ASM Metals HandBook Vol. 14 - Forming and Forging
Подождите немного. Документ загружается.
Proceedings of the Fifth European Symposium on Powder Metallurgy, Vol 1, 1978, p 32
26.
W.B. James, New Shaping Methods for P/M Components, in Powder Metallurgy 1986--State of the Art,
Vol 2, Powder Metallurgy in Science and Practical Technology series, Verlag Schmid GmbH, 1986, p 71
27.
H.A. Kuhn, S. Pillay, and H. Chung, Computer-Aided Preform Design for Powder Forging,
Mod. Dev.
Powder Metall., Vol 12, 1981, p 643
28.
S. Pillay and H.A. Kuhn, "Computerized P
owder Metallurgy (P/M) Forging Techniques," Final Technical
Report AD-A090 043, Rock Island Arsenal, Sept 1980
29.
S. Pillay, "Computer-
Aided Design of Preforms for Powder Forging," Ph.D. thesis, University of
Pittsburgh, 1980
30.
H.A. Kuhn and B.L. Ferguson, An Expert Systems Approach to Preform Design for Powder Forging,
Met.
Powder Rep., Vol 40 (No. 2), 1985, p 93
31.
C.L. Downey and H.A. Kuhn, Designing P/M Preforms for Forging Axisymmetric Parts,
Int. J. Powder
Metall., Vol 11 (No. 4), 1975, p 255
32.
P.J. Guichelaar and R.D. Pehlke, Gas Metal Reactions During Induction Sintering, in
1971 Fall Powder
Metallurgy Conference Proceedings, Metal Powder Industries Federation, 1972, p 109
33.
J.H. Hoffmann and C.L. Downey, A Comparison of the Energy Requi
rements for Conventional and
Induction Sintering, Mod. Dev. Powder Metall., Vol 9, 1977, p 301
34.
R.F. Halter, Recent Advances in the Hot Forming of P/M Preforms, Mod. Dev. Powder Metall.,
Vol 7,
1974, p 137
35.
J.E. Comstock, How to Pick a Hot-Forging Lubricant, Am. Mach., Oct 1981, p 141
36.
T. Tabata, S. Masaki, and K. Hosokawa, A Compression Test to Determine the Coefficient of Friction in
Forging P/M Preforms, Int. J. Powder Metall., Vol 16 (No. 2), 1980, p 149
37.
M. Stromgren and R. Koos, Hoganas' Contribution to Powder Forging Developments, Met. Powder Rep.,
Vol 38 (No. 2), 1983, p 69
38.
T. Altan, "Characteristics and Applications of Various Types of Forging Equipment, Technical Report
MFR72-02, Society of Manufacturing Engineers
39.
J.W. Spretnak, "Technical Notes on Forging," Forging Industry Educational and Research Foundation
40.
Forging Design Handbook, American Society for Metals, 1972
41.
J.E. Jenson, Ed., Forging Industry Handbook, Forging Industry Association, 1970
42.
S. Mocarski and P.C. Eloff, Equipment Considerations for Forging Powder Preforms,
Int. J. Powder
Metall., Vol 7 (No. 2), 1971, p 15
43.
G. Bockstiegel and M. Stromgren, "Hoganas Automatic PM-
Forging System, Concept and Application,
Technical Paper 790191, Society of Automotive Engineers, 1979
44.
H.A. Kuhn, Deformation Processing of Sintered Powder Materials, in Powder Metallurgy Processing--
New
Techniques and Analyses, Academic Press, 1978, p 99
45.
H.A. Kuhn, M.M. Hagerty, H.L. Gaigher, and A. Lawley, Deformation Characteristics of Iron-
Powder
Compacts, Mod. Dev. Powder Metall., Vol 4, 1971, p 463
46.
H.A. Kuhn and C.L. Downey, "Deformation Characteristics and Plasticity Theory of Sintered Powder
Materials," Int. J. Powder Metall., Vol 7 (No. 1), 1971, p 15
47.
H.A. Kuhn, Fundamental Principles of Powder Preform Forging, in
Powder Metallurgy for High
Performance Applications, Proceedings of the 18th Sagamore Army Materials Research Conference,
Syracuse University Press, 1972, p 153
48.
H.A. Kuhn and C.L. Downey,
How Flow and Fracture Affect Design of Preforms for Powder Forging,
Powder Metall. Powder Technol., Vol 10 (No. 1), 1974, p 59
49.
