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Патент USA US2111454

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Watented Mar. l5, ‘i938 I
2,111,454
HIGH STRENGTH CORROSION RESISTANT
FERROUS ALLOY SHEETS
Victor ll. Lawrence, Norristown, Pa; assignor to
Alan Wood Steel Company, a corporation of
Pennsylvania
No Drawing. Original ‘application May 25, 1935,
Serial No. 23,520. Divided and this applica
tion May 15, 1937, Serial No. 142,828
3 Claims. (Cl. 148-31)
This invention .relates to the production of other desirable physical properties, that are ob-'
tainable by cold rolling and at the same time
rolled iron and steel sheets and plates character
either bene?cially affect, or at least not mate
ized by relatively high resistance to rust and cor
rosion, and having‘ high. tensile strength‘ and rially decrease, the corrosion resistance proper
ductility as well as other physical properties that ties of the, alloy ascompared with those that
would be exhibited by a similar alloy worked by
make for ease of fabrication by methods involv
the hot rolling process.
ing welding, bending and similar operations.
By the term "cold rolling” I mean a rolling
As pointed out in my ‘co-pending application,
Serial'No. 23,520, ?led May 25, 1935, of which this operation carried on with the slab, plate or other
body of metal in‘ the cold state orat least at ,a
in is a division, it has long been common practice to temperature below the lower‘ critical range at the
cold roll iron and steel to obtain increased
beginning of the rolling operation,‘ and in which
strength. However, cold rolling hasthe disad
vantage that it lowers the corrosion resistance of the metal is brought at least to the state of hard-'
the metal. Therefore, cold rolling is not applied ness known commercially as “% hard cold rolled”. ' ' '
The comparison ofthe properties of such acold
lid where it is desired that the ?nished sheet or plate rolled sheet is made with those of a sheet of sim
shall have a high resistance to corrosion, and,
ilar analysis thate has been hot rolled and an; .'
consequently, it has not been practical to pro
'
‘I
_
,
, -,
v
duce cold rolled sheets and plates from special healed or normalized.
The new product that I claim as my invention
iron and steel alloys designed by reason of their
may be produced by selecting a copper-contain-i' 20
composition to have ‘high corrosion resistance. ing
iron or steel alloy, of the ferritic type'and bra ,
In other words, the sacri?ce of corrosion resist
ance of these alloys has been such as to make it suitable composition to exhibit resistance to cor
and at the same time readily rollable when
unattractive from the commercial standpoint to rosion
heated, and heating this alloy, in the form of a
cold roll them to obtain high strength. There
or billet of suitable thickness, to a temper 25
fore, where it is desired to produce sheets and slab
ature
‘above or within the upper critical range
plates having both high corrosion resistance and and then
while accelerating the cooling of ‘
high strength, resort has been had to special iron the metal rolling
by applying water ‘or any other cooling
and steel alloys combining to a" greater or lesser
medium, the combined rolling and cooling being
extent the properties of high strength and cor
until the metal has cooled or quenched 30.
rosion resistance when the alloy is formed into continued
to below the critical range. The rolling may be
sheets or plates by hot rolling.
'
continued after the temperature is below the crit- ‘
Steel sheets of high strength have been pro
duced by the alloying of iron with hardening ical'range, in this way combining the effect. of
rolling and quenching‘ and imparting to the
elements—carbon, manganese, chromium, nickel, cold
metal greater tensile and elastic strength with
molybdenum, etc., but the fabrication by welding less
of ductility to the piece than would re
of such iron alloys has involved di?lculties which sult loss
by either cold rolling or quenching“ applied
have made them commerciallyiundesirable for
uses requiring their welding, and the maximum individually. The rolling carried on after the
- weldable limits of ferrous alloys hardened by metal is below the critical range does not appear 40’
to adversely a?ect the corrosion resistance prop
40. additions of. one of the above elements, or combi
erties of the metal.
'
nations of these elements, established by the pres
I have found that the rolling operation is ad
ent welding technique is too low to permit more
vantageously carried out in a conventional three
than ,moderate increases in strength.
