CA1271650A - High tensile structural steel with favourable weldability - Google Patents
High tensile structural steel with favourable weldabilityInfo
- Publication number
- CA1271650A CA1271650A CA000468597A CA468597A CA1271650A CA 1271650 A CA1271650 A CA 1271650A CA 000468597 A CA000468597 A CA 000468597A CA 468597 A CA468597 A CA 468597A CA 1271650 A CA1271650 A CA 1271650A
- Authority
- CA
- Canada
- Prior art keywords
- weight
- high tensile
- steel
- structural steel
- tensile structural
- 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 - Fee Related
Links
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
- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
-
- 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
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- 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
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)
- Heat Treatment Of Articles (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The invention concerns a high tensile structural steel which is suited for oil quenching and tempering and nevertheless possesses favourable weldability with high tensile strength. In addition to containing alloying metals usual in a high tensile steel, such as Mn, Cr, Ni and Mo, the steel also contains from 0.005 to 0.03% by weight Nb.
The invention concerns a high tensile structural steel which is suited for oil quenching and tempering and nevertheless possesses favourable weldability with high tensile strength. In addition to containing alloying metals usual in a high tensile steel, such as Mn, Cr, Ni and Mo, the steel also contains from 0.005 to 0.03% by weight Nb.
Description
The invention concerns a structural steel with favour-able weldability which incorporates the following alloy components:
Carbon < 0.24 weight %I preferably < 0.22 weight %
Silicon 0.02 to 0.80 " " " 0.30 to 0.60 " "
Manganese 0.80 to 1.60 " " " 1.20 to 1.50 " "
Phosphorus < 0.025 " " " < 0.015 " "
Sulphur < 0.025 ~ - < 0.015 Chromium 0.80 to 1.6 " " " l.OQ to 1.40 " "
Nickel 0.30 to 1.8 " " " 0.80 to 1.50 " "
Molybdenum 0.20 to 0.80 " " " 0.30 to 0.60 Boron < 0.005 " " " < ~-003 plus aluminium and/or titanium for fixation of nitxogen, and processes for preparing such steels by oil quenching e~
tempering.
Such high tensile structural steels with favourable weldability generally obtain their favourable properties as a result of water quenching and tempering. As examples can be quotea the American steels T 1 and N-A-XTRA.
For plant reasons however water quenching and tempering is not always feasible. In fact oil quenching and tempering is frequently preferable. In addition oil quenched and tempered steels possess a number of advantages over those quenched and f~ tempered in water, for example that of the reduced internal stresses and of the reduced deformation during flame cutting and welding.
This invention seeks to provide a steel which is suited . - 1 - ~.~
~27~6~ 26706 13 to oil quenching and tempering and nevertheless possesses favour~
able weldability with high tensile strength.
Thus this invention seeks to provide a high tensile structural :~ - la -,~
."~
steel of the type descrlbed initially having a niobium content of approximately 0.005 to 0.03 weight %, preferably 0.008 to 0.02 welght %.
I'he steel proposed as the subject of the invention is suited for oil quenching and tempering by virtue of its chemica' composition.
As a result steels in accordance with the invention can also be subsequently processed everywhere where water quenching and tempering is not possible, or not desirable. Notwithstanding this when using the steel in accordance with the invention one has a material which is equivalent to existing water quenched and tempered steels in tensile strength and weldability.
In an alternative alloy according to this invention) titan:ium is replaced by an i.ncreased aluminium cont~nt, in an approximate concentration of 0.020 to 0.08 weight %, preferably of 0.030 to 0.060 weight %. In yet another alloy according to this invention~ the combination of aluminium, niobium and boron is of special significance.
