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Improvement in wear characteristics of steel tools by metal ion implantation
Nude= In-rumea "_s girl, Mletbods in Physics Research B90/81 (1993) 233-236 North-Holland
HGLU
13sam Inter$.^.üons with Materials "Atoms
Improvement in `dear characteristics of steel tools by metal ion implantation D.M. Rück
Gesellschaft für Schwerionenforsclmng mbH, FF 110552, 6100 Darmstadt, Germany
D. Boos
Institut für Umformtechnik, Holzgortenstmsse 17, 7000 Stuttgart, Gemany
I.G . Brown
Lawrence Berkeley Lab~ratory, University of California, Berkeley, CA 94720, USA
The annual economic loss induced by wear damage of steel tools is estimated to be DM 34 billion . Ion implantation is known to be a promising method for impro, ing the wear behaviour of metal surfaces. The effect of nitrogen implantation into steel has been investigated by a number of workers and good results have been obtained for several types of steel, especially for steel with high chromium content. However, few investigations of the effect of petal ion implantation into steel have been made. We have investigated the effect of metal ion implantation into high speed steel dies, using high current metal ion beams from a repetitively pulsed vacuum arc ion source . The testing method was, the upsetting, which is comparable to actual forming processes and simulates the wear strain of the tools used in the metal forming industry. Here we describe the metal ion implantation facility and the wear testing apparatus and procedure, and discuss the results we have obtained . 1. Introduction Upsetting as a basic metal forming method is often used to simulate basic processes theoretically and experimentally . The investigations of Weiergräber, Nehl and Westheide [1-3] have shown that in cold forging the load on both the upsetting tools (one untreated and one treated) is equal . Therefore the upsetting process is an ideal one for comparison of the wear rated of treated (coated or implanted) and untreated tools in the same Metal -on implantation and metal + nitrogen or carbrne implantation has been shown by several authors to improve the hardness and wear behaviour of different steels [5-7] . But testing has been, done with pin on disc machines, which is hardly comparable with the wear condition on real tools . The improvement of wear behaviour for ion implanted tools has been summarized in a survey article by Lempert [8], where the described implanted tools were mostly treated with nitrogen . 2. Experimental The upsetting tools were implanted at the LBL laboratory with the equipment shown in fig . 1 [4] and
at the implantation facility at GSI [9]. Both apparatus are described in detail very extensively in the cited publications. The implantation conditions at the LBL facility are summarized in the following. Polished tools made of high speed steel (AISI M2), mounted on a watercooled target support were implanted with metal ions in a vacuum vessel with p = 2 X 10 -6 mbar. The used ion source was the MEWA ion source, a vacuum arc ion source, which delivered an ion beam of 250 ps pulse length and a repetition rate of 15 Hz. The ion beam current in a pulse was several mA, which leads to an average ion beam current of about 100 WA . We used the ions Al, Cu, Hf, Y and Er. The used ion doses are indicated in figs . 5, 6 and 7, respectively . The extraction voltage used was 60 kV. The implantation of N and C was performed at the GSI implantation facility with a do ion beam . The ion beam current was chosen such that the temperatures of the tools were kept below 200°C. The used energies are indicated in the figures respectively. The upsetting tests were carried out a, the Institute für Umformtechnik at the University of Stuttgart . The hardness was measured with a Fischer scope hardness instrument, which measured the hardness under load . The process of testing is described in the following. For studying the wear of metal forming tools, cylindrical
0168-583X/93/$06.00 0 1993 - Elsevier Science Publishers B.V . All rights reserved
Ila . METAL MODIFICATION (a)
234
D.M. Mick et ul. j lr:p)LCC:7:.:::: ü: wear characteristics ojsteel tools Ion energy: seem current : Species :
10 - 300 keV Up to -3 A pulse, -30 mA mean Li. C, Mg. AI, Si, Ca, Sc, TI, V, Cr, Mn, Fe, Co, Ni, Cu, Zn Ge, Sv, Y, Zr. Nb. Ma, Pd. Ag, Cd, In, Sn, Ba, La, Ce, Pr. Nd, Sm, Gd, Uy, Ho, Br, Tm, Yb . HI, Ta, W, Ir, PI, Au, Ph, BI . Th, U.
