[go: up one dir, main page]

US20070248484A1 - Steel Shell for a Suction Roll and a Method of Producing a Steel Product - Google Patents

Steel Shell for a Suction Roll and a Method of Producing a Steel Product Download PDF

Info

Publication number
US20070248484A1
US20070248484A1 US11/574,266 US57426605A US2007248484A1 US 20070248484 A1 US20070248484 A1 US 20070248484A1 US 57426605 A US57426605 A US 57426605A US 2007248484 A1 US2007248484 A1 US 2007248484A1
Authority
US
United States
Prior art keywords
steel
suction roll
austenite
roll shell
steel contains
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.)
Abandoned
Application number
US11/574,266
Inventor
Mats Liljas
Pelle Johansson
Conny Bergkvist
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.)
Outokumpu Oyj
Original Assignee
Outokumpu Oyj
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 Outokumpu Oyj filed Critical Outokumpu Oyj
Assigned to OUTOKUMPU OYJ reassignment OUTOKUMPU OYJ ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: BERGKVIST, CONNY, JOHANSSON, PELLE, LILJAS, MATS
Publication of US20070248484A1 publication Critical patent/US20070248484A1/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/48—Suction apparatus
    • D21F1/50—Suction boxes with rolls
    • 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
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • 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
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • 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
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • 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
    • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
    • 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
    • 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
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • 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
    • 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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/52—Ferrous alloys, e.g. steel alloys containing chromium with nickel with cobalt
    • 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
    • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F3/00—Press section of machines for making continuous webs of paper
    • D21F3/02—Wet presses
    • D21F3/10—Suction rolls, e.g. couch rolls
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F3/00—Press section of machines for making continuous webs of paper
    • D21F3/02—Wet presses
    • D21F3/10—Suction rolls, e.g. couch rolls
    • D21F3/105—Covers thereof

