- Email: [email protected]
Generation and forming of spray-formed flat products
Journal of Materials Processing Technology 115 (2001) 55±60
Generation and forming of spray-formed ¯at products E. Brinksmeiera,*, M. SchuÈnemannb a
Institute for Materials Science (IWT), Bremen, Germany b University of Bremen, Bremen, Germany
Abstract Cylindrical or billet-like semi-®nished materials are already manufactured industrially by means of spray forming. Examples of end products produced from such materials are cylinder liners and welding electrodes. The advantages of spray forming, exploited during the production of the raw materials for these components, are the homogeneity of the produced material, the high cooling speeds in the spray cone, the ¯exibility of the spray-forming facilities and the extended alloying capabilities. For ¯at products, however, a process-determined porosity, which appears negligible with large volume products, as well as problems with the production of a geometry suitable for subsequent treatment obstruct the commercial use of the potentials of spray forming in the ®eld of ¯at or sheet metals. The production of ¯at and sheet metals and the examination of the workability in subsequent manufacturing of such products is the subject of this paper. # 2001 Elsevier Science B.V. All rights reserved. Keywords: Rolling; Spray forming
1. Spray forming of flat products Preceding work shows that the high cooling speeds and the extended alloying possibilities of the spray forming or Osprey process can also lead to new products, if parts with small height-to-width ratio are required [1]. The production of ¯at products by spray forming offers the possibility of the generation of thin semi-®nished materials with optimised material properties. The small initial thickness of the semi®nished materials reduces the range of subsequent forming steps. At present, the porous layers prevent the industrial application of spray-formed ¯at products. Spray forming for example would enable the production of electrotechnical steels [2] with silicon contents of more than 3.25 wt.%. The existence of pores raises the magnetic reluctance to an unacceptable level. Hence, 100% density is inevitable. The spraying of tapes or sheet metals requires special measures in order to achieve a rectangular pro®le [3,4]. After atomisation, the mass distribution present in the spray cone leads to conical product cross-sections. An even product height, as it is required for ¯at products, can be achieved by the application of a reciprocating (scanning) or slot-like nozzle atomiser. Beyond this, the possibility of the * Corresponding author. Present address: Fachgebiet Fertigungsverfahren und Labor fur Mikrozerspanung, Universitat Bremen, Badgasteiner Strasse 1, D-28359 Bremen, Germany. E-mail address: [email protected] (E. Brinksmeier).
application of several parallel arranged nozzles exists. These three ways have in common that the substrate is translated underneath the spray cone (Fig. 1). The principle of experimental setup for these three solutions is alike for melting and atomisation. The melt is poured into a crucible and emanates through the nozzle opening. The melt jet which is atomised by means of an atomising gas forms the spraying cone and ®nally compacts on substrate. In the production of ¯at products, the substrate is usually put on posts. By this measure, the areas with strongly decreasing deposit height are situated in the spraying shadow of the substrate. Hence, the edges of the product are ``trimmed''. The geometry of the product can be further optimised by variation of the frequency of oscillation and the de¯ection angle of the atomiser. 1.1. Product density A mixture from already rigid, partly and completely liquid particles occurs in the spray cone. The particle distribution is a function of the gas±metal relation and of the melt overheat temperature. If this relation is unfavourably shifted towards the rigid particles or if the substrate carries off too much energy, cavities in the ®rst deposit layer cannot be ®lled during compacting with liquid material. A strongly pronounced pore layer in the lower region of the ¯at deposit clearly indicates the in¯uence of the heat dissipation by the substrate. The substrate can be regarded as a heat sink,
0924-0136/01/$ ± see front matter # 2001 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 4 - 0 1 3 6 ( 0 1 ) 0 0 7 6 4 - 6
56
E. Brinksmeier, M. SchuÈnemann / Journal of Materials Processing Technology 115 (2001) 55±60
Fig. 1. Generation of flat products.
whereby a part of the enthalpy brought in by the spray cone is dissipated. The impact of the atomiser gas at the upper boundary of the deposit causes additional disturbances. Disturbances, in particular cavities, are undesirable for different reasons. With materials susceptible to cracking, pores in the so-called ``as-sprayed''-status lead to an impairment of the material quality compared to completely dense material. Beside the material impairment, the cavities can be initial points for cracking and thus for material failure in subsequent treatment, especially in forming operations. 1.2. Porosity and metallographic structure
The substrates utilised in the experiments consisted of a castable, ®reproof concrete, which is dried at 3008C in a furnace after casting. This material is suitable for spray forming purposes because of its high thermal shock resistance and the small heat conductivity. In the context of the investigations, castable ®reproof materials of different manufacturers were examined. Main parts of these ceramics are alumina or cordierite. All substrates from these masses show small hardness and slight resistance to abrasive wear which are drawbacks because of the substrate wear. An additional shortcoming of these materials is the adherence of small
In Fig. 2, the distribution of the pores across the deposit height is shown. It is obvious that the local density changes along the product height. The porous layers at the upper and lower boundary are characterised by a high number of irregularly formed pores, while the middle area of the sample almost achieves the maximum theoretical density of Ck 45. The investigation of the density by hydrostatic weighing [5] resulted in a density of 7.55 g/cm3 for the deposits, i.e. a porosity of 3.7%. It is to mention that in all cases, the average or global density of a sample was measured. Additional, but neglectable, changes of the global density of a specimen are caused by the machining, since a small material volume with high pore proportion is removed. The metallographic investigations show a ®ne equi-axed ferritic±perilitic structure in the pore-interspersed areas. In the denser middle, an area with ferrite on the austenite grain boundaries occurs. The ferrite needles grow into the austenite grains. 1.3. Experimental setup and process parameters The spray-forming facilities used in the collaborative research program 372 at the University of Bremen are suitable for the production of diverse product geometries from steels and copper alloys. The spraying parameters for the two experiments are represented in Table 1.
Fig. 2. Pore distribution in height direction.
E. Brinksmeier, M. SchuÈnemann / Journal of Materials Processing Technology 115 (2001) 55±60 Table 1 Spray-forming parameters
57
2. Flat rolling
Parameter
Value
Material Tundish nozzle diameter (mm) Atomiser gas pressure (bar) Distance substrate/atomiser nozzle (mm) Substrate dimension (mm) Substrate translational displacement (mm/s)
Ck 45 4 2.5 600 158 600 5
Atomiser Scan angle (8) Scan frequency (Hz)
6 5
concrete particles at the lower surface of the deposit. These particles affect the material quality, especially if they are pressed into the material in subsequent rolling. They are therefore not suitable for spray forming, if in-line processing is considered.
In order to improve the material properties, the samples were hot-rolled. The rolling and heat treatment sequences of the experiments are represented in Fig. 3. After the initial heating, the samples were rolled in max. three passes. The peripheral speed of the rolls amounted to 30 m/min. Because of constant circumferential speed of the rolls and the decreasing specimen height the strain rate j_ h increases from 35 to 70 s 1. Due to the geometry of the rolls (diam. 100 mm) the specimen had to be pointed to be pulled in. The rolling forces were measured with a piezoelectric gauge which was placed underneath the lower chuck of the rolling mill. The specimen width was between 14.9 and 15.8 mm. The maximum specimen width was determined by the rolling mills performance characteristics. The initial height range was 14.5±14.9 mm. As it was necessary to have a ®nal height of approx. 7 mm to enable machining of the tensile test specimen, jh max 0:75 was chosen.
Fig. 3. Rolling and heat treatment procedures for the hot rolling of Ck 45.
Fig. 4. Rolling forces in hot rolling of steel (grey: range of Ftheo).
58
E. Brinksmeier, M. SchuÈnemann / Journal of Materials Processing Technology 115 (2001) 55±60
Fig. 5. Density distribution in hot rolling.
Fig. 6. Specimens after hot rolling with different height reductions.
A comparison of the rolling forces Ftheo and the measured rolling forces is given in Fig. 4. Based on the ¯ow stress given by Doege et al. [6], the values were inter- and extrapolated to ®t the given conditions. The formation of the sample density is described in Fig. 5. Independent of the initial density, the density increases are distinct until a strain of jh 0:5 is reached. A ®nal average density of 7.78 g/cm3 is achieved. Further rolling does affect the density less signi®cantly. Three examples of deformed specimens can be seen in Fig. 6. The strain is increasing from the top to the bottom specimen. The cracks, which can be seen at the specimen surface, only affect the cinder layer. They do not further propagate into the material. The pointed tip of the specimen can clearly be seen at the right side. Despite the inhomogeneous density distribution the deformation was evenly distributed. Measurement of the change in the specimen width revealed that simple equations can be applied to calculate lateral ¯ow. The deviations to an equation given by Kopp [7] are less than 5%. It has to be stated that the lateral ¯ow is positive after the ®rst rolling (0.11 mm) and negative after
the last roll pass ( 0.36 mm). A comparison of the measured and the calculated ¯ow is given in Fig. 7. The analysis of the measured rolling forces and the resulting deformation stresses supports the assumption that during the rolling, the porous regions are compressed ®rst.
Fig. 7. Deviation of the measured lateral flow from the calculated lateral flow [7] after hot rolling.
E. Brinksmeier, M. SchuÈnemann / Journal of Materials Processing Technology 115 (2001) 55±60
In the ®rst state of the forming process, the deformation stress is lower than literature values for fully dense material. Starting from a strain of approx. jh 0:5, a deformation resistance is in a range which corresponds to the literature values for completely dense material. 3. Material properties For the determination of the material properties, tensile tests were executed with material in the as-sprayed state and with hot rolled samples. Two tensile test specimens were manufactured from each rolling sample. In DIN 50125, the mechanical characteristics of a heat treatable steel Ck 45 are indicated as follows: tensile strength Rm: 700±850 N/mm2, 0.2%-ductile yield: 500 N/ mm2, ductile yield: 14%. Comparing literature values to measured values of the tensile testing shown in Fig. 8, it can be seen that spray-formed material achieves comparable values after strains of jh 0:5. Despite the remaining pores, there are no indications that these pores in¯uence the characteristic values, since all sample fractures occurred within the expansion area of the samples. 4. Summary The investigations show the possibility to generate ¯at steel products by spray forming and hot-rolling. The optimisation possibilities by optimised substrates and substrate movements could be used to improve the quality of the spray-formed material. A further optimisation of the material quality is possible by subsequent treatment. The material properties attainable by hot rolling are satisfying by use of Ck 45. Detailed analysis of the material ¯ow and porosity annihilation will be done by FE-analysis. The FE-Code DEFORM 2D has therefore been installed and is presently under investigation. Special emphasis will be laid on the local forming parameters. So far it can be stated that the deformation behaviour of this special material is comparable to those materials
Fig. 8. Material properties of hot rolled Ck 45 (DIN 1.1191).
Fig. 9. Outline of an integrated spray forming and rolling facility.
59
60
E. Brinksmeier, M. SchuÈnemann / Journal of Materials Processing Technology 115 (2001) 55±60
produced via conventional primary shaping methods. In the future, the process engineering knowledge within the SFB 372 will be used in order to improve the quality of the sprayed products during the spray process so that the extent of the subsequent treatment can be reduced distinctly. The overall objective of this project is to set up a facility which enables inline processing of the spray-formed products. In the ®nal stage, this facility shall also provide a protective atmosphere. This is considered to be the only way of preventing internal oxidation of the porous material. Fig. 9 shows an outline of this facility. In addition, materials will be used whose characteristics are pre-destinated to improvement by spray forming. Examples are segregation-sensitive materials or materials whose contents of alloying elements can be increased over the contents possible in casting. Acknowledgements The authors acknowledge the ®nancial support given by the Deutsche Forschungsgemeinschaft (DFG) within
the collaborative research program SFB 372 ``Spray Forming''. References [1] K. Bauckhage, V. Uhlenwinkel, Zu den MoÈglichkeiten eines automatisierten und optimierten SpruÈhkompaktierbetriebes, HTM 51 (5) (1996) 289±297. [2] J. Wood (Ed.),The continuous production of steel and alloy strip using spray forming, Proceedings of the Second ICSF, September 13±15, 1993, pp. 235±245. [3] E. Brinksmeier, T. Brockhoff, M. SchuÈnemann, SpruÈhkompaktieren und Walzen von Flachprodukten, HTM 52 (5) (1997) 304±308. [4] E. Brinksmeier, T. Brockhoff, M. SchuÈnemann, Spray forming and rolling of low carbon steel, Ann. German Acad. Soc. Produc. Eng. (WGP) VI (1) (1999) 7±10. [5] F. Speiweck, H. Bettin, H. Toth, Einfache FestekoÈrperdichtebestimmung mit einer oberschaligen Waage, WaÈgen und Dosieren, Vol. 6, 1990. [6] E. Doege, H. Meyer-Nolkemper, I. Saeed, Flieûkurvenatlas Metallischer Werkstoffe, Hanser, MuÈnchen, 1986. [7] R. Kopp, P.J. Mauck, Warmwalzen von Halbzeug und Fertigerzeugnissen, in: G. Spur (Ed.), Handbuch der Fertigungstechnik, Vol. 2, No. 1, Hanser, MuÈnchen, 1983, pp. 145±147.
Generation and forming of spray-formed ¯at products E. Brinksmeiera,*, M. SchuÈnemannb a
Institute for Materials Science (IWT), Bremen, Germany b University of Bremen, Bremen, Germany
Abstract Cylindrical or billet-like semi-®nished materials are already manufactured industrially by means of spray forming. Examples of end products produced from such materials are cylinder liners and welding electrodes. The advantages of spray forming, exploited during the production of the raw materials for these components, are the homogeneity of the produced material, the high cooling speeds in the spray cone, the ¯exibility of the spray-forming facilities and the extended alloying capabilities. For ¯at products, however, a process-determined porosity, which appears negligible with large volume products, as well as problems with the production of a geometry suitable for subsequent treatment obstruct the commercial use of the potentials of spray forming in the ®eld of ¯at or sheet metals. The production of ¯at and sheet metals and the examination of the workability in subsequent manufacturing of such products is the subject of this paper. # 2001 Elsevier Science B.V. All rights reserved. Keywords: Rolling; Spray forming
1. Spray forming of flat products Preceding work shows that the high cooling speeds and the extended alloying possibilities of the spray forming or Osprey process can also lead to new products, if parts with small height-to-width ratio are required [1]. The production of ¯at products by spray forming offers the possibility of the generation of thin semi-®nished materials with optimised material properties. The small initial thickness of the semi®nished materials reduces the range of subsequent forming steps. At present, the porous layers prevent the industrial application of spray-formed ¯at products. Spray forming for example would enable the production of electrotechnical steels [2] with silicon contents of more than 3.25 wt.%. The existence of pores raises the magnetic reluctance to an unacceptable level. Hence, 100% density is inevitable. The spraying of tapes or sheet metals requires special measures in order to achieve a rectangular pro®le [3,4]. After atomisation, the mass distribution present in the spray cone leads to conical product cross-sections. An even product height, as it is required for ¯at products, can be achieved by the application of a reciprocating (scanning) or slot-like nozzle atomiser. Beyond this, the possibility of the * Corresponding author. Present address: Fachgebiet Fertigungsverfahren und Labor fur Mikrozerspanung, Universitat Bremen, Badgasteiner Strasse 1, D-28359 Bremen, Germany. E-mail address: [email protected] (E. Brinksmeier).
application of several parallel arranged nozzles exists. These three ways have in common that the substrate is translated underneath the spray cone (Fig. 1). The principle of experimental setup for these three solutions is alike for melting and atomisation. The melt is poured into a crucible and emanates through the nozzle opening. The melt jet which is atomised by means of an atomising gas forms the spraying cone and ®nally compacts on substrate. In the production of ¯at products, the substrate is usually put on posts. By this measure, the areas with strongly decreasing deposit height are situated in the spraying shadow of the substrate. Hence, the edges of the product are ``trimmed''. The geometry of the product can be further optimised by variation of the frequency of oscillation and the de¯ection angle of the atomiser. 1.1. Product density A mixture from already rigid, partly and completely liquid particles occurs in the spray cone. The particle distribution is a function of the gas±metal relation and of the melt overheat temperature. If this relation is unfavourably shifted towards the rigid particles or if the substrate carries off too much energy, cavities in the ®rst deposit layer cannot be ®lled during compacting with liquid material. A strongly pronounced pore layer in the lower region of the ¯at deposit clearly indicates the in¯uence of the heat dissipation by the substrate. The substrate can be regarded as a heat sink,
0924-0136/01/$ ± see front matter # 2001 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 4 - 0 1 3 6 ( 0 1 ) 0 0 7 6 4 - 6
56
E. Brinksmeier, M. SchuÈnemann / Journal of Materials Processing Technology 115 (2001) 55±60
Fig. 1. Generation of flat products.
whereby a part of the enthalpy brought in by the spray cone is dissipated. The impact of the atomiser gas at the upper boundary of the deposit causes additional disturbances. Disturbances, in particular cavities, are undesirable for different reasons. With materials susceptible to cracking, pores in the so-called ``as-sprayed''-status lead to an impairment of the material quality compared to completely dense material. Beside the material impairment, the cavities can be initial points for cracking and thus for material failure in subsequent treatment, especially in forming operations. 1.2. Porosity and metallographic structure
The substrates utilised in the experiments consisted of a castable, ®reproof concrete, which is dried at 3008C in a furnace after casting. This material is suitable for spray forming purposes because of its high thermal shock resistance and the small heat conductivity. In the context of the investigations, castable ®reproof materials of different manufacturers were examined. Main parts of these ceramics are alumina or cordierite. All substrates from these masses show small hardness and slight resistance to abrasive wear which are drawbacks because of the substrate wear. An additional shortcoming of these materials is the adherence of small
In Fig. 2, the distribution of the pores across the deposit height is shown. It is obvious that the local density changes along the product height. The porous layers at the upper and lower boundary are characterised by a high number of irregularly formed pores, while the middle area of the sample almost achieves the maximum theoretical density of Ck 45. The investigation of the density by hydrostatic weighing [5] resulted in a density of 7.55 g/cm3 for the deposits, i.e. a porosity of 3.7%. It is to mention that in all cases, the average or global density of a sample was measured. Additional, but neglectable, changes of the global density of a specimen are caused by the machining, since a small material volume with high pore proportion is removed. The metallographic investigations show a ®ne equi-axed ferritic±perilitic structure in the pore-interspersed areas. In the denser middle, an area with ferrite on the austenite grain boundaries occurs. The ferrite needles grow into the austenite grains. 1.3. Experimental setup and process parameters The spray-forming facilities used in the collaborative research program 372 at the University of Bremen are suitable for the production of diverse product geometries from steels and copper alloys. The spraying parameters for the two experiments are represented in Table 1.
Fig. 2. Pore distribution in height direction.
E. Brinksmeier, M. SchuÈnemann / Journal of Materials Processing Technology 115 (2001) 55±60 Table 1 Spray-forming parameters
57
2. Flat rolling
Parameter
Value
Material Tundish nozzle diameter (mm) Atomiser gas pressure (bar) Distance substrate/atomiser nozzle (mm) Substrate dimension (mm) Substrate translational displacement (mm/s)
Ck 45 4 2.5 600 158 600 5
Atomiser Scan angle (8) Scan frequency (Hz)
6 5
concrete particles at the lower surface of the deposit. These particles affect the material quality, especially if they are pressed into the material in subsequent rolling. They are therefore not suitable for spray forming, if in-line processing is considered.
In order to improve the material properties, the samples were hot-rolled. The rolling and heat treatment sequences of the experiments are represented in Fig. 3. After the initial heating, the samples were rolled in max. three passes. The peripheral speed of the rolls amounted to 30 m/min. Because of constant circumferential speed of the rolls and the decreasing specimen height the strain rate j_ h increases from 35 to 70 s 1. Due to the geometry of the rolls (diam. 100 mm) the specimen had to be pointed to be pulled in. The rolling forces were measured with a piezoelectric gauge which was placed underneath the lower chuck of the rolling mill. The specimen width was between 14.9 and 15.8 mm. The maximum specimen width was determined by the rolling mills performance characteristics. The initial height range was 14.5±14.9 mm. As it was necessary to have a ®nal height of approx. 7 mm to enable machining of the tensile test specimen, jh max 0:75 was chosen.
Fig. 3. Rolling and heat treatment procedures for the hot rolling of Ck 45.
Fig. 4. Rolling forces in hot rolling of steel (grey: range of Ftheo).
58
E. Brinksmeier, M. SchuÈnemann / Journal of Materials Processing Technology 115 (2001) 55±60
Fig. 5. Density distribution in hot rolling.
Fig. 6. Specimens after hot rolling with different height reductions.
A comparison of the rolling forces Ftheo and the measured rolling forces is given in Fig. 4. Based on the ¯ow stress given by Doege et al. [6], the values were inter- and extrapolated to ®t the given conditions. The formation of the sample density is described in Fig. 5. Independent of the initial density, the density increases are distinct until a strain of jh 0:5 is reached. A ®nal average density of 7.78 g/cm3 is achieved. Further rolling does affect the density less signi®cantly. Three examples of deformed specimens can be seen in Fig. 6. The strain is increasing from the top to the bottom specimen. The cracks, which can be seen at the specimen surface, only affect the cinder layer. They do not further propagate into the material. The pointed tip of the specimen can clearly be seen at the right side. Despite the inhomogeneous density distribution the deformation was evenly distributed. Measurement of the change in the specimen width revealed that simple equations can be applied to calculate lateral ¯ow. The deviations to an equation given by Kopp [7] are less than 5%. It has to be stated that the lateral ¯ow is positive after the ®rst rolling (0.11 mm) and negative after
the last roll pass ( 0.36 mm). A comparison of the measured and the calculated ¯ow is given in Fig. 7. The analysis of the measured rolling forces and the resulting deformation stresses supports the assumption that during the rolling, the porous regions are compressed ®rst.
Fig. 7. Deviation of the measured lateral flow from the calculated lateral flow [7] after hot rolling.
E. Brinksmeier, M. SchuÈnemann / Journal of Materials Processing Technology 115 (2001) 55±60
In the ®rst state of the forming process, the deformation stress is lower than literature values for fully dense material. Starting from a strain of approx. jh 0:5, a deformation resistance is in a range which corresponds to the literature values for completely dense material. 3. Material properties For the determination of the material properties, tensile tests were executed with material in the as-sprayed state and with hot rolled samples. Two tensile test specimens were manufactured from each rolling sample. In DIN 50125, the mechanical characteristics of a heat treatable steel Ck 45 are indicated as follows: tensile strength Rm: 700±850 N/mm2, 0.2%-ductile yield: 500 N/ mm2, ductile yield: 14%. Comparing literature values to measured values of the tensile testing shown in Fig. 8, it can be seen that spray-formed material achieves comparable values after strains of jh 0:5. Despite the remaining pores, there are no indications that these pores in¯uence the characteristic values, since all sample fractures occurred within the expansion area of the samples. 4. Summary The investigations show the possibility to generate ¯at steel products by spray forming and hot-rolling. The optimisation possibilities by optimised substrates and substrate movements could be used to improve the quality of the spray-formed material. A further optimisation of the material quality is possible by subsequent treatment. The material properties attainable by hot rolling are satisfying by use of Ck 45. Detailed analysis of the material ¯ow and porosity annihilation will be done by FE-analysis. The FE-Code DEFORM 2D has therefore been installed and is presently under investigation. Special emphasis will be laid on the local forming parameters. So far it can be stated that the deformation behaviour of this special material is comparable to those materials
Fig. 8. Material properties of hot rolled Ck 45 (DIN 1.1191).
Fig. 9. Outline of an integrated spray forming and rolling facility.
59
60
E. Brinksmeier, M. SchuÈnemann / Journal of Materials Processing Technology 115 (2001) 55±60
produced via conventional primary shaping methods. In the future, the process engineering knowledge within the SFB 372 will be used in order to improve the quality of the sprayed products during the spray process so that the extent of the subsequent treatment can be reduced distinctly. The overall objective of this project is to set up a facility which enables inline processing of the spray-formed products. In the ®nal stage, this facility shall also provide a protective atmosphere. This is considered to be the only way of preventing internal oxidation of the porous material. Fig. 9 shows an outline of this facility. In addition, materials will be used whose characteristics are pre-destinated to improvement by spray forming. Examples are segregation-sensitive materials or materials whose contents of alloying elements can be increased over the contents possible in casting. Acknowledgements The authors acknowledge the ®nancial support given by the Deutsche Forschungsgemeinschaft (DFG) within
the collaborative research program SFB 372 ``Spray Forming''. References [1] K. Bauckhage, V. Uhlenwinkel, Zu den MoÈglichkeiten eines automatisierten und optimierten SpruÈhkompaktierbetriebes, HTM 51 (5) (1996) 289±297. [2] J. Wood (Ed.),The continuous production of steel and alloy strip using spray forming, Proceedings of the Second ICSF, September 13±15, 1993, pp. 235±245. [3] E. Brinksmeier, T. Brockhoff, M. SchuÈnemann, SpruÈhkompaktieren und Walzen von Flachprodukten, HTM 52 (5) (1997) 304±308. [4] E. Brinksmeier, T. Brockhoff, M. SchuÈnemann, Spray forming and rolling of low carbon steel, Ann. German Acad. Soc. Produc. Eng. (WGP) VI (1) (1999) 7±10. [5] F. Speiweck, H. Bettin, H. Toth, Einfache FestekoÈrperdichtebestimmung mit einer oberschaligen Waage, WaÈgen und Dosieren, Vol. 6, 1990. [6] E. Doege, H. Meyer-Nolkemper, I. Saeed, Flieûkurvenatlas Metallischer Werkstoffe, Hanser, MuÈnchen, 1986. [7] R. Kopp, P.J. Mauck, Warmwalzen von Halbzeug und Fertigerzeugnissen, in: G. Spur (Ed.), Handbuch der Fertigungstechnik, Vol. 2, No. 1, Hanser, MuÈnchen, 1983, pp. 145±147.