F.G. Hanejko, P/M Hot Forming, Fundamentals and Properties, Prog. Powder Metall., Vol 33, 1977, p 5
50.
H.F. Fischmeister,
B. Aren, and K.E. Easterling, Deformation and Densification of Porous Preforms in Hot
Forging, Powder Metall., Vol 14 (No. 27), 1971, p 144
51.
G. Bockstiegel and U. Bjork, The Influence of Preform Shape on Material Flow, Residual Porosity, and
Occurrence of Flaws in Hot-Forged Powder Compacts, Powder Metall., Vol 17 (No. 33), 1974, p 126
52.
M. Watanabe, Y. Awano, A. Danno, S. Onoda, and T. Kimura, Deformation and Densification of P/M
Forging Preforms, Int. J. Powder Metall., Vol 14 (No. 3), 1978, p 183
53.
G. Sjoberg, Material Flow and Cracking in Powder Forging, Powder Metall. Int., Vol 7 (No. 1), 1975, p 30
54.
H.L. Gaigher and A. Lawley, Structural Changes During the Densification of P/M Preforms,
Powder
Metall. Powder Technol., Vol 10 (No. 1), 1974, p 21
55.
P.W. Lee and H.A. Kuhn, Fracture in Cold Upset Forging--A Criterion and Model, Metall. Trans.,
Vol 4,
April 1973, p 969
56.
C.L. Downey and H.A. Kuhn, Application of a Forming Limit Concept to the Design of Powder Preforms
for Forging, J. Eng. Mater. Technol. (ASME Series H), Vol 97 (No. 4), 1975, p 121
57.
S.K. Suh, "Prevention of Defects in Powder Forging," Ph.D. thesis, Drexel University, 1976
58.
S.K. Suh and H.A. Kuhn, Three Fracture Modes and Their Prevention in Forming P/M Preforms, Mo
d. Dev.
Powder Metall., Vol 9, 1977, p 407
59.
C.L. Downey, "Powder Preform Forging--
An Analytical and Experimental Approach to Process Design,"
Ph.D. thesis, Drexel University, 1972
60.
B.L. Ferguson, "P/M Forging of Components for Army Applications," Tri-
Service Manufacturing
Technology Advisory Group Program Status Review, 1979, p F1
61.
M. Stromgren and M. Lochon, Development and Fatigue Testing of a Powder Pinion Gear for a Passenger
Car Gear Box, Mod. Dev. Powder Metall., Vol 15, 1985, p 655
62.
W.J. Huppmann, Forces During Forging of Iron Powder Preforms, Int. J. Powder Metall.,
Vol 12 (No. 4),
1976, p 275
63.
Y. Nilsson, O. Grinder, C.Y. Jia, and Q. Jiazhong, "Hot Repressing of Sintered Steel Properties," STU 498,
The Swedish Institute for Metals Research, 1985
64.
O. Grinder, C.Y. Jia, and Y. Nilsson, Hot Upsetting and Hot Repressing of Sintered Steel Preforms,
Mod.
Dev. Powder Metall., Vol 15, 1984, p 611
65.
Q. Jiazhong, O. Grinder, and Y. Nilsson, Mechanical Properties of Low Temperature Po
wder Forged Steel,
in Horizons of Powder Metallurgy, Part II, Verlag Schmid, 1986, p 653
66.
G. Bockstiegel and H. Olsen, Processing Parameters in the Hot Forming of Powder Preforms, in
Powder
Metallurgy, Third European Powder Metallurgy Symposium, Conference Supplement Part 1, 1971, p 127
67.
Surface Roughness Averages for Common Production Methods, Met. Prog., July 1980, p 51
68.
R. Koos, G. Bockstiegel, and C. Muhren, "Machining Studies of PM-
Forged Materials," Technical Paper
790192, Society of Automotive Engineers, 1979
69.
U. Engstrom, Machinability of Sintered Steels, Powder Metall., Vol 26 (No. 3), 1983, p 137
Powder Forging
W. Brian James, Michael J. McDermott, and Robert A. Powell, Hoeganaes Corporation
Mechanical Properties
Wrought steel bar stock undergoes extensive deformation during cogging and rolling of the original ingot. This creates
inclusion stringers and leads to planes of weakness, which affect the ductile failure of the material. The mechanical
properties of wrought steels vary considerably according to the direction test pieces are cut from the wrought billet.
