of molybdenum, tungsten, owing to adopt Mn, N for Ni, therefore cost is lower, is the ideal material that replaces traditional austenitic stainless steel.In fact, enter 2000 since, the development of duplex stainless steel presents two kinds of trend.Improve on the one hand further steel interalloy constituent content obtaining more high strength and better solidity to corrosion, about the patent of this respect Chinese patent ZL03806936.9 is arranged, publication application CN101057002 and CN1768156.Turn to exploitation to contain Cr amount about 21% on the other hand, low nickel amount and do not contain molybdenum or only contain the economical diphase stainless steel of a small amount of molybdenum reducing the cost and the price of duplex stainless steel, thereby increases duplex stainless steel and the stainless competitive edge of other types.
The patent EP1327008 of EUROPEAN PATENT OFFICE has announced a kind of austenite-ferrite duplex stainless steel, its composition range (weight %): 0.02～0.07%C, 3.0～8.0%Mn, 19.0～23.0%Cr, 1.1～1.7%Ni, 0.1～2.0%Si, 0.15～0.3%N, the alloying element that may comprise have the Cu, the 0.003～0.005%B that are not more than 1.0% Mo or W, are not more than 1.0% ,≤0.004%Ti ,≤0.002%Nb ,≤0.04%V ,≤0.03%Ce or Ca, surplus is Fe or unavoidable impurities.After 1050 ℃ of anneal, this dual phase steel has higher intensity, superior corrosion resistance energy and welding property, Ni constituent content in the steel is reduced to 1.1～1.7% simultaneously, compare with the austenitic stainless steel of widespread use and to have the significantly reduced characteristic of cost, its application target is to replace 304 austenitic stainless steels.But,, therefore erosion resistance is affected owing to contain 5% Mn in this duplex stainless steel; Because Ni content is below 1.7% in the alloy, therefore its impact value significantly reduces when low temperature, is difficult to satisfy the application under cold condition simultaneously.
Usually, Cr21 is the manganese that contains in the economical diphase stainless steel more than 5%, its effect is to be that manganese is more weak austenite former on the one hand, the most important thing is increase with manganese amount in the stainless steel, can significantly improve the solubleness of nitrogen in steel, thereby the strong austenitizing that utilizes nitrogen is used for replacing nickel expensive, rare in the steel, the suitable phase ratio of stable or control.But manganese all is negative to the influence of stainless erosion resistance basically.The experimental formula of estimating the anti-pitting attack performance of duplex stainless steel is: PREN (equivalent of anti-the spot corrosion)=Cr%+3.3Mo%+30N%-Mn%, by this formula as seen, the manganese of every interpolation 1% will make alloy PREN value reduce by 1, be equivalent to offset add 0.3% the Mo raising to pitting resistance.The reason that Mn influences pitting corrosion resistance is that manganese and sulphur form MnS, or along with manganese amount in the steel increases, the chrome content among the MnS reduces, and caused MnS is mixed in the dissolving in the corrosive medium, usually becomes the starting point of spot corrosion, crevice corrosion.
In view of this consideration, Mo content has further improved in POSCO Co., Ltd. on the basis of patent EP1327008, reduced simultaneously Mn content to a certain extent, applied for Chinese patent CN101090988, its Ni content is 1.0～3.0, Mo is increased to 0.5～2.5, this goal of the invention is further to improve corrosion resistance nature, the compositing range of the alloy compositions of its patent application guarantees that alloy has the performance that CPT is higher than 20 ℃, its corrosion resisting property is better than nickeliferous 12% 316 stainless steels, but the raising of Mo content will significantly improve the cost of alloy, so the target that this composition alloy replaces is mainly 316 type stainless steels.
Summary of the invention
The object of the present invention is to provide the duplex stainless steel and the manufacture method thereof of a kind of pitting corrosion resistance and excellent in low temperature toughness, Mn content is controlled at 0～1.5%, to improve corrosion resistance nature; Adjust the content of elements such as N, Ni simultaneously, make steel not contain or only contain under the condition of a small amount of your elements Mo, has high strength, excellent corrosion resistance nature and under room temperature and low temperature good impelling strength, cost is lower simultaneously, the hot-work difficulty is little, can be widely used in coastal building, field of petrochemical industry, replaces nickel content up to 304 austenitic stainless steels more than 8% under room temperature and cold condition.
