EP0256429B1 - Acier de construction résistant à la fissuration par corrosion sous contraintes - Google Patents

Acier de construction résistant à la fissuration par corrosion sous contraintes Download PDF

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Publication number
EP0256429B1
EP0256429B1 EP87111293A EP87111293A EP0256429B1 EP 0256429 B1 EP0256429 B1 EP 0256429B1 EP 87111293 A EP87111293 A EP 87111293A EP 87111293 A EP87111293 A EP 87111293A EP 0256429 B1 EP0256429 B1 EP 0256429B1
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EP
European Patent Office
Prior art keywords
corrosion cracking
stress corrosion
titanium
steel
carbon
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP87111293A
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German (de)
English (en)
Other versions
EP0256429A1 (fr
Inventor
Lutz Dr. Meyer
Ludwig Dr. Hachtel
Günter Robusch
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thyssen Stahl AG
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Thyssen Stahl AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Thyssen Stahl AG filed Critical Thyssen Stahl AG
Priority to AT87111293T priority Critical patent/ATE58183T1/de
Publication of EP0256429A1 publication Critical patent/EP0256429A1/fr
Application granted granted Critical
Publication of EP0256429B1 publication Critical patent/EP0256429B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium

Definitions

  • the invention relates to the use of a weldable structural steel with high resistance to intergranular stress corrosion cracking, in particular in nitrate solutions, and good weldability.
  • Damage due to intergranular stress corrosion cracking occurs in high-performance wind heaters that are operated at very high temperatures. This damage is triggered as a result of the increased formation of nitrogen oxides in the hot wind heated to temperatures of over 1,300 ° C and the formation of a nitrate-containing electrolyte when the wind moisture condenses on the system components of the hot water heater, which are usually made of unalloyed or low-alloyed steels.
  • a remedial measure against damage due to stress corrosion cracking which has proven itself for two decades, is the application of external thermal insulation, the so-called outer insulation, by means of which the sheet temperature can be raised to such an extent that the condensate that triggers the stress corrosion cracking is not separated.
  • high-alloy steels such as stainless CrNiMo steels
  • stainless CrNiMo steels has also proven itself, for example for the particularly exposed high-stress compensators in the line systems of the hot water heaters or as a support material for clad sheets.
  • DE-PS 2907 152 discloses a steel for lining furnaces, boilers and high-temperature heaters in which combustion gases containing nitrogen oxide occur.
  • This steel contains additives of chrome, molybdenum and niobium.
  • the ratio of niobium: (carbon + nitrogen) should not be greater than 7. While the alloying elements chromium and molybdenum are important for the formation of a passive layer on the surface of the steel, part of the carbon and nitrogen should be bound by niobium in order to avoid chromium depletion at the grain boundaries during welding or when exposed to heat. The sum of carbon and nitrogen should not exceed 0.06%. With regard to the stoichiometric setting ratio, niobium is lower than carbon and nitrogen. Chromium carbides and carbonitrides must also necessarily form. Titanium is mentioned as another carbide and nitride forming element. However, it should not be as effective as niobium.
  • DE-PS 2819 227 describes a manganese steel which is to be used in the normalized state as a material for such components which are exposed to alkaline, neutral or weakly acidic solutions, in particular for hot air heaters.
  • This steel contains a relatively high carbon content of up to 0.18% and, in addition to manganese, niobium and copper, coordinated phosphorus and sulfur contents in order to avoid intergranular hydrogen-induced cracks.
  • the steel can also optionally contain nickel, chromium and titanium. A complicated procedure is prescribed for the welding of steel, in order to achieve a higher resistance of welded structures against stress corrosion cracking and against other crack formation.
  • the invention is based on the object of proposing a weldable structural steel which can be welded according to a simple method and which, with little effort for alloy elements, has a high resistance to stress corrosion cracking, in particular in nitrate solutions, and has good toughness and formability.
  • the complete bonding of the carbon and nitrogen by the strong carbonitride former titanium with a higher than stoichlometric concentration of the titanium enables a higher resistance to stress corrosion cracking to be achieved.
  • titanium is not recommended in DE-PS 2907 152
  • the titanium additive according to the invention has proven to be particularly effective in order, in cooperation with the chromium content of 2.0 to 5.5% provided according to the invention, to provide a high level of security against stress corrosion cracking, particularly among the conditions that characterize the hot water heater.
  • a chromium content of less than 2% has proven to be ineffective. If the chromium content is increased above 5.5%, the workability of the steel is increasingly impaired and the costs increase.
