CA1070144A - Structural member made of low alloyed steel corrosion resistant to sea water - Google Patents
Structural member made of low alloyed steel corrosion resistant to sea waterInfo
- Publication number
- CA1070144A CA1070144A CA258,242A CA258242A CA1070144A CA 1070144 A CA1070144 A CA 1070144A CA 258242 A CA258242 A CA 258242A CA 1070144 A CA1070144 A CA 1070144A
- Authority
- CA
- Canada
- Prior art keywords
- percent
- weight
- sea water
- structural member
- content
- 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
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Classifications
-
- 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
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
-
- 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
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A structural member for sea water desalination plants that operate according to the flash distillation process, e.g. a flash chamber, which member comes into contact with sea water, said member being made of a low alloyed steel and being at least three to ten times more resistant than St 37-type steel to the static and dyanamic corrosion of aerated sea water ranging in temperature up to 115°C, which steel contains no molybdenum and consists essentially of: 0.01 to 0.15 percent in wieght of carbon; 2.0 to 4.5 percent in weight of chromium; 0.1 to 1.0 percent in weight of columbium;
optionally copper, nickel and manganese in an amount of between 0.0 and maximally 2.5 percent in weight taken all together; optionally fine grain formers, such as aluminum, titanium and vanadium in an amount of between 0.0 and maximally 0.2 percent in weight taken all together and; balance iron and impurities due to melting, such as silicon, all of which alloying elements bein below the passivating limit.
A structural member for sea water desalination plants that operate according to the flash distillation process, e.g. a flash chamber, which member comes into contact with sea water, said member being made of a low alloyed steel and being at least three to ten times more resistant than St 37-type steel to the static and dyanamic corrosion of aerated sea water ranging in temperature up to 115°C, which steel contains no molybdenum and consists essentially of: 0.01 to 0.15 percent in wieght of carbon; 2.0 to 4.5 percent in weight of chromium; 0.1 to 1.0 percent in weight of columbium;
optionally copper, nickel and manganese in an amount of between 0.0 and maximally 2.5 percent in weight taken all together; optionally fine grain formers, such as aluminum, titanium and vanadium in an amount of between 0.0 and maximally 0.2 percent in weight taken all together and; balance iron and impurities due to melting, such as silicon, all of which alloying elements bein below the passivating limit.
Description
The invention relates to a low-alloyed steel having im~
proved eorrosion behaviour r in partieular relative to sea water.
Unalloyed steels eorrode to different degrees when subjeet-; ed to sea water, brackish water, polluted fresh water, the atmos-phexe and the soils in the area of sueh waters, depending on the eoneentration, the pH~value, the gas eontent (in partieular the oxygen eontent), the flow rate and the temperature of the ag-gressive media. For this reason construction parts and struetures of unalloyed steels, such as ships, marine structures, are pro-teeted against eorrosion by a eoating.
Often, however, teehnical and eeonomieal considerations do not permit eorrosion protection by eoating, or they require a . corrosion-inhibiting behaviour of the base material in case of danger of damage to the eoating.
: The influence of corrosion can impair the safety and func-tioning of a strueture (e.g. by redueing the supporting eross section, by cracks, leaks and the like). In certain cases of . application also the amount of the corrosion products formed can negatively affect the functioning, e.g. a clogging of heat ex-~ 20 ehanger tubes and pipes in sea water desalination plants or eooling systems.
: Therefore, a material to get into eontact with eorroding - media ought to have an improved behaviour against plane eorrosion as well as against loeal corrosion.