Powder forged materials, on the other hand, undergo relatively little material deformation, and their mechanical properties
have been shown to be relatively isotropic (Ref 70). The directionality of properties in wrought steel is illustrated in Table
4.
Table 4 Comparison of transverse and longitudinal mechanical properties of wrought steels
Ultimate
tensile strength
Yield strength,
0.2% offset
Impact
energy
Fatigue
endurance
limit
Material Specimen
orientation
MPa ksi MPa ksi J ft·lb MPa
ksi
Elongation,
%
Reduction
of
area, %
Longitudinal
820 119 585 85 . . . . . . . . . . . .
25.5
64
5046
Transverse 825 120 600 87 . . . . . . . . . . . .
11.5
21
Longitudinal
1095 159 1005 146 . . . . . . . . . . . .
19.0
55
4340
Transverse 1095 159 1000 145 . . . . . . . . . . . .
13.5
30
Longitudinal
1060-
1215
154-
176
905-
1070
131-
155
. . . . . . . . . . . .
12-15
53-57
8620
Transverse 1070-
1240
155-
180
905-
1240
131-
157
. . . . . . . . . . . .
4-8
10-15
Longitudinal
920-980 133-
142
. . . . . . 100 74 310 45 17-19
60-62
EN-16
(a)
, lot
Y
Transverse 910-950 132-
138
. . . . . . 10 7.4 250 36 5-12
8-24
Longitudinal
960-1000 139-
145
. . . . . . 100 74 400 58 17-18
58-62
EN-16
(a)
, lot
Z
Transverse 950-970 138-
141
. . . . . . 10 7.4 290 42 7-10 6-15
Data on 5046 and 4340 are from Ref 71; data on 8620 are from Ref 72; data on EN-16 are from Ref 73.
(a)
Composition of EN-16: Fe-1.7Mn-0.27Mo.
Mechanical properties of powder forged materials are usually intermediate to the transverse and longitudinal properties of
wrought steels. The rotating-bending fatigue properties of powder forged material also have been shown to fall between
the longitudinal and transverse properties of wrought steel of the same tensile strength (Ref 74). This is illustrated in Fig.
16.
Fig. 16 Comparison of fatigue resistance of powder forged and wrought materials. Source: Ref 74.
While the performance of machined laboratory test pieces follows the intermediate trend described above, in the case of
actual components, powder forged parts have been shown to have superior fatigue resistance (Fig. 17). This has generally
been attributed not only to the relative mechanical property isotropy of powder forgings but also to their better surface
finish and finer grain size.
Fig. 17 Fatigue curves for powder forged and drop forged connecting rods. Source: Ref 75.
The present section reviews the mechanical properties of powder forged materials. The data presented represent results
obtained on machined standard laboratory test pieces. Data will be reported for four primary materials. The first two
material systems are based on prealloyed powders (P/F-4600 and P/F-2000). The third material based on an iron-copper-
carbon alloy, was used by Toyota in 1981 to make P/F connecting rods; Ford Motor Company introduced powder forged
rods with a similar chemistry in 1986. Mechanical property data are therefore presented for copper and graphite powders
mixed with an iron powder base to produce materials that generally contain 2% Cu. Some powder forged components are
made from plain carbon steel. This is the fourth and final material for which mechanical property data are presented.
Forging Mode. It is well known that the forging mode has a major effect on the mechanical properties of components.
With this in mind, the mechanical property data reported in this section were obtained on specimens that were either hot
upset or hot re-press forged. The forging modes used to produce billets for mechanical property testing are shown in Fig.
18.
Fig. 18 Forging modes used in production of billets for mechanical testing.
Dimensions, given in inches, are
average values.
Longitudinal test specimens 10 mm (0.4 in.) in diameter (for tensile and fatigue testing) and 10.8 × 10.8 mm (0.425 ×
0.425 in.) square (for impact testing) were then cut from the forged billets. These specimen sizes represent comparable 10
mm (0.4 in.) diam ruling sections used for heat treatment and were the section sizes used unless otherwise noted.
Heat Treatments. There were three heat treatments used in developing the properties of the prealloyed powder forged
materials: case carburizing, blank carburizing, and through-hardening (quenching and tempering).
Case carburizing was applied to materials with a nominal core carbon content of 0.20 to 0.25%. Blank carburizing is
intended to produce a microstructure similar to that found in the core of case carburized samples. At the 0.20 to 0.25% C
level, this results in a core hardness of 45 to 55 HRC.
