Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACRGROUND OF THE INVEN~IO~I
The imention is based on the well-known production of coins using stainle5s steel
plated blanlcs, ie. blanks cons:>~;- g of a co..,~Gsite sar,d~icll confo~ g to DE ~8 17
657 Al ~th a ferritic chromium steel corc plated on either side with higha quality
~ustenitic chro.,-iu~-- nickel steel.
Mints are as a general rulc conservative in thcir a~titude and seldom depart from
co..v~.lional techniq.,~ ~ The face value of a coin u~ed to be equal to the ~alue of the
weight of copper, silver or gold it cG~t~ r~i The inc~eas;~g demand for coins resulting
~rom ;...Iu~ io., and the growth of CO~IU~ ICC meant that, from thc nud-
r.;..~tcen~h century onwards, the metsl value of the coms in circulation camc tor.,~r~,.e.lt a mere ~action of their nonunal Yaluc. When replacing the t~dition~l
coinage metals, namely gold and silver, with other matcrials ~lle...~ were o~en made
to rctain the colour ofthe coins, using niclcel as a sobstinlte for silver and cert~n alloys
of copper instead of gold.
As early as 1920, Ullmann's "Enzyklop~die der tccluu5~,11e.l Chemie" (Urban &
Sch-40u4e~n~c~, 8th edinon, 1920), p 59 ff., ~ives various methods of plating core
matenals. On p. 71, in panicular, the plating of cop~,l~-c and copl~e,~:~nc/niclcel
alloys ~nth copper, iron and steel is descnbed, vvhich at least gives the outward
impression th~t the coin is made ofthe matenal uscd to platc it.
If, ho~-~, it is intended to use such plating p~ocesses to produce an cspccially cheap
coin onc possibility is to roll-clad p1ain carbon steel strip on both sides with higher
~uality metal and punch blanks out for ~ ;ng as coin. Rumania in thc carly 1940swas the first countly to introduce nickel plated steel coins (denolnin~tion 100 lei)
m~nuf~ctl-red by this process. The plating on cither side accounted for 3 .5% of the
coin's thickness; its weight WaQ 8.5 g and its tiametet 28 mm. The p~ nQ werefollowed by the Bu~garians who uscd an 80~/o copper/20% nickel alloy to pla~e their
coins
'rbe success of this method in these COUI~tlieS resulted in plated coins of this kind being
introduccd in Germany in ls48. Thcse were 1, ~ and 10 pfcnniE~ pieces, followed
somewhat later by a 2 pferu~ig piece.
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Coins struck ~om rolled co,npos;tes of this l~nd have edges at which the carbon steel
core is ~posed Even though the thin film of higher quali~ plating drawn over these
edges when the blanks are punched out is soon abraded by ~qn~lling. this does not
co.,~ u~e a problcm in our te.~ . .te climlte In thc tropic~ rusting is more app~ ..t
and tho edges havc to be protecled. One way of doing th~s i9 elcctroplating blank~
made ~om rolled Co~lpGSitCs with higher qualisy metals in accordance with DE 39 40
244 Al.
Another possibility is to electroplat~ plain carbon steel blanlcs all o~er.
A disa~v~ntage of clc~rùpla~ing is the problem of env;,~ c..~-fricndly dispostl of the
waste water from the process. The finishir~g of rolled composites by electroplating also
constitutes a cost factor that grows in sig.~ificau~ce in imcr-le proportion to the ssze of
he coins ~lecsroplating the srnaller coins in a series cu,,,p,;~--g diff~rent sizes take~ a
dis~ropo, .iona~e amo~nt of time.
In this linc of developmr~ t thc stainless steel coin c~l rG~ n~ to DE 38 17 6S7 A1
dcl~ ,ib~ at thc outset meets the requirernent of increased corrosion rcs;~lance, when
used in the maMer snd for the purposc ~ ;sa~, and can bc ,. ~ ~ by the
efficies~t and c~ono.,l;~l rolling process, protucing a rolled composite c.~.-c;~l;ng of a
stainless stcel core plated with stainless steel and blanks r. ~ui~h~g no electroplating and
gi~ing risc to nonc ofthe ~ nl cnv;.on .~ *l p~b1e...s.
The stainle~s stee3s used, namely X6Crl7 for the core u~d X5CrN119I I for ~he plating,
are both suitable for hcading ant lhc. ~fol ~ for coinage and are 50 similar with regard
to the relevant prop~ s of stren8th ~hat the cor.,pGs;Le tak~s the starnp well despite
the hi8h solidity of thc corc.
Ha-ving said this, it must be added that the hi8her strength ofthe core by c~ ;son
with copper plated carbon steel blanks rcquires more mec~nical force and, in
particular, more wear resistant ,~."~,ing tools when ~hc coins arc struck
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.
