6 Solid forming Forging
6.3 M aterials, billet production and surface treatment
Materials u sed in solid form in g are m ain ly u n alloyed , low-alloy an d h igh -alloy carbon steels, n on -ferrou s ligh t an d h eavy alloys su ch as alu -
m in iu m , m agn esiu m , titan iu m an d cop p er an d th eir alloys cf. Sect. 4.2.2
. Sign ifican t factors in th e selection of m aterials are form ability flow stress, th e p ath of th e flow cu rve cf.
Fig. 6.1.5 , th e p erm issible
flu ctu ation s in m aterial com p osition an d issu es related to billet p rep ara- tion in clu d in g p relim in ary h eat treatm en t, coatin g an d in term ed iate
treatm en t.
6.3.1 M aterials
Steels Low-carbon an d low-alloy steels are p articu larly su ited for cold form ing.
With a carbon con ten t of u p to 0.2 , th e con dition s for form in g are very favorable, u p to 0.3 favorable an d u p to 0.45 difficu lt, wh ich resu lts in
low form ability, tru e strain an d h igh er p ress forces. Ph osp h oru s an d su l- p h u r con ten t sh ou ld rem ain below 0.035 , as th ese com p on en ts ten d to
redu ce form ability. Th e con ten t of n itrogen is restricted to less th an 0.01 for reason s of su scep tibility to agein g. Pre-h eat-treated steels can be u sed for
p arts wh ich are sen sitive to warp in g valve tap p et rods an d wh ose h igh stren gth u p to 1,100 Nm m
2
p erm it on ly m in im al deform ation . In som e cases, m icro-alloyed steels con tain in g boron , wh ich p erm it p en etration
h arden in g, are rep lacin g alloyed steels with th e p rescribed fu ll h eat treat- m en t.
All steels wh ich can be cold form ed , can also be warm form ed . How- ever, it sh ou ld be em p h asized th at even steels con tain in g a h igh er carb o n
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
co n t en t , fo r exam p le fro m 0.45 t o 1.0 , can b e easily fo rm ed , i. e. with ou t costly in term ed iate h eat treatm en t. In d u ctive h ard en in g steels
su ch as Cf 53, Cf 60 an d th e ball bearin g steels 100 Cr 6 are classical exam p les of ap p lication for warm form in g. For p ractice-orien ted calcu -
lation of force an d en ergy req u irem en ts, a good ap p roxim ation for th e flow stress cu rve for h ot forgin g can be obtain ed by m u ltip lyin g th e cold
forgin g flow cu rve valu es with a factor of 0.3 to 0.5. Figure 6.3.1
in d icates th e tem p eratu re-d ep en d en t variation of th e flow stress cu rves for Ck 15
an d Cf 53. Table 6.3.1
p ro vid es a su m m ary o f t h e m o st im p o rt an t st eel m at erial gro u p s. It list s n o t o n ly t h e DIN an d Eu ro st an d ard d esign at io n s bu t also
t h e abbreviat io n s fo r sim ilar m at erials in acco rd an ce wit h t h e Am erican AISI an d A.S.T.M st an d ard s as well as wit h t h e Jap an ese JIS st an d ard .
Th e last co lu m n p ro vid es in fo rm at io n o n wh et h er t h e st eel is su it able fo r h o t fo rm in g H, warm fo rm in g W o r co ld fo rm in g C. Fo r m o re
in fo rm at io n o n wo rkp iece m at erials, p lease refer t o DIN wo rksh eet s 17 006, 17 100, 17 200, 17 210, 17 240, 17 440. Flo w st ress cu rves fo r co ld
fo rm in g are given in t h e VDI Gu id elin es 3134, 3200 sh eet 2 ferro u s m et als an d sh eet 3 n o n -ferro u s m et als.
451
M aterials, billet production and surface treatment
Fig. 6.3.1
Temperature-dependent flow curves Ck 15 and Cf 53
true strain [-]
flow stress
k [N
mm ]
f
6 material k
material f 3
0,2 0,4
0,6 0,8
1,0 0,2
0,4 0,6
0,8 1,0
° °
6 ° 7 °
° °
° 6 °
7 ° °
= s
-
= s
-
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
452
Solid forming Forging Table 6.3.1: Selection of steels for solid forming
M aterial group No.