Definitions

  • the invention relates to a steel shell for a suction roll and a method of producing a steel product, in which method a piece of steel material is worked by a cutting operation such as milling, turning and/or drilling.
  • Stainless steel is used in fields in which a high corrosion resistance is necessary.
  • a high corrosion resistance may be required in environments within off-shore, paper and pulp industry and chemical industry.
  • suction roll shells for paper machines that are manufactured from stainless steel.
  • One type of stainless steel is the so called duplex steels that contain ferrite and austenite.
  • Duplex steels are known to combine a high mechanical strength and toughness with a good corrosion resistance, in particular in terms of stress corrosion and corrosion fatigue. For corrosion resistance as well as mechanical properties such as weldability, it is important that the steel is well balanced in terms of the essential components austenite and ferrite. In modem development of duplex steels, it is desired to have a micro-structure containing 35-65% ferrite, the remainder being austenite.
  • duplex steels are increasingly competing with traditional austenite stainless steels.
  • Such a steel material is described in published U.S. patent application Ser. No. 2003/0172999.
  • the steel material described in this publication is a ferrite-austenite stainless steel having a micro-structure essentially consisting of 35-65% by volume ferrite and 35-65% by volume austenite.
  • the steel in question has a chemical composition containing 0.005-0.07 C, 0.1-2.0 Si, 3-8 Mn, 19-23 Cr, 0.15-0.30 N och 0.5-1.7 Ni, in % by weight. Some other components may also be included.
  • Nitrogen is of considerable importance to the steel described in US 2003/0172999, since nitrogen is dominant as austenite former and contributes to the strength of the steel as well as to its corrosion resistance. For this reason, it was estimated that the nitrogen content of the steel should be in the range of 0.15-0.30%, and preferably in the range of 0.20-0.24%. However, it has been previously shown that steel types of such a high nitrogen content are poor in cuttability.
  • a stainless steel intended to be used for a particular product must be subjected to some type of cutting operation, such as milling, turning or drilling.
  • austenite and duplex stainless steels are poor in cuttability and hence various measures are undertaken in order to increase cuttability of the stainless steel.
  • nitrogen in stainless steel decreases cuttability.
  • U.S. Pat. No. 4,769,213 a method is suggested for increasing cuttability of a martensite stainless steel by reducing carbon and nitrogen contents such that the total content of carbon and nitrogen together is not more than 0.05% by weight.
  • martensite steels have a poorer corrosion resistance.
  • austenite stainless steels For austenite stainless steels, it is suggested in U.S. Pat. No. 5,482,674 that the content of carbon and nitrogen should be reduced such that neither the content of carbon nor the content of nitrogen is more than about 0.035% by weight. It is also known that the addition of sulphur may increase cuttability. Accordingly, U.S. Pat. No. 4,784,828 suggests that sulphur should be added to an austenite stainless steel in order to increase cuttability. It is also stated that the contents of carbon and nitrogen should be very low, in total up to 0.065% by weight. However, compared with duplex steels, austenite steels have a lower strength.
  • a stainless steel suitable for a suction roll shell should be of martensite type, among other things containing carbon at a % by weight of more than 0 but not more than 0.06, silicon at a % by weight above 0 but not more than 2, manganese at a % by weight above 0 but not more than 2, nickel at 3-6% by weight, chromium at 14-17% by weight, molybdenum at 1-3% by weight and copper at a % by weight of from 0.5 to 1.5.
  • the present invention aims at providing a solution to the problem of finding a steel material that exhibits a high strength as well as a good corrosion resistance, and that moreover is suitable for cutting operations without having to be subjected to sulphur addition treatment. It is also an object of the invention to provide a suction roll shell with good corrosion resistance, which is easy to manufacture by cutting operations.
  • a steel material of the type described in above mentioned US 2003/0172999 not only has a high strength and a good corrosion resistance, but that the material in question also is suitable for cutting operations such as turning, milling and drilling, without the material in question having been treated by addition of sulphur.
  • the inventors have also found that the material in question is particularly suitable as a material for paper machine suction rolls, and that it is advantageous to manufacture a suction roll shell of such a material.
  • the invention relates to a suction roll shell of this material.
  • the invention can also be understood as a method for cutting operations, in particular when manufacturing suction roll shells, but also in manufacturing of other products, e.g. rotating machine parts, such as shafts.
  • the invention can also be defined in terms of a use of said steel as a workpiece in cutting operation of steel.
  • the suction roll shell according to the invention is made of a stainless ferrite-austenite steel having a micro-structure essentially consisting of 35-65% by volume of ferrite and 35-65% by volume of austenite.
  • the steel composition will be described in greater detail in the detailed description.
  • the invention also relates to a suction roll comprising the inventive suction roll shell.
  • the cutting operation comprises drilling of at least one through hole, and preferably drilling of a plurality of holes.
  • the method comprises drilling of hundreds of thousands of holes. A corresponding drilled length is several kilometres.
  • the cutting operation may also comprise turning of outside and inside faces of the shell.
  • FIG. 1 shows the bending of a blank for a suction roll shell.
  • FIG. 2 shows a blank having been bent and welded together to form a shell.
