ZA200700114B - Austenitic stainless steel composition and use thereof for the production of structural parts for land transport means and containers - Google Patents
Austenitic stainless steel composition and use thereof for the production of structural parts for land transport means and containers Download PDFInfo
- Publication number
- ZA200700114B ZA200700114B ZA200700114A ZA200700114A ZA200700114B ZA 200700114 B ZA200700114 B ZA 200700114B ZA 200700114 A ZA200700114 A ZA 200700114A ZA 200700114 A ZA200700114 A ZA 200700114A ZA 200700114 B ZA200700114 B ZA 200700114B
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- ZA
- South Africa
- Prior art keywords
- steel
- composition
- steel composition
- austenitic stainless
- stainless steel
- Prior art date
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- 239000000203 mixture Substances 0.000 title claims description 38
- 238000004519 manufacturing process Methods 0.000 title claims description 11
- 229910000963 austenitic stainless steel Inorganic materials 0.000 title claims description 7
- 229910000831 Steel Inorganic materials 0.000 claims description 49
- 239000010959 steel Substances 0.000 claims description 49
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 12
- 229910052804 chromium Inorganic materials 0.000 claims description 7
- 239000011651 chromium Substances 0.000 claims description 7
- 229910052748 manganese Inorganic materials 0.000 claims description 7
- 229910052710 silicon Inorganic materials 0.000 claims description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- 229910052759 nickel Inorganic materials 0.000 claims description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- 229910000859 α-Fe Inorganic materials 0.000 claims description 5
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 4
- 238000003723 Smelting Methods 0.000 claims description 4
- 229910001566 austenite Inorganic materials 0.000 claims description 4
- 229910052750 molybdenum Inorganic materials 0.000 claims description 4
- 229910052717 sulfur Inorganic materials 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 229910052698 phosphorus Inorganic materials 0.000 claims description 3
- 229910052718 tin Inorganic materials 0.000 claims description 3
- 229910052719 titanium Inorganic materials 0.000 claims description 3
- 238000005260 corrosion Methods 0.000 description 23
- 230000007797 corrosion Effects 0.000 description 23
- 239000011572 manganese Substances 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000010949 copper Substances 0.000 description 2
- 230000002939 deleterious effect Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- -1 or even corrosive Substances 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- 230000004580 weight loss Effects 0.000 description 2
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical class Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000008267 milk Substances 0.000 description 1
- 210000004080 milk Anatomy 0.000 description 1
- 235000013336 milk Nutrition 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
Description
AUSTENITIC STAINLESS STEEL COMPOSITION AND USE
THEREOF FOR THE PRODUCTION OF STRUCTURAL PARTS FOR LAND
TRANSPORT MEANS AND CONTAINERS
The present invention relates to an improved steel composition that can in particular be used for the manufacture of structural parts for land transport means and also for the manufacture of containers for all types of industries, such as for example the chemical industry or the agro- alimentary industry.
More generally, this novel composition may advantageously be used for all applications requiring a high potential for absorbing energy, in particular in the event of accidents, and also good resistance to both pitting corrosion and generalized corrosion.
The problem of weight reduction is a constant preoccupation of manufacturers of transport means in general, and of manufacturers and users of transport tanks in particular. Because of weight limitations imposed on trucks for example, the manufacturers of these trucks are always seeking technical solutions allowing them to reduce the weight of the structure, while increasing the volume of products transported and reducing the amount of steel needed to manufacture a tank, and reducing the thickness of the steel sheet used.
However, it is not conceivable to lower the safety of these trucks, and a reduction in the thickness of the steel sheet can be accepted only if this steel has an improved energy absorption potential. This energy absorption potential, also called crash resistance, may be evaluated by the product Ry, x
A, in which Ry, represents the tensile strength in MPa of the steel and A represents the elongation in % of the steel. Its improvement therefore depends on both these factors and on their variation.