Faraday Cup
lm
Fig. l . Ion implantation facility at LBL. raw pieces of DIN 16 MnCr 5 (similar to AISI 5120) having an initial diameter of 15 mm and a height of 15 mm were upset (flattened) to a height of 5 .5 mm (strain to = (ho lh .)) . The raw pieces were sheared from rolled bars, covered by a 12 to 15 wm zinc phosphate layer, !ubricatcd by soap !ubricant I1;nnderhibe 236 (nure alkali soap), and upset to a strain of e = In(ho lh 1 ) = 1 .0. As tool material for the upsetting dies the cold working steel 1 .2.374 (X155CrMo 121, AISI D2) and the high speed working steel 1 .3343 (AISI M2) were used . The cold working steel was hardened to a Rockwell C hardness of HRC 61-63 and the high speed steel to HRC F2-64. The upsetting dies were used with an initial roughness R, :5 1 lLm . The wear tests under work blank lubrication
shearing
cold metal forming
phosphating upsetting process soap coating Fig . 2. Scheme of the upsetting process .
final workpiece
simulated production condition were carried out using a C-frame knuckle joint press (Maypres, Typ MKN 1-63/6) with 630 kN press rating and a 60 mm total height of stroke. Transport of the raw pieces into the metal forming machine was carried out by a vibrating conveyor . and the pieces were. put into the dies by a pneumatic wrench. After the metal forming process, the workpieces were blown out by pneumatic pressure. The machine was run. a t a rate of 40 stroke/min. During upsetting a cylindrical raw piece is flattened between plane parallel plates, as shown in fig . 2 . The area of contact between the workpieces and the dies increases with the cross-section of the workpiece . Furthermore, because of the bulging of the workpiece which occurs during upsetting, a portion of the cylindrical surface of the workpiece contacts the die . Due to the shearing process before upsetting, the end faces of the raw pieces have a high roughness, and the roughness peaks can exceed the thickness of the lubricant film even at the beginning of the forming process. Wear begins primarily by adhesive bonding of the workpiece and die material . Eventually the adhesive joints are torn off and cause strong abrasive wear in the die surface . Wear causes a characteristics profile .-lace which is measured by means of an on the die sm inductive transducer . As quantitative measure of wear the linear amount of wear WI (as a maxiinum value) and the planar amount of wear Wq are used and plotted vs the number of upset pieces . The curves obtained this way exhibit a range of initial wear where
D.M . Mick et al. / lmprovernent
to wear characteristics of steel tools
235 . 5,000
1 .4
profile determination by inductive scanning
15,000
1 .2
WI (max)
E i sectional view
amount of was; . i r,5 linear and planar (planar wear : wear depth 1 Is integrated on the die 0,5 L diameter) in 0
1
ç
0 .e
0 a.
0.6
.m Û
0.4 0.2 0 -0.2 -0.4 -20
the wear per upset pieces is rather high . In this range the roughness peaks were smoothed, the area of contact between workpiece and die increased, and a lower rate of wear resulted . For measuring the amount of wear the production is interrupted at preselected number of upset workpieces. The dies are taken out of the machine for measuring the roughness profiles, examples of which are shown in fig. 3. In the centre of the die where there is no relative motion between workpiece and die, there is minimum wear. Wear increases with distance from the centre and exhibits a maximum below the edge of the initial raw piece . The dashed area in fig. 4 shows the surface of the die after 20000 upset workpieces. 3. Results The wear behaviour for hafnium ion-implanted and unimplanted upsetting dies is shown in fig . 5 . The linear wear rate WI (upper figure) and the planar rate Wq (lower figure) are shown as a function of the number of upsetting operations . The upsetting die material was high speed working steel AISI M2 (DIN 1 .3343). The wear reduction of the implanted tools compared with the unimplanted tools is 40-45% after 20000 upsettings. With increasing number of upsettings the supporting surface area is increased and hence the slope of the wear curve decreases . After the running in period the wear rate of the of hafnium ion-implanted does show a lower slope than for unim-
-10
0
mm
10
20
Center of The Upsetting Die amount of planar wear after:
wear rate as a function of the number of upsettings
Fig. 3 . Wear determination of upsetting tools.