  • FIG. 3 shows schematically a first step of working the shell shown in FIG. 2 .
  • FIG. 4 shows a second step of working the shell.
  • FIG. 5 shows a completed suction roll shell.
  • FIGS. 6-9 show the result of comparative tests in which the steel used according to the invention is compared with other steels in terms of cuttability.
  • FIG. 1 a first step in the manufacturing of a suction roll shell is shown.
  • an essentially planar blank 1 is roller bent between two rollers 2 , 3 , as is known as such and need not be described in greater detail herein.
  • the ends of the blank 1 are welded together such that a weld joint unites the blank 1 to form a segment 9 .
  • a plurality of segments are then united by circular joints to form a shell that is heat treated after the welding.
  • FIG. 3 shows how the thus achieved shell 9 can be subjected to a working operation, such as turning.
  • FIG. 1 shows how the thus achieved shell 9 can be subjected to a working operation, such as turning.
  • FIG. 3 shows a turning tool 5 acting on the face of the shell 9 .
  • the object of the turning operation is to ensure that the face of the shell 9 is smooth and regular.
  • FIG. 4 shows schematically a subsequent step in the manufacturing process, in which the shell 9 is drilled by a drill 6 , whereby the shell is provided with a number of through holes 7 .
  • FIG. 5 shows the completed suction roll shell 8 with its circular cylindrical shell 9 and the through holes 7 thereof.
  • FIG. 5 also shows schematically that the ends of the suction roll shell 8 can be closed by side covers 10 .
  • a vacuum source not shown
  • Suction roll shells have previously been manufactured from a material sold under the name 3RE60 Avesta SRG.
  • This steel is a stainless ferrite-austenite steel that has been improved in respect of cuttability by sulphur treatment and that has the following typical composition in % by weight.
  • steel 3RE60 has been used for about 30 years for the manufacturing of suction roll shells, and about 10 years ago it was provided with an additive for improved cuttability and its name was changed to 3RE60 SRG.
  • the steel is called 3RE60 Avesta SRG.
  • This steel has a microstructure essentially consisting of 35-65% by volume of ferrite and 35-65% by volume of austenite, and its chemical composition contains in % by weight: C 0.005 Si 0.1-2.0 Mn 3-8 Cr 19-23 Ni 0.5-1.7 N 0.15-0.3
  • a steel that is particularly suitable for this application suitably contains: optionally Mo and/or W at a total content of no more than 1.0 (Mo+W/2), optionally Cu up to a maximum of 1.0 Cu, balance being iron and impurities.
  • Mo+W/2 a total content of no more than 1.0
  • Cu a maximum of 1.0 Cu
  • balance iron and impurities.
  • the steel contains 0.02-0.05 C.
  • the steel contains 0.18-0.26 N and advantageously 20-23 Cr.
  • the steel contains 0.8-1.70 Ni, and even more preferred 1.35-1.7 Ni.
  • the steel contains 0.22 N, 21.5 Cr, 1.5 Ni, 0.3 Mo, 5 Mn and not more than 0.04 C.
  • a steel is sold by Outokumpu Stainless AB, Box 74, SE-774 22, AVESTA.
  • This steel is sold by Outokumpu under the name LDX 2101®.
  • the name is a trademark registered in the European Union.
  • the LDX 2101® steel is particularly suitable to be used in a suction roll shell.
  • Particularly suitable contents of copper and silicon are 0.3 Cu and 0.7 Si, respectively.
  • the guideline values 0.3 Cu and 0.7 Si (in % by weight) are used for LDX 2101®.
  • the steel of the type mentioned above has a relatively high nitrogen content. As it is known that nitrogen tends to impair cuttability, it would be expected that cuttability is poorer. However, it has been surprisingly shown that the cuttability of the steel used according to the present invention is considerably higher than expected.
  • FIG. 6 shows the results of a comparative test in which an LDX 2101® steel were compared with two other, cuttability-improved, austenite steels called 304L PRODEC® and 316L PRODEC®, respectively.
  • the steel 304L PRODEC® has the following composition in % by weight: C 0.02 Si 0.5 Mn 1.5 Cr 18.2 Ni 8.4 Mo essentially none N 0.07 S 0.02
  • the steel 316L PRODEC® has the following composition: C 0.02 Si 0.5 Mn 1.5 Cr 17.2 Ni 11.2 Mo 2.3 N 0.05 S 0.02
  • FIG. 7 shows the results of an additional comparative test between an LDX 2101® steel and steels 304L PRODEC® and 316L PRODEC®.
  • FIG. 7 shows a test with a working time of 15 minutes, in which turning was made by a cutting edge of hard metal. Under these circumstances, a cutting speed was achieved for an LDX 2102® steel that was somewhat lower in comparison with the other two steels. The difference is however marginal.
  • FIG. 8 shows another test in which the steel LDX 2101® is compared with a conventional duplex steel sold under the name 2205.
  • This steel which is more highly alloyed than LDX 2101®, is standardized (EN 1.4462) and is used in a great number of applications. It has no cuttability-improving additives and is not used for this type of suction roll shells.
  • 2205 has the following composition: C 0.02 Si 0.4 Mn 1.5 Cr 22.2 Ni 5.7 Mo 3.1 N 0.17 S 0.001
  • FIG. 9 yet another test is shown in FIG. 9 .
  • an LDX 2101® steel was compared with three other steel types used for suction roll shells, i.e. 2304 Avesta SRG, 3RE60 Avesta SRG and 2205 Avesta SRG. All steels designated SRG (Suction Roll Grade) are cuttability-improved by sulphur addition.
  • the steel 2304 Avesta SRG has the following typical composition: C 0.02 Si 0.8 Mn 1.5 Cr 22.7 Ni 4.7 Mo 0.3 N 0.09 S 0.02
  • the steel 2205 Avesta SRG has the following typical composition: C 0.017 Si 0.6 Mn 1.35 Cr 22.0 Ni 5.7 Mo 2.9 N 0.13 S 0.02
  • the advantage is obtained, among other things, that the completed roll shell achieves a very good corrosion resistance.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Paper (AREA)
  • Rolls And Other Rotary Bodies (AREA)
  • Reduction Rolling/Reduction Stand/Operation Of Reduction Machine (AREA)
  • Coating With Molten Metal (AREA)
  • Bending Of Plates, Rods, And Pipes (AREA)
  • Heat Treatment Of Articles (AREA)
  • Adjustment And Processing Of Grains (AREA)
  • Compressor (AREA)
  • Applications Or Details Of Rotary Compressors (AREA)

