CN1032926C - Fe-Cr-Ni anti-corrosion high alloy - Google Patents

Abstract

The present invention relates to a Fe-Cr-Ni base high alloy with high temperature resistance and sulphuric acid and sulfate radical corrosion resistance, which belongs to the high alloy field and has ingredients: at most 0.02 of C, 17 to 22 of Cr, 31 to 36 of Ni, 2.5 to 4.5 of Mo, 2.0 to 3.0 of Si, 3.0 to 4.0 of Cu, 0.4 to 0.6 of Nb, less than 0.004 of S and P and Fe as the rest. The cost of the alloy is lower than that of the same type products and nickel base alloy. Because low C, S and P are additionally added with Si, the sulphuric acid corrosion resistance and the aluminium sulfate resistance of the present invention are greatly better than that of the same type products and nickel base alloy. The present invention has good heat conductivity, high temperature and oxidation resistance performance and stress corrosion resistance performance, and is suitable for the requirements of chemical engineering industry and pharmacy industry, particularly for the requirements of the industrialization generation of Al2(SO4)3.

Description

A kind of Fe-Cr-Ni anti-corrosion high alloy

The present invention relates to the high alloy field, specifically just provided the iron chromium nickelio high alloy of a kind of anti-sulfuric acid and radical corrosion.

At industrial circles such as chemical industry, chemical fertilizer, pharmacy, the vitriolic use is very wide, the corrosion of production unit just becomes a very stubborn problem, under the normal temperature situation, usually adopt high silicon cast iron or soft steel, but under hot environment, used vaporizer during as manufacture Tai-Ace S 150, the sulfuric acid reaction still that pharmaceutical factory is used then must adopt comparatively special material.At present employed high temperature sulfuric acid corrosion material has following four kinds: (1) plumbous material or ward off lead material, advantage is that machine-shaping is convenient, low price.But this kind material is poisonous, contaminate environment, infringement workman are healthy, and it is not long to influence quality product and work-ing life; (2) titanium molybdenum, titanium tantalum alloy are longer work-ing life, but cost an arm and a leg; (3) nickel-base alloy is at 60%H ₂SO ₄Following concentration, but boiling temperature district life-time service, handling ease, but also have shortcoming on the high side; (4) siderochrome nickel-base alloy, as U.S. alloy Carpent-20cd-3, its composition is C≤0.07; Cr23, Ni38, Mo3.5, Cu3.5, Nb0.6, the 2u943 alloy of the Soviet Union, composition are C≤0.06, Cr29, Ni25, Mo3.0, Cu3.5, Ti is suitable for using in the various concentration sulfuric acid in humidity province below 30 ℃, has easy to processly, and price is than nickel-base alloy, advantage that titanium alloy is cheap.But the non-homogeneous attenuate of the forms of corrosion of this kind alloy, the phenomenon that has local corrosion to increase the weight of occurs, the worm-eaten spot appears behind the life-time service under the high-temperature high concentration sulphuric acid environment, thereby still people's satisfaction in addition of corrosion resistance nature, the corrosion peak appears in this kind alloy when sulfuric acid concentration is 70% left and right sides in addition, and environment for use is restricted.And the alloying level of this kind alloy is still very high, and cost is not very low.

The object of the present invention is to provide a kind of high-temperature corrosion resistance performance more excellent, the siderochrome nickel base superalloy that the use temperature scope is wideer and cost is lower.

To the effect that of the present invention: the composition of alloy design following (weight percent, below all with):

C Cr Ni Mo Si Cu Nb SP Fe≤0.02 17,/22 31/36 its best composition scope of 2.5/4.5 2.0/3.0 3.0/4.0 0.4/0.6≤0.004 surplus is in C Cr Ni Mo Si Cu Nb SP Fe≤0.01 18,/21 32/35 3.5/4.5 3.0/4.0 2.0/3.0 0.4/0.6≤0.004 surplus