Boron alloyed heat treatable structural steels have been known for a considerable time, but these are alloyed with titanium for the necessary fixation of nitrogen, to prevent the formation of boron nitrides ~boron f carbonitrides). As a result however part of the carbon content is bonded to titanium as titanium does not form pure nitrides, but carbonitrides with a high proportion of carbon. The titanium carbonitrides form very coarse crystals or crystallites which are visible locally in the secondary structure,and which do not make any positive contribution to the steel quality. When using aluminium instead of titanium in steel alloys according to this invention, nitrides are formed exclusively which, in a favourable precipitated form, contribute under certain conditions to strengthening of the matrix. I'he alloying element boron where not bonded . .
to nitrogen and/or to carbon delays the transformation processes and thus encourages hardening and tempering susceptibility. As a result transformation also takes place in the martensite stage, that is to say even at a lower cooling rate than is prevalent during oil hardening.
In the case of the structural steel according to the invention toughness is considerable even in the low temper stage, so that it is possible to vary the tempering temperature within wide limits.
In this way the yield strength can be varied over a range from 550 N/mm2 up to approximately lO00 N/mm2 without altering the chemical composition and can be suited to requirements. The temperatures here are approximately 200 degrees c~ntigrade to 650 degrees centigrade. This advantage is apparellt particular:ly whe~n small quantities oE high tcnsil~
steels have to be produced with di:fferent properties. Thus it is also possible to compensate for the cooling conditions caused by different plate thicknesses and to compensate for the resultant structural differences in respect of the mechanical properties.
The low niobium content is of particular importance with the structural steel which is the subject of the invention. It has been established by research that the effect of this element is obtained even at 0.005 weight %. Above this threshold value the precipitation strengthening effect is less so that considerably higher proportions do not provide any significant advantages. This effect is particularly advantageous with the steel according to the invention at lnw tempering temperature, since (as is the case with practically all heat treatable steels) during welding loss of strength, the so-called hardness sag, readily takes place in the heat affected zone. Precipitation strengthening . .
5~
in the matrix counteracts this loss of strength. In addition it does not happen, as is for example the case with the element vanadium, that solution o~ the carbonitrides takes place in the heat affected zone accom-panied by renewed precipitation in the case of possible stress relief heat treatment and the resultant embrittlement effect, because the niobium carbonitrides are very much more stable. No embrittlement effect on the welded material need be anticipated with such low proportions of niobium.
A steel according to this invention is suitable for use everywhere where extremely high stresses are anticipated, for example in lightweight construction (mobile construction), in the productioll of ships' masts and supporting frames.
}ligh tensile structural steels in accordance with this invention and which contain an increased amount of Ni, in the range of 1.0%
to 3.0% with 1.5% to 2.8% being preferred, possess considerable toughness at low temperatures so that steels of this type can be used to advantage everywhere where relatively low temperatures occur accompanied by very high stresses, for example in the case o:E submarine craft.
The features described in the specification and in the patent claims can be essential for implementation of the invention both individually and in any optional combinations.
Carbon < 0.24 weight %I preferably < 0.22 weight %
Silicon 0.02 to 0.80 " " " 0.30 to 0.60 " "
Manganese 0.80 to 1.60 " " " 1.20 to 1.50 " "
Phosphorus < 0.025 " " " < 0.015 " "
Sulphur < 0.025 ~ - < 0.015 Chromium 0.80 to 1.6 " " " l.OQ to 1.40 " "
Nickel 0.30 to 1.8 " " " 0.80 to 1.50 " "
Molybdenum 0.20 to 0.80 " " " 0.30 to 0.60 Boron < 0.005 " " " < ~-003 plus aluminium and/or titanium for fixation of nitxogen, and processes for preparing such steels by oil quenching e~
tempering.
Such high tensile structural steels with favourable weldability generally obtain their favourable properties as a result of water quenching and tempering. As examples can be quotea the American steels T 1 and N-A-XTRA.
For plant reasons however water quenching and tempering is not always feasible. In fact oil quenching and tempering is frequently preferable. In addition oil quenched and tempered steels possess a number of advantages over those quenched and f~ tempered in water, for example that of the reduced internal stresses and of the reduced deformation during flame cutting and welding.
