- Email: [email protected]
Machining characteristics of electroslag cast steel for hot-working tools
Journal of Materials Processing Technology 153–154 (2004) 654–659
Machining characteristics of electroslag cast steel for hot-working tools Y.H. Moon a,∗ , J.W. Kim b , D.W. Lee a a
Department of Mechanical Engineering, Engineering Research Center for Net Shape and Die Manufacturing Technology, Pusan National University, Pusan 609 735, Republic of Korea b LG Electronics Co., ChangWon, Republic of Korea
Abstract The machining characteristics of a tool steel manufactured by the electroslag casting process have been investigated in this study. For the evaluation of machinability, lathe turning and drilling tests were conducted. Since the chip shape characteristics reflect cutting resistance, chip shapes at different cutting speeds are examined as a means to compare the turning machinability of the tool steels. For the drilling tests, the standard deviation of drill motor current was measured by a Hall sensor and used as a measure of the drilling resistance. Machining characteristics of the tool steels are usually correlated with the mechanical properties, such as tensile strength and ductility. Turning was favoured in steels with higher tensile strength, while the opposite is true for drilling. The annealed electroslag cast steel showed good turning machinability in view of the chip shapes produced. The quenched and tempered condition had slightly better drilling machinability as compared to the annealed condition for the electroslag cast steel. © 2004 Elsevier B.V. All rights reserved. Keywords: Electroslag casting; Lathe turning; Drilling; Machinability
1. Introduction
2. Experimental details
Electroslag casting [1–3] is a method of producing ingots in a water cooled metal mould by the heat generated in the electrically conductive slag when current passes through a consumable steel electrode. The method can produce material for high quality hot-working tool steels in a variety of shapes. Although good ductility and toughness as well as high strength at elevated temperature are important requirements for the hot-working tool steels, good machinability is also required. Therefore in this study, the machining characteristics of electroslag cast steel were investigated and compared with the machinability of other hot-working tool steels. For the evaluation of machinability, the lathe turning and drilling tests were performed [4–9]. In lathe turning tests, the cutting resistance and chip shapes at various cutting condition were investigated. For the drilling tests, the standard deviation of feed motor current measured with a Hall sensor was used to assess the drilling resistance.
2.1. Materials preparation Fig. 1 shows a schematic drawing of the electroslag casting system used in the study and the electroslag casting conditions are given in Table 1. The chemical composition of electroslag cast steel was adjusted to match AISI-L6 so that a comparison of the electroslag cast product could be made with a forged product. H13 was also tested. To investigate the effect of heat treatment, annealed specimens and quenched and tempered specimens were prepared. The annealed specimens were held at 790 ◦ C for 12 h then air cooled. The quenched and tempered specimens were heated to 810 ◦ C, held for 1 h followed by oil quenching and tempering at 600 ◦ C for 1 h. The chemical compositions of test materials are given in Table 2. In the table, L6(ESC) means ‘Electro Slag Cast’ specimen having the same chemical composition as AISI-L6. 2.2. Tensile and hardness testing procedures
∗ Corresponding author. Tel.: +82-51-510-2472; fax: +82-51-512-1722. E-mail addresses: [email protected] (Y.H. Moon), [email protected] (J.W. Kim), [email protected] (D.W. Lee).
0924-0136/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jmatprotec.2004.04.326
Tensile testing was performed on a servo-hydraulic mechanical testing machine at the room temperature, and the size of test specimen adhered to ASTM A370. The strain
Y.H. Moon et al. / Journal of Materials Processing Technology 153–154 (2004) 654–659
655
Fig. 2. Diagram of measuring system for lathe turning. Table 3 Cutting conditions for the turning and drilling tests Condition
Fig. 1. Schematic drawing of electroslag casting process.