Principal feature of the present invention is: the content of I, C, S, P is all controlled very lowly, inclusion does not seldom almost have the second phase particle in the alloy, has reduced the potential corrosion that produces because of inclusion, thereby alloy is even attenuate in corrosion process; 2, added a spot of Si in the alloy, Si can improve anti-pitting attack ability significantly in the Fe-Cr-Ni alloy, and rich Si can improve passivation in the passive film, because of SiO ₂Film is dissolved in acid hardly, and Si can also stop the suction H-H reaction of steel, thereby the antagonism sulfuric acid corrosion has goodish effect.Si can also improve the oxidation-resistance property of alloy significantly in addition.But the add-on of Si can not be higher than 3%, otherwise can increase resistance to deformation, forms processing difficulties, and it is unfavorable to be lower than 2% o'clock antagonism grain boundary corrosion; 3, relative 2k043 of the alloying level of this alloy and Corpent-2ocb-3 are low, thereby cost is also lower.The effect of various alloying elements in this alloy is described in detail in detail below.Nickel is the austenitic area forming element, can obtain single austenite structure, have extraordinary processing characteristics, welding property, and Ni is a metal stable on the thermodynamics, it is good to add nickel sulfuric-resisting corrosive effect in the alloy, and nickel content is 34% o'clock, sulfuric-resisting corrosive effect the best, more add into effect very unobvious, because Ni belongs to expensive or the semi-precious metal, in order to reduce cost, the present invention is limited in the content of nickel between 31-36%.Cr is a unsettled element on the thermodynamics, but it has dual nature, and is both very active, very easily passivation again, its passive film CrO ₂The density height, chemical stability is good, utmost point indissoluble is separated in water and acid, and the content of Cr in alloy has certain limit, has only content to be higher than at 12% o'clock, its passive film just has fine and close spinel structure, have amorphous structure more than 19%, but content is higher than at 28% o'clock, the processing characteristics that σ mutual-assistance alloy can occur degenerates, thereby in this alloy, the content of Cr is controlled between 17～22%.Add in the time of Cu and Mo and can suppress the passive film reduction of dissolved effectively, improve the sulfuric-resisting corrosive power, the amount of Cu is lower than the not effect of raising to performance in 3% o'clock, be higher than at 4% o'clock owing in alloy, be difficult to dissolving, can cause the hot-work difficulty again, thereby the content of Cu should be limited in 3～4% and is advisable.In addition, Mo also can improve the anti-general corrosion and the local corrosive power of steel, but the amount of Mo should not add too much, otherwise can cause processing difficulties, and lumber recovery is low, and cost improves, and the content of Mo should be limited in 2.5～4.5% and be advisable.Nb is active great element, also has dual nature, and passivation speed is exceedingly fast, and the effect of Nb removes the Cization thing of the preferential Nb of generation in this alloy, and outside the Cization thing of the harmful phase Cr of minimizing generated, what is more important Nb was to the contribution of alloying.This alloy is a fully austenitic structure, and the intracrystalline composition is evenly distributed, and crystal boundary place cast alloy is than some segregation of deformation states alloy, but corrosion resistance nature is produced harmful effect.The mechanism of its sulfuric acid corrosion resistant is the passive film of numerous structures, Cr ₂O ₃, Cr ₃O ₄, MoSi ₂, Cu ₁₅Si ₄, FeCr ₂O ₃, CuOFeO ₃, FeOCr ₂O ₃, NiOCr ₂O ₃, NiOFe ₂O ₃, these films have plenty of spinel type, have plenty of the non-crystalline state type, very fine and close and stable make this alloy to have good high temperature resistance sulfuric acid corrosion performance.This alloy is at 120 ℃ below the temperature, and annual corrosion rate can be controlled in below the 0.4mm/ in the various concentration sulfuric acid liquid, and in 40% following concentration sulfuric acid liquid, temperature range can be brought up to 141 ℃.In addition, this alloy also has excellent mechanical property and heat conductivity.Embodiment is described in detail in detail below.

Embodiment 1,2,3

Press the good composition of compatibility, with technically pure iron, Ni, Si elder generation drops in the vacuum induction furnace and carries out melting, after treating to melt substantially, adds Cr, and Mo Nb gets composition respectively as 1,2, No. 3 alloy in the table 1.Its mechanical property, heat-conductive characteristic and corrosion-resistant antioxidant property are shown in table 2,3,4,5.

Table 1 alloy ingredient

C Cr Ni Mo Si Cu Nb S, P Fe 1 0.01 20 34 4.0 4.0 3.0 0.6≤0.004 surplus 2 0.005 17 31 2.5 2.0 2.0 0.4≤0.004 surplus 3 0.002 21 35 4.5 4.0 3.0 0.6≤0.004 surplus

Table 2 mechanical property

σ?b(MPa)

T(℃) 1 2 3

200 645 624 654

400 591 581 601

600 426 399 432

800 215 213 225

900 102 108 1121,2, No. 3 alloys all broke under the 196MPa stress at 600 ℃ in lasting 1 year.

Table 3 thermal conductivity

T(℃) λ

1 2 3

250 0.0401 0.040 0.0401

300 0.0422 0.0421 0.0402

400 0.0453 0.0452 0.0460

500 0.0485 0.0483

600 0.0527 0.0503 0.0489

700 0.0569 0.0534 0.0489

800 0.0601 0.0567 0.0602

900 0.0603 0.0595 0.0611

Table 4 sulfuric acid corrosion resistant rate (mm/)

H ₂SO ₄Concentration (%) temperature (℃) 123

10 80 0.0244 0.215 0.285

100 0.090 0.085 0.115

Seethe with excitement 0.218 0.208 0.288

20 80 0.060 0.055 0.090

100 0.105 0.100 0.185

Seethe with excitement 0.241 0.237 0.290

30 80 0.006 0.004 0.010

100 0.139 0.130 0.161

Seethe with excitement 0.021 0.021 0.035

40 80 0.001 0.001 0.011

100 0.170 0.165 0.218

Seethe with excitement 0.200 0.205 0.314

50 80 0.028 0.026 0.039

100 0.245 0.240 0.275

Seethe with excitement 0.081 0.086 0.157

60 80 0.006 0.006 0.016

100 0.305 0.300 0.365

Seethe with excitement 5.909 6.009 6.321

70 80 0.060 0.060 0.080

100 0.190 0.180 0.211

Seethe with excitement 6.539 6.730 7.534

80 80 0.606 0.006 0.016

100 0.087 0.087 0.120

11.225 11.885 14.355Al seethe with excitement ₂(SO ₄) ₃100 0.0035 0.0035 0.0045

Table 5 antioxidant property is under 1000 ℃ of situations

Time (h) weightening finish

1 2 3

24 -0.0002089 0.0002091 0.0002090

72 0.0003415 0.0003425 0.0003417

96 0.0008535 0.00085 0.0008541

120 0.0008648 0.0008657 0.0008646

148 0.0015956 0.0016006 0.0015960

Three kinds of alloys are at 100 ℃ of Al ₂(SO ₄) ₃Solution, the 196MPa effect is not seen corrosion after 2640 hours down.

At 100 ℃ of 10%H ₂SO ₄, the 196MPa effect was not down seen macro etch in 2640 hours yet.

In a word, used noble metal is less in this alloy, and cost is lower than alloy of the same type, more is lower than Nickel-base alloy, sulfuric acid corrosion resistant and the erosion of sulfuric-resisting root-rot all are better than the latter greatly, and have preferably Thermal conductivity, resistance to high temperature oxidation and stress corrosion performance are particularly suitable for chemical industry, the industries such as pharmacy Needs.

Claims (2)

1. siderochrome nickle-base corrosion-resisting high alloy, it is characterized in that: the composition scope of alloy is as follows: (weight percent) C Cr Ni Mo Si Cu Nb≤0.02 17,/22 31/36 2.5/4.5 2.0/3.0 3.0/4.0 0.4/0.6

S、P Fe

≤ 0.00 4 surplus.

2. by the described iron chromium nickelio high alloy of claim 1, it is characterized in that best composition scope is as follows: (weight percent) C Cr Ni Mo Si Cu Nb≤0.01 18,/21 32/35 3.5/4.5 2.0/3.0 3.0/4.0 0.4/0.6

S、P Fe

≤ 0.004 surplus.