This invention seeks to provide a steel which is suited . - 1 - ~.~
~27~6~ 26706 13 to oil quenching and tempering and nevertheless possesses favour~
able weldability with high tensile strength.
Thus this invention seeks to provide a high tensile structural :~ - la -,~
."~
steel of the type descrlbed initially having a niobium content of approximately 0.005 to 0.03 weight %, preferably 0.008 to 0.02 welght %.
I'he steel proposed as the subject of the invention is suited for oil quenching and tempering by virtue of its chemica' composition.
As a result steels in accordance with the invention can also be subsequently processed everywhere where water quenching and tempering is not possible, or not desirable. Notwithstanding this when using the steel in accordance with the invention one has a material which is equivalent to existing water quenched and tempered steels in tensile strength and weldability.
In an alternative alloy according to this invention) titan:ium is replaced by an i.ncreased aluminium cont~nt, in an approximate concentration of 0.020 to 0.08 weight %, preferably of 0.030 to 0.060 weight %. In yet another alloy according to this invention~ the combination of aluminium, niobium and boron is of special significance.
Boron alloyed heat treatable structural steels have been known for a considerable time, but these are alloyed with titanium for the necessary fixation of nitrogen, to prevent the formation of boron nitrides ~boron f carbonitrides). As a result however part of the carbon content is bonded to titanium as titanium does not form pure nitrides, but carbonitrides with a high proportion of carbon. The titanium carbonitrides form very coarse crystals or crystallites which are visible locally in the secondary structure,and which do not make any positive contribution to the steel quality. When using aluminium instead of titanium in steel alloys according to this invention, nitrides are formed exclusively which, in a favourable precipitated form, contribute under certain conditions to strengthening of the matrix. I'he alloying element boron where not bonded . .
to nitrogen and/or to carbon delays the transformation processes and thus encourages hardening and tempering susceptibility. As a result transformation also takes place in the martensite stage, that is to say even at a lower cooling rate than is prevalent during oil hardening.
In the case of the structural steel according to the invention toughness is considerable even in the low temper stage, so that it is possible to vary the tempering temperature within wide limits.
In this way the yield strength can be varied over a range from 550 N/mm2 up to approximately lO00 N/mm2 without altering the chemical composition and can be suited to requirements. The temperatures here are approximately 200 degrees c~ntigrade to 650 degrees centigrade. This advantage is apparellt particular:ly whe~n small quantities oE high tcnsil~
steels have to be produced with di:fferent properties. Thus it is also possible to compensate for the cooling conditions caused by different plate thicknesses and to compensate for the resultant structural differences in respect of the mechanical properties.
The low niobium content is of particular importance with the structural steel which is the subject of the invention. It has been established by research that the effect of this element is obtained even at 0.005 weight %. Above this threshold value the precipitation strengthening effect is less so that considerably higher proportions do not provide any significant advantages. This effect is particularly advantageous with the steel according to the invention at lnw tempering temperature, since (as is the case with practically all heat treatable steels) during welding loss of strength, the so-called hardness sag, readily takes place in the heat affected zone. Precipitation strengthening . .
5~
in the matrix counteracts this loss of strength. In addition it does not happen, as is for example the case with the element vanadium, that solution o~ the carbonitrides takes place in the heat affected zone accom-panied by renewed precipitation in the case of possible stress relief heat treatment and the resultant embrittlement effect, because the niobium carbonitrides are very much more stable. No embrittlement effect on the welded material need be anticipated with such low proportions of niobium.
A steel according to this invention is suitable for use everywhere where extremely high stresses are anticipated, for example in lightweight construction (mobile construction), in the productioll of ships' masts and supporting frames.
}ligh tensile structural steels in accordance with this invention and which contain an increased amount of Ni, in the range of 1.0%
to 3.0% with 1.5% to 2.8% being preferred, possess considerable toughness at low temperatures so that steels of this type can be used to advantage everywhere where relatively low temperatures occur accompanied by very high stresses, for example in the case o:E submarine craft.
The features described in the specification and in the patent claims can be essential for implementation of the invention both individually and in any optional combinations.