Abstract

A suction roll shell having a plurality of through holes is made of a stainless ferrite-austenite steel having a micro-structure essentially consisting of 35-65% by volume of ferrite and 35-65% by volume of austenite. The steel has a composition containing, among other things, 0.005-0.07 C and 0.15-0.30 N, in % by weight.

Description

    TECHNICAL FIELD
  • The invention relates to a steel shell for a suction roll and a method of producing a steel product, in which method a piece of steel material is worked by a cutting operation such as milling, turning and/or drilling.
    • BACKGROUND OF THE INVENTION
  • Stainless steel is used in fields in which a high corrosion resistance is necessary. A high corrosion resistance may be required in environments within off-shore, paper and pulp industry and chemical industry. One example is suction roll shells for paper machines, that are manufactured from stainless steel. One type of stainless steel is the so called duplex steels that contain ferrite and austenite. Duplex steels are known to combine a high mechanical strength and toughness with a good corrosion resistance, in particular in terms of stress corrosion and corrosion fatigue. For corrosion resistance as well as mechanical properties such as weldability, it is important that the steel is well balanced in terms of the essential components austenite and ferrite. In modem development of duplex steels, it is desired to have a micro-structure containing 35-65% ferrite, the remainder being austenite. In fields requiring high strength and good corrosion resistance, duplex steels are increasingly competing with traditional austenite stainless steels. Such a steel material is described in published U.S. patent application Ser. No. 2003/0172999. The steel material described in this publication is a ferrite-austenite stainless steel having a micro-structure essentially consisting of 35-65% by volume ferrite and 35-65% by volume austenite. The steel in question has a chemical composition containing 0.005-0.07 C, 0.1-2.0 Si, 3-8 Mn, 19-23 Cr, 0.15-0.30 N och 0.5-1.7 Ni, in % by weight. Some other components may also be included.
  • Nitrogen is of considerable importance to the steel described in US 2003/0172999, since nitrogen is dominant as austenite former and contributes to the strength of the steel as well as to its corrosion resistance. For this reason, it was estimated that the nitrogen content of the steel should be in the range of 0.15-0.30%, and preferably in the range of 0.20-0.24%. However, it has been previously shown that steel types of such a high nitrogen content are poor in cuttability.
  • Most often, a stainless steel intended to be used for a particular product must be subjected to some type of cutting operation, such as milling, turning or drilling. In their selves, austenite and duplex stainless steels are poor in cuttability and hence various measures are undertaken in order to increase cuttability of the stainless steel. It is previously known that the presence of nitrogen in stainless steel decreases cuttability. In for example U.S. Pat. No. 4,769,213, a method is suggested for increasing cuttability of a martensite stainless steel by reducing carbon and nitrogen contents such that the total content of carbon and nitrogen together is not more than 0.05% by weight. However, compared with duplex steels, martensite steels have a poorer corrosion resistance. For austenite stainless steels, it is suggested in U.S. Pat. No. 5,482,674 that the content of carbon and nitrogen should be reduced such that neither the content of carbon nor the content of nitrogen is more than about 0.035% by weight. It is also known that the addition of sulphur may increase cuttability. Accordingly, U.S. Pat. No. 4,784,828 suggests that sulphur should be added to an austenite stainless steel in order to increase cuttability. It is also stated that the contents of carbon and nitrogen should be very low, in total up to 0.065% by weight. However, compared with duplex steels, austenite steels have a lower strength.
  • U.S. Pat. No. 4,964,924 suggests use of a martensite stainless steel in a suction roll. In that publication, it is stated that since they are difficult to drill, stainless ferrite-austenite duplex steels are unsuitable as materials for suction rolls. Instead, it is suggested that a stainless steel suitable for a suction roll shell should be of martensite type, among other things containing carbon at a % by weight of more than 0 but not more than 0.06, silicon at a % by weight above 0 but not more than 2, manganese at a % by weight above 0 but not more than 2, nickel at 3-6% by weight, chromium at 14-17% by weight, molybdenum at 1-3% by weight and copper at a % by weight of from 0.5 to 1.5.
  • The present invention aims at providing a solution to the problem of finding a steel material that exhibits a high strength as well as a good corrosion resistance, and that moreover is suitable for cutting operations without having to be subjected to sulphur addition treatment. It is also an object of the invention to provide a suction roll shell with good corrosion resistance, which is easy to manufacture by cutting operations.
    • ACCOUNT OF THE INVENTION
  • Surprisingly, the present inventors have found that a steel material of the type described in above mentioned US 2003/0172999, not only has a high strength and a good corrosion resistance, but that the material in question also is suitable for cutting operations such as turning, milling and drilling, without the material in question having been treated by addition of sulphur. The inventors have also found that the material in question is particularly suitable as a material for paper machine suction rolls, and that it is advantageous to manufacture a suction roll shell of such a material. Accordingly, the invention relates to a suction roll shell of this material. The invention can also be understood as a method for cutting operations, in particular when manufacturing suction roll shells, but also in manufacturing of other products, e.g. rotating machine parts, such as shafts. The invention can also be defined in terms of a use of said steel as a workpiece in cutting operation of steel.
  • Hence, the invention relates to a suction roll shell having a plurality of through holes. The suction roll shell according to the invention is made of a stainless ferrite-austenite steel having a micro-structure essentially consisting of 35-65% by volume of ferrite and 35-65% by volume of austenite. The steel composition will be described in greater detail in the detailed description.
  • The invention also relates to a suction roll comprising the inventive suction roll shell.
  • In a preferred embodiment, the cutting operation comprises drilling of at least one through hole, and preferably drilling of a plurality of holes. In a particularly advantageous embodiment, the method comprises drilling of hundreds of thousands of holes. A corresponding drilled length is several kilometres. The cutting operation may also comprise turning of outside and inside faces of the shell.
    • BRIEF DESCRIPTION OF THE DRAWINGS
  • FIG. 1 shows the bending of a blank for a suction roll shell.
  • FIG. 2 shows a blank having been bent and welded together to form a shell.
  • FIG. 3 shows schematically a first step of working the shell shown in FIG. 2.
  • FIG. 4 shows a second step of working the shell.
  • FIG. 5 shows a completed suction roll shell.
  • FIGS. 6-9 show the result of comparative tests in which the steel used according to the invention is compared with other steels in terms of cuttability.
    • DETAILED DESCRIPTION OF THE INVENTION