  • titanium carbide compound one atom of titanium and one atom of carbon are bonded to one another.
  • a stoichiometric mass ratio of 4: 1 is necessary due to the atomic weight of 48 for titanium and 12 for carbon, i.e. that for the stoichiometric setting of a certain carbon content at least four times the mass content of titanium is required.
  • carbon and nitrogen are bonded together by titanium, stoichiometric setting results in a somewhat lower stoichiometric ratio because of the higher atomic weight of nitrogen of 14.
  • the required titanium content must therefore be at least 3.5 times higher than the sum of the carbon and nitrogen contents.
  • titanium is an alloying element that, with sufficient concentration and taking into account the carbon and nitrogen contents, can bind the phosphorus in the steel or at least severely restrict its activity. According to the invention, the harmful influence of phosphorus is therefore suppressed or eliminated with a titanium content which is over-stoichiometric with respect to the sum of carbon and nitrogen.
  • a content of at most 0.02% by weight is provided according to the invention.
  • a higher phosphorus content would increase the undesirable tendency to stress corrosion cracking.
  • the sulfur content is also at most 0.02% by weight. A higher sulfur content affects the workability during welding and forming and can also undesirably set part of the alloying element titanium.
  • the steel according to the invention contains 0.2 to 2.5% manganese.
  • a lower manganese content deteriorates the toughness and the surface quality of the sheet.
  • Manganese contents of more than 2.5% by weight make metallurgical production more difficult and increase costs without causing any appreciable improvement in properties.
  • nickel can be added up to 1.0%.
  • a higher nickel content does not further improve the toughness, but makes the steel considerably more expensive.
  • Aluminum is contained within the specified limits due to the manufacturing process.
  • the silicon content is limited to 0.5%. A higher silicon content can impair welding behavior and brittle fracture protection.
  • the economic advantage for the manufacturer and operator of hot-water systems or similar units becomes particularly clear when using the steel according to the invention, because the measures which have been necessary to date against the occurrence of stress corrosion cracking, such as external insulation of the hot-water heater or the use of expensive stainless austenitic steels, spare.
  • the steel used according to the invention is also suitable for components of heat exchangers, as well as of furnaces, boilers, containers, vessels and pipelines, which are particularly exposed to nitrate solutions.
  • Table 1 shows the chemical composition of the steels examined.
  • the comparative steel A is a known unalloyed steel and the comparative steels B and C are known alloyed steels with different contents of chromium and / or titanium.
  • Steel D falls within the scope of DE-PS 2907152.
  • Steels E1 and E2 are composed according to the invention.
  • Table 2 shows the tensile strength, yield strength and elongation at break of the investigated steels and the behavior of the steels towards stress corrosion cracking when tested with a constant strain rate by specifying the fracture constriction and when testing under constant load by specifying the service life until fracture.
  • the conditions of the two stress crack corrosion tests at constant strain rate and constant load are detailed in the lower part of Table 2.
  • the tempered state was also examined in addition to the normalized state in order to enable a comparison in both heat treatment states.
  • the values determined show the improved resistance of the steels E1 and E2 according to the invention to stress corrosion cracking.
  • the contraction of the fracture after constant elongation represents a much sharper criterion than the service life after constant stress.
  • the differentiation in favor of the steel according to the invention is therefore highly significantly clearer in the first-mentioned test criterion. Often only the milder test conditions with constant load are discussed in the literature.
  • Figure 1 shows the results of the test for resistance to stress corrosion cracking, expressed in the fracture constriction of all the steels examined.
  • the diagram shows the improvement in the resistance to stress corrosion cracking of the steels E1 and E2 according to the invention.
  • Figure 2 shows the appearance of specimens tested for stress corrosion cracking. The degree of constriction as a measure of the resistance to stress corrosion cracking can be clearly seen.
  • Figure 3 shows microscopic images from the surface area of the samples tested for intergranular stress corrosion cracking. This shows the difference in the mechanism of structural change caused by the corrosion medium combined with mechanical tensile stress.
  • Figure 3a shows a crack that was created under the test conditions with reference steel A.
  • Figures 3b and 3c make it clear for the steel E2 according to the invention in a normalized or tempered state that the classic destruction by stress corrosion cracking does not occur here.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
  • Chemical Or Physical Treatment Of Fibers (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Prevention Of Electric Corrosion (AREA)
  • Secondary Cells (AREA)