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for preparing a high tensile structural steel with favourable weldability with the following alloy components:
Carbon < 0.24 weight %
Silicon 0.20 to 0.80 " "
Manganese 0.80 to 1.60 " "
Phosphorus < 0.025 " "
Sulphur < 0.025 " "
Chromium 0.80 to 1.6 " "
Nickel 0.30 to 3.00 " "
Molybdenum 0.20 to 0.80 " "
Boron < 0.005 " "
plus an amount of aluminium or titanium effective for fixation of nitrogen, characterized by a niobium content of 0.005 to 0.03 weight %, which process comprises oil quenching and tempering a steel having said alloy components.
Carbon < 0.24 weight %
Silicon 0.20 to 0.80 " "
Manganese 0.80 to 1.60 " "
Phosphorus < 0.025 " "
Sulphur < 0.025 " "
Chromium 0.80 to 1.6 " "
Nickel 0.30 to 3.00 " "
Molybdenum 0.20 to 0.80 " "
Boron < 0.005 " "
plus an amount of aluminium or titanium effective for fixation of nitrogen, characterized by a niobium content of 0.005 to 0.03 weight %, which process comprises oil quenching and tempering a steel having said alloy components.
2. A process for preparing a high tensile structural steel according to claim 1 containing the following alloy components:
Carbon < 0.22 weight %
Silicon 0.30 to 0.60 " "
Manganese 1.20 to 1.50 " "
Phosphorus < 0.015 " "
Sulphur < 0.015 " "
Chromium 1.00 to 1.40 " "
Nickel 0.80 to 2.80 " "
Molybdenum 0.30 to 0.60 " "
Boron < 0.003 " "
which process comprises oil quenching and tempering a steel having said alloy components.
Carbon < 0.22 weight %
Silicon 0.30 to 0.60 " "
Manganese 1.20 to 1.50 " "
Phosphorus < 0.015 " "
Sulphur < 0.015 " "
Chromium 1.00 to 1.40 " "
Nickel 0.80 to 2.80 " "
Molybdenum 0.30 to 0.60 " "
Boron < 0.003 " "
which process comprises oil quenching and tempering a steel having said alloy components.
3. A process for preparing a high tensile structural steel with favourable weldability with the following alloy components:
Carbon < 0.24 weight %
Silicon 0.20 to 0.80 " "
Manganese 0.80 to 1.60 " "
Phosphorus < 0.025 " "
Sulphur < 0.025 " "
Chromium 0.80 to 1.6 " "
Nickel 0.30 to 1.8 " "
Molybdenum 0.20 to 0.80 " "
Boron < 0.005 " "
plus an amount of aluminium or titanium effective for fixation of nitrogen, characterized by a niobium content of 0.005 to 0.03 weight %, which process comprises oil quenching or: oil tempering a steel having said alloy components.
Carbon < 0.24 weight %
Silicon 0.20 to 0.80 " "
Manganese 0.80 to 1.60 " "
Phosphorus < 0.025 " "
Sulphur < 0.025 " "
Chromium 0.80 to 1.6 " "
Nickel 0.30 to 1.8 " "
Molybdenum 0.20 to 0.80 " "
Boron < 0.005 " "
plus an amount of aluminium or titanium effective for fixation of nitrogen, characterized by a niobium content of 0.005 to 0.03 weight %, which process comprises oil quenching or: oil tempering a steel having said alloy components.
4. A process for preparing a high tensile structural steel according to claim 3 containing the following alloy components:
Carbon < 0.22 weight %
Silicon 0.30 to 0.60 " "
Manganese 1.20 to 1.50 " "
Phosphorus < 0.015 " "
Sulphur < 0.015 " "
Chromium 1.00 to 1.40 " "
Nickel 0.80 to 1.50 " "
Molybdenum 0.30 to 0.60 weight %
Boron < 0.003 "
plus an amount of aluminium or titanium effective for fixation of nitrogen, characterized by a niobium content of 0.008 to 0.020 weight %, which process comprises oil quenching and tempering a steel having said alloy components.