For achieving the above object, technical scheme of the present invention is:
The duplex stainless steel of pitting corrosion resistance and excellent in low temperature toughness, its chemical component weight per-cent is: C 0.01～0.10%, Si 0.2～1.0%, 0＜Mn＜1.5%, Cr 20.0～22.0%, and Ni 1.8～4.0%, N 0.08～0.2%, 0＜Mo＜0.5%, one or more among W, the Cu≤1.0%, all the other are Fe and inevitable impurity.
Carbon carbon is strong austenite former, can replace Ni to a certain extent, promotes austenite to form, and the stable austenite tissue, can improve stainless intensity simultaneously.But when carbon content was too high, carbon combined the back and forms rich chromium carbide at crystal boundary with chromium, cause intergranular corrosion.In addition, the rich chromium carbide of formation also reduces the impelling strength of steel.Cross low carbon content and will increase difficulty and cost in the preparation process.Therefore, the design carbon content is 0.01%～0.10% in the steel of the present invention.
Silicon silicon is the element that contains usually in the Manufacture Of Iron And Steel By Melting.In duplex stainless steel, silicon is that ferrite forms and stable element.Silicon is used for deoxidation in fusion process, silicon can improve the hot strength of ferritic phase simultaneously, contains the silicon more than 0.2% in the therefore general dual phase steel.Will reduce the solubleness of nitrogen when but silicone content is too high, and quicken separating out of intermetallic phase.Therefore, the design silicone content is 0.2%～1.0% in the steel of the present invention.
Manganese manganese is that a kind of austenite forms and stable element, can utilize manganese to replace nickel to a certain extent, obtains austenite structure, and the interpolation of manganese simultaneously can significantly improve the solubleness of nitrogen.But manganese all is negative to the influence of stainless erosion resistance basically.The experimental formula of estimating the anti-pitting attack performance of duplex stainless steel is: PREN (equivalent of anti-the spot corrosion)=%Cr+3.3%Mo+30%N-%Mn, by this formula as seen, the manganese of every interpolation 1% will make alloy PREN value reduce by 1, be equivalent to offset add 0.3% the Mo raising to pitting resistance.The reason that Mn influences pitting corrosion resistance is that manganese and sulphur form MnS, or along with manganese amount in the steel increases, chrome content among the MnS reduces, caused MnS is mixed in the dissolving in the corrosive medium, usually become the starting point of spot corrosion, crevice corrosion, so emphasis control Mn content is 0%～＜1.5% in the steel of the present invention.
Chromium chromium is the most important element that steel obtains corrosion resistance nature.The minimum chromium content that usually obtains erosion resistance is 12%.But when chromium content is low, the Fe-Cr binary phase diagram shows martensitic phase will occur, and the raising of Cr content simultaneously can significantly strengthen corrosion resistance nature, so Cr content is controlled at more than 18% in the steel of the present invention.But when the Cr too high levels, will increase intermetallic phase and separate out, because Cr is main ferrite former, therefore too high Cr will need corresponding high Ni equivalent to cooperate with it simultaneously, to guarantee to obtain duplex structure.Therefore, chromium content is controlled at 20.0%～22.0% in the steel of the present invention.
Nickel nickel is basic austenite former, is austenizer main in austenitic stainless steel and the duplex stainless steel.And can improve the impelling strength of steel, reduce the tough-crisp transition temperature (Ductile-brittle transition temperature is called for short DBTT) of steel, at nickel content less than 4～5% o'clock, along with nickel content increases, impelling strength especially low-temperature impact toughness significantly improves.But because nickel costs an arm and a leg, it is a crucial difficult problem that reduces the stainless steel production cost, therefore nickel content is controlled at 1.8%～4.0% in the steel of the present invention, to guarantee still to have after Mn, N reduce in the steel phase ratio, guarantee that simultaneously steel has excellent impact toughness under room temperature especially low temperature near 50: 50.