upsettings upsettings
0+ 0 O" II + Ill
5,000 10,000 15,000 20,000
upsettings upsettings upsettings upsettings
0+0+6-0 Fig . 4. Rate of wear during the upsetting process . planted dies. The re-ults of the upsetting proc.;ss for all implanted upsetting dies and the unimplanted one are summarized in fig. 6 . The linear amount of wear after 5000, 10000 and 20000 upsettings is shown as a percentage of the wear of the unimplanted dies. An improvement of the wear behaviour of the dies can be seen for Hf, Er and Y implanted dies. In some cases e .g. for Hf and N impl-oration, an improvement is seen upsetting die material: AISI M2 strain In (h, /h, ) : e m 1 .0 workplace material : AIS15120 number of strokes: 40 In ?' lubricant: Bonderlube 236 Implantation: hafniun :-Ion s J ion Implanted 2 '10"Hf-Ionen / c .,1 .
2.0 i 1 .5 c 3
(Hf" ;Hf" ;Hf") ;60 kV R,,, .0.552 gm
1 .0 0.5
ô
x Ç
3
0 20 75 10 5 0
5,000
10,000
15,000
20,000
Number of Upsettings Fig . 5 . Results of the upsettings for implanted and unimplanted dies . Ila. METAL MODIFICATION (a)
236
D.M. Rück et al. / lmprouemen , ir, wtar characteristics o(steei tools
140 after 5.000 u settrn s 120 1C0 80 60 40 20
W 140 120 `0 100 80 ô 40 20 E 0 1-'0
120 -' 100
w
mi
i
Fit HI
a fter 10.000 uu o se:ti n , 7;
_
afte r20 .000 uosettmfc g_
60 60 40 20 0
r-
r.
V1
V4
V2
4. Summary
t.
V3 V14 V5
Upsetting Dies
V9
V6
V7
V55
metal-ion implantation with 60 kV nitrogen-ion-implantation with 160 kV V55 AISI D2, other dies AISI M2 V1 Hf-ions2 " 10' r/cm2 V6 AI-ions 5 "10'%M 2 V2 Er-ions 2 " 10"/cm2 Cu-ions d " 10'%cm 2 V3 Er-ions2 " 10'7cm2 V7 Cu-ions3 "10'%cm 2 N-ions 2 " 10"/cm2 Al-ions5-10'elcm 2 V4 Hf-ions 2-10'e/cm2 V9 C-ions 6-1 017/_2 Wons 2 " 10"/Cm 2 V14 Y- ions 2 " 10'%cm2 V5 Y-ions 2 " 10'9Cm 2 V55 Hf-ions 2,5 "10'3cm 2 Wons 2 " 10"/cm2 Fig. 6. Results of metal implanted upsettings tools . 15 .000
universal hardness for load = 100 mN
10.000
r~
' '
'
T2
' '
Acknowledgements The authors thank D. Vogt for technical support at the GSI implantation facility and K.D . Leible for carrying out the hardness measurements .