As is known the inherent corrosion proteetion of steels is eaused by the formation of a more or less dense protective layer .-- on the surfaee. In high alloyed corrosion and aeid resistant . steels this proteetive layer consists of a thin, but very dense, adhering layer of metal oxide that is largely resistant to ehem-ical media, the so-called "passive" layer. Low alloyed steels - ~70~
. .
can also be protected against atmospherlc corrosion by forming coyering layers, which, however, cannot be compared with a passive layer. These comparatively thick, but increasingly dense covering layers are ormed by initial corrosion in the course of numerous wet and dry periods and consist mairlly of water-insoluble crystallized corrosion products. Although these layers arc not as dense as closed oxide layers, they still prevent or reduce, respectively, the admission of oxygen to the surface of the steel. ~ith these low alloyed steels which are known as weather-proof structural steels the possibility of forming a protective layer largely gets lost in the case of constant immersion or the protective effect of the covering layer largely gets lost in the case of chlorine containing aggressive media.
For the last mentioned corrosion conditions, high alloyed steels forming a passive layer h~ve been the only materials hitherto available.
But for economical reasons it is not always possible to use them. On the other hand, the contents of passivating alloying elements required is so high that the production and processing of such steels is limited.
It would be advantageous to have a low alloyed steel having improved corrosion resistance to sea water and in particular locali~ed corrosion resistance, whose strength and workability meet about the demands made on structural steel, whose production costs, however, are far below those of high alloyed steels forming a passive layer.
In general terms the present invention makes use of a combination of alloying elements which, due to their affinity to oxygen, can form stable oxides and covering layers and which can also form hardly soluble complexes with chlorine compounds.
More particularly, the present invention provides a structural member for sea water desalination plants that operate according to the flash distillation process, e.g. a flash chamber, which member comes into contact with sea water, said member being made of a low alloyed steel and being at Y
~ - 2 -',, ", : ', .
. ' ' ' ' '-`' 1~70~
:
least three to ten times more resistant than St 37-type steel to the static and dyanamic corrosion of aerated sea water ranging in temperature up to 115C, which steel contains no molybdenum and consists essentially of:
0.01 to 0.15 percent in weight of carbon; 2.0 to ~.5 percent in weight of chromium; 0.1 to 1.0 percent in weight of columbium; optionally copperJ
nickel, and manganese in an amountof between 0.0 and maximally 2.5 percent in weight taken all together; optionally fine grain formers, such as aluminum, titanium and vanadium in an amount of between 0.0 and maximally 0.2 percent in wei~ht taken all together; and balance iron and impurities due . 10 to melting, such as silicon, all of which alloying elements being below the '; passivating limit. ,''' .:..
~' .
~,:
. .
:
!'~
'' .
'' ~ - 2a -.
.. ' ' ' , ' .
.: .
.
',:, 70~44 Here all the contents of alloying elements are below the passivating limit.
It was found that the chromium con-tent in the steel of the invention, whose upper limit (4.5%) is far below the limit for complete chromium passivation ~13.5% chromium), causes the excellent resistance of the steels of the invention to plane corrosionl wherein a raising of the limit beyond 4.5% does not lead to furthcr lmprovement. Such a steel it was found - would, however, be very prone to localized corrosion without a content of columbium. According to the invention, this proneness to localized corrosion is inhibited by the ad-ditional columbium content. The copper content has the same kind of effect;
it has shown that the effect of the chromium-columbium-combination can be improved by the addition of copper.
Thus, a preferred composition of steel consists in that the steel has a carbon content of between 0.01 and 0.1% by weight, a chromium content of between 3.0 and 4.0% by weight, a columbium content of between 0.5 and . ' , 1.0% by weight, a copper content of between 0.5 and 1.0% by weight, a manganese content of between 0.3 and 0.6% by weight and an aluminum content of between 0.02 and 0.1% by weight.
-~ For reasons of production and with a view to a further improvement of the corrosion resistance, an additional nickel content is advantageous, which ought to amount to at least half the . ...
` - 3 _ ..
,,~'' ~7~4~
copper content.
According to a ~urther preferred embodiment, the steel of the invention contains fine grain formers, such as aluminum, titanium and vanadium, in the amounts of between 0.02 and 0.2 by weight titanium and/or between 0.05 and 0.15 ~ by weight vanadium and/or between 0.02 and 0.1 ~ by weight aluminum, but totalling not more than 0.2 % by weight.