Cutting speed (m/min) Feed (mm/rev) Depth of cut (mm)
Table 1 Electroslag casting conditions Test variable
Input value
Remarks
Flux
66% CaF2 –28% Al2 O3 –5% CaO 11 10–12 38–45
–
Slag height (cm) Current (kA) Voltage (V)
Turning
Drilling
First
Second
Third
37.7 0.102
37.7 0.051 0.5
6.28 0.102
30 0.32 0.3
– – Voltage in slag pool
rate for tensile testing was 2 × 10−3 s−1 . Hardness was measured on a micro-Vickers hardness tester. The load on the micro-Vickers indenter was 150 kgf. Averaged hardness values are reported based on five measurements for each material. To account for positional differences in electroslag cast specimens, testing was done at several locations on both the upper and lower sides of the ingot.
Fig. 3. Schematic drawing of experimental set-up for drilling test.
chip shape was examined to evaluate lathe turning machinability. The experimental set-up for the drilling test is schematically shown in Fig. 3. An estimation of the cutting forces during drilling was determined through the measurement of spindle motor current by a Hall sensor. Specimens were 150 mm thick. A 5 mm diameter drill bit with cemented carbide inserts coated with TiN was used. Drilling tests were performed at a cutting speed of 30 m/min and a feed rate 0.32 mm/rev.
2.3. Lathe turning and drilling test procedures A diagram for the lathe turning measuring system is shown in Fig. 2. Specimens of 10 mm diameter and 100 mm length were used. Table 3 shows the test conditions. For the turning tests, all specimens were dry machined with TiN coated inserts. A depth of 0.05 mm was used for each of the three traverses along the specimen. The cutting force was measured and the Table 2 Chemical composition of materials AISI-grade
C
Si
Mn
P
S
Ni
Cr
Mo
V
Al
L6 H13 L6(ESC)
0.51 0.36 0.51
0.22 1.0 0.24
0.97 0.44 0.92
0.015 0.028 0.012
0.002 0.009 0.005
1.56 – 1.95
0.94 5.3 0.96
0.47 1.3 0.47
0.11 0.98 0.12
0.002 – 0.008
656
Y.H. Moon et al. / Journal of Materials Processing Technology 153–154 (2004) 654–659
Fig. 4. Comparison of tensile strength at room temperature.
Fig. 6. Variation of the cutting forces at two different cutting speeds (feed rate: 0.102 mm/rev).
3. Results and discussion
3.2.1. Cutting resistance The cutting forces measured at two different cutting speeds are shown in Fig. 6.
For the annealed steels, an increase in cutting speed decreased the cutting force. For the quenched and tempered condition no significant difference was seen as cutting speed increased. For the annealed materials, H13 required the highest cutting force followed by L6(ESC) and L6. For the quenched and tempered condition, the cutting force for L6 was the highest. For the two cutting speeds of 6.28 m/min and 37.7 m/min, the cutting force of L6(ESC) was lower than L6 by 2 N and 5 N, respectively. The annealed materials required less cutting force irregardless of cutting speed. The quenched and tempered materials had a higher cutting force than the annealed materials because the cutting resistance increased due to their increased strength. The cutting forces measured at two different feed rates are shown in Fig. 7. With increasing feed rate, the cutting forces increased. In the annealed condition, the cutting force of L6(ESC) was higher than L6 by 18 N at 0.051 mm/rev and by 6 N at 0.102 mm/rev. H13 required the highest cutting force. In the quenched and tempered materials, the cutting force for L6(ESC) was lower than L6 by 6 N and 4.5 N for the two
Fig. 5. Hardness value measured at room temperature.
Fig. 7. Variation of the cutting forces at two different feed rates (cutting speed: 37.7 m/min).