Nitrogen nitrogen element is a kind of strong austenite former.Nitrogen is to form and stable austenite key factor mutually in the dual phase steel.The adding of nitrogen simultaneously helps improving the intensity and the corrosion resistance nature of steel, especially anti-pitting attack performance and slit and corrosion resistant performance.When but nitrogen content is too high, will increase the risk that forms mutually between nitrogen containing metal, the raising that improves melting and hot worked difficulty, especially nitrogen content simultaneously will cause serious hot rolling limit to split rate, cause being difficult to producing existing producing on the line.Therefore, nitrogen in steel content of the present invention is controlled at 0.08%～0.2%.
The molybdenum molybdenum is very beneficial for improving the corrosion resistance nature of steel, and its mechanism is to stablize passive film and promote the enrichment of chromium element in passive film, and the main effect of adding molybdenum is to improve erosion resistance.But the molybdenum too high levels will cause fragility to quicken mutually to separate out, and increase cost of alloy simultaneously, so the molybdenum content in the steel of the present invention is controlled at below 0.5%.
Tungsten tungsten is one of optional element among the present invention.The effect of tungsten in dual phase steel is similar to molybdenum, can improve the corrosion resistance nature of steel.Tungsten can also reduce the activity at austenite/ferritic phase interface, suppresses the formation of intermetallic phase.Promote intermetallic phase to generate when but W content is too high on the contrary.Therefore W content is controlled at below 1.0% in the steel of the present invention.
Copper copper also is one of optional element among the present invention.Copper is a kind of austenite former, and the adding of copper can improve the erosion resistance of dual phase steel in reductive acid, helps improving the slit and corrosion resistant performance simultaneously.But be unfavorable for hot workability during the copper too high levels.Therefore copper content is controlled at below 1.0% in the steel of the present invention.
Must take all factors into consideration each element to tissue and Effect on Performance effect.(1) Ni, N, Mn, Cu etc. are austenite formers, Cr, Mo, Si etc. are ferrite formers, must guarantee enough austenite formers, guaranteeing austenite phase, thereby guarantee austenite/ferrite two-phase proportion of 50%: 50% near 50%.Usually, adopt chromium equivalent and nickel equivalent to come reference, Cr
Cq=%Cr+1.5%Mo+1.5%Si, Ni
Eq=%Ni+30% (C+N)+0.5%Mn+0.3%Cu.By calculating Cr
EqAnd Ni
Eq, cooperate the result of Schaeffler-Delong to control the phase ratio, so after Mn, N content reduce among the present invention, must suitably improve Ni content and balance each other guaranteeing; (2) to the influence of cost.Ni and Mo are the key factors that influences cost, and simultaneously the Mo price is again far above Ni, so the present invention should reduce Mo content as far as possible until not containing Mo, control Ni content to a certain extent; (3) to the influence of mechanics and hot workability.N is the key factor that improves intensity, N, Mn can reduce cost after replacing Ni simultaneously, but the N too high levels causes smelting difficulty to be strengthened, produce serious limit during hot-work and split, the impelling strength when the N too high levels has reduced low temperature simultaneously, so the present invention is under the prerequisite of controlling cost, the comprehensive content of adjusting Ni, N, Mn, guarantee the existing high strength of alloy, good low-temperature flexibility is arranged again, manufacturability and low cost; (4) to the influence of erosion resistance.As previously mentioned, adopt PREN (equivalent of anti-the spot corrosion)=%Cr+3.3%Mo+30%N-%Mn to characterize pitting resistance, as can be seen, at Cr, N equal size fixedly the time, Mo and Mn will be the key elements that influences erosion resistance, the raising of Mo helps solidity to corrosion, but Mo costs an arm and a leg, and it is excessive that too high levels causes that cost increases; The reduction of Mn is the effective ways that improve erosion resistance, but Mn is the key element that improves the N solid solubility, therefore the reduction of Mn just in time in (3) reduction of N content be complementary, so the present invention is by reducing below the Mn content to 1.5%, to improve corrosion resistance nature under the condition that does not raise the cost.The present invention is carried out to branch design and manufacture method is selected around above-mentioned four principles just.