The p~lc n~ involYet in minting stainlcs~ steel coins havc accor~ ly bcen ~
rc_u.~ obstacle so ~heir uridu~ead usc The high 0.2% proof strcn~th of the
requisite stainless steels - at lcas~ ~00 I~lmrn~ in thc case of a~ e XSCrNil810(Gerrnan Matcrial~ S~andard 1.4~01) ~nd X5Cr~i l 812 (Garnan ~aterials Standard
1.4303) and at least 2S0 N/mm~ in the case of fcrrite X6Crl7 (Gcrman Materi~ls
Stantart 1.4306) - pcnnits only a low relicf, ic a vcry fl~ stamp i.n~es~on, thehei~h~ of thc rclief being unable to exceet that of the onginal rollcd matcrial by more
than approx 20%.
In addition to the lovr relicfthat has hitherto been a.,L,~ ~'e wcar ~n the ~ g
tool is vcly grcat as a result of the hardncss ofthe stainlcss steds used. ~hcrea- the
h~.J... ss value of soft a~lne~led ferntfc CL,~ IJ~ steel X6Crl7 may be bctvveen I45
and lS5 HV 30, a muc~t lower hardncss can be achie ed ~rith non-ferrous metals, eg
70 to 85 HV 30 tn thc case of copper alloys. Given that the savice life of the ~"'Y;"8
tool r~ 5~n~5 ~ complcx function of n~ll,e.vus factors inct.Jdi-,g matial, shape,
stroke speed etc., thc hardness of the coin blank is nnn~theless one of the major
influ~cn.
The aim of the in~'e.~ti~A iS to produce an il~c ~ycl~7;~., plated coin requ~.tng no
l.cat,.l~lt of the edges after the blanks havc becn punched out to assure ad! ~ e
conro~;on rP~ noc, even if the coins are to be expose~ to l-..fa~,ou-~'c co~ ons~
which is cnvironnlc.~l-friendly and ~c~r~ b'c, docs not a.lv~,seJy af~ect thc sen~ice life
of the stamping tools ~nd offers more scope with re8ard to relief impression.
DESCRIP~ION OF TH~ NTION
The invention relates to a plated coin consisting of a
minimum 80 ~ by mass of chromuum steel with a ferritic,
austenitic or duplex stmcture wherein the core consiscs of
soft or solution ~nne~l ed stainless steel whose o, 2 ~ proof
strength at room teT:~perature is at least 220 N/mm2, plated or~
either side with non-~errous ~netal whose 0, 2 ~ proof strength
is a minimvm of 40 N/mm2 below the 0, 2 ~ proof strength of
che core.
Surprisingly, the bi8 ~li~, e..ce in the 0 2% proof ,~ th~, ie. forming the hardstainless stccl through a r.,l~ti~_ly soft int~,.,..cdh~c snaterial, presents no obstacle to
~tta;~lmenr ofthe dcsired rcliefimpression and no s;an;~ shortening ofthe sesvice
life of the ,l A "l-;"g tools was observed. Appar~ .~tl~ the soft plating works as a
lubricant betweal the stamping tool and the contours of the hl~pre~;on.
The vely much lower 0.2% proof ~ .l.s of the non-ferrous me~als - eg. only max.
100 Nlrnrn2 in the case of soft anncalcfJ copper, max. 160 Nl~run2 in the casc of so*
n~ t brass Cu~8 and ~nax 150 NIITun2 in the r.,asc of so~ nr~1e~ tin bronze
CuSn2 - ~u~,.;a;n~l~ permit thc ~lr:~ ~ At of a Yery much deeper and c~caner
i,n~cs~;on despite thc stainlcss steel corc, ~ ;~B~B the disat~ar tage ofthe flat
~ .on p.u...,ced on stainless sled by about one half~ depc~ g on thc ~h ~L ..~5 of
thc plating, and n ~ ~ a. J;ngly ~. v. h d ng a ~gh relie
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These findings led to the use of higher strength stainlcss steeis and a further
development involving the ~h ~ g of blsnks with a soft or solution aMealet stainless
steel corc whose 0.2% proof strength is at least 220 N/mm2, plsted on either side with
non.ferrous metal whosc 0.2% proof strcngth is a min;-rlu-rt of 25% below the 0.2%
proof strength of thc core.
From the point of vie~ of cconG~ it was especially advantageous to producc coiris
with a ~tainless steel core made up (in % by mass) 29 follows (German Materials
Standard 1.4003)
C s0.03
Si S2.0
Mn 0.S to 1.5
P 5 0.045
S 5 0.030
N c0.03
Cr 10.S to 12.S
- Nl 0.3 to I
,dcr iron and smetting impunties.
With modem methods of steel p,od~ ;on it i8 possiblc to make stainless steel vcr,Y
cheaply ant adapt it - as in the case of the stainless sted referrcd to abovc which
co.lfo~n.s to Ge~nan Materials Standard 1.4003 - to resist certain kinds of co--vs;~,c
i"nucnce, ie. to be econu"ucal with e,.p~ s,~e alloy ,Olllj)O~,.ltS.