DIN 1654 Eurostandard
American Japanese
Suitable for cold C, standard AISI
standard warm W
A.S.T.M . JIS
and hot H forming general 1.0303
QSt 32-3
C4C Armco
C structural steel
1.0213 QSt 34-3
C7C SS34
C 1.0204
UQSt 36 C11G1C
C 1.0160
UPSt37-2 H
1.0224 UQSt-38
C14G1C SS41
C 1.0538
PSt50-2 H
case-hardening 1.0301
C10 C10
C1008 S10C
W, H steels
1.1121 Ck10
C10E C1010
S 9CK C, W, H
1.1122 Cq10
C10C C1010
S 9CK C, H
1.0401 C15
C15 S15C
W, H 1.1141
Ck15 C15E
C1015 S15CK
C, W, H 1.1142
Cq15 C15C
C1015 S15Ck
C 1.5919
15CrNi6 C
1.7016 17Cr3
C 1.7131
16M nCr5 SCr22
C, W, H 1.7321
20M oCr4 C
heat-treatable 1.6523 21NiCrM o2
C steels
1.1151 Ck22
C22E C1020
S20C C
1.1152 Cq22
C22C C1020
C 1.0501
C35 S30C
W, H 1.1181
Ck35 C35E
C1035 S35K
C, W 1.1172
Cq35 C35C
S35K C, W, H
1.0503 C45
S40C W, H
1.1191 Ck45
C45E C1045
S45C C, W, H
1.1192 Cq45
C45C C
1.1193 Cf45
C45G W
1.1213 Cf53
C53G W
– Cf60
C60G W
alloyed 1.5508
22B2 C
heat-treatable 1.5510
28B2 C
steels 1.5511
35B2 C
1.5523 19M nB4
C 1.7076
32CrB4 C
1.7033 34Cr4
5130 -40 SCr1
C, W, H 1.7035
41Cr4 5130 -40
SCr4 C, W, H
1.7218 25CrM o4
4120 32 C, W, H
1.7220 34CrM o4
4135 SCM 3
C, W, H 1.7225
42CrM o4 4140 -42
SCM 4 C, W, H
1.6582 34CrNiM o6
C, H stainless steels
1.4016 X6Cr17
C, ferritic 1.4006
X10Cr13 X10Cr13
C, martensitic 1.4024
X15Cr13 X15Cr13
C, H, austenitic 1.4303
X5CrNi18-12 X4CrNi18-12
C, austenitic 1.4567
X3CrNiCu18-9 X3CrNiCu18-9-4
C, austenitic roller bearing steel 1.3505
100Cr6 52100
SUJ1 2 C, W
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
Alum inium alloys Wrou gh t alu m in iu m m aterials wh ich h ave been m an u factu red by form -
in g, n ot castin g, are u sed for form in g p rocesses. Alu m in iu m with a fin e- grain ed m icrostru ctu re offers a n u m ber of ad van tages over coarser-
grain ed alu m in iu m : Im p roved form ability, su p erior su rface q u ality of com p on en ts an d greater stren gth . Ultra-p u re an d p u re alu m in iu m Table
6.3.2 p erm it an extru sion ratio cross-section al red u ction of u p to 95
tu be p rod u ction . With an in creasin g m agn esiu m con ten t, it is p ossible to set h igh er stren gth ch aracteristics. Age-h ard en able, corrosion -resistan t
alu m in iu m alloys su ch as A1MgSi1 exh ibit h igh stren gth ch aracteristics as a resu lt of h eat agein g wh ich exceed th e valu es ach ieved wh en in a
strain -h ard en ed state. Flow cu rves for alu m in iu m m aterials are also giv- en in th e VDI d irectives 3134 an d 3200.
Copper alloys Like alu m in iu m , cop p er an d its alloys offer ou tstan d in g extru sion cap a-
bility. Th e yield stress in creases with in creasin g alloyin g elem en ts, wh ereby form in g sh ou ld take p lace wh ile th e m aterial is in a soft-
an n ealed state. In th e case of tech n ically p u re cop p er, m ain ly E-Cu an d SE-Cu are u sed , for exam p le, in th e p rod u ction of term in als. Am on g th e
variety of d ifferen t bron zes u sed , th e tin bron ze with 1 to 2 Sn an d sil- icon bron ze is m ost wid ely form ed . If alloy elem en ts su ch as ch rom e, zir-
con iu m , beryliu m or silicon Cu Ni2Si are p resen t, m an y cop p er m ateri-
453
M aterials, billet production and surface treatment
M aterial group No. DIN 1712 25 45 ISO AA JIS pure ultra-pure aluminium 3.0285 Al 99,8 Al 99,8 1080A A1080
3.0275 Al 99,7 Al 99,7 1070A A1070 3.0255 Al 99,5 Al 99,5 1050A A1050
non age-hardenable alloys 3.0515 Al M n1 AlM n1 3103 A3003 3.3315 Al M g1 AlM g1 5005A
3.3535 Al M g3 AlM g2,5 5754 3.3555 Al M g5 AlM g5 5056A
hardenable alloys 3.3206 Al M g Si 0,5 6060 6063 A6063 3.2315 AlM gSi 1 6082 6061 A6082
3.1325 AlCuM g 1 2017A A2017 3.4365 AlZnM gCu 1,5 7075 A7075
Table 6.3.2: Selection of aluminium materials for cold and hot extrusion
Metal Forming Handbook Schuler c Springer-Verlag Berlin Heidelberg 1998
M aterial group Abbreviation
No. DIN
US designation UNS JIS
pure copper E-Cu F20
2.0060 1787
ETP 99,95 C0-0,04O C11000 OFCu
SF-Cu 2.0090
1787 DHP Copper C12200
DCu copper alloys
CuZn10 2.0230.10
17660 Commercial copper C22000
BS , RBS CuZn28
2.0261.10 17660
Cartridge brass 70 C26000 RBS
CuZn40 2.0360
17660 M untz M etal C28000
RBS CuNi2Si
2.0855 17666
Silicon bronze C64700 CN 1
CuNi12Zn24 2.0730.10
17663 65Ni-12Ag C75700
CuNi20Fe 2.0878.10
17664 Cu-20Ni C71000
CuAl11Ni 2.0978
17665 Aluminium bronze C63200
CuSn2 2.1010
17662 Phosphor bronze C50500
als are age-h ard en able th rou gh h eat treatm en t. Th e m ost im p ortan t cop - p er alloys are th e brass fam ily. Th e form ability of th e m aterial im p roves
as th e cop p er con ten t in creases an d th e Zn con ten t d ecreases. With a Zn con ten t above 36 , th e m aterials becom e brittle an d th eir cold form a-
bility d ecreases rap id ly. As a resu lt, h ot form in g m eth od s sh ou ld p refer- ably be u sed . Flow stress cu rves for cop p er alloys are given in th e VDI
Gu id elin es 3134 an d 3200. O t h er m at erials su ch as lead , zin c, t in , t it an iu m o r zirco n iu m an d
t h eir allo ys can also be su ccessfu lly fo rm ed . Ho wever, in t erm s o f q u an - t it y an d eco n o m ic sign ifican ce, t h ese p lay o n ly a m in o r ro le.
6.3.2 Billet or slug preparation
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