The manufacture method of the duplex stainless steel of pitting corrosion resistance of the present invention and excellent in low temperature toughness may further comprise the steps:
1) its chemical component weight per-cent is: C 0.01～0.10%, Si 0.2～1.0%, 0＜Mn＜1.5%, Cr 20.0～22.0%, Ni 1.8～4.0%, and N 0.08～0.2%, 0＜Mo＜0.5%, among W, the Cu one or more≤1.0%, all the other are Fe and inevitable impurity;
2) press mentioned component and smelt, die casting or continuous casting form strand;
3) strand is put into process furnace and is heated to 1100～1250 ℃ and insulation after, on forging line or hot rolling unit, be machined to desired thickness, anneal then or pickling annealing, its annealing temperature is controlled at 1030～1100 ℃.
Further, smelting process is that vacuum induction is smelted, or, electric furnace-argon oxygen decarburization AOD, or the outer concise LF stove of electric furnace-argon oxygen decarburization AOD-stove is smelted.
Again, the control superheating temperature is 30～50 ℃ during die casting, by controlling the pore that superheating temperature avoids the effusion of nitrogen to cause, because pore will cause hot workability, mechanics and corrosion resistance nature to worsen.
Have, the control superheating temperature was 30～50 ℃ when the present invention adopted die casting again, and the control superheating temperature is 30～50 ℃ when adopting continuous casting, and the slab pulling rate is 0.8～2m/min during continuous casting.
The present invention compared with prior art has the following advantages:
Existing low nickel economical diphase stainless steel such as Chinese patent ZL02145172.9 (Gao Meng, contain Al and contain rare earth), Chinese patent CN101090988 (contains the Mn more than 1.5, and contain higher Mo to obtain more high corrosion resistance, replace nickeliferous 12% 316 type austenitic stainless steels), Chinese patent CN1718833 (low N, nickel is greater than 4.8%, C is higher than 0.09% and contain Ti 0.25～0.50, Nb0.10～0.20, V 0.10～0.20), European patent EP 1327008 is (with Cr, Mn, Ni, N is main added elements, contain the Ni below 1.7, replace 304 type austenitic stainless steels, but its low-temperature flexibility is relatively poor), the duplex stainless steel of above-mentioned patent is substantially with Cr, Mn, Ni, N etc. are main added elements, its outstanding feature is to contain higher Mn, its objective is and utilize Mn to significantly improve N solubleness, the effect of certain austenitizing is arranged again simultaneously, replace below the Ni to 2% in the steel, thereby reduce cost.But the raising of Mn content significantly reduces corrosion resistance nature, in order to remedy the reduction of corrosion resistance nature, adds your elements Mo of high level again, as Chinese patent CN101090988, causes the rising of cost again; Simultaneously Ni is replaced back alloy low-temperature flexibility by N and significantly reduces, and is difficult to use at low temperatures and the hot procedure difficulty that will become.
The present invention controls to below 1.5% Mn content until 0, nitrogen content is controlled at 0.08～0.20, simultaneously Ni content is controlled at 1.8～4.0, alloy just can obtain high pitting resistance under the condition that does not contain or only contain a small amount of your elements Mo, simultaneously alloy at low temperatures toughness do not reduce substantially, can under high temperature and low temperature, replace ni content up to 8% 304 austenitic stainless steels.
The present invention controls to below 1.5% Mn content until 0, thereby has effectively reduced the disadvantageous effect of manganese to corrosion resistance nature, improves the especially anti-pitting attack of erosion resistance of alloy; Nitrogen content is controlled at 0.08～0.20, guarantees yield strength more than 400Mpa, reduce simultaneously and smelt and hot worked difficulty, the generation that the limit is split when reducing hot rolling.
The present invention is controlled at 1.8～4.0 to guarantee that alloy still keeps impelling strength not reduce under-60 ℃ low temperature with Ni content, and Mo content is controlled at below 0.5%, and with the material cost of control alloy, alloy is compared cost with 304 and significantly reduced.
Duplex stainless steel of the present invention can utilize existing stainless steel to produce line and produce in batches, concrete preparation method is casting after vacuum induction furnace, electric furnace-AOD stove smelting or electric furnace-AOD-LF stove are smelted, the control superheating temperature is about 30～50 ℃ when die casting, and cooperation cooling fast, or adopt cooling rate continuous cast method faster, avoid the effusion of nitrogen, the control superheating temperature is 30～50 ℃ during continuous casting, and the slab pulling rate is 0.8～2m/min.