Preferably the steel has a sulphur content of maximumly 0.017 ~ by weight and a phosphorus content of maximumly 0.015 %
- 10 by weightA
-The following Table 1 gives three steel compositions I, II, III, which in tests have proved to be corrosion resistant.
.
Steel No. C Si Mn P S Al Cr Ni Cu Nb ;-I 391 0.057 0.28 0.50 0.015 0.017 0.031 3.10 0.5 0.98 0.64 %
II 411 0.07 0.30 0.49 0.014 0~013 0.040 3.04 _ 0.52 0.32 ~
III 381 0.07 o.26 0.47 0.013 0.017 0.048 3.I5 _ _ 0.33 %
~;The mechanical properties of these steels after normalizing are the following:
!
- 20Steel 0.2 2 e~B 5 kp/mm ~
I 45.6 62.1 28.6 II 26.0 46.9 37.3 III 30.7 49.8 36.0 The following Tables 2, 3, 4 and 5 illustrate the corrosion behaviour of steels I, II, III in detail as compared to a soft, unalloyed control steel of the St 37-type.
.
~ Table 2 relates to dynamic corrosion tests in steels I, II
`'~,' :
~)7~
and III in the laboratory in artificial sea water (produced ; according to ASTM D 1141), whose temperature was 75C at one time and 115C at another time. The oxygen content of the sea water was also varied: it was 40 ppb in one case and 500 ppb (1 ppb = 1 part per billion ~ 0.0000001 %) in the other case.
The pH-value was 7.4 in both test series and the water rate was
proved eorrosion behaviour r in partieular relative to sea water.
Unalloyed steels eorrode to different degrees when subjeet-; ed to sea water, brackish water, polluted fresh water, the atmos-phexe and the soils in the area of sueh waters, depending on the eoneentration, the pH~value, the gas eontent (in partieular the oxygen eontent), the flow rate and the temperature of the ag-gressive media. For this reason construction parts and struetures of unalloyed steels, such as ships, marine structures, are pro-teeted against eorrosion by a eoating.
Often, however, teehnical and eeonomieal considerations do not permit eorrosion protection by eoating, or they require a . corrosion-inhibiting behaviour of the base material in case of danger of damage to the eoating.
: The influence of corrosion can impair the safety and func-tioning of a strueture (e.g. by redueing the supporting eross section, by cracks, leaks and the like). In certain cases of . application also the amount of the corrosion products formed can negatively affect the functioning, e.g. a clogging of heat ex-~ 20 ehanger tubes and pipes in sea water desalination plants or eooling systems.
: Therefore, a material to get into eontact with eorroding - media ought to have an improved behaviour against plane eorrosion as well as against loeal corrosion.
As is known the inherent corrosion proteetion of steels is eaused by the formation of a more or less dense protective layer .-- on the surfaee. In high alloyed corrosion and aeid resistant . steels this proteetive layer consists of a thin, but very dense, adhering layer of metal oxide that is largely resistant to ehem-ical media, the so-called "passive" layer. Low alloyed steels - ~70~
. .
can also be protected against atmospherlc corrosion by forming coyering layers, which, however, cannot be compared with a passive layer. These comparatively thick, but increasingly dense covering layers are ormed by initial corrosion in the course of numerous wet and dry periods and consist mairlly of water-insoluble crystallized corrosion products. Although these layers arc not as dense as closed oxide layers, they still prevent or reduce, respectively, the admission of oxygen to the surface of the steel. ~ith these low alloyed steels which are known as weather-proof structural steels the possibility of forming a protective layer largely gets lost in the case of constant immersion or the protective effect of the covering layer largely gets lost in the case of chlorine containing aggressive media.
For the last mentioned corrosion conditions, high alloyed steels forming a passive layer h~ve been the only materials hitherto available.
But for economical reasons it is not always possible to use them. On the other hand, the contents of passivating alloying elements required is so high that the production and processing of such steels is limited.