  • In the following, the manufacturing of suction roll shells is schematically described. With reference to FIG. 1, a first step in the manufacturing of a suction roll shell is shown. As is shown in FIG. 1, an essentially planar blank 1 is roller bent between two rollers 2, 3, as is known as such and need not be described in greater detail herein. After bending to an essentially circular shape, the ends of the blank 1 are welded together such that a weld joint unites the blank 1 to form a segment 9. A plurality of segments are then united by circular joints to form a shell that is heat treated after the welding. FIG. 3 shows how the thus achieved shell 9 can be subjected to a working operation, such as turning. FIG. 3 shows a turning tool 5 acting on the face of the shell 9. The object of the turning operation is to ensure that the face of the shell 9 is smooth and regular. FIG. 4 shows schematically a subsequent step in the manufacturing process, in which the shell 9 is drilled by a drill 6, whereby the shell is provided with a number of through holes 7. FIG. 5 shows the completed suction roll shell 8 with its circular cylindrical shell 9 and the through holes 7 thereof. FIG. 5 also shows schematically that the ends of the suction roll shell 8 can be closed by side covers 10. When the suction roll shell 8 is used, its interior will be connected to a vacuum source (not shown), which results in air being drawn from the outside and in via the through holes 7. Only a few holes are shown in the drawings. It should be realised however that in real applications the number of holes can be very large, such as 100,000 holes or more.
  • Suction roll shells have previously been manufactured from a material sold under the name 3RE60 Avesta SRG. This steel is a stainless ferrite-austenite steel that has been improved in respect of cuttability by sulphur treatment and that has the following typical composition in % by weight.
    C 0.02
    Si 1.50
    Cr 18.5
    Ni 4.90
    Mo 2.80
    N 0.08
    S 0.02
  • With good results, steel 3RE60 has been used for about 30 years for the manufacturing of suction roll shells, and about 10 years ago it was provided with an additive for improved cuttability and its name was changed to 3RE60 SRG. Nowadays, the steel is called 3RE60 Avesta SRG.
  • It has now been surprisingly shown that another ferrite-austenite steel exists that has in addition a high nitrogen content, and that has equally good or in some respects even better cuttability than the cuttability-improved 3RE60 Avesta SRG. This steel has a microstructure essentially consisting of 35-65% by volume of ferrite and 35-65% by volume of austenite, and its chemical composition contains in % by weight:
    C 0.005
    Si 0.1-2.0
    Mn 3-8
    Cr 19-23
    Ni 0.5-1.7
    N 0.15-0.3
  • A steel that is particularly suitable for this application suitably contains: optionally Mo and/or W at a total content of no more than 1.0 (Mo+W/2), optionally Cu up to a maximum of 1.0 Cu, balance being iron and impurities. For the ferrite and austenite formers in the alloy, i.e. chromium and nickel equivalents, the following conditions should preferably be true:
  • 20<Creeq<24.5
  • 10<Nieq, where
    Creq=Cr+1.5 Si+Mo+2+Ti+0.5 Nb
    Nieq=Ni+0.5 Mn+30 (C+N)+0.5 (Cu+Co).
  • In an advantageous embodiment, the steel contains 0.02-0.05 C. Suitably, the steel contains 0.18-0.26 N and advantageously 20-23 Cr. In a preferred embodiment, the steel contains 0.8-1.70 Ni, and even more preferred 1.35-1.7 Ni.
  • A steel of this composition is described in published U.S. patent application Ser. No. 2003/0172999.
  • In a particularly advantageous embodiment of the invention, the steel contains 0.22 N, 21.5 Cr, 1.5 Ni, 0.3 Mo, 5 Mn and not more than 0.04 C. Such a steel is sold by Outokumpu Stainless AB, Box 74, SE-774 22, AVESTA. This steel is sold by Outokumpu under the name LDX 2101®. The name is a trademark registered in the European Union. Accordingly, the LDX 2101® steel is particularly suitable to be used in a suction roll shell. Particularly suitable contents of copper and silicon are 0.3 Cu and 0.7 Si, respectively. The guideline values 0.3 Cu and 0.7 Si (in % by weight) are used for LDX 2101®.
  • Compared with e.g. steel 3RE60 Avesta SRG, the steel of the type mentioned above has a relatively high nitrogen content. As it is known that nitrogen tends to impair cuttability, it would be expected that cuttability is poorer. However, it has been surprisingly shown that the cuttability of the steel used according to the present invention is considerably higher than expected.
  • FIG. 6 shows the results of a comparative test in which an LDX 2101® steel were compared with two other, cuttability-improved, austenite steels called 304L PRODEC® and 316L PRODEC®, respectively. The steel 304L PRODEC® has the following composition in % by weight:
    C 0.02
    Si 0.5
    Mn 1.5
    Cr 18.2
    Ni 8.4
    Mo essentially none
    N 0.07
    S 0.02
  • The steel 316L PRODEC® has the following composition:
    C 0.02
    Si 0.5
    Mn 1.5
    Cr 17.2
    Ni 11.2
    Mo 2.3
    N 0.05
    S 0.02
  • As the nitrogen content of both cuttability-improved austenite steels 304L PRODEC® an 316L PRODEC® is considerably lower than in an LDX 2101® steel, it would normally be expected for these steels to be better in cuttability than an LDX 2101® steel. In turning tests it was however shown that for an LDX 2101® steel, working time 30 minutes, high-speed steel tools being used, a considerably higher cutting speed was possible as compared with the other two steels, which is shown in FIG. 6.
  • FIG. 7 shows the results of an additional comparative test between an LDX 2101® steel and steels 304L PRODEC® and 316L PRODEC®. FIG. 7 shows a test with a working time of 15 minutes, in which turning was made by a cutting edge of hard metal. Under these circumstances, a cutting speed was achieved for an LDX 2102® steel that was somewhat lower in comparison with the other two steels. The difference is however marginal.
  • FIG. 8 shows another test in which the steel LDX 2101® is compared with a conventional duplex steel sold under the name 2205. This steel, which is more highly alloyed than LDX 2101®, is standardized (EN 1.4462) and is used in a great number of applications. It has no cuttability-improving additives and is not used for this type of suction roll shells. 2205 has the following composition:
    C 0.02
    Si 0.4
    Mn 1.5
    Cr 22.2
    Ni 5.7
    Mo 3.1
    N 0.17
    S 0.001
  • In the test, a comparison was made in terms of the useful life of the tool when milling with a cutting edge of hard metal. As is evident from FIG. 8, the useful life of the tool was considerably longer when working an LDX 2101® steel as compared with working of the steel 2005.
  • Finally, yet another test is shown in FIG. 9. In the test shown in FIG. 9, an LDX 2101® steel was compared with three other steel types used for suction roll shells, i.e. 2304 Avesta SRG, 3RE60 Avesta SRG and 2205 Avesta SRG. All steels designated SRG (Suction Roll Grade) are cuttability-improved by sulphur addition. The steel 2304 Avesta SRG has the following typical composition:
    C 0.02
    Si 0.8
    Mn 1.5
    Cr 22.7
    Ni 4.7
    Mo 0.3
    N 0.09
    S 0.02
  • The steel 2205 Avesta SRG has the following typical composition:
    C 0.017
    Si 0.6
    Mn 1.35
    Cr 22.0
    Ni 5.7
    Mo 2.9
    N 0.13
    S 0.02
  • In the test shown in FIG. 9, a comparison was made in respect of the cutting speed that can be achieved for a drilled length of 1000 mm without tool failure, in different materials. As is evident from FIG. 9, LDX 2101® is considerably better than the cuttability-improved steels 2205 Avesta SRG and 2304 Avesta SRG, and in this respect it is equally good as the cuttability-improved steel 3RE60 Avesta SRG, despite the fact that LDX 2101® contains considerably more nitrogen than the steel 3RE60 Avesta SRG. It is a clear technical advantage if cuttability of the material can be achieved without so called cuttability-improving additives such as sulphur, as these lead to a number of drawbacks such as impaired rollability and impaired corrosion resistance.
  • It is to be understood that although the invention has been described in terms of a suction roll shell and a method, those are just different aspects of one and the same invention, as the method according to the invention is suited to be used for manufacturing of the suction roll shell according to the invention.
  • By the invention, the advantage is obtained, among other things, that the completed roll shell achieves a very good corrosion resistance.