3.1. Tensile properties Fig. 4 shows the tensile strength at room temperature for the test materials. In the annealed condition, L6(ESC) has the highest tensile strength, while in the quenched and tempered condition, the tensile strength of all the materials is about the same. Room temperature hardness is shown in Fig. 5. The hardness values of the quenched and tempered materials are higher than those of the annealed materials. The trend among the materials is similar to that of tensile strength. In the annealed condition, the difference in hardness values is large with L6(ESC) having the highest hardness followed by L6 and H13. 3.2. Lathe turning machinability
Y.H. Moon et al. / Journal of Materials Processing Technology 153–154 (2004) 654–659 Table 4 Classification of chip types (ISO3685) Classification
Chip type
Chip form
Remarks
Type 1
Bad
Type 2 Type 3
Continuous, constant, irregular chips Short continuous chips Short chips
Type 4
Arc chips
Preferred
Type 5
Elemental chips
Acceptable
Preferred Preferred
feed rates and H13 had the lowest value. Therefore, the level of cutting resistance of electroslag cast steel, L6(ESC), is judged to be acceptable when compared with that of forged L6. 3.2.2. Chip disposability In lathe turning, the chip morphology is also an important way to evaluate machinability and is a factor in how easy they are removed (i.e. disposability). A long continuous chip can interrupt the normal cutting process, and could harm the operator. Short broken type chips are preferred with the arc type being the best (see ISO3685 [10]). Chip shapes have been classified into five categories as shown in Table 4. Figs. 8 and 9 show the chip morphology obtained at two different cutting speeds for the annealed steels and quenched and tempered steels, respectively. At the cutting speed of 6.28 m/min, short chips were generated, whereas at the cutting speed of 37.7 m/min, long continuous type chips were generated. The chip morphology changes significantly depending on the heat treatment as well as the cutting conditions. At the cutting speed of 6.28 m/min in annealed materials (see Fig. 8), L6(ESC) produced short
657
continuous chips whereas L6 yielded short chips with some elemental chips and H13 gave elemental chips with some arc chips. Therefore, L6(ESC) had the best chip disposability. For the cutting speed of 37.7 m/min in annealed materials, L6(ESC) and H13 produced short continuous chips, whereas L6 showed irregular continuous chips. Therefore in the annealed condition, the chip disposability of L6(ESC) is estimated to be good when compared to forged L6. Fig. 9 shows the chips obtained for the quenched and tempered materials. At the cutting speed of 6.28 m/min L6(ESC) gave short continuous chips and arc chips, while L6 showed long continuous chips. H13 produced elemental chips similar with those of from the annealed H13. Therefore L6(ESC) had the best disposability. The chips obtained at the higher cutting speed of 37.7 m/min from all materials showed regular continuous chips, and the chip disposability was bad. As a result, in the quenched and tempered condition, L6(ESC) shows better chip disposability when compared with L6, and H13 is the worst. 3.3. Drilling machinability Standard deviation of current measurements were obtained by a current sensor and used to assess the drilling machinability. An increase in standard deviation of the current implies that the cutting resistance is higher and tool wear is greater. Fig. 10 shows the motor current for the motor idling without drilling. The standard deviation for this baseline condition is about 0.031. Fig. 11 shows the standard deviation of the motor current for the drilling of both the annealed steels and the quenched and tempered steels. In the annealed condition, the standard deviation for H13 showed the lowest value and L6(ESC) was higher than L6. In quenched and tempered condition,
Fig. 8. Chip morphology at two different cutting speeds for annealed condition.
658
Y.H. Moon et al. / Journal of Materials Processing Technology 153–154 (2004) 654–659
Fig. 9. Chip morphology at two different cutting speeds for quenched and tempered condition.
L6(ESC) and L6 had nearly identical values while H13 had the highest. Therefore, the drilling machinability of L6(ESC) is judged to be similar with that of forged L6. 4. Conclusions The machinability of electroslag cast steel was measured using lathe turning and drilling. The results obtained are summarized as follows:
Fig. 10. Idling graph for the time.
(1) For the annealed steels, the cutting force of L6(ESC) is higher than L6 while H13 requires the highest value. In contrast for the quenched and tempered condition, L6(ESC) is lower than L6 and H13 has the lowest value. (2) In the lathe turning test, L6(ESC) exhibits better chip morphology for disposability than L6, whereas H13 is the worst. The chips produced at the cutting speed of 37.7 m/min from the quenched and tempered materials are regular continuous chips making chip disposability bad. (3) The drilling machinability of L6(ESC) is similar to forged L6. (4) The overall machining characteristics of L6(ESC) is judged to be good when compared to other hot-working tool steels. References
Fig. 11. Comparison of standard deviation with time.