\
high rolling mill through which the pieces are
Summarizing the above, sheets and light struc
to and fro. A tilting table is provided atv 45
is tural shapes formed from iron or steel alloys com passed
each
side
of the mill to catch the pieces as they
bining higher resistance to corrosion, high
strength, and good welding properties; have not are rolled and lift them into the return pass.‘
been available at a reasonable cost of production.‘ The starting material-billet, slab,‘ plate or
I have found that by appropriate selection of break-down-is.brought at the appropriate tem '50
perature .from a furnace disposed conveniently
= the iron or steel analysis with respect to work
near the entering side of the mill. The rolls are
ability and resistance to corrosion, and conduct
kept cool by means of water sprays which elim
ing the rolling operations in the manner herein
after more particularly described, it is possible to inate change in shape of the rollskdue to heating
produce sheets, platesand other relatively thin and at the same time promoting the cooling of" the
structural shapes having the high strength and 7 pieces being passed through the rolls. The proc
2
2,111,454
ess can also be carried out on mills other than
suitable relation is maintained between the rate
of cooling of the material as it undergoes’ rolling
ample, two-high or-four-high continuous mills, , and quenching and the rate of reduction to the
providing the material is cooled and quenched desired thickness. In the case of heavier sheets,
during the rolling operation by the application of say, %"--1%" in thickness, the slab should be
Water or other cooling medium.
heated to about 2000’ F., or well above the A03
The product may be produced from any one critical range. Starting with a slab of say
of a wide range of copper-containing iron and
11/2”-3" thick, reduction to about %” may be
steel alloys of the non-austenitic or ferritic type. expected at the time the temperature of the slab
10' One of the advantages of the present invention
or plate has fallen to the Ac: point, or around
resides in the fact that the product produced 1750° F. for a low carbon steel. The rolling and
from relatively cheap iron and steel alloys will quenching should then be continued, the larger.
meet strength and corrosion resistance speci?
part of the further reduction occurring with the
cations that heretofore could only be met by steel in the Aer-AC3 range. However, it is pref
resort to more expensive iron and steel alloys.
erable to so conduct the operation as to insure
A group of relatively inexpensive corrosion re
that. some further reduction must be effected
sistant iron and steel alloys that are amenable
after the temperature of the metal has fallen be
to the process of my application Serial No. 23,520, low the A01 range. In this way it is insured that
and can be formed into sheets and ‘plates having there will not be any annealing effect which
20 relatively high strength without detrimental
would tend to nullify the results of the accelerat— 20
effect on their corrosion resistance, are those cop
ed cooling and rolling treatment. At, the same
per-containing iron and steel alloys in which the time, further improvement in the strength prop
carbon content is kept under 0.50%, the copper erties of the sheet is brought about in this ?nal
is under 0.80%, and phosphorus is less than stage under conditions opproaching those of cold
0.10%. I have found, ‘for example, that im
rolling but without the detrimental effects on the 25
provement in strength values of the order noted corrosion resistance of the product that is char
below may be obtained by rolling a copper-bear
acteristic of cold rolling.
ing steel of the following analysis range under
When starting with pieces that have already
the conditions of accelerated quenching herein
been brought down to a relatively thin cross-sec~
30' before described:
tion by hot rolling, they may be brought to the 30
Percent combined quenching and rolling operation of the.
C _______________________________ __ 0.1
—0.3
present invention at a temperature within the
Mn _____________________________ __ 0.30
-0.70
A03 critical range. For example, starting with
S _____ ___ ________________________ __ minus-0.04
steel sheets or break-downs that have been hot
35 P _______________________________ __ .06 -0.10 rolled to 1%" and which it is desired to reduce to
35
Cu _____________________________ __ 0.35
— .50
sheets of 1%" thickness, the temperature at the
beginning of the combined quenching and roll
ing operation may be about 1600° F.
Elastic
Ultimate
limit
strength
While the invention has been described with
lbs/sq. in
lbs/sq. in.