Quenching and tempering was applied to achieve through hardened microstructures over a range of forged carbon
contents. A low-temperature temper or stress relief at 175 °C (350 °F) resulted in core hardnesses in the range of 55 to 65
HRC for materials with carbon contents of 0.4% and above. In addition, higher-temperature tempers were designed to
achieve core hardnesses of 45 to 55 HRC and 25 to 30 HRC in these higher-carbon samples. Details of these heat
treatments are given below.
Case Carburizing. Specimens were austenitized for 8 h at 955 °C (1750 °F) in an endothermic gas atmosphere with a
dew point of -11 °C (+12 °F). They were then cooled to 830 °C (1525 °F) and stabilized at temperature in an endothermic
gas atmosphere with a dew point of +2 °C (+35 °F). The specimens were quenched in a fast quench rate oil with agitation
at a temperature of 65 °C (150 °F). They were then stress relieved at 175 °C (350 °F) for 2 h. This heat treatment resulted
in a case depth of about 1.52 mm (0.060 in.), with a 1.0% carbon content in the case and a nominal core carbon of 0.25%.
Blank Carburizing. The forged samples were austenitized for 2 h at 955 °C (1750 °F) in a dissociated ammonia and
methane atmosphere. They were quenched with agitation in a fast quench rate oil at 65 °C (150 °F). The samples were
reaustenitized at 845 °C (1550 °F) for 30 min in a dissociated ammonia and methane atmosphere, followed by oil
quenching with agitation in oil held at 65 °C (150 °F). They were then stress relieved at 175 °C (350 °F) for 2 h in a
nitrogen atmosphere.
Through-Hardening. This quench and temper heat treatment consisted of austenitizing the specimens for 1 h at 955 °C
(1750 °F) in a dissociated ammonia and methane atmosphere, followed by quenching with agitation in a fast quench rate
oil at 65 °C (150 °F). The specimens were reaustenitized at 845 °C (1550 °F) for 30 min in a dissociated ammonia and
methane atmosphere, followed by quenching with agitation in oil at 65 °C (150 °F). They were stress relieved for 1 h at
175 °C (350 °F) in a nitrogen atmosphere or tempered at the various temperatures listed in the tables. This procedure
resulted in a uniform microstructure throughout the cross section.
Hardenability. Jominy hardenability curves are presented in Fig. 19 for the P/F-4600, P/F-2000, and iron-copper-
carbon alloys. Testing was carried out according to ASTM A 255. Specimens were machined from upset forged billets
that had been sintered at 1120 °C (2050 °F) in dissociated ammonia.
Fig. 19 Jominy hardenability curves for (a) P/F-4600, (b) P/F-2000, and (c) iron-copper-
carbon materials at
various forged-carbon levels. Vickers hardness was determined at a 30 kgf load.
Tempering Response. Tempering curves (core hardness versus carbon content and tempering temperature) are
presented in Fig. 20 for P/F-2000 and P/F-4600. The curves for P/F-4600 cover ruling sections of 10 mm (0.40 in.) to
25.4 mm (1.0 in.).
Fig. 20 Effect of tempering temperature and carbon content on the core hardness of (a) P/F-
2000 for a ruling
section of 10 mm (0.40 in.), and of P/F-
4600 materials for ruling sections of (b) 10 mm (0.40 in.), (c) 19 mm
(0.75 in.), and (d) 25.4 mm (1.0 in.).
Tensile, Impact, and Fatigue Properties. Tensile properties were determined on test pieces with a gage length of
25.4 mm (1 in.) and a gage diameter of 6.35 mm (0.25 in.). Testing was carried out according to ASTM E 8 using a
crosshead speed of 0.5 mm/min (0.02 in./min). Room-temperature impact testing was carried out on standard Charpy V-
notch specimens according to ASTM E 23. Rotating-bending fatigue (RBF) testing was performed using single-load,
cantilever, rotating fatigue testers. Dimensions of the RBF test specimen are shown in Fig. 21.
Fig. 21 Dimensions (in inches) of RBF test specimens.
The tensile, impact, and fatigue data for the various materials are summarized in Tables 5, 6, 7 and Fig. 22 and 23.
Table 5 Mechanical property and fatigue data for P/F-4600 materials
Sintered at 1120 °C (2050 °F) in dissociated ammonia unless otherwise noted.