M. Weiergrüber, Werkzeugverschleiss in der Massivumformung, Berichte aus dem Institute für Umformtechnik, no. 73 (Springer, Berlin, Heidelberg, New York, Tokio, 1983). [21 E . Nehl, Einfluss von Verfahrensparametern auf den Werkzeugverschleiss bei der Massivumformung, in : Tagungsband Neuere Ent ;vicklungen in der Massitn:+nformung, Forschungsgesellschaft Umformtechnik mbh. (Stuttgart, 1985) . [31 H . Westheide, Einfluss von OberOifchenbeschichturgen auf den Werkzeugverschleiss bei der Massivumformung, Berichte aus dem Institut fur Umformtechnik no. 87 (Springer, 1986). [4) I .G. Brown, M .R. Dickinson, J .E. Galvin, X . Godechot and R .A . MacGill, Nucl . Instr . and Meth . B55 (1991) 506. [5] I .L. Singer, J . Vac. Sci. Technol . A l (1983). [6] G . Dearnaley et al., J. Vac . Sci . Technol . A3 (1985) 1684 . [7] A . Kluge et al ., Mater. Sci. Eng. Al 15 (1989) 261. [8) G. tempert, Surf. Coatings Technol . 34 ( 1 988) 185. [9) D.M. Rück et al ., Nuci . 'Cracks Radial . Meas. 19 (1991) [1]
5.000
01 ``` ' ' ' unimplanted T1
Upsetting tests provide a useful method to examine the wear behaviour of too!s in real forming industry . The wear behaviour of tools could be improved by implanting metal ions into M2 steel. Best results were obtained for Hf implanted dies showing improvement of 40% . Work has been started to transform these fcsutts to the L n_kward extrusion punches.
References
Z c ~
after 20000 upsettings whereas after only 5000 upsettings the wear behaviour was less good . Measuring the hardness, an increase of up to 30% could be found out for Hf and Er implanted samples. The results are summarized in fig. 7 . Investigations to clarify the reason for the improvements of the wear beha-lour achieved by ion implantation of big atoms like Hf, Y and Er are in progress. In the case of metai -r nitrogen impiantation we try to find out if the formation of hard nitrides are thc . reasons for the reduction of wear.
'
T3
' '
Metal-Ion-Implantation
'
T4
' '
metal-ion implantation with 60 kV T7 Hr-Ions 1-10-2 T2 Er-Ions 1 "to'%rn2 T3 Er-Ions 1 " 10"lcm' T4 Y-lons2 " 10'%cm2 universal hardness: UCI (Fe. Fischer) UCI: Ultrasonic Contact Impedance Fig . 7. Results of the hardness measurement.
951.
HGLU
13sam Inter$.^.üons with Materials "Atoms
Improvement in `dear characteristics of steel tools by metal ion implantation D.M. Rück
Gesellschaft für Schwerionenforsclmng mbH, FF 110552, 6100 Darmstadt, Germany
D. Boos
Institut für Umformtechnik, Holzgortenstmsse 17, 7000 Stuttgart, Gemany
I.G . Brown
Lawrence Berkeley Lab~ratory, University of California, Berkeley, CA 94720, USA
The annual economic loss induced by wear damage of steel tools is estimated to be DM 34 billion . Ion implantation is known to be a promising method for impro, ing the wear behaviour of metal surfaces. The effect of nitrogen implantation into steel has been investigated by a number of workers and good results have been obtained for several types of steel, especially for steel with high chromium content. However, few investigations of the effect of petal ion implantation into steel have been made. We have investigated the effect of metal ion implantation into high speed steel dies, using high current metal ion beams from a repetitively pulsed vacuum arc ion source . The testing method was, the upsetting, which is comparable to actual forming processes and simulates the wear strain of the tools used in the metal forming industry. Here we describe the metal ion implantation facility and the wear testing apparatus and procedure, and discuss the results we have obtained . 