[1] B.I. Medovar, G.A. Boyko, Electroslag Technology, Springer-Verlag, New York, NY, USA, 1990. [2] B.E. Paton, B.I. Medovar, G.A. Boiko, Electroslag Casting, Naukova Dumka Publisher, Kiev, Russia, 1981.
Y.H. Moon et al. / Journal of Materials Processing Technology 153–154 (2004) 654–659 [3] R.G. Baligidad, U. Prakash, A.R. Krishna, Effect of carbon addition on structure and mechanical properties of electroslag remelted Fe–20 wt.% Al alloy, Mater. Sci. Eng. A249 (1998) 97– 102. [4] P.L. Tso, An investigation of chip types in grinding, J. Mater. Process. Technol. 53 (1995) 521–532. [5] B. Worthington, The effect of rake face configuration on the curvature of the chip in metal cutting, Int. J. Mach. Tool Des. Res. 15 (1975) 223–239. [6] J. Roberg, A. Ber, R. Wertheim, Chip control in cut-off tools, Ann. CIRP 40/1 (1991) 73–77.
659
[7] G.E. Dieter, Mechanical Metallurgy, 3rd ed., McGraw-Hill, New York, NY, USA, 1987. [8] L.H. Van Vlack, Elements of Materials Science and Engineering, 5th ed., Addison-Wesley, New York, NY, USA, 1984. [9] T.Y. Kim, J.W. Kim, Adaptive cutting force control for a machining center by using indirect cutting force measurements, Int. J. Mach. Tools Manuf. 36 (1996) 925–937. [10] J. Fei, I.S. Jawahir, A new approach for chip-form characterization in metal machining, in: Proceedings of the First S.M. Wu Symposium on Manufacturing Science (1994) 11–17.
Machining characteristics of electroslag cast steel for hot-working tools Y.H. Moon a,∗ , J.W. Kim b , D.W. Lee a a
Department of Mechanical Engineering, Engineering Research Center for Net Shape and Die Manufacturing Technology, Pusan National University, Pusan 609 735, Republic of Korea b LG Electronics Co., ChangWon, Republic of Korea
Abstract The machining characteristics of a tool steel manufactured by the electroslag casting process have been investigated in this study. For the evaluation of machinability, lathe turning and drilling tests were conducted. Since the chip shape characteristics reflect cutting resistance, chip shapes at different cutting speeds are examined as a means to compare the turning machinability of the tool steels. For the drilling tests, the standard deviation of drill motor current was measured by a Hall sensor and used as a measure of the drilling resistance. Machining characteristics of the tool steels are usually correlated with the mechanical properties, such as tensile strength and ductility. Turning was favoured in steels with higher tensile strength, while the opposite is true for drilling. The annealed electroslag cast steel showed good turning machinability in view of the chip shapes produced. The quenched and tempered condition had slightly better drilling machinability as compared to the annealed condition for the electroslag cast steel. © 2004 Elsevier B.V. All rights reserved. Keywords: Electroslag casting; Lathe turning; Drilling; Machinability
1. Introduction
2. Experimental details
Electroslag casting [1–3] is a method of producing ingots in a water cooled metal mould by the heat generated in the electrically conductive slag when current passes through a consumable steel electrode. The method can produce material for high quality hot-working tool steels in a variety of shapes. Although good ductility and toughness as well as high strength at elevated temperature are important requirements for the hot-working tool steels, good machinability is also required. Therefore in this study, the machining characteristics of electroslag cast steel were investigated and compared with the machinability of other hot-working tool steels. For the evaluation of machinability, the lathe turning and drilling tests were performed [4–9]. In lathe turning tests, the cutting resistance and chip shapes at various cutting condition were investigated. For the drilling tests, the standard deviation of feed motor current measured with a Hall sensor was used to assess the drilling resistance.