Claims (20)

1-19. (canceled)
20. A suction roll shell with a plurality of through holes, wherein the shell is made of a stainless ferrite-austenite steel having a micro-structure essentially consisting of 35-65% by volume of ferrite and 35-65% by volume of austenite, and having a chemical composition containing 0.005-0.07 C, 0.1-2.0 Si, 3-8 Mn, 19-23 Cr, 0.5-1.7 Ni, 0.15-0.30 N, in % by weight.
21. A suction roll shell according to claim 20 wherein the steel contains
a) optionally Mo and/or W at a total content of no more than 1.0 (Mo+W/2)
b) optionally Cu up to a maximum of 1.0 Cu, balance being iron and impurities, and that for the ferrite and austenite formers in the alloy, i.e. the chromium and nickel equivalents, the following conditions are true:
c) 20<Creq<24.5
d) 10<Nieq, where

e) Creq=Cr+1.5 Si+Mo+2 Ti+0.5 Nb
f) Nieq=Ni+0.5 Mn+30 (C+N)+0.5 (Cu+Co).
22. A suction roll shell according to claim 20, wherein the steel contains 0.02-0.05 C.
23. A suction roll shell according to claim 20, wherein the steel contains 0.18-0.26 N.
24. A suction roll shell according to claim 20, wherein the steel contains 20-23 Cr.
25. A suction roll shell according to claim 20, wherein the steel contains 0.8-1.70 Ni.
26. A suction roll shell according to claim 25, wherein the steel contains 1.35-1.7 Ni.
27. A suction roll shell according to claim 20, wherein the steel contains 0.22 N, 21.5 Cr, 1.5 Ni, 0.3 Mo, 5 Mn, no more than 0.04 C, and preferably 0.3 Cu and preferably 0.7 Si.
28. A suction roll, comprising a suction roll shell according to claim 20.
29. A method of producing a steel product, comprising:
providing a steel workpiece, and
working of the workpiece by cutting operation,
wherein the steel of the workpiece is a stainless ferrite-austenite steel having a micro-structure essentially consisting of 35-65% by volume of ferrite and 35-65% by volume of austenite, and having a chemical composition containing 0.005-0.07 C, 0.1-2.0 Si, 3-8 Mn, 19-23 Cr, 0.5-1.7 Ni, 0.15-0.30 N, in % by weight.
30. A method according to claim 29, wherein the steel contains
a) optionally Mo and/or W at a total content of no more than 1.0 (MO+W/2)
b) optionally Cu up to a maximum of 1.0 Cu, balance being iron and impurities, and that for the ferrite and austenite formers in the alloy, i.e. the chromium and nickel equivalents, the following conditions are true:
c) 20<Creq<24.5
d) 10<Nieq, where

e) Creq=Cr+1.5 Si+Mo+2 Ti+0.5 Nb
f) Nieq=Ni+0.5 Mn+30 (C+N)+0.5 (Cu+Co).
31. A method according to claim 30, wherein the steel contains 0.02-0.05 C.
32. A method according to claim 30, wherein the steel contains 0.18-0.26 N.
33. A method according to claim 30, wherein the steel contains 20-23 Cr.
34. A method according to claim 30, wherein the steel contains 0.8-1.70 Ni.
35. A method according to claim 30, wherein the steel contains 0.22 N, 21.5 Cr, 1.5 Ni, 0.3 Me, 5 Mn and no more than 0.04 C.
36. A method according to claim 29, wherein the cutting operation comprises drilling of at least one through hole.
37. A method according to claim 29, wherein the cutting operation comprises turning.
38. A method according to claim 36, wherein drilling of at least one through hole takes place after a preceding turning step.
US11/574,266 2004-09-07 2005-08-19 Steel Shell for a Suction Roll and a Method of Producing a Steel Product Abandoned US20070248484A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE0402141-6 2004-09-07
SE0402141A SE528375C2 (en) 2004-09-07 2004-09-07 A suction roll sheath made of steel as well as a method for producing a suction roll sheath
PCT/SE2005/001220 WO2006041344A1 (en) 2004-09-07 2005-08-19 A steel shell for a suction roll and a method of producing a steel product

