U.S. patent application number 12/656760 was filed with the patent office on 2010-09-30 for manufacturing method and steel for heavy munition casings.
This patent application is currently assigned to RHEINMETALL WAFFE MUNITION GMBH. Invention is credited to Wolfgang Arrenbrecht, Walter Grimm.
Application Number | 20100242774 12/656760 |
Document ID | / |
Family ID | 39870500 |
Filed Date | 2010-09-30 |
United States Patent
Application |
20100242774 |
Kind Code |
A1 |
Arrenbrecht; Wolfgang ; et
al. |
September 30, 2010 |
Manufacturing method and steel for heavy munition casings
Abstract
A manufacturing method for a heavy munition casing is provided,
in which steel is rolled as a rough sheet or is forged as a slab
depending on the desired casing size. Steel plates (2) produced in
this way have a thickness that is somewhat greater than the
manufacturing diameter of the munition casing (5). The steel used
for this purpose has longitudinally oriented manganese sulfides
(3), which are also shaped in the lateral direction, in addition to
main shaping in the longitudinal direction, by shaping to form the
shaped steel plate (2), and assume a longitudinally extending
plate-shape as well. The initial material for the casing (5) is
taken from an approximately rectangular steel plate (2),
transversely with respect to the deformation direction. The
quadrilateral piece obtained in this way is then turned to be round
and is mechanically processed to form the shape of the casing
(5).
Inventors: |
Arrenbrecht; Wolfgang;
(Schwalmtal, DE) ; Grimm; Walter; (Solms,
DE) |
Correspondence
Address: |
GRIFFIN & SZIPL, PC
SUITE PH-1, 2300 NINTH STREET, SOUTH
ARLINGTON
VA
22204
US
|
Assignee: |
RHEINMETALL WAFFE MUNITION
GMBH
Unterluss
DE
|
Family ID: |
39870500 |
Appl. No.: |
12/656760 |
Filed: |
February 16, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP2008/006109 |
Jul 25, 2008 |
|
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12656760 |
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Current U.S.
Class: |
102/493 ;
148/334; 148/645; 148/649 |
Current CPC
Class: |
C22C 38/18 20130101;
C22C 38/38 20130101; C21D 9/16 20130101; C22C 38/60 20130101; C22C
38/04 20130101; C21D 8/00 20130101; F42B 5/28 20130101 |
Class at
Publication: |
102/493 ;
148/645; 148/649; 148/334 |
International
Class: |
F42B 12/22 20060101
F42B012/22; C21D 8/00 20060101 C21D008/00; C22C 38/22 20060101
C22C038/22 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 15, 2007 |
DE |
10 2007 038 662.3 |
Claims
1. A manufacturing method for the production of a steel or of steel
plates, wherein the method comprises the following steps: (a)
rolling steel plates as a rough sheet or forging steel plates as a
slab, depending on a desired size; and (b) through shaping of the
rough sheet or through producing a shaped plate, wherein manganese
sulfides situated in the shaped plate, in addition to the main
shaping in a longitudinal direction, are also deformed in a
transverse direction and assume a longitudinally extended shape so
that the manganese sulfides form in a plate-shape.
2. A manufacturing method according to claim 1, wherein the shaped
plate is quenched and tempered to the desired strength preferably
directly after shaping.
3. A manufacturing method according to claim 2, wherein the desired
strength is in the range of 900-1200 N/mm.sup.2.
4. Steel for use for the manufacture of a heavy munition casing
according to claim 1, wherein the steel comprises: (a) 0.30 to
0.60% carbon, by weight; (b) a maximum of 1.0% silicon, by weight;
(c) a maximum of 2.0% manganese, by weight: (d) a maximum of 0.05%
phosphorus, by weight; (e) 0.03 to 0.25% sulfur, by weight: (f) a
maximum of 2.0% chromium, by weight; (g) a maximum of 0.5%
molybdenum, by weight: (h) as well as a remainder of iron and
unavoidable impurities.
5. Steel according to claim 4, comprising: (a) 0.35 to 0.45%
carbon, by weight; (b) 0.30 to 0.60% silicon, by weight; (c) 1.40
to 1.60% manganese, by weight: (d) a maximum of 0.035% phosphorus,
by weight; (e) 0.05 to 0.10% sulfur, by weight: (f) 1.80 to 2.10%
chromium, by weight; (g) 0.15 to 0.25% molybdenum, by weight: (h)
as well as a remainder of iron and unavoidable impurities.
6. A munition casing, produced according to the manufacturing
method according to claim 1, wherein the munition casing includes:
(a) steel comprising i. 0.30 to 0.60% carbon, by weight; ii. a
maximum of 1.0% silicon, by weight; iii. a maximum of 2.0%
manganese, by weight; iv. a maximum of 0.05% phosphorus, by weight;
v. 0.03 to 0.25% sulfur, by weight: vi. a maximum of 2.0% chromium,
by weight; vii. a maximum of 0.5% molybdenum, by weight; viii. as
well as a remainder of iron and unavoidable impurities: (b) a
casing wall made by taking an initial piece from a plate made of
the steel, wherein the initial piece is taken transverse to a
deformation direction through sawing, and wherein the casing wall
defines an interior space; and (c) plate-shaped manganese sulfides
situated radially in high density in the steel in a cross section
of the casing wall, wherein the manganese sulfides embrittle the
steel and are arranged radially in the casing wall so that when the
interior space is under a bursting pressure, local fractures are
triggered in the casing wall.