Duplex stainless steel of the present invention has good anti-pitting attack performance and low-temperature flexibility: yield strength Rp is 400MPa～485MPa, and unit elongation δ is 45%～55%, and room temperature ballistic work AkV is 240J/cm
2～300J/cm
2, ballistic work is 220J/cm in the time of-60 ℃
2～280J/cm
2, pitting attack equivalent value PREN=Cr%+3.3%Mo+30N%-Mn% is about 24～29,17 ℃～24 ℃ of critical pitting temperatures.
Description of drawings
Fig. 1 is the alloy metallograph of the embodiment of the invention 1.
Fig. 2 varies with temperature the synoptic diagram of rule for the impact value of the embodiment of the invention 2 alloys.
Embodiment
The embodiment of the invention is an example with the Production Flow Chart that electric furnace-AOD smelts: adding electric furnaces such as ferrochrome, ferronickel and steel scrap are melted, after molten clear with molten steel to going into the AOD stove, in the AOD stove, take off C, take off S and increase N, control the blowing of N, when the smelting composition reaches requirement, molten steel to going into tundish, and is cast on vertical-bending caster.The superheating temperature of continuous casting is 30～50 ℃, and the slab pulling rate is 0.8～2m/min.Continuous casting steel billet put into roll end formula and add stove and be heated to 1100～1250 ℃, after being rolled down to desired thickness on the hot continuous rolling unit, batch.Carry out successive pickling annealing then, obtain to have the tissue of ferritic-austenitic double structure, thereby obtain good impact property and corrosion resistance nature.
Table 1 is depicted as the chemical ingredients of embodiment of the invention steel grade, table 1 provided simultaneously as a comparison case the low-nickel type duplex stainless steel of having developed at present and the chemical ingredients of object 304 austenitic stainless steels that replace of steel plan of the present invention.
The alloy metallograph of embodiment 1 is (austenite accounts for 50% mutually) as shown in Figure 1, and the temperature variant rule of alloy impact value of embodiment 2 as shown in Figure 2.Table 2 has provided the result that generation is split on limit in steel of the present invention and the contrast mechanical property of steel grade and corrosive nature and the hot procedure.Wherein the phase ratio of duplex stainless steel adopts the quantitative metallography method, and sample is through electrolytic corrosion, and etching reagent is 40g KOH+100ml H
2O, corrosion current 0.3～0.8A/cm
2Mechanical property is all taken from the hot-roll annealing plate, wherein impact property according to the GB/T229 summer than v-notch normal of impact, specimen size 10 * 10 * 55mm, probe temperature are respectively 20 ℃, 0 ℃ ,-20 ℃ ,-40 ℃ ,-60 ℃.Anti-pitting attack equivalent calculates according to general formula PREN=Cr%+3.3Mo%+30N%-Mn%.
Table 1 unit: mass percent
| Embodiment | ??C | ??Si | ??Mn | ??Cr | ??Ni | ??N | ??Mo | ??Cu | ??W | ??Fe |
| ??1 | ??0.01 | ??1.0 | ??1.49 | ??20 | ??2.5 | ??0.16 | ??0.3 | ??0.3 | ??-- | Surplus |
| ??2 | ??0.03 | ??0.4 | ??1.0 | ??22 | ??2.5 | ??0.2 | ??0.49 | ??1.0 | ??-- | Surplus |
| ??3 | ??0.1 | ??0.2 | ??-- | ??22 | ??4.0 | ??0.08 | ??-- | ??-- | ??-- | Surplus |
| ??4 | ??0.03 | ??0.6 | ??0.5 | ??21 | ??1.8 | ??0.15 | ??-- | ??-- | ??-- | Surplus |
| ??5 | ??0.05 | ??0.5 | ??0.8 | ??21 | ??3.2 | ??0.13 | ??0.3 | ??0.5 | ??0.3 | Surplus |
| ??6 | ??0.04 | ??0.5 | ??0.4 | ??21.5 | ??3.5 | ??0.12 | ??-- | ??0.3 | ??0.5 | Surplus |
| ??7 | ??0.03 | ??0.6 | ??1.0 | ??21 | ??1.8 | ??0.18 | ??-- | ??-- | ??1.0 | Surplus |
| Comparative Examples 2101 duplex stainless steels | ??0.03 | ??0.22 | ??5 | ??21.0 | ??1.5 | ??0.20 | ??0.3 | ??0.3 | ??-- | Surplus |
| Comparative Examples 304 austenitic stainless steels | ??0.05 | ??-- | ??-- | ??18 | ??-- | ??-- | ??-- | ??-- | ??-- | Surplus |