It would be advantageous to have a low alloyed steel having improved corrosion resistance to sea water and in particular locali~ed corrosion resistance, whose strength and workability meet about the demands made on structural steel, whose production costs, however, are far below those of high alloyed steels forming a passive layer.
In general terms the present invention makes use of a combination of alloying elements which, due to their affinity to oxygen, can form stable oxides and covering layers and which can also form hardly soluble complexes with chlorine compounds.
More particularly, the present invention provides a structural member for sea water desalination plants that operate according to the flash distillation process, e.g. a flash chamber, which member comes into contact with sea water, said member being made of a low alloyed steel and being at Y
~ - 2 -',, ", : ', .
. ' ' ' ' '-`' 1~70~
:
least three to ten times more resistant than St 37-type steel to the static and dyanamic corrosion of aerated sea water ranging in temperature up to 115C, which steel contains no molybdenum and consists essentially of:
0.01 to 0.15 percent in weight of carbon; 2.0 to ~.5 percent in weight of chromium; 0.1 to 1.0 percent in weight of columbium; optionally copperJ
nickel, and manganese in an amountof between 0.0 and maximally 2.5 percent in weight taken all together; optionally fine grain formers, such as aluminum, titanium and vanadium in an amount of between 0.0 and maximally 0.2 percent in wei~ht taken all together; and balance iron and impurities due . 10 to melting, such as silicon, all of which alloying elements being below the '; passivating limit. ,''' .:..
~' .
~,:
. .
:
!'~
'' .
'' ~ - 2a -.
.. ' ' ' , ' .
.: .
.
',:, 70~44 Here all the contents of alloying elements are below the passivating limit.
It was found that the chromium con-tent in the steel of the invention, whose upper limit (4.5%) is far below the limit for complete chromium passivation ~13.5% chromium), causes the excellent resistance of the steels of the invention to plane corrosionl wherein a raising of the limit beyond 4.5% does not lead to furthcr lmprovement. Such a steel it was found - would, however, be very prone to localized corrosion without a content of columbium. According to the invention, this proneness to localized corrosion is inhibited by the ad-ditional columbium content. The copper content has the same kind of effect;
it has shown that the effect of the chromium-columbium-combination can be improved by the addition of copper.
Thus, a preferred composition of steel consists in that the steel has a carbon content of between 0.01 and 0.1% by weight, a chromium content of between 3.0 and 4.0% by weight, a columbium content of between 0.5 and . ' , 1.0% by weight, a copper content of between 0.5 and 1.0% by weight, a manganese content of between 0.3 and 0.6% by weight and an aluminum content of between 0.02 and 0.1% by weight.
-~ For reasons of production and with a view to a further improvement of the corrosion resistance, an additional nickel content is advantageous, which ought to amount to at least half the . ...
` - 3 _ ..
,,~'' ~7~4~
copper content.
According to a ~urther preferred embodiment, the steel of the invention contains fine grain formers, such as aluminum, titanium and vanadium, in the amounts of between 0.02 and 0.2 by weight titanium and/or between 0.05 and 0.15 ~ by weight vanadium and/or between 0.02 and 0.1 ~ by weight aluminum, but totalling not more than 0.2 % by weight.
Preferably the steel has a sulphur content of maximumly 0.017 ~ by weight and a phosphorus content of maximumly 0.015 %
- 10 by weightA
-The following Table 1 gives three steel compositions I, II, III, which in tests have proved to be corrosion resistant.
.
Steel No. C Si Mn P S Al Cr Ni Cu Nb ;-I 391 0.057 0.28 0.50 0.015 0.017 0.031 3.10 0.5 0.98 0.64 %
II 411 0.07 0.30 0.49 0.014 0~013 0.040 3.04 _ 0.52 0.32 ~
III 381 0.07 o.26 0.47 0.013 0.017 0.048 3.I5 _ _ 0.33 %
~;The mechanical properties of these steels after normalizing are the following:
!