The p.~fc.~d metals for plating arc non-ferrous alloys con~ ;ng 60% to 1Q0%
copper. Copper alloys such as brass containing at least 1% to 2.S% by mass tin are
cquslly suita~le
Copper alloys in particular offer the possibility of varying colour, eg. the reddish tone
of pure copper and ~he gold tone of brass, 71tho~gh it must be noted that the ed~e of
the coin will bc of a different colour. Wlth a view to the easy distinction bctween coins
that is otcen desired particularly in less afrluent countries, the inYeMion offers a Yariety
of colours and colour co"t,d,Ls including coins with a reddish to yellow face and a
bllle-white to off-white ed8e or, alternatively, a largely uniform o~verall colour with a
white face and blue-white to off-white edge. On the other hand, the carbon steel core
Ii3cdy to be used in such countries will lead to the edge bcco.. ~.ng dirty 8rey-biack with
use or, in the tropics, even rusty.
Aside from such cons;d~ ions, it is also advantageous to be able ~o s~a~np the blanks
punched out of rolled co"~ os;l~ strip con,;s~ing of a stainless steel core plated on both
sides without having to cl~l~6~e the edges.
Examples of coins produced in accordance with the invention are as follows.
1. Copper with an 0.2~l/D proof strength of max. 100 NlrNn: on austenitic steel
XSCrNi l 810 (Gerrnzn Materials Standart 1.4301) with an 0 2% proof strengh
- of at least. 200 Nlmm' The plating is rolled on to the core to a th~cL-npss of 2 x
3% coppcr ant thc resultant co.,.posi~e strip made into coins. The faccs and
edges of thc coins c~ince no noteworth~ di~.c.~ce in corrosion re, ~ e
when used in the manner and for the pu~pose e..~;s~ged.
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The blue-white colour of the edge provides a clear contrast ~nth the reddish
colour of ~he faces. Both the production scrap and the coins themselves can be
re~ycled and used for the production of speci~l alloy., cont~inir~g copper such
as X3CrCuMoTi2723 (German Materials Standard 1.4S03), MCr20CuMo
(Ge~marl Materials Standard Z.45~3) and NiC~2lMo (Gcrman Matenals
Standard 2.S858)
2. Brass CuZn28 4ith ar 0.2% proofstrength of max. 160 NJmrn2 on ausi~,.ul;c
stéel X~CrNil81Z (German Mataials Standard 1.4303) with an 0.2% proof
strength of at least. 200 N/mm2 and norrnally 220 Nlrnrn2 to 250 N/rnrn~. The
plating is rolled on to the core to a thicl~ness of 2 x 2.5% brass and the
resultant co."~ e strip made into coins. The faces and edges of the coins
evince no no~eworthy Ji~ ce in corrosion ~ ce ~hen used in the
manner and for the purpo.,e envisaged. The blue.-white colour of the ed8e
provides a clear contrast with the yellow colour of the faces. Both the
production scrap and the coins themselves can be recycled in the usual way for
bras~, p~ated coins.
3. Nlckel 99.2 with an 0.2% proof strcngdl of 120 N~rnrn~ to 150 M/r~ on
ferritic chromium steel X2Crl I (Gerrnan Ma2en~1s Standart l .4003) w~th an
0.2% proof strength of 220 ~7/mm~ to 2S0 N/rnrn~ or X6Crl7 (Gerrnan
Materials Standard 1.4016) with an 0.2% proof strength of 275 ~i/mrn2 to ~40
N/rnrn~. The plating is rolled on to the core to a thickness of 2 x 2.5%, 2 ~c 5%
or 2 x 10% nickel and the result~nt composite strip made into coins and
tokens. The faccs and edges of the coins e~nnce no noteworthy Ji~re.~ce in
corrosion .~;,l~r.~ c when used in the manner and for the purpose envisaged.
The edges and faces lre of virtuallr uniform coloùr. Both thc production scrap
and the coins thc.~:,el~cs can be rccyclcd as alloy steel scrap with no difflculty.
With rcgard ~o suitabillty for coin testing d~ices, matenals 1 and 2 are not
ferrom~gnetic whereas rT-ateris13 is. A plated coin with a carbon steel core is slways
ferrom~gnetic. Selection can be m~de acco.Jingly.
~lle invention also allows wide scope for sclection of varjous kinds of relief and is
especially well suited to 8 y~O;e ': g stalllp.
Convensional production procedures ar,d, to a larBe extent, conventional equipmes~t
can ~e used. Acco. ~in,21~, the plating and punching out of the blanlcs is almost slways
followed by ~he cold forming of a nlillcd edgc. The finished blaslks are then so~
~nne~ed and sent to the mint for stamping.
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