2.1. Materials preparation Fig. 1 shows a schematic drawing of the electroslag casting system used in the study and the electroslag casting conditions are given in Table 1. The chemical composition of electroslag cast steel was adjusted to match AISI-L6 so that a comparison of the electroslag cast product could be made with a forged product. H13 was also tested. To investigate the effect of heat treatment, annealed specimens and quenched and tempered specimens were prepared. The annealed specimens were held at 790 ◦ C for 12 h then air cooled. The quenched and tempered specimens were heated to 810 ◦ C, held for 1 h followed by oil quenching and tempering at 600 ◦ C for 1 h. The chemical compositions of test materials are given in Table 2. In the table, L6(ESC) means ‘Electro Slag Cast’ specimen having the same chemical composition as AISI-L6. 2.2. Tensile and hardness testing procedures
∗ Corresponding author. Tel.: +82-51-510-2472; fax: +82-51-512-1722. E-mail addresses: [email protected] (Y.H. Moon), [email protected] (J.W. Kim), [email protected] (D.W. Lee).
0924-0136/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jmatprotec.2004.04.326
Tensile testing was performed on a servo-hydraulic mechanical testing machine at the room temperature, and the size of test specimen adhered to ASTM A370. The strain
Y.H. Moon et al. / Journal of Materials Processing Technology 153–154 (2004) 654–659
655
Fig. 2. Diagram of measuring system for lathe turning. Table 3 Cutting conditions for the turning and drilling tests Condition
Fig. 1. Schematic drawing of electroslag casting process.
Cutting speed (m/min) Feed (mm/rev) Depth of cut (mm)
Table 1 Electroslag casting conditions Test variable
Input value
Remarks
Flux
66% CaF2 –28% Al2 O3 –5% CaO 11 10–12 38–45
–
Slag height (cm) Current (kA) Voltage (V)
Turning
Drilling
First
Second
Third
37.7 0.102
37.7 0.051 0.5
6.28 0.102
30 0.32 0.3
– – Voltage in slag pool
rate for tensile testing was 2 × 10−3 s−1 . Hardness was measured on a micro-Vickers hardness tester. The load on the micro-Vickers indenter was 150 kgf. Averaged hardness values are reported based on five measurements for each material. To account for positional differences in electroslag cast specimens, testing was done at several locations on both the upper and lower sides of the ingot.
Fig. 3. Schematic drawing of experimental set-up for drilling test.
chip shape was examined to evaluate lathe turning machinability. The experimental set-up for the drilling test is schematically shown in Fig. 3. An estimation of the cutting forces during drilling was determined through the measurement of spindle motor current by a Hall sensor. Specimens were 150 mm thick. A 5 mm diameter drill bit with cemented carbide inserts coated with TiN was used. Drilling tests were performed at a cutting speed of 30 m/min and a feed rate 0.32 mm/rev.
2.3. Lathe turning and drilling test procedures A diagram for the lathe turning measuring system is shown in Fig. 2. Specimens of 10 mm diameter and 100 mm length were used. Table 3 shows the test conditions. For the turning tests, all specimens were dry machined with TiN coated inserts. A depth of 0.05 mm was used for each of the three traverses along the specimen. The cutting force was measured and the Table 2 Chemical composition of materials AISI-grade
C
Si
Mn
P
S
Ni
Cr
Mo
V
Al
L6 H13 L6(ESC)
0.51 0.36 0.51
0.22 1.0 0.24
0.97 0.44 0.92
0.015 0.028 0.012
0.002 0.009 0.005
1.56 – 1.95
0.94 5.3 0.96
0.47 1.3 0.47
0.11 0.98 0.12
0.002 – 0.008
656
Y.H. Moon et al. / Journal of Materials Processing Technology 153–154 (2004) 654–659
Fig. 4. Comparison of tensile strength at room temperature.
Fig. 6. Variation of the cutting forces at two different cutting speeds (feed rate: 0.102 mm/rev).