Ultimate
tensile
strength
0.2% offset
yield strength
Room-
temperature
Charpy V-notch
impact energy
Fatigue
endurance
limit
Forging
mode
Carbon,
%
Oxygen,
ppm
MPa
ksi MPa ksi
Elongation,
% in 25
mm (1 in.)
Reduction
of area,
%
J ft · lb
Core hardness,
HV30
MPa
ksi
Ratio of fatigue
endurance to
tensile strength
Blank carburized
Upset 0.24 230 1565
227
1425 207 13.6 42.3 16.3 12.0 487 565 82
0.36
Re-press 0.24 210 1495
217
1325 192 11.0 34.3 12.9 9.5 479 550 80
0.37
Upset
(a)
0.22 90 1455
211
1275 185 14.8 46.4 22.2 16.4 473 550 80
0.38
Re-press
(a)
0.25 100 1455
211
1280 186 12.5 42.3 16.8 12.4 468 510 74
0.36
Upset
(b)
0.28 600 1585
230
1380 200 7.8 23.9 10.8 8.0 513 590 86
0.37
Re-press
(b)
0.24 620 1580
229
1305 189 6.8 16.9 6.8 5.0 464 455 66
0.29
Quenched and stress relieved
Upset 0.38 270 1985
288
1505 218 11.5 33.5 11.5 8.5 554 . . . . . .
. . .
Re-press 0.39 335 1960
284
1480 215 8.5 21.0 8.7 6.4 . . . . . . . . .
. . .
Upset 0.57 275 2275
330
. . . . . . 3.3 5.8 7.5 5.5 655 . . . . . .
. . .
Re-press 0.55 305 1945
282
. . . . . . 0.9 2.9 8.1 6.0 . . . . . . . . .
. . .
Upset 0.79 290 940 136
. . . . . . 0.0 0.0 1.4 1.0 712 . . . . . .
. . .
Re-press 0.74 280 1055
153
. . . . . . 0.0 0.0 2.4 1.8 . . . . . . . . .
. . .
Upset 1.01 330 800 116
. . . . . . 0.0 0.0 1.3 1.0 672 . . . . . .
. . .
Re-press 0.96 375 760 110
. . . . . . 0.0 0.0 1.6 1.2 . . . . . . . . .
. . .
Quenched and tempered
Upset
(c)
0.38 230 1490
216
1340 194 10.0 40.0 28.4 21.0 473 . . . . . .
. . .
Re-press
(c)
. . . . . . 1525
221
1340 194 8.5 32.3 . . . . . . . . . . . . . . .
. . .
Upset
(d)
0.60 220 1455
211
1170 170 9.5 32.0 13.6 10.0 472 . . . . . .
. . .
Re-press
(d)
. . . . . . 1550
225
1365 198 7.0 23.0 . . . . . . . . . . . . . . .
. . .
Upset
(e)
0.82 235 1545
224
1380 200 8.0 16.0 8.8 6.5 496 . . . . . .
. . .
Re-press
(e)
. . . . . . 1560
226
1340 194 6.0 12.0 . . . . . . . . . . . . . . .
. . .
Upset
(f)
1.04 315 1560
226
1280 186 6.0 11.8 9.8 7.2 476 . . . . . .
. . .
Re-press
(f)
. . . . . . 1480
215
1225 178 6.0 11.8 . . . . . . . . . . . . . . .
. . .
Upset
(g)
0.39 260 825 120
745 108 21.0 57.0 62.4 46.0 269 . . . . . .
. . .
Upset
(g)
0.58 280 860 125
760 110 20.0 50.0 44.0 32.5 270 . . . . . .
. . .
Upset
(h)
0.80 360 850 123
600 87 19.5 46.0 24.4 18.0 253 . . . . . .
. . .
Upset
(i)
1.01 320 855 124
635 92 17.0 38.0 13.3 9.8 268 . . . . . .
. . .
(a)
Sintered at 1260 °C (2300 °F) in dissociated ammonia.
(b)
Sintered at 1120 °C (2050 °F) in endothermic gas atmosphere.
(c)
Tempered at 370 °C (700 °F).
(d)
Tempered at 440 °C (825 °F).
(e)
Tempered at 455 °C (850 °F).
(f)
Tempered at 480 °C (900 °F).
(g)
Tempered at 680 °C (1255 °F).
(h)
Tempered at 695 °C (1280 °F).
(i)
Tempered at 715 °C (1320 °F)