Moreover, a reduction in corrosion resistance of the steel! cannot be envisioned, in particular for applications in the fields of chemistry or agro- alimentary, in which it is frequent practice to store and transport acid, or even corrosive, liquids.
The grades of steel currently on the market do not allow the requirement of improved crash resistance and the requirement of good corrosion resistance to be met simultaneously. Thus, grades of the 301, 301LN, 304 or 305 type do not have good corrosion resistance characteristics, whereas grades of 316 duplex steel do not have satisfactory crash resistance.
Taking into account these aspects, the object of the present invention is to provide an improved steel composition that has good pitting corrosion and generalized corrosion resistance characteristics and a higher energy absorption potential than that of the steel grades of the prior art.
The first subject of the invention is formed by an austenitic stainless steel composition comprising, in % by weight:
C< 0.03% 14% = Crs17% 8% = Ni< 10% 20%= Mos 3.5%
Mn < 2.0%
Si £ 1.0%
N= 0.20%
Cus 1.0%
Ti< 0.01%
Co= 0.5%
Sn = 0.4%
P< 0.045%
S =0.030%, the balance consisting of iron and inevitable impurities resulting from the smelting.
The steel composition according to the invention makes it possible to obtain a stainless steel having an austenitic structure, but the austenite of which is sufficiently unstable at room temperature (Md value), which steel has a corrosion resistance of the same level as that of the 316L grade, in particular as regards pitting corrosion, and good processability by control of the delta- ferrite content.
The steel composition according to the invention may also have the following additional features, taken individually or in combination: — the steel composition comprises less than 16.0% chromium: — the steel composition comprises less than 9.5% nickel; — the steel composition has an austenite stability index Md30, defined by the formula:
Md30 = 497 — 462(%C+%N) — 9.2x%Si — 8.1x%Mn —-13.7x%Cr — 20 x%Ni -18.5x%Mo between -130°C and +90°C, preferably between 0°C and 60°C and more preferably between 0°C and 30°C; : — the steel composition has a delta-ferrite content of 7% or less; and — the steel composition has a value of the product Ri, x A, in which Ry, is the tensile strength of the steel and A is the elongation of the steel, greater ~ than 32 000 and preferably greater than 34 000.
The second subject of the invention is formed by the use of the steel according to the invention for manufacturing containers and for manufacturing oo structural parts for land transport means. :
Within the context of this application, the expression “land transport means” should be understood to mean automobiles, but also rail transport means of all kinds. The containers to which the invention refers may especially be used for transporting all kinds of liquid, solid or gaseous substances such as, for example, acids, milk or wine.
The invention will now be described in detail, the scope of the claims of course not being limited by this description.
SU 007/001 14 . i
The austenitic stainless steel composition according to the invention comprises up to 0.03% carbon. In a preferred embodiment, the carbon content is between 0.022% and 0.027%.
The composition also comprises chromium with a content of from 14% to 17%, preferably between 14% and 16.5%, more particularly preferably between 14% and 16.0% and better still between 15% and 15.2%. Chromium is an essential element for corrosion resistance of the grade. its content is limited owing to its influence on the stability of the austenitic structure.
The composition also comprises nickel with a content of from 8% to 10%, preferably between 8% and 9.5%, more particularly preferably between 8% and 9.0% and better still between 8.9% and 9.1%. The main effect of this element is its favorable action on the generalized corrosion resistance. Its content is limited because of its high cost and its influence on the stability of the austenitic structure.
The composition further comprises molybdenum with a content of from 2.0% to 3.5%, preferably between 2.0% and 3.0% and more particularly preferably between 2.9% and 3.1%. This element allows the corrosion resistance, particularly the pitting corrosion resistance, of the grade to be improved, but it must be limited because of its hardening effect.
The composition may also comprise up to 2.0% manganese, advantageously up to 1.45% manganese. In a preferred embodiment, the manganese content is between 1.3% and 1.45%.
The composition may also comprise up to 1.0% silicon, advantageously up to 0.5% silicon. In a preferred embodiment, the silicon content is between 0.35% and 0.5%. This element may be used as a deoxidizing agent during the smelting of the grade, but it must be limited because of its deleterious influence on the formability of the grade.
The composition may also comprise nitrogen with a maximum content of 0.20%, preferably 0.03%. In a preferred embodiment, the nitrogen content is between 0.02% and 0.03%.
This element has a hardening effect when it is present in solid solution in the steel. Thus, it may help to increase the tensile strength R,, but at the same time it reduces the elongation A. Its addition is therefore limited to the abovementioned values.
The composition may also contain copper with a maximum content of 1.0%, preferably 0.4%. Copper also acts as a hardening element when it is 5 present in solid solution. Its content is limited to 0.4% owing to its negative influence on the corrosion resistance but also on the hot formability of the grade.
Finally, the composition may contain residual elements, such as titanium with a maximum content of 0.01%, cobalt with a maximum content of 0.5%, tin with a maximum content of 0.4%, phosphorus with a maximum content of 0.045% and sulfur with a maximum content of 0.030%.
In particular, the sulfur content is limited to 0.030%, preferably. to 0.0080% and more particularly preferably to 0.0060%, because of its deleterious influence on the corrosion resistance. Furthermore, it may be easily combined with manganese to generate inclusions of the MnS type, which are undesirable.
Mechanical properties
Steels having the compositions given in Table 1 were smelted, then continuously cast in the form of slabs and hot-rolled down to a thickness of 8 mm. Each hot-rolled strip was then continuously annealed at a temperature of 1150°C, before being cold-rolled down to a final thickness of 4.2 mm.
Each cold-rolled strip was then continuously annealed at a temperature of 1040°C.
The mechanical properties of each cold-rolled strip were measured, these being given in Table 2.
The following abbreviations have been used: » Arepresents the elongation of the steel, expressed in %: * Rm represents the tensile strength of the steel, expressed in MPa: and * A represents the delta-ferrite content, expressed in % and measured by XRD after electropolishing.
The compositions of steels A and B are according to the present invention, whereas the composition of steel C is a comparative example.
Table 1
Cc Cr Ni Mo Mn Si N Cu P S
Sell) [0 |) |) [| |) [%) | ®%) |eem (A Joos [is [592 [208 [1% [os [pow [oz oor | 90 (®[o00 [i547 [908 [301 [5 [0% [ower [or7 fours |W
Table 2
Rm A Rmx A [Grain size A Md30
Steel | (MPa) {(%) (ASTM) (%) (°C)
Corrosion resistance
The pitting corrosion resistance and the generalized corrosion resistance of the specimens were measured according to the following procedures:
Pitting corrosion
As per ASTM G 61, the steel specimens were dipped into a solution containing 0.5M NaCl and having a pH of 6.6, at a temperature of 23°C. The specimens were then ground in the wet state using a 1200 SiC grinding paper.
The breaking potential of each specimen was then measured at a rate of 100 mV/min, starting from the free corrosion potential. The final current was 50 pA/cm?,
Generalized corrosion
As per ASTM G 61, the steel specimens were dipped into a solution containing 2M H,SO,, at a temperature of 23°C. The specimens were then ground in the wet state using a 1200 SiC grinding paper.
The critical current (the maximum current reached during the active phase) of each specimen was then measured at a rate of 10 mV/min, from -750 mV/SCE to 1200 mV/SCE, and the weight loss was measured.
The following abbreviations have been employed: » BP represents the breaking potential, expressed in mV relative to the
SCE (saturated calomel electrode); » CC represents the critical current, expressed in pA/cm?; and » WL represents the weight loss, expressed in mm/year.
The results of the corrosion tests are given in Table 3.
Table 3
Steel BP CC WL
RR ey
I I LC BLL
As may be seen from these tests, the steel composition according to the invention makes it possible to achieve very high levels of the product RmxA, mainly due to an improvement in the elongation, the Ry, value remaining constant. This improved elongation has the additional advantage of facilitating the subsequent manufacture of containers, since the steel is more easily formable.