Carbon < 0.22 weight %
Silicon 0.30 to 0.60 " "
Manganese 1.20 to 1.50 " "
Phosphorus < 0.015 " "
Sulphur < 0.015 " "
Chromium 1.00 to 1.40 " "
Nickel 0.80 to 1.50 " "
Molybdenum 0.30 to 0.60 weight %
Boron < 0.003 "
plus an amount of aluminium or titanium effective for fixation of nitrogen, characterized by a niobium content of 0.008 to 0.020 weight %, which process comprises oil quenching and tempering a steel having said alloy components.
5. A process according to claim 3 or 4 wherein in said high tensile structural steel only aluminium is used for nitrogen fixation, and in which the aluminium is present in an approximate concentration of from about 0.020 to about 0.08 weight %.
6. A process according to claim 3 or 4 wherein in said high tensile structural steel only aluminium is used for nitrogen fixation, and in which the aluminium is present in an approximate concentration of from about 0.030 to 0.060 weight %.
7. A process according to claim 1 or 2 wherein in said high tensile structural steel the Ni content is of the order of 1.0 to 3.0 weight %.
8. A process according to claim 1 or 2 wherein in said high tensile structural steel the Ni content is of the order of 1.5 to 2.8 weight %.
9. A process according to claim 1 or 2 wherein the temper-ing temperature is between about 200 and 650°C.
10. A process according to claim 3 or 4 wherein the temper-ing temperature is between about 200 and 650°C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU22585/83A AU573553B2 (en) | 1983-12-20 | 1983-12-20 | High tensile structural steel with favourable weldability |
| AU22585/83 | 1983-12-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1271650A true CA1271650A (en) | 1990-07-17 |
Family
ID=3711774
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000468597A Expired - Fee Related CA1271650A (en) | 1983-12-20 | 1984-11-26 | High tensile structural steel with favourable weldability |
Country Status (9)
| Country | Link |
|---|---|
| KR (1) | KR900000280B1 (en) |
| AU (1) | AU573553B2 (en) |
| BR (1) | BR8406524A (en) |
| CA (1) | CA1271650A (en) |
| EG (1) | EG17092A (en) |
| IL (1) | IL73465A (en) |
| MX (1) | MX162376A (en) |
| NZ (1) | NZ210174A (en) |
| ZA (1) | ZA849877B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BR8404270A (en) * | 1984-08-27 | 1986-04-01 | Marchesan Implement & Maquin | STEEL COMPOSITION FOR AGRICOLE DISCS |
-
1983
- 1983-12-20 AU AU22585/83A patent/AU573553B2/en not_active Ceased
-
1984
- 1984-10-31 MX MX203233A patent/MX162376A/en unknown
- 1984-11-09 IL IL73465A patent/IL73465A/en unknown
- 1984-11-09 NZ NZ210174A patent/NZ210174A/en unknown
- 1984-11-12 EG EG698/84A patent/EG17092A/en active
- 1984-11-26 CA CA000468597A patent/CA1271650A/en not_active Expired - Fee Related
- 1984-12-03 KR KR1019840007613A patent/KR900000280B1/en not_active IP Right Cessation
- 1984-12-18 BR BR8406524A patent/BR8406524A/en unknown
- 1984-12-19 ZA ZA849877A patent/ZA849877B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| KR900000280B1 (en) | 1990-01-24 |
| EG17092A (en) | 1991-08-30 |
| NZ210174A (en) | 1988-04-29 |
| KR850004999A (en) | 1985-08-19 |
| BR8406524A (en) | 1985-10-15 |
| ZA849877B (en) | 1985-06-17 |
| MX162376A (en) | 1991-05-02 |
| AU2258583A (en) | 1985-06-27 |
| IL73465A (en) | 1987-10-20 |
| IL73465A0 (en) | 1985-02-28 |
| AU573553B2 (en) | 1988-06-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |