CN1341770A

CN1341770A - Ferritic stainless seamless steel tube capable of resisting seawater corrosion

Info

Publication number: CN1341770A
Application number: CN 01114400
Authority: CN
Inventors: 束润涛
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-08-01
Filing date: 2001-08-01
Publication date: 2002-03-27

Abstract

The present invention relates to a seawater corrosion resistant ferritic stainless steel seamless steel tube, and is characterized by adding rare earth into high-alloy pure ferritic stainless steel, after smelted, making it into seamless steel tube by means of drawing process. As compared with 316L austenite stainless steel said invention has no alloy elements sensitive to stress corrosion in its composition design, so that it possesses congenital immunocompentence to stress corrosion, and also possesses excellent complete corrosion-resisting capability, and can be extensively used in the seawater cooling equipments of petroleum industry, chemical industry and power industry, and can be used in the heat-exchanger and air cooling equipment with high-concentration chlorine ion corrosion.

Description

The ferritic stainless seamless steel tube of seawater corrosion resistance

The present invention relates to corrosion-resistant pipe shell heat exchanger, condenser and the air cooler weldless steel tube of industries such as oil, chemical industry, electric power.

In industries such as oil, chemical industry, electric power, many coastal enterprises make water coolant with seawater mostly and use, and contain a large amount of salinities and the corrosion product of other microorganism in the seawater in order to save Freshwater resources.In the environment of seawater and other chloride ion corrosion, tube and shell heat exchanger, condenser and finned air cooler, because the thin (δ≤3.5mm) of heat transfer tube and finned tube parent tube wall thickness, plain carbon stool pipe (as No. 10, No. 20) does not possess corrosion resistance, generally can only be with just corrosion failure of some months, though and austenitic stainless steel has anti-preferably pitting corrosion, spot corrosion and uniform corrosion performance,, in the chloride ion-containing media environment, uses austenitic stainless steel (18-8,304L, 316,316L) anticorrosion stress-resistant performance extreme difference owing to having limited it.Some electric power enterprises are done heat exchanger tube with copper pipe, though copper pipe has good heat-conducting, copper pipe easily causes corroding dezincify when temperature is high slightly.Doing with seawater in the corrosive environment of heat-eliminating medium for a long time, be difficult to find a kind of alternative material of economy and durability always, many enterprises have to be dealt with the form of spraying, but the work-ing life of carbon steel spraying can be above 2 years yet, come off easily because carbon steel is sprayed under the effect of high temperature and flow velocity, still be difficult to satisfy the requirement of production equipment long-term operation.Recently some enterprises bring into use expensive duplex stainless steel (SAF2205, SAF2507 etc.) and titanium material, but are difficult to generally be applied owing to it costs an arm and a leg.

The objective of the invention is provides a kind of both anti-muriatic stress corrosion for industries such as oil, chemical industry, electric power, the high alloy ferrite stainless steel tubing that has very strong anti-muriate spot corrosion ability again, and make interchanger and air cooler with high alloy ferrite stainless steel tubing.

The objective of the invention is by following scheme implementation:

Develop a kind of both anti-muriatic stress corrosion, have the very strong anti-muriate spot corrosion and the high alloy ferrite stainless steel tubing of crevice corrosion ability again, its corrosion resistance nature is higher than ferritic stainless steel 1Cr17Mo2Ti commonly used, has good welding property simultaneously again.(%) is as follows for its chemical ingredients:

C≤0.08; Si≤0.60; Mn≤0.90; Cr:16.0-32.0; Mo:1.50-3.50; Ni≤0.25; Cu≤0.25; Ti:5 * C≤0.80; S≤0.030; P≤0.030; RE add-on≤0.20; Surplus is iron (Fe).

Embodiment 1 chemical ingredients (%) is as follows:

C≤0.06; Si≤0.50; Mn≤0.60; Cr:17.0-21.0; Mo:1.50-3.50; Ni≤0.20; Cu≤0.20; Ti:5 * C≤0.80; S≤0.015; P≤0.030; RE add-on≤0 20; Surplus is iron (Fe).Determine that according to the proportioning of chemical ingredients in the steel its grade of steel is 0Cr19Mo2TiRE.The tubing of 0Cr19Mo2TiRE is mainly used in temperature less than 80 ℃ seawater heat exchanger.

Embodiment 2 chemical ingredientss (%) are as follows:

C≤0.06; Si≤0.50; Mn≤0.60; Cr:28.0-32.0; Mo:1.50-3.50; Ni≤0.20; Cu≤0.20; Ti:5 * C≤0.80; S≤0.015; P≤0.030; RE add-on≤0.20; Surplus is iron (Fe).Determine that according to the proportioning of chemical ingredients in the steel its grade of steel is 0Cr30Mo2TiRE.Because Cr content is very high in the steel, its corrosion resistance nature is better than 0Cr19Mo2TiRE greatly.The tubing of 0Cr30Mo2TiRE is mainly used in temperature greater than 80 ℃ seawater heat exchanger.A. the content owing to austenite former Ni in the steel is extremely low, so 0Cr19Mo2TiRE and 0Cr30Mo2TiRE belong to pure ferritic stainless steel, when Cu+Ni in the steel≤0.50%, the 0Cr19Mo2TiRE of annealed state and 0Cr30Mo2TiRE do not produce the chloride stress cracking corrosion failure.B. in order to prevent intergranular corrosion, stabilizing element Ti must satisfy: 5 * C≤Ti≤0.80%.Xiang Gangzhong adds Ti, can make the carbide, the nitride that contain chromium in the steel transfer to form titaniferous carbide, nitride, and carbon and nitrogen are played static stabilization, and the crystal grain of refinement ferritic stainless steel.C. add rare earth (RE) and be the outstanding feature of the technical program in composition design, the adding of rare earth is to control form, size and the quantity of steel inclusion, the up to the present domestic precedent that does not also add rare earth in stainless steel.Because rare earth (RE) can have great affinity interaction with low melting point metal and nonmetal composition S, O, N, C, the Si in the steel, can control the form and the size of the inclusion in the steel effectively, pure steel, the corrosion resistance and the impelling strength of raising steel.Simultaneously, because C, N in rare earth energy and the steel form corresponding compounds, when welding, can stop heat affected zone Cr effectively ₂₃C ₆And Cr ₂N separates out at crystal boundary, is quite useful to the intergranular corrosion resistance ability that improves ferritic stainless steel.The ability of rare earth desulfurization and deoxidation and calcium magnesium seemingly and can be controlled form, size and the quantity of the inclusion of oxygen and sulphur in the steel effectively, and the optimum ratio relation of rare earth and sulphur (RE/S) residual component in steel should be controlled in 2 to 6.09Cr2AlMoRE that has developed according to me and the inclusion comparative analysis of 12Cr2AlMoV, in the photo of 1000 times of amplifications, the inclusion of 12Cr2AlMoV is obviously more than 09Cr2AlMoRE, and the inclusion of 09Cr2AlMoRE is few and small, the inclusion of 09Cr2AlMoRE all≤5 μ m, and the inclusion that does not contain rare earth 12Cr2AlMoV all 〉=5 μ m.d. are because Cr and Mo among the 0Cr19Mo2TiRE are suitable with the 316L steel, its anti-pitting performance is better than 304L. 0Cr30Mo2TiRE owing to the effect of RE alloying and the raising of chromium, and it is suitable with pure nickel in some medium that its corrosion resistance nature is better than dual phase steel 0Cr25Ni5Mo3N..E.0Cr19Mo2TiRE, the 0Cr30Mo2TiRE steel can be smelted with electric furnace, open hearth or external refining.Weldless steel tube adopts the method manufacturing of cold-drawn.0Cr19Mo2TiRE, 0Cr30Mo2TiRE steel all adopt annealing to heat-treat.

With the heat transfer tube (3-2) of 0Cr19Mo2TiRE or 0Cr30Mo2TiRE steel tubing manufacturing interchanger and condenser, with spot corrosion and the pitting corrosion of muriate and microorganism in the opposing seawater, and muriatic stress corrosion.Available common 16Mn forging of tube sheet (3-1) or 304L, 316L stainless steel are in order to prevent to produce too much carbide Cr at weld heat-affected zone ₂₃C ₆And Cr ₂N, the welding material of 0Cr19Mo2TiRE should be used Ultralow Carbon Stainless Steel welding wire H00Cr24Ni13Nb or H00Cr18Ni12Mo2; The welding material of 0Cr30Mo2TiRE should be used the dual phase steel argon arc welding welding wire of Ultralow Carbon Stainless Steel welding wire H00Cr24Ni13Nb or Cr 〉=25%, weld with argon arc welding, without preheating and thermal treatment, weld seam is ferrite and austenite duplex structure, still has goodish corrosion resistance nature.

The ferritic stainless seamless steel tube of seawater corrosion resistance of the present invention belongs to pure ferritic stainless steel, has excellent corrosion resisting performance, is a kind of inexpensive steel grade.0Cr19Mo2TiRE, 0Cr30Mo2TiRE steel pipe and equipment often can be used for refining oil, chlorion (100-140 ℃) corrosion of decompression overhead condenser, the corrosive environment of petrochemical industry and power system seawater (20-50 ℃) condenser, and interchanger at the bottom of high temperature resistance naphthenic acid (〉=220 ℃) and high temperature sulphur (〉=240 ℃) the corrosive tower in the oil refining apparatus.Compare with the 316L austenitic stainless steel, owing to there is not the alloying element of counter stress corrosion-susceptible in the composition design, the counter stress corrosion has the geneogenous ability of exempting from service, thereby has goodish anticorrosion stress-resistant performance.Simultaneously, because chromium, molybdenum content are higher in the steel, its anti-general corrosion performance is also quite superior.The total cost of 0Cr19Mo2TiRE, 0Cr30Mo2TiRE tubing and equipment is lower than the 316L austenitic stainless steel, and can overcome the insoluble stress corrosion harm of 316L austenitic stainless steel institute, has boundless market outlook.Industries such as oil, chemical industry, electric power be can be widely used in and the working condition of condenser or interchanger and the interchanger and the air cooler of other environment middle and high concentration chloride ion corrosion made with seawater.

Claims

1. the ferritic stainless seamless steel tube of a seawater corrosion resistance, it is made of alloying elements such as C, Si, Mn, S, P and Cr, Mo, Ti, and it is characterized in that: add RE (rare earth) in alloying constituent, its chemical ingredients is as follows: C≤0.08%; Si≤0.60%; Mn≤0.90%; Cr:16.0-32.0%; Mo:1.50-3.50%; Ni≤0.25%; Cu≤0.25%; Ti:5 * C≤0.80%; S≤0.030%; P≤0.030%; RE add-on≤0.20%; Surplus is iron (Fe).

2. as claims 1 described ferritic stainless seamless steel tube, it is characterized in that: rare earth and sulphur (RE/S) ratio relation of residual component in steel should be controlled in 2 to 6.