Table 2
| Embodiment | Thermal treatment temp (℃) | Austenite phase ratio (%) | Yield strength (MPa) | ??δ(％) | Room temperature AkV (J) | AkV in the time of-60 ℃ (J) | ??PRE ??N | Critical pitting temperature (℃) | Situation is split on the hot rolling limit |
| ??1 | ??1050 | ??55 | ??450 | ??55 | ??280 | ??250 | ??24 | ??17 | The limit is not split |
| ??2 | ??1050 | ??53 | ??485 | ??50 | ??280 | ??260 | ??29 | ??24 | Slight limit is split |
| ??3 | ??1050 | ??48 | ??400 | ??45 | ??300 | ??280 | ??24 | ??17 | The limit is not split |
| ??4 | ??1050 | ??52 | ??445 | ??51 | ??240 | ??220 | ??26 | ??21 | The limit is not split |
| ??5 | ??1050 | ??53 | ??425 | ??51 | ??285 | ??268 | ??25 | ??20 | The limit is not split |
| ??6 | ??1050 | ??49 | ??420 | ??49 | ??290 | ??275 | ??25.6 | ??21 | The limit is not split |
| ??7 | ??1050 | ??52 | ??465 | ??50 | ??240 | ??220 | ??27 | ??23 | Slight limit is split |
| Comparative Examples 2101 duplex stainless steels | ??1050 | ??50 | ??450 | ??46 | ??220 | ??60 | ??23 | ??14 | Severe edge fracture |
| Comparative Examples 304 austenitic stainless steels | ??1050 | ??-- | ??260 | ??55 | ??-- | ??-- | ??18 | ??4 | The limit is not split |
By table 1 and the visible steel of the present invention of Fig. 2 because manganese content is low until not containing manganese, and adjusted Ni, alloying element contents such as N, alloy has obtained good pitting corrosion resistance and low-temperature flexibility, specifically be Mn content is controlled to below 1.5% until 0 to improve corrosion resistance nature, nitrogen content is controlled at 0.08～0.20 to guarantee that yield strength is more than 400Mpa, reduce simultaneously and smelt and the hot-work difficulty, reduce the degree that generation is split on the limit, again Ni content is controlled at 1.8～4.0 to guarantee that alloy still keeps impelling strength not reduce under-60 ℃ low temperature, alloy just can obtain high pitting resistance under the condition that does not contain or only contain a small amount of your elements Mo simultaneously, so cost is lower.Compare with nickeliferous 1.1～1.7% 2101 type duplex stainless steels, low-temperature flexibility and pitting resistance significantly improve, compare with object 304 austenitic stainless steels (containing 8% nickel) that steel plan of the present invention replaces, nickel in the steel is partly replaced, can further reduce material cost, have higher corrosion resistance nature and intensity simultaneously, can under room temperature and low temperature, replace nickel content, remedy the low temperature field that 2101 type duplex stainless steels are difficult to use up to 304 austenitic stainless steels more than 8%.
Claims (4)
1. the duplex stainless steel of pitting corrosion resistance and excellent in low temperature toughness, its chemical component weight per-cent is:
C 0.01～0.10%, and Si 0.2～1.0%, 0＜Mn＜1.5%, and Cr 20.0～22.0%, and Ni 1.8～4.0%, and N 0.08～0.2%, 0＜Mo＜0.5%, one or more among W, the Cu≤1.0%, all the other are Fe and inevitable impurity.
2. the manufacture method of the duplex stainless steel of pitting corrosion resistance and excellent in low temperature toughness may further comprise the steps:
1) its chemical component weight per-cent is: C 0.01～0.10%, Si 0.2～1.0%, 0＜Mn＜1.5%, Cr 20.0～22.0%, Ni 1.8～4.0%, and N 0.08～0.2%, 0＜Mo＜0.5%, among W, the Cu one or more≤1.0%, all the other are Fe and inevitable impurity;
2) press mentioned component and smelt, die casting or continuous casting form strand;
3) strand is put into process furnace and is heated to 1100～1250 ℃ and insulation after, on forging line or hot rolling unit, be machined to desired thickness, anneal then or pickling annealing, its annealing temperature is controlled at 1030～1100 ℃.