1. Introduction Upsetting as a basic metal forming method is often used to simulate basic processes theoretically and experimentally . The investigations of Weiergräber, Nehl and Westheide [1-3] have shown that in cold forging the load on both the upsetting tools (one untreated and one treated) is equal . Therefore the upsetting process is an ideal one for comparison of the wear rated of treated (coated or implanted) and untreated tools in the same Metal -on implantation and metal + nitrogen or carbrne implantation has been shown by several authors to improve the hardness and wear behaviour of different steels [5-7] . But testing has been, done with pin on disc machines, which is hardly comparable with the wear condition on real tools . The improvement of wear behaviour for ion implanted tools has been summarized in a survey article by Lempert [8], where the described implanted tools were mostly treated with nitrogen . 2. Experimental The upsetting tools were implanted at the LBL laboratory with the equipment shown in fig . 1 [4] and
at the implantation facility at GSI [9]. Both apparatus are described in detail very extensively in the cited publications. The implantation conditions at the LBL facility are summarized in the following. Polished tools made of high speed steel (AISI M2), mounted on a watercooled target support were implanted with metal ions in a vacuum vessel with p = 2 X 10 -6 mbar. The used ion source was the MEWA ion source, a vacuum arc ion source, which delivered an ion beam of 250 ps pulse length and a repetition rate of 15 Hz. The ion beam current in a pulse was several mA, which leads to an average ion beam current of about 100 WA . We used the ions Al, Cu, Hf, Y and Er. The used ion doses are indicated in figs . 5, 6 and 7, respectively . The extraction voltage used was 60 kV. The implantation of N and C was performed at the GSI implantation facility with a do ion beam . The ion beam current was chosen such that the temperatures of the tools were kept below 200°C. The used energies are indicated in the figures respectively. The upsetting tests were carried out a, the Institute für Umformtechnik at the University of Stuttgart . The hardness was measured with a Fischer scope hardness instrument, which measured the hardness under load . The process of testing is described in the following. For studying the wear of metal forming tools, cylindrical
0168-583X/93/$06.00 0 1993 - Elsevier Science Publishers B.V . All rights reserved
Ila . METAL MODIFICATION (a)
234
D.M. Mick et ul. j lr:p)LCC:7:.:::: ü: wear characteristics ojsteel tools Ion energy: seem current : Species :
10 - 300 keV Up to -3 A pulse, -30 mA mean Li. C, Mg. AI, Si, Ca, Sc, TI, V, Cr, Mn, Fe, Co, Ni, Cu, Zn Ge, Sv, Y, Zr. Nb. Ma, Pd. Ag, Cd, In, Sn, Ba, La, Ce, Pr. Nd, Sm, Gd, Uy, Ho, Br, Tm, Yb . HI, Ta, W, Ir, PI, Au, Ph, BI . Th, U.
Faraday Cup
lm
Fig. l . Ion implantation facility at LBL. raw pieces of DIN 16 MnCr 5 (similar to AISI 5120) having an initial diameter of 15 mm and a height of 15 mm were upset (flattened) to a height of 5 .5 mm (strain to = (ho lh .)) . The raw pieces were sheared from rolled bars, covered by a 12 to 15 wm zinc phosphate layer, !ubricatcd by soap !ubricant I1;nnderhibe 236 (nure alkali soap), and upset to a strain of e = In(ho lh 1 ) = 1 .0. As tool material for the upsetting dies the cold working steel 1 .2.374 (X155CrMo 121, AISI D2) and the high speed working steel 1 .3343 (AISI M2) were used . The cold working steel was hardened to a Rockwell C hardness of HRC 61-63 and the high speed steel to HRC F2-64. The upsetting dies were used with an initial roughness R, :5 1 lLm . The wear tests under work blank lubrication
shearing
cold metal forming
phosphating upsetting process soap coating Fig . 2. Scheme of the upsetting process .
final workpiece
simulated production condition were carried out using a C-frame knuckle joint press (Maypres, Typ MKN 1-63/6) with 630 kN press rating and a 60 mm total height of stroke. Transport of the raw pieces into the metal forming machine was carried out by a vibrating conveyor . and the pieces were. put into the dies by a pneumatic wrench. After the metal forming process, the workpieces were blown out by pneumatic pressure. The machine was run. a t a rate of 40 stroke/min. During upsetting a cylindrical raw piece is flattened between plane parallel plates, as shown in fig . 2 . The area of contact between the workpieces and the dies increases with the cross-section of the workpiece . Furthermore, because of the bulging of the workpiece which occurs during upsetting, a portion of the cylindrical surface of the workpiece contacts the die . Due to the shearing process before upsetting, the end faces of the raw pieces have a high roughness, and the roughness peaks can exceed the thickness of the lubricant film even at the beginning of the forming process. Wear begins primarily by adhesive bonding of the workpiece and die material . Eventually the adhesive joints are torn off and cause strong abrasive wear in the die surface . Wear causes a characteristics profile .-lace which is measured by means of an on the die sm inductive transducer . As quantitative measure of wear the linear amount of wear WI (as a maxiinum value) and the planar amount of wear Wq are used and plotted vs the number of upset pieces . The curves obtained this way exhibit a range of initial wear where
D.M . Mick et al. / lmprovernent
to wear characteristics of steel tools
235 . 5,000
1 .4
profile determination by inductive scanning
15,000
1 .2
WI (max)
E i sectional view
amount of was; . i r,5 linear and planar (planar wear : wear depth 1 Is integrated on the die 0,5 L diameter) in 0
1
ç
0 .e
0 a.
0.6
.m Û
0.4 0.2 0 -0.2 -0.4 -20
the wear per upset pieces is rather high . In this range the roughness peaks were smoothed, the area of contact between workpiece and die increased, and a lower rate of wear resulted . For measuring the amount of wear the production is interrupted at preselected number of upset workpieces. The dies are taken out of the machine for measuring the roughness profiles, examples of which are shown in fig. 3. In the centre of the die where there is no relative motion between workpiece and die, there is minimum wear. Wear increases with distance from the centre and exhibits a maximum below the edge of the initial raw piece . The dashed area in fig. 4 shows the surface of the die after 20000 upset workpieces. 3. Results The wear behaviour for hafnium ion-implanted and unimplanted upsetting dies is shown in fig . 5 . The linear wear rate WI (upper figure) and the planar rate Wq (lower figure) are shown as a function of the number of upsetting operations . The upsetting die material was high speed working steel AISI M2 (DIN 1 .3343). The wear reduction of the implanted tools compared with the unimplanted tools is 40-45% after 20000 upsettings. With increasing number of upsettings the supporting surface area is increased and hence the slope of the wear curve decreases . After the running in period the wear rate of the of hafnium ion-implanted does show a lower slope than for unim-
-10
0
mm
10
20
Center of The Upsetting Die amount of planar wear after:
wear rate as a function of the number of upsettings
Fig. 3 . Wear determination of upsetting tools.
upsettings upsettings
0+ 0 O" II + Ill
5,000 10,000 15,000 20,000
upsettings upsettings upsettings upsettings
0+0+6-0 Fig . 4. Rate of wear during the upsetting process . planted dies. The re-ults of the upsetting proc.;ss for all implanted upsetting dies and the unimplanted one are summarized in fig. 6 . The linear amount of wear after 5000, 10000 and 20000 upsettings is shown as a percentage of the wear of the unimplanted dies. An improvement of the wear behaviour of the dies can be seen for Hf, Er and Y implanted dies. In some cases e .g. for Hf and N impl-oration, an improvement is seen upsetting die material: AISI M2 strain In (h, /h, ) : e m 1 .0 workplace material : AIS15120 number of strokes: 40 In ?' lubricant: Bonderlube 236 Implantation: hafniun :-Ion s J ion Implanted 2 '10"Hf-Ionen / c .,1 .
2.0 i 1 .5 c 3
(Hf" ;Hf" ;Hf") ;60 kV R,,, .0.552 gm
1 .0 0.5
ô
x Ç
3
0 20 75 10 5 0
5,000
10,000
15,000
20,000
Number of Upsettings Fig . 5 . Results of the upsettings for implanted and unimplanted dies . Ila. METAL MODIFICATION (a)
236
D.M. Rück et al. / lmprouemen , ir, wtar characteristics o(steei tools
140 after 5.000 u settrn s 120 1C0 80 60 40 20
W 140 120 `0 100 80 ô 40 20 E 0 1-'0
120 -' 100
w
mi
i
Fit HI
a fter 10.000 uu o se:ti n , 7;
_
afte r20 .000 uosettmfc g_
60 60 40 20 0
r-
r.
V1
V4
V2
4. Summary
t.
V3 V14 V5
Upsetting Dies
V9
V6
V7
V55
metal-ion implantation with 60 kV nitrogen-ion-implantation with 160 kV V55 AISI D2, other dies AISI M2 V1 Hf-ions2 " 10' r/cm2 V6 AI-ions 5 "10'%M 2 V2 Er-ions 2 " 10"/cm2 Cu-ions d " 10'%cm 2 V3 Er-ions2 " 10'7cm2 V7 Cu-ions3 "10'%cm 2 N-ions 2 " 10"/cm2 Al-ions5-10'elcm 2 V4 Hf-ions 2-10'e/cm2 V9 C-ions 6-1 017/_2 Wons 2 " 10"/Cm 2 V14 Y- ions 2 " 10'%cm2 V5 Y-ions 2 " 10'9Cm 2 V55 Hf-ions 2,5 "10'3cm 2 Wons 2 " 10"/cm2 Fig. 6. Results of metal implanted upsettings tools . 15 .000
universal hardness for load = 100 mN
10.000
r~
' '
'
T2
' '
Acknowledgements The authors thank D. Vogt for technical support at the GSI implantation facility and K.D . Leible for carrying out the hardness measurements .
M. Weiergrüber, Werkzeugverschleiss in der Massivumformung, Berichte aus dem Institute für Umformtechnik, no. 73 (Springer, Berlin, Heidelberg, New York, Tokio, 1983). [21 E . Nehl, Einfluss von Verfahrensparametern auf den Werkzeugverschleiss bei der Massivumformung, in : Tagungsband Neuere Ent ;vicklungen in der Massitn:+nformung, Forschungsgesellschaft Umformtechnik mbh. (Stuttgart, 1985) . [31 H . Westheide, Einfluss von OberOifchenbeschichturgen auf den Werkzeugverschleiss bei der Massivumformung, Berichte aus dem Institut fur Umformtechnik no. 87 (Springer, 1986). [4) I .G. Brown, M .R. Dickinson, J .E. Galvin, X . Godechot and R .A . MacGill, Nucl . Instr . and Meth . B55 (1991) 506. [5] I .L. Singer, J . Vac. Sci. Technol . A l (1983). [6] G . Dearnaley et al., J. Vac . Sci . Technol . A3 (1985) 1684 . [7] A . Kluge et al ., Mater. Sci. Eng. Al 15 (1989) 261. [8) G. tempert, Surf. Coatings Technol . 34 ( 1 988) 185. [9) D.M. Rück et al ., Nuci . 'Cracks Radial . Meas. 19 (1991) [1]
5.000
01 ``` ' ' ' unimplanted T1
Upsetting tests provide a useful method to examine the wear behaviour of too!s in real forming industry . The wear behaviour of tools could be improved by implanting metal ions into M2 steel. Best results were obtained for Hf implanted dies showing improvement of 40% . Work has been started to transform these fcsutts to the L n_kward extrusion punches.
References
Z c ~
after 20000 upsettings whereas after only 5000 upsettings the wear behaviour was less good . Measuring the hardness, an increase of up to 30% could be found out for Hf and Er implanted samples. The results are summarized in fig. 7 . Investigations to clarify the reason for the improvements of the wear beha-lour achieved by ion implantation of big atoms like Hf, Y and Er are in progress. In the case of metai -r nitrogen impiantation we try to find out if the formation of hard nitrides are thc . reasons for the reduction of wear.
'
T3
' '
Metal-Ion-Implantation
'
T4
' '
metal-ion implantation with 60 kV T7 Hr-Ions 1-10-2 T2 Er-Ions 1 "to'%rn2 T3 Er-Ions 1 " 10"lcm' T4 Y-lons2 " 10'%cm2 universal hardness: UCI (Fe. Fischer) UCI: Ultrasonic Contact Impedance Fig . 7. Results of the hardness measurement.
951.