7. A munition casing according to claim 6, wherein the thickness of
the plate is somewhat greater than a manufacturing diameter of the
munition casing, wherein a width of the plate corresponds to at
least a length of the munition casing.
8. Steel according to claim 4, wherein the steel has a strength in
the range of 900-1200 N/mm.sup.2.
9. Steel for use for the manufacture of a heavy munition casing
according to claim 1, wherein the steel consists essentially of:
(a) 0.35 to 0.45% carbon, by weight; (b) 0.30 to 0.60% silicon, by
weight; (c) 1.40 to 1.60% manganese, by weight; (d) a maximum of
0.035% phosphorus, by weight; (e) 0.05 to 0.10% sulfur, by weight;
(f) 1.80 to 2.10% chromium, by weight; (g) 0.15 to 0.25%
molybdenum, by weight; (h) as well as a remainder of iron and
unavoidable impurities, wherein the steel has a strength in the
range of 900-1200 N/mm.sup.2.
10. Steel for use for the manufacture of a heavy munition casing
according to claim 1, wherein the steel consists of: (a) 0.35 to
0.45% carbon, by weight; (b) 0.30 to 0.60% silicon, by weight; (c)
1.40 to 1.60% manganese, by weight; (d) a maximum of 0.035%
phosphorus, by weight; (e) 0.05 to 0.10% sulfur, by weight; (f)
1.80 to 2.10% chromium, by weight; (g) 0.15 to 0.25% molybdenum, by
weight; (h) as well as a remainder of iron and unavoidable
impurities.
11. Steel according to claim 10, wherein the steel has a strength
in the range of 900-1200 N/mm.sup.2.
12. Steel according to claim 4, wherein the steel includes
plate-shaped manganese sulfides.
13. Steel according to claim 9, wherein the steel includes a phase
comprising plate-shaped manganese sulfides.
14. Steel according to claim 10, wherein the steel includes a phase
comprising plate-shaped manganese sulfides formed by the manganese
and the sulfur.
15. A munition casing according to claim 6, wherein the thickness
of the plate is somewhat greater than a manufacturing diameter of
the munition casing, wherein a width of the plate corresponds to at
least a multiple of a length of the munition casing.
Description
[0001] The starting product for the manufacture of heavy munition
casings is bar steel rolled or forged to be round. The casings are
subsequently produced from this preliminary material by
chip-removing manufacturing operations.
[0002] A method for increasing the strength of quenched and
tempered steel and its use for the production of a search-igniter
sub-munition casing is disclosed with DE 39 18 700 C2. The quenched
and tempered steel here is the quenched and tempered steel
30CrNiMo8.
[0003] The conventional material for heavy munition casings is a
quenched and tempered steel with largely isotropic material
properties, such as in particular a 42CrMo4- or a 34CrMo4 steel
that is highly quenched and tempered, for example to strength
values above 1100 N/mm.sup.2. The high strength is to promote a
low-deformation complex fracture structure at bursting. However in
practice, under conventional conditions only a tough, plastic
fracture structure is formed at the bursting apart of a smooth
munition casing (FIG. 1a).
[0004] In contrast, brittle steels only cause a bursting apart into
a few main fractures (FIG. 1b). The addition of embrittling phases
such as sulfur, hardened as manganese sulfide, predominantly
promotes the formation of longitudinally orientated fractures,
without triggering the desired complex fracture behavior.
[0005] For this reason, net-shaped predetermined fracture points
are inserted through mechanical material removal (FIG. 1c) to
realize the desired brittle, multipart fracture behavior in a
supplementing manner and at high cost. This manufacturing process
is very laborious.
[0006] The object of the invention is to simplify this process and
to disclose a steel that enables a simplification.
[0007] The object is achieved by the features of claim 1 as well as
claim 4. Advantageous embodiments are shown respectively in the
subordinate claims.
[0008] The present invention is based on the concept of simplifying
or replacing the very laborious manufacturing process by using a
suitable improved steel concept. A suitable steel material is used
that combines the desired high-strength material properties for
heavy munition casings with a complex, multipart burst
behavior.
[0009] The use of a highly quenched and tempered steel with a
transverse plate-shaped manganese sulfide phase is provided for, in
particular the use of a manganese-chromium alloyed quenched and
tempered steel with a transverse fiber structure.
[0010] A quenched and tempered steel of this type is realized in
that the steel plate, whose thickness is somewhat greater than the
manufacturing diameter of a munition casing, is rolled as a rough
sheet or forged as a slab, depending on the desired casing size.
The steel used for this has longitudinally orientated manganese
sulfides. Through the shaping to produce a plate, the manganese
sulfides in addition to the main shaping in the longitudinal
direction are also deformed in the transverse direction and finally
assume a longitudinally extended shape in the form of a plate. The
initial material is now no longer taken from a round steel, but
transverse to the deformation direction from the approximately
rectangular steel plate, for example by sawing. The quadrilateral
piece obtained in this manner is then turned to be round and is
mechanically processed to comply with the drawing. In the wall
cross section of the munition casing the plate-shaped manganese
sulfides are arranged radially in high density. During the
bursting, these manganese sulfides serve as natural predetermined
fracture points and effect a multipart fracture behavior of the
munition casing.
[0011] The munition casing produced according to this manufacturing
process has the desired multipart fracture behavior during the
bursting, without a further heat treatment or an additional
incorporation of predetermined fracture points being required; the
burst behavior of the munition casing corresponds to the desired
multipart fracture structure that according to prior art could only
be achieved by predetermined fracture points. Thus the insertion of
predetermined fracture points can also be omitted.
[0012] The invention is to be explained in more detail based on an
exemplary embodiment with drawing.
[0013] They show:
[0014] FIG. 1 a-c Fracture behavior at the bursting apart of the
munition casings according to the prior art,
[0015] FIG. 1 d The fracture behavior at the bursting apart of the
munition casing according to the invention,
[0016] FIG. 2 A diagrammatic representation of the position of the
unworked casings in a steel plate and reference to the deformation
direction of the manganese sulfides,
[0017] FIG. 3 the radial arrangement of the manganese sulfides in a
munition casing upon use.
[0018] FIG. 1 a-c show the fracture behavior of conventionally
produced munition casings, to which reference has already been made
in the specification introduction.
[0019] FIG. 2 shows a diagrammatic representation of the position
of the unworked casings or initial pieces 1 in a steel plate 2. 3
refers to the incorporated manganese sulfides.
[0020] The steel plates 2, whose thickness is somewhat greater than
the manufacturing diameter of the casing 5, are rolled as a rough
sheet or forged as a slab, depending on the desired casing size.
The width of the steel plates 2 corresponds thereby at least to the
length of a munition casing 5, preferably a multiple thereof.
Through the shaping to produce a plate 2, in addition to the main
shaping, the manganese sulfides 3 are deformed in the longitudinal
direction and also in the transverse direction, and finally assume
a longitudinally extended shape in the form of a plate. Directly
after the heat shaping, the steel plate 2 is quenched and tempered
for strength during use. The proposed steel thereby ensures an
adequate through quenching and tempering over the entire cross
section. The steel or the steel plate 2 has longitudinally
orientated manganese sulfides 3 in high density. The fibers formed
through manganese sulfide phases are obtained using an initially
quenched and tempered, slab-shaped starting body (steel plate 2)
with a high proportion of manganese sulfides, from which initial
pieces 1 for the casing 5 are now taken transverse to the
deformation direction through sawing or the like.
[0021] Due to the high sulfur content, the steel 2 is easily
machinable in spite of high strength. The quadrilateral piece 1
removed from the steel plate 2 is sawed to be round in a further
manufacturing operation and is mechanically processed to comply
with the drawing, i.e. the sections are mechanically processed by
turning and drilling to the dimensions.
[0022] The plate-shaped manganese sulfides 3 are arranged radially
in high density in the wall cross section of the munition casing 5
(FIG. 3). The embrittling sulfides are now situated radially in the
casing wall 4 and under bursting pressure in the function of the
munition casing 5, trigger local fractures, i.e. during bursting
the sulfides function as natural predetermined fracture points and
cause a multipart fracture behavior of the munition casing 5 (FIG.
1 d).
[0023] The steel to be quenched and tempered for use is preferably
produced with the following chemical composition:
0.30 to 0.60% carbon Max. 1.0% silicon Max. 2.0% manganese Max.
0.05% phosphorus 0.03 to 0.25% sulfur Max. 2.0% chromium Max. 0.5%
molybdenum as well as remainder of iron and unavoidable
impurities.
[0024] The following composition has shown itself to be preferred
within these ranges:
0.35 to 0.45% carbon 0.30 to 0.60% silicon 1.40 to 1.60% manganese
Max. 0.035% phosphorus 0.05 to 0.10% sulfur 1.80 to 2.10% chromium
0.15 to 0.25% molybdenum as well as remainder of iron and
unavoidable impurities.
[0025] Comparable steels have been sold for a long time under
material No. 1.2312 for plastic molds (Steel/Iron List, Verlag
Stahl Eisen, Dusseldorf).
[0026] This manganese/chromium alloyed steel or the steel plate 2
is preferably quenched and tempered to the desired strength
directly after the shaping, which strength is preferably in the
range of 900-1200 N/mm.sup.2. The through quenching and tempering
of this manganese/chromium alloyed quenched and tempered steel has
been proved up to approx. 400 mm plate thickness and is thus
adequate for all munition sizes.
[0027] FIG. 2 Deformation direction [0028] Position of the casing
in the steel plate [0029] Manganese sulfides
[0030] FIG. 3 Wall section of munition casing [0031] Position of
the manganese sulfides
* * * * *