The low delta-ferrite content is also favorable as regards weldability and corrosion resistance of the grade. - This novel steel composition allows the thickness of the steel sheet required for manufacturing a container to be significantly reduced, thereby lowering its cost, allows the transportable load to be increased and also allows energy to be saved when the container returns empty.
Thus, it should be noted that a reduction of 0.1 mm in the thickness of the sheet represents an increase of 35 kg in the transportable load. If the performance characteristics of the grade according to the invention are taken into account, a 0.2 mm reduction of the steel sheet may be achieved in most cases.
Claims (11)
1. An austenitic stainless steel composition comprising, in % by weight: C< 0.03% 14% < Crs 17% 8% < Ni< 10% 20%= Mos 3.5% Mn=< 2.0% Si £ 1.0% N= 0.20% Cus 1.0% Ti= 0.01% Co=< 0.5% Sn< 0.4% P< 0.045% S = 0.030%, the balance consisting of iron and inevitable impurities resulting from the smelting.
2. The steel composition as claimed in claim 1, which further comprises less than 16.0% chromium.
3. The steel composition as claimed in claim 1 or 2, which further comprises less than 9.5% nickel. | :
4. The steel composition as claimed in any one of claims 1 to 3, which further comprises, in % by weight:
0.022% < C= 0.027% 15% < Crs 15.2% 89%<=< Ni< 9.1% 29% =< Mos 3.1%
1.3% < Mn< 1.45%
0.35% < Sis< 0.5%
0.02% < N= 0.03% Cu< 0.4% Ti< 0.01% Co=< 0.5% Sn £ 04% P< 0.045% S £ 0.030%, the balance consisting of iron and inevitable impurities resulting from the smelting.
5. The steel composition as claimed in any one of claims 1 to 4, characterized in that the austenite stability index Md30, defined by the formula: Md30 = 497 — 462(%C+%N) — 9.2x%Si — 8.1x%Mn —13.7x%Cr — 20 x%Ni ~18.5x%Mo is between -130°C and + 90°C.
6. The steel composition as claimed in any one of claims 1 to 5, characterized in that the austenite stability index Md30, defined by the formula: Md30 = 497 — 462(%C+%N) — 9.2x%Si — 8.1x%Mn —13.7x%Cr — 20 x%Ni —-18.5x%Mo is between 0°C and 60°C.
7. The steel composition as claimed in any one of claims 1 to 6, characterized in that its delta-ferrite content is 7% or less.
8. The steel composition as claimed in any one of claims 1 to 7, characterized in that the value of the product R,, x A, in which Ry, is the tensile strength of the steel and A is the elongation of the steel, is greater than 32 000.
8. The steel composition as claimed in any one of claims 1 to 8, characterized in that the value of the product Ry, x A, in which Ry, is the tensile strength of the steel and A is the elongation of the steel, is greater than 34 000.
10. The use of an austenitic stainless steel having the composition as claimed in any one of claims 1 to 9 for manufacturing containers.
11. The use of an austenitic stainless steel having the composition as claimed in any one of claims 1 to 9 for manufacturing structural parts for land transport means. :
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA200700114A ZA200700114B (en) | 2007-01-05 | 2007-01-05 | Austenitic stainless steel composition and use thereof for the production of structural parts for land transport means and containers |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ZA200700114A ZA200700114B (en) | 2007-01-05 | 2007-01-05 | Austenitic stainless steel composition and use thereof for the production of structural parts for land transport means and containers |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| ZA200700114B true ZA200700114B (en) | 2008-02-27 |
Family
ID=40639604
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| ZA200700114A ZA200700114B (en) | 2007-01-05 | 2007-01-05 | Austenitic stainless steel composition and use thereof for the production of structural parts for land transport means and containers |
Country Status (1)
| Country | Link |
|---|---|
| ZA (1) | ZA200700114B (en) |
-
2007
- 2007-01-05 ZA ZA200700114A patent/ZA200700114B/en unknown
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