3. the manufacture method of the duplex stainless steel of pitting corrosion resistance as claimed in claim 2 and excellent in low temperature toughness is characterized in that, smelting process is that vacuum induction is smelted, or, electric furnace-argon oxygen decarburization AOD, or the outer concise LF stove of electric furnace-argon oxygen decarburization AOD-stove is smelted.
4. the manufacture method of the duplex stainless steel of pitting corrosion resistance as claimed in claim 2 and excellent in low temperature toughness, it is characterized in that, the control superheating temperature is 30～50 ℃ when adopting die casting, and the control superheating temperature is 30～50 ℃ when adopting continuous casting, and the slab pulling rate is 0.8～2m/min during continuous casting.
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Cited By (14)
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| CN105256121A (en) * | 2015-10-21 | 2016-01-20 | 苏州雷格姆海洋石油设备科技有限公司 | Thermal treatment method for improving low-temperature toughness and corrosion resistance of 22Cr-type stainless steel forging |
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| CN102002646A (en) * | 2010-10-12 | 2011-04-06 | 西安建筑科技大学 | Economic biphase stainless steel with high mechanical property and superior corrosion resistance |
| CN102296247A (en) * | 2011-08-29 | 2011-12-28 | 江苏九胜特钢制品有限公司 | Double phase stainless steel alloy material and its preparation method |
| CN102605288B (en) * | 2012-03-13 | 2015-03-25 | 宝山钢铁股份有限公司 | Economical double-phase stainless steel with good welding property and manufacturing method for stainless steel |
| CN102605288A (en) * | 2012-03-13 | 2012-07-25 | 宝山钢铁股份有限公司 | Economical double-phase stainless steel with good welding property and manufacturing method for stainless steel |
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| CN102851606A (en) * | 2012-09-05 | 2013-01-02 | 浙江汉威阀门制造有限公司 | Low cost double phase stainless steel material for valve, and preparation method thereof |
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| CN103074551B (en) * | 2013-01-14 | 2014-11-05 | 浙江大学 | Two-phase stainless steel alloy and preparation method thereof |
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| CN105463562A (en) * | 2014-09-05 | 2016-04-06 | 上海金保莱不锈钢有限公司 | Manufacturing method for seamless stainless steel pipe resistant to corrosion of anions |
| CN105441830A (en) * | 2014-09-25 | 2016-03-30 | 宝钢不锈钢有限公司 | Acid-corrosion-resistant high-strength low-nickel duplex stainless steel and manufacturing method thereof |
| CN105441830B (en) * | 2014-09-25 | 2018-11-02 | 宝钢不锈钢有限公司 | A kind of acid corrosion-resistant high intensity low nickel duplex stainless steel and its manufacturing method |
| CN105256121A (en) * | 2015-10-21 | 2016-01-20 | 苏州雷格姆海洋石油设备科技有限公司 | Thermal treatment method for improving low-temperature toughness and corrosion resistance of 22Cr-type stainless steel forging |
| CN105256121B (en) * | 2015-10-21 | 2017-07-28 | 苏州雷格姆海洋石油设备科技有限公司 | A kind of heat treatment method of raising 22Cr type stainless steel forgings low-temperature flexibilities and decay resistance |
| CN107900612A (en) * | 2017-11-02 | 2018-04-13 | 江苏巨能机械有限公司 | The processing technology of large-scale two phase stainless steel rotary drum disk |
| CN107900612B (en) * | 2017-11-02 | 2019-10-18 | 江苏巨能机械有限公司 | The processing technology of large-scale two phase stainless steel rotary drum disk |
| CN114075640A (en) * | 2020-08-13 | 2022-02-22 | 宝武特种冶金有限公司 | High-corrosion-resistance austenitic stainless steel and manufacturing method thereof |
| CN114395739A (en) * | 2022-01-22 | 2022-04-26 | 福州大学 | Niobium-titanium composite reinforced duplex stainless steel and preparation method thereof |
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