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE2005/001220 A-371-Of-International WO2006041344A1 (en) 2004-09-07 2005-08-19 A steel shell for a suction roll and a method of producing a steel product

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US14/719,760 Continuation US20150252529A1 (en) 2004-09-07 2015-05-22 Steel shell for a suction roll and a method of producing a steel product

Publications (1)

Publication Number Publication Date
US20070248484A1 true US20070248484A1 (en) 2007-10-25

Family

ID=33308722

Family Applications (2)

Application Number Title Priority Date Filing Date
US11/574,266 Abandoned US20070248484A1 (en) 2004-09-07 2005-08-19 Steel Shell for a Suction Roll and a Method of Producing a Steel Product
US14/719,760 Abandoned US20150252529A1 (en) 2004-09-07 2015-05-22 Steel shell for a suction roll and a method of producing a steel product

Family Applications After (1)

Application Number Title Priority Date Filing Date
US14/719,760 Abandoned US20150252529A1 (en) 2004-09-07 2015-05-22 Steel shell for a suction roll and a method of producing a steel product

Country Status (16)

Country Link
US (2) US20070248484A1 (en)
EP (1) EP1786975B1 (en)
JP (1) JP4758430B2 (en)
KR (1) KR20070110246A (en)
CN (2) CN101806009B (en)
AT (1) ATE444394T1 (en)
BR (1) BRPI0514969B1 (en)
CA (1) CA2584275C (en)
DE (1) DE602005016943D1 (en)
EA (1) EA010540B1 (en)
ES (1) ES2333737T3 (en)
PL (1) PL1786975T3 (en)
SE (1) SE528375C2 (en)
SI (1) SI1786975T1 (en)
TW (1) TWI393788B (en)
WO (1) WO2006041344A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2279276A1 (en) 2008-05-16 2011-02-02 Outokumpu Oyj Stainless steel product, use of the product and method of its manufacture
CN111910117A (en) * 2020-07-15 2020-11-10 丁国旺 Carbon and nitrogen alloying method for smelting high-strength stainless steel

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FI121340B (en) * 2008-12-19 2010-10-15 Outokumpu Oy Duplex stainless steel
CN102864380A (en) * 2012-09-05 2013-01-09 忻峰 Low-nickel stainless steel alloy and preparation method thereof
CN102864381A (en) * 2012-09-05 2013-01-09 陈敏 Low-nickel stainless steel alloy material
CN102851618A (en) * 2012-09-05 2013-01-02 徐琼 Low nickel stainless steel alloy material and preparation method thereof
CN102864385A (en) * 2012-09-05 2013-01-09 忻峰 Low-nickel stainless steel alloy
CN102864386A (en) * 2012-09-05 2013-01-09 陈敏 Low-nickel stainless steel alloy material and preparation method
CN102851602A (en) * 2012-09-05 2013-01-02 徐琼 Low nickel stainless steel alloy material
FI125734B (en) * 2013-06-13 2016-01-29 Outokumpu Oy Duplex ferritic austenitic stainless steel
JP6520327B2 (en) * 2015-04-08 2019-05-29 株式会社大林組 Manufacturing method of joint fitting for segment and joint fitting for segment
CN110270798B (en) * 2019-06-27 2020-09-29 福建维普斯厨卫科技有限公司 Production process of multifunctional faucet comprising cylindrical bathroom main body
CN113025891B (en) * 2021-02-08 2022-07-22 江阴兴澄特种钢铁有限公司 Duplex stainless steel S32101 steel plate and manufacturing method thereof

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3736131A (en) * 1970-12-23 1973-05-29 Armco Steel Corp Ferritic-austenitic stainless steel
US4832765A (en) * 1983-01-05 1989-05-23 Carpenter Technology Corporation Duplex alloy
US5746891A (en) * 1996-07-25 1998-05-05 Withers; William David Wear indicators for seal strip of a suction roll of a paper making machine
US6033497A (en) * 1997-09-05 2000-03-07 Sandusky International, Inc. Pitting resistant duplex stainless steel alloy with improved machinability and method of making thereof
US6096441A (en) * 1997-06-30 2000-08-01 Usinor Austenoferritic stainless steel having a very low nickel content and a high tensile elongation
US6344094B1 (en) * 1999-06-15 2002-02-05 Kubota Corporation Ferritic-austenitic two-phase stainless steel
US20030172999A1 (en) * 2000-09-27 2003-09-18 Elisabeth Alfonsson Ferritic-austenitic stainless steel

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3111455A (en) * 1961-05-29 1963-11-19 Sandusky Foundry & Machine Com Suction roll shell and method of making same
EP0683241B1 (en) * 1994-05-21 2000-08-16 Yong Soo Park Duplex stainless steel with high corrosion resistance
JPH09202943A (en) * 1996-01-25 1997-08-05 Kubota Corp High corrosion resistance, high strength and high toughness duplex stainless steel and suction roll body members for paper machines
JPH09256109A (en) * 1996-03-18 1997-09-30 Kubota Corp High toughness and high corrosion fatigue strength duplex stainless steel with excellent drill workability
JP3621818B2 (en) * 1998-01-09 2005-02-16 三菱重工業株式会社 Cast stainless steel
FI103829B (en) * 1998-05-14 1999-09-30 Valmet Corp Suction roll
JP2000248339A (en) * 1999-02-26 2000-09-12 Nisshin Steel Co Ltd Austenitic free cutting stainless steel excellent in workability and corrosion resistance
JP3720223B2 (en) * 1999-10-15 2005-11-24 株式会社クボタ Duplex stainless steel excellent in heat fatigue resistance, corrosion fatigue resistance, drilling workability, etc.
SE526603C3 (en) * 2003-01-24 2005-11-16 Sandvik Intellectual Property Coated cemented carbide insert
EP1609883B1 (en) * 2004-06-24 2017-09-20 Sandvik Intellectual Property AB Coated metal cutting tool