- 20Steel 0.2 2 e~B 5 kp/mm ~
I 45.6 62.1 28.6 II 26.0 46.9 37.3 III 30.7 49.8 36.0 The following Tables 2, 3, 4 and 5 illustrate the corrosion behaviour of steels I, II, III in detail as compared to a soft, unalloyed control steel of the St 37-type.
.
~ Table 2 relates to dynamic corrosion tests in steels I, II
`'~,' :
~)7~
and III in the laboratory in artificial sea water (produced ; according to ASTM D 1141), whose temperature was 75C at one time and 115C at another time. The oxygen content of the sea water was also varied: it was 40 ppb in one case and 500 ppb (1 ppb = 1 part per billion ~ 0.0000001 %) in the other case.
The pH-value was 7.4 in both test series and the water rate was
2 and 2.5 m/sec, respectively. The erosion is measured in mg/dm2 day.
Dynamic corrosion in artificial sea water.
,:
Steel 75C/40 ppb 02/pH=7.4/2 m/s ¦115C/500ppb 02/pH=7.4/2.5m/s ~ erosion in mg/dm day ; I 2 70 unalloyed control steel 35 300 Table 3 shows the corrosion behaviour relative to agitated natural sea water. For 90% of the tests carried out over a period of 2.5 months a pH-value of 7.5 was usedl and for 10 % a pH-value of 4.2 was used (flushing of the test sheets and plates with acidic water). The tests were carried out at three temperatures, i.e. 35C, 76C and 114C, and different oxygen contents, i.e.
150 ppb, 25 ppb and 15 ppb. The numerical values represent the erosion in mg/dm2 day.
` Dynamic corrosion in natural sea waterl 2.5 months, pH-value 7.5 (90%); 4.2 (10%); erosion values in mg/dm2 day.
,".
~1~7~i4 . . . _ e Steel 35C/150 ppb 76 C/25 ppb 11~C/15 ppb ,, . .
unalloyed control steel 100 250 300 :
Table 4 represents the corrosion behaviour of steels I, II
and III in still, artificial and natural sea water having dif-ferent oxygen contents. Here, too, the tests were carried out by varying time, temperature and oxygen concentration.
TABI.E 4 Statical corrosion in artificial and natural sea water.
- Erosion values in mg/dm2 day.
i. ~ .
Steel artificial natural lOOh/75C/100 ppb 2000h/75C/50 ppb I
unalloyed control steel 10 25 In Table 5 the corrosion behaviour of steels I, II and III
under free weather exposure in industrial atmosphere is re-presen-ted and compared to the unalloyed control steel.
::.
Free weather exposure in industrial atmosphere - exposure 250 daysO
;"~.' ~70~
.. _ _ . .. . .... ~
Steel Erosion in mg/dm2 day ____ .... _ .
~'unalloyed control steel 25 ... .. . . ... __._. _ There results that the steels according to the invention , have a substantially higher corrosion resistance as compared to unalloyed structural steel, and under the roughest conditions, e.g. under the influence of hot, aerated sea water, their re-sistance is three to ten times better than that of an unalloyed steel. Still, the steel of the invention can be processed just like unalloyed structural steel. The production costs of a steel - of the invention are not higher than about twice the costs of unalloyed structural steel and substantially lower than those of high alloyed steels.
The steels of the invention can be subjected to heat-treatment in a common manner. They are especially well suited for use as working material for sea water desalination plants working according to the flash distillation process in the as-rolled, normalized, annealed or quenched and tempered condition.
In such plants the temperature of the sea water (brine) to be ; evaporated ranges between 35 and 120C and the oxygen contents :
- of the brine in the different flash chambers are between 20 and 500 ppb.
With the steels of the invention it is possible not only to make the flash chambers and water containers hitherto made of common structural steel much more durable and resista~t, but also to replace the high alloyed chromium nickel steels~
. `:
'',,'
Dynamic corrosion in artificial sea water.