Claims (4)

1. Utilisation d'un acier de constuction constitué de (en % en masse) :
0,01 à 0,04 % de carbone
jusqu'à 0,012 % d'azote
0,08 à 0,22 % de titane avec la proportion Ti ≥ 3,5 · (C + N)
0,2 à 2,5 % de manganèse
2,0 à 5,5 % de chrome
0,01 à 0,10 % d'aluminium
jusqu'à 0,5 % de silicium
jusqu'à 1,0 % de nickel
jusqu'à 0,02 % de phosphore
jusqu'à 0,02 % de soufre
le reste étant du fer et les impurtés inévitables, comme matière première pour des pièces de constuction de récupérateurs de chaleur et pour des pièces de construction d'échangeurs thermiques ainsi que des fours, de chaudières, de récipients et de conduites tubulaires qui doivent présenter une résistance élevée à la corrosion fissurante intercristalline, en particulier dans les solutions de nitrate.
2. Utilisation d'un acier de construction selon la revendication 1, constitué de :
0,01 à 0,02 % de carbone
jusqu'à 0,005 % d'azote
0,08 à 0,15 % de titane avec la proportion Ti ≥ 3,5 (C + N)
0,2 à 2,0 % de manganèse
2,5 à 5,5 % de chrome
0,01 à 0,10 % d'aluminium
jusqu'à 0,5 % de silicium
jusqu'à 0,01 % de phosphore
jusqu'à 0,01 % de soufre
le reste étant du fer et les impurtés inévitables, dans l'application de la revendication 1.
3. Utilisation d'un acier de construction ayant la composition selon la revendication 1 ou 2 comme matière première pour des pièces de construction de résupérateurs de chaleur et pour des pièces de construction d'échangeurs thermiques ainsi que de fours, de chaudières, de récipients et de conduites tubulaires, qui doivent être soudables sans fissure sans prétraitement et post-traitement thermiques.
4. Utilisation d'un acier de construction ayant la composition selon la revendication 1 ou 2 comme matière premiûre pour des pièces de construction de récupérateurs de chaleur et pour des pièces de construction d'échangeurs thermiques ainsi que de fours, de chaudières, de récipients et de conduites tubulaires, qui, avec une sollicitude mécanique et corrosive simultanée, doivent présenter une durée de vie de plus de 2400 h lors d'un essai de corrosio fissurante due à la contrainte dans une solution bouillante contenant 100 g de nitrate/1 sous une charge constante de 1,4 Rp 0,2 et une striction supérieure à 40 % après un essai de corrosion fissurante dua à la contrainte dans une solution à 90°C contenant 10 g de nitrate/1 à une vitesse d'allongement constante.
EP87111293A 1986-08-14 1987-08-05 Acier de construction résistant à la fissuration par corrosion sous contraintes Expired - Lifetime EP0256429B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT87111293T ATE58183T1 (de) 1986-08-14 1987-08-05 Spannungsrisskorrosionsbestaendiger baustahl.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3627668A DE3627668C1 (de) 1986-08-14 1986-08-14 Gut schweissbaren Baustahl mit hoher Bestaendigkeit gegen Spannungsrisskorrosion
DE3627668 1986-08-14

Publications (2)

Publication Number Publication Date
EP0256429A1 EP0256429A1 (fr) 1988-02-24
EP0256429B1 true EP0256429B1 (fr) 1990-11-07

Family

ID=6307425

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87111293A Expired - Lifetime EP0256429B1 (fr) 1986-08-14 1987-08-05 Acier de construction résistant à la fissuration par corrosion sous contraintes

Country Status (7)

Country Link
US (1) US4919885A (fr)
EP (1) EP0256429B1 (fr)
JP (1) JPS63105950A (fr)
KR (1) KR880003024A (fr)
AT (1) ATE58183T1 (fr)
DE (2) DE3627668C1 (fr)
ES (1) ES2018801B3 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH08946B2 (ja) * 1988-08-19 1996-01-10 株式会社神戸製鋼所 耐食性に優れた吸収式熱機器用鋼材および管
US6149862A (en) * 1999-05-18 2000-11-21 The Atri Group Ltd. Iron-silicon alloy and alloy product, exhibiting improved resistance to hydrogen embrittlement and method of making the same
US6737018B2 (en) * 2001-01-16 2004-05-18 Jfe Steel Corporation Corrosion-resistant chromium steel for architectural and civil engineering structural elements
EP1794486B1 (fr) * 2004-09-28 2011-04-06 Gall & Seitz Systems GmbH Tuyau a paroi double
DE102007005154B4 (de) * 2007-01-29 2009-04-09 Thyssenkrupp Vdm Gmbh Verwendung einer Eisen-Chrom-Aluminium-Legierung mit hoher Lebensdauer und geringen Änderungen im Warmwiderstand
US10639719B2 (en) 2016-09-28 2020-05-05 General Electric Company Grain boundary engineering for additive manufacturing

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2320185A1 (de) * 1973-04-19 1974-10-31 Thyssen Huette Ag Verwendung eines stahls

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2315156A (en) * 1941-10-10 1943-03-30 Clifford P Larrsbee Low-alloy corrosion-resistant steel
FR1333278A (fr) * 1962-08-29 1963-07-26 Yawata Iron & Steel Co Rail ayant une résistance à la traction élevée et résistant à la corrosion
IT1000219B (it) * 1973-12-06 1976-03-30 Centro Speriment Metallurg Acciaio per impieghi marini ad elevata resistenza meccanica
GB1568616A (en) * 1977-09-02 1980-06-04 British Steel Corp Corrosion resistant steels
JPS54112717A (en) * 1978-02-24 1979-09-03 Nippon Steel Corp Steel products with nitrate stress corrosion cracking resistance
DE2819227C2 (de) * 1978-05-02 1984-06-14 Stahlwerke Peine-Salzgitter Ag, 3150 Peine Schweißbarer Manganstahl sowie Verfahren zum Schweißen dieses Manganstahles
US4261739A (en) * 1979-08-06 1981-04-14 Armco Inc. Ferritic steel alloy with improved high temperature properties
JPS5817055A (ja) * 1981-07-17 1983-02-01 Canon Inc シ−ト材取扱い装置
JPS6024352A (ja) * 1984-06-22 1985-02-07 Sumitomo Metal Ind Ltd 湿潤炭酸ガス腐食抵抗及び溶接性にすぐれたラインパイプ用鋼

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2320185A1 (de) * 1973-04-19 1974-10-31 Thyssen Huette Ag Verwendung eines stahls

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Handbook of Stainless Steel (1973) MC Greaw-Hill, p. 14-11 *

Also Published As

Publication number Publication date
KR880003024A (ko) 1988-05-13
JPS63105950A (ja) 1988-05-11
JPH0437153B2 (fr) 1992-06-18
ES2018801B3 (es) 1991-05-16
US4919885A (en) 1990-04-24
DE3627668C1 (de) 1988-03-24
DE3766040D1 (de) 1990-12-13
ATE58183T1 (de) 1990-11-15
EP0256429A1 (fr) 1988-02-24

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