40
particular reference to the production of sheets, 40
it will be understood that bene?cial results may
Ordinary hot rolled _________________ __
33, 000
55, 000-65, 000
be obtained in producing other products of thin
Present process ______________________ __
70, 000
90, 000
cross-section such as light plates and strips. In
fact, any structural shape that may be formed by
and, what is particularly important, these values rolling and having a cross-section of a similar
are obtainable without adversely affecting the thinness as sheets and light plates is to be con 45
corrosion resistance of the alloy.
sidered as within the scope of the invention. Ex
When the product is intended to be fabricated cept where the context indicates a more restrict
by welding, the proportion of carbon should be ed meaning, the term “sheet” as used in the speci
kept below about 0.30%, and should be propor
?cation and appended claims is to be understood
tionately lower if one or more other hardening as including plates and other structural shapes of 50
elements are present in the analysis. By the thin cross-section.’
term “hardening element” is meant any element
The term “slab” as used in the speci?cation is
which will cause the steel to become appreciably to be understood as including not only slabs as
Cl 01 hardened by air quenching from around 2400° F.,
this term is applied in its more restricted sense in 55
i. e., temperatures adjacent to the welding tem
the rolling industry but also billets, plates and
perature zone.
sheets which have been preliminarily worked by
Except to the extent that such alloys are ex
hot rolling from the original cast ingots, and
cluded for uses requiring welding as above indi
which are intended to be further reduced to bring
60 cated, the product may be produced fromv com
them to ?nal dimension.
60
mercially available copper-containing irons and
I claim:
steels of the ferritic type that contain, besides
1. As an improved article of manufacture, a
copper, greater or lesser amounts of one or more
rolled sheet of a corrosion resistant ferrous-base
of the elements chromium, manganese, molyb
alloy of the ferritic type containing an effective
denum, nickel, silicon, phosphorus and vanadium. amount but less than 0.8% copper, less than 0.5% 65
In carrying out the rolling operation the tem
carbon, and less than 0.1% phosphorus, said sheet
perature at which the slab or other partially re
having the corrosion resistance properties of a
duced shape is brought to the rolls will vary some
hot rolled sheet of like analysis, and said rolled
what depending on the thickness of the slab and
70 the thickness desired in the ?nished sheet or sheet being further characterized by the strength
properties and a physical structure such as is pro
plate. The thickness of the slab brought to the duced by heating said alloy to a temperature at 70
rolling operation should also be considered in least approximating the upper critical point, then
relation to the temperature, the extent of the simultaneously subjecting the alloy to rolling and
reduction required and the time involved in quenching and continuing said combined rolling
75 effecting the reduction, so as to insure that a and quenching treatment until the temperature
75
the conventional three-high rolling mill, for ex
H
,iiintu
of the rolled product has been brought below the
-
'
of the rolled product has been brought below the
2. As an improved article of manufacture par
ticularly adapted to be fabricated by welding, a
lower critical range.
3. As an improved article of manufacture,v a
rolled sheet of a steel alloy of the ferritic type
rous-base alloy of corrosion resistance analysis
and of the ferritic type, containing hardening ele
0.04%, phosphorus ODS-0.1%, and copper 0.35
0.5%, said sheet having the corrosion resistance
ments in an amount not exceedingsthe hardening
equivalent of 0.3% carbon. said sheet having the
corrosion resistance properties of a hot rolled
sheet of like analysis, and said rolled sheet being
by the strength properties and a physical 'struc
lower critical range.
.
rolled sheet composed of a copper-containing fer- * containing carbon (Ll-0.3%, sulphur less than
further characterized by the strength properties
and a physical structure such as is produced by
heating said alloy to a temperature at least ap
proximating the upper critical point, then simul
taneously subjecting v the alloy to rolling and
quenching and continuing said combined rolling
and quenching treatment until the temperature
properties of a hot rolled sheet of like analysis,
and said rolled sheet being further characterized
ture such as is produced by heating said alloy to
a temperature at least aproximating the upper
critical point, then simultaneously subjecting the
alloy to rolling and quenching and continuing said
combined rolling and quenching treatment until 15
the temperature of the rolled product has been
brought below the lower critical range.
VICTOR H. LAWRENCE.
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