,:
Steel 75C/40 ppb 02/pH=7.4/2 m/s ¦115C/500ppb 02/pH=7.4/2.5m/s ~ erosion in mg/dm day ; I 2 70 unalloyed control steel 35 300 Table 3 shows the corrosion behaviour relative to agitated natural sea water. For 90% of the tests carried out over a period of 2.5 months a pH-value of 7.5 was usedl and for 10 % a pH-value of 4.2 was used (flushing of the test sheets and plates with acidic water). The tests were carried out at three temperatures, i.e. 35C, 76C and 114C, and different oxygen contents, i.e.
150 ppb, 25 ppb and 15 ppb. The numerical values represent the erosion in mg/dm2 day.
` Dynamic corrosion in natural sea waterl 2.5 months, pH-value 7.5 (90%); 4.2 (10%); erosion values in mg/dm2 day.
,".
~1~7~i4 . . . _ e Steel 35C/150 ppb 76 C/25 ppb 11~C/15 ppb ,, . .
unalloyed control steel 100 250 300 :
Table 4 represents the corrosion behaviour of steels I, II
and III in still, artificial and natural sea water having dif-ferent oxygen contents. Here, too, the tests were carried out by varying time, temperature and oxygen concentration.
TABI.E 4 Statical corrosion in artificial and natural sea water.
- Erosion values in mg/dm2 day.
i. ~ .
Steel artificial natural lOOh/75C/100 ppb 2000h/75C/50 ppb I
unalloyed control steel 10 25 In Table 5 the corrosion behaviour of steels I, II and III
under free weather exposure in industrial atmosphere is re-presen-ted and compared to the unalloyed control steel.
::.
Free weather exposure in industrial atmosphere - exposure 250 daysO
;"~.' ~70~
.. _ _ . .. . .... ~
Steel Erosion in mg/dm2 day ____ .... _ .
~'unalloyed control steel 25 ... .. . . ... __._. _ There results that the steels according to the invention , have a substantially higher corrosion resistance as compared to unalloyed structural steel, and under the roughest conditions, e.g. under the influence of hot, aerated sea water, their re-sistance is three to ten times better than that of an unalloyed steel. Still, the steel of the invention can be processed just like unalloyed structural steel. The production costs of a steel - of the invention are not higher than about twice the costs of unalloyed structural steel and substantially lower than those of high alloyed steels.
The steels of the invention can be subjected to heat-treatment in a common manner. They are especially well suited for use as working material for sea water desalination plants working according to the flash distillation process in the as-rolled, normalized, annealed or quenched and tempered condition.
In such plants the temperature of the sea water (brine) to be ; evaporated ranges between 35 and 120C and the oxygen contents :
- of the brine in the different flash chambers are between 20 and 500 ppb.
With the steels of the invention it is possible not only to make the flash chambers and water containers hitherto made of common structural steel much more durable and resista~t, but also to replace the high alloyed chromium nickel steels~
. `:
'',,'
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A structural member for sea water desalination plants that operate according to the flash distillation process which member comes into contact with sea water, said member being made of a low alloyed steel and being at least three to ten times more resistant than St 37-type steel to the static and dynamic corrosion of aerated sea water ranging in temperature up to 115°C, which steel contains no molybdeum and consists essentially of: 0.01 to 0.15 percent in weight of carbon; 2.0 to 4.5 percent in weight of chromium; 0.1 to 1.0 percent in weight of columbium; optionally copper, nickel and manganese in an amount of between 0.0 and maximally 2.5 percent in weight taken all together;
optionally a fine grain former in an amount of between 0.0 and maximally 0.2 percent in weight taken all together; and balance iron and impurities due to melting all of which alloying elements being below the passivating limit.
optionally a fine grain former in an amount of between 0.0 and maximally 0.2 percent in weight taken all together; and balance iron and impurities due to melting all of which alloying elements being below the passivating limit.
2. A structural member as set forth in claim 1 wherein said fine grain former is selected from aluminum, titanium and vanadium.