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3736131A (en) * 1970-12-23 1973-05-29 Armco Steel Corp Ferritic-austenitic stainless steel
US4832765A (en) * 1983-01-05 1989-05-23 Carpenter Technology Corporation Duplex alloy
US5746891A (en) * 1996-07-25 1998-05-05 Withers; William David Wear indicators for seal strip of a suction roll of a paper making machine
US6096441A (en) * 1997-06-30 2000-08-01 Usinor Austenoferritic stainless steel having a very low nickel content and a high tensile elongation
US6033497A (en) * 1997-09-05 2000-03-07 Sandusky International, Inc. Pitting resistant duplex stainless steel alloy with improved machinability and method of making thereof
US6344094B1 (en) * 1999-06-15 2002-02-05 Kubota Corporation Ferritic-austenitic two-phase stainless steel
US20030172999A1 (en) * 2000-09-27 2003-09-18 Elisabeth Alfonsson Ferritic-austenitic stainless steel

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2279276A1 (en) 2008-05-16 2011-02-02 Outokumpu Oyj Stainless steel product, use of the product and method of its manufacture
CN111910117A (en) * 2020-07-15 2020-11-10 丁国旺 Carbon and nitrogen alloying method for smelting high-strength stainless steel

Also Published As

Publication number Publication date
KR20070110246A (en) 2007-11-16
WO2006041344A1 (en) 2006-04-20
TW200609363A (en) 2006-03-16
CN101018908B (en) 2012-11-07
CN101806009A (en) 2010-08-18
SI1786975T1 (en) 2010-01-29
SE0402141L (en) 2006-03-08
JP2008512579A (en) 2008-04-24
EA010540B1 (en) 2008-10-30
BRPI0514969A (en) 2008-07-01
EP1786975B1 (en) 2009-09-30
PL1786975T3 (en) 2010-03-31
CN101806009B (en) 2012-08-22
SE0402141D0 (en) 2004-09-07
SE528375C2 (en) 2006-10-31
JP4758430B2 (en) 2011-08-31
WO2006041344A8 (en) 2007-05-31
TWI393788B (en) 2013-04-21
EP1786975A1 (en) 2007-05-23
ATE444394T1 (en) 2009-10-15
ES2333737T3 (en) 2010-02-26
US20150252529A1 (en) 2015-09-10
CA2584275C (en) 2016-11-15
EA200700421A1 (en) 2007-10-26
CA2584275A1 (en) 2006-04-20
DE602005016943D1 (en) 2009-11-12
BRPI0514969B1 (en) 2018-05-15
CN101018908A (en) 2007-08-15

Similar Documents

Publication Publication Date Title
US20150252529A1 (en) Steel shell for a suction roll and a method of producing a steel product
JP5553508B2 (en) High strength steel for seamless weldable steel pipe
KR101141828B1 (en) Turbine rotor and manufacturing method of turbine rotor
US4058650A (en) Back material of metal band saw high in fatigue strength
JPH05287455A (en) Martensitic stainless steel for oil well
EP1518939B9 (en) Sulfur free cutting steel for machine structural use
US20240410041A1 (en) Alloy for Mud Motor Shaft Applications with High Strength, High Impact Toughness and Excellent Fatigue Life
JP2020026744A (en) Method of manufacturing bucket
EP0133959A1 (en) Case hardening steel suitable for high temperature carburizing
JPH0841599A (en) Martensitic stainless steel with excellent corrosion resistance in the weld
US12473619B2 (en) Low phosphorus, zirconium micro-alloyed, fracture resistant steel alloys
US5788922A (en) Free-machining austenitic stainless steel
JPH04247851A (en) High mn austenitic steel
JP2012041632A5 (en)
JPH06145903A (en) High corrosion fatigue strength stainless steel
JP2740595B2 (en) Duplex stainless steel with excellent drillability
JPS5852464A (en) High corrosion fatigue strength duplex stainless steel
JP2889020B2 (en) High Mn non-magnetic steel with excellent machinability
US20050191203A1 (en) Steel for machine structural use having improved machinability
JP2580300B2 (en) Free-cutting duplex stainless cast steel
JP2740597B2 (en) Duplex stainless steel with excellent drillability
JPH09263896A (en) High hardness non-magnetic stainless steel and high hardness non-magnetic stainless steel wire rod
JPH11286745A (en) Tool and its production
JPS63169363A (en) Free cutting austenitic stainless steel
JPH01198448A (en) Two-phase stainless steel having excellent drill workability

Legal Events

Date Code Title Description
AS Assignment

Owner name: OUTOKUMPU OYJ, FINLAND

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LILJAS, MATS;JOHANSSON, PELLE;BERGKVIST, CONNY;REEL/FRAME:018930/0741

Effective date: 20070206

STCB Information on status: application discontinuation

Free format text: ABANDONED -- AFTER EXAMINER'S ANSWER OR BOARD OF APPEALS DECISION