3. A structural member as set forth in claim 2 wherein the carbon content ranges between 0.01 and 0.1 percent in weight, the chromium content ranges between 3.0 and 4.0 percent in weight, the columbium content ranges between 0.5 and 1.0 percent in weight, and with a copper content ranging between 0.5 and 1.0 percent in weight, a manganese content ranging between 0.3 and 0.6 percent in weight and an aluminum content ranging between 0.02 and 0.1 percent in weight.
4. A structural member as set forth in claim 3 wherein said alloyed steel includes nickel in an amount corresponding to at least half the copper content.
5. A structural member as set forth in claim 1, wherein said fine grain former is at least one element selected from the group consisting of titanium in an amount ranging between 0.02 and 0.2 percent in weight, vanadium in an amount ranging between 0.05 and 0.15 percent in weight and aluminum in an amount ranging between 0.02 and 0.1 percent in weight.
6. A structural member as set forth in either of claims 1, 2 or 5 wherein said alloyed steel includes a sulphur content of maximumly 0.017 percent in weight and a phosphorus content of maximumly 0.015 percent in weight.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT106176A AT354498B (en) | 1976-02-16 | 1976-02-16 | LOW-ALLOY STEEL WITH IMPROVED CORROSION BEHAVIOR AGAINST SEAWATER |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1070144A true CA1070144A (en) | 1980-01-22 |
Family
ID=3505738
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA258,242A Expired CA1070144A (en) | 1976-02-16 | 1976-07-30 | Structural member made of low alloyed steel corrosion resistant to sea water |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS6012419B2 (en) |
| AT (1) | AT354498B (en) |
| BE (1) | BE844769A (en) |
| CA (1) | CA1070144A (en) |
| FR (1) | FR2340990A1 (en) |
| GB (1) | GB1512127A (en) |
| IT (1) | IT1066210B (en) |
| NL (1) | NL180526C (en) |
| SE (1) | SE426406B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54112717A (en) * | 1978-02-24 | 1979-09-03 | Nippon Steel Corp | Steel products with nitrate stress corrosion cracking resistance |
| JPH02137223U (en) * | 1989-04-19 | 1990-11-15 | ||
| CN108950399A (en) * | 2018-08-10 | 2018-12-07 | 武汉钢铁集团鄂城钢铁有限责任公司 | The 550MPa grade bridge structural steel plate and its manufacturing method of a kind of low crackle of high-strength and high ductility |
-
1976
- 1976-02-16 AT AT106176A patent/AT354498B/en not_active IP Right Cessation
- 1976-07-02 SE SE7607593A patent/SE426406B/en not_active IP Right Cessation
- 1976-07-30 IT IT5071076A patent/IT1066210B/en active
- 1976-07-30 CA CA258,242A patent/CA1070144A/en not_active Expired
- 1976-07-30 NL NL7608490A patent/NL180526C/en not_active IP Right Cessation
- 1976-07-30 BE BE169461A patent/BE844769A/en not_active IP Right Cessation
- 1976-07-30 JP JP51092241A patent/JPS6012419B2/en not_active Expired
- 1976-07-30 GB GB3194176A patent/GB1512127A/en not_active Expired
- 1976-07-30 FR FR7623438A patent/FR2340990A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| NL180526B (en) | 1986-10-01 |
| JPS6012419B2 (en) | 1985-04-01 |
| FR2340990B1 (en) | 1981-08-21 |
| AT354498B (en) | 1980-01-10 |
| NL180526C (en) | 1987-03-02 |
| GB1512127A (en) | 1978-05-24 |
| JPS5299916A (en) | 1977-08-22 |
| SE7607593L (en) | 1977-08-17 |
| NL7608490A (en) | 1977-08-18 |
| IT1066210B (en) | 1985-03-04 |
| ATA106176A (en) | 1979-06-15 |
| BE844769A (en) | 1976-11-16 |
| SE426406B (en) | 1983-01-17 |
| FR2340990A1 (en) | 1977-09-09 |
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