3. Results and discussion
3.2.1. Cutting resistance The cutting forces measured at two different cutting speeds are shown in Fig. 6.
For the annealed steels, an increase in cutting speed decreased the cutting force. For the quenched and tempered condition no significant difference was seen as cutting speed increased. For the annealed materials, H13 required the highest cutting force followed by L6(ESC) and L6. For the quenched and tempered condition, the cutting force for L6 was the highest. For the two cutting speeds of 6.28 m/min and 37.7 m/min, the cutting force of L6(ESC) was lower than L6 by 2 N and 5 N, respectively. The annealed materials required less cutting force irregardless of cutting speed. The quenched and tempered materials had a higher cutting force than the annealed materials because the cutting resistance increased due to their increased strength. The cutting forces measured at two different feed rates are shown in Fig. 7. With increasing feed rate, the cutting forces increased. In the annealed condition, the cutting force of L6(ESC) was higher than L6 by 18 N at 0.051 mm/rev and by 6 N at 0.102 mm/rev. H13 required the highest cutting force. In the quenched and tempered materials, the cutting force for L6(ESC) was lower than L6 by 6 N and 4.5 N for the two
Fig. 5. Hardness value measured at room temperature.
Fig. 7. Variation of the cutting forces at two different feed rates (cutting speed: 37.7 m/min).
3.1. Tensile properties Fig. 4 shows the tensile strength at room temperature for the test materials. In the annealed condition, L6(ESC) has the highest tensile strength, while in the quenched and tempered condition, the tensile strength of all the materials is about the same. Room temperature hardness is shown in Fig. 5. The hardness values of the quenched and tempered materials are higher than those of the annealed materials. The trend among the materials is similar to that of tensile strength. In the annealed condition, the difference in hardness values is large with L6(ESC) having the highest hardness followed by L6 and H13. 3.2. Lathe turning machinability
Y.H. Moon et al. / Journal of Materials Processing Technology 153–154 (2004) 654–659 Table 4 Classification of chip types (ISO3685) Classification
Chip type
Chip form
Remarks
Type 1
Bad
Type 2 Type 3
Continuous, constant, irregular chips Short continuous chips Short chips
Type 4
Arc chips
Preferred
Type 5
Elemental chips
Acceptable
Preferred Preferred
feed rates and H13 had the lowest value. Therefore, the level of cutting resistance of electroslag cast steel, L6(ESC), is judged to be acceptable when compared with that of forged L6. 3.2.2. Chip disposability In lathe turning, the chip morphology is also an important way to evaluate machinability and is a factor in how easy they are removed (i.e. disposability). A long continuous chip can interrupt the normal cutting process, and could harm the operator. Short broken type chips are preferred with the arc type being the best (see ISO3685 [10]). Chip shapes have been classified into five categories as shown in Table 4. Figs. 8 and 9 show the chip morphology obtained at two different cutting speeds for the annealed steels and quenched and tempered steels, respectively. At the cutting speed of 6.28 m/min, short chips were generated, whereas at the cutting speed of 37.7 m/min, long continuous type chips were generated. The chip morphology changes significantly depending on the heat treatment as well as the cutting conditions. At the cutting speed of 6.28 m/min in annealed materials (see Fig. 8), L6(ESC) produced short
657
continuous chips whereas L6 yielded short chips with some elemental chips and H13 gave elemental chips with some arc chips. Therefore, L6(ESC) had the best chip disposability. For the cutting speed of 37.7 m/min in annealed materials, L6(ESC) and H13 produced short continuous chips, whereas L6 showed irregular continuous chips. Therefore in the annealed condition, the chip disposability of L6(ESC) is estimated to be good when compared to forged L6. Fig. 9 shows the chips obtained for the quenched and tempered materials. At the cutting speed of 6.28 m/min L6(ESC) gave short continuous chips and arc chips, while L6 showed long continuous chips. H13 produced elemental chips similar with those of from the annealed H13. Therefore L6(ESC) had the best disposability. The chips obtained at the higher cutting speed of 37.7 m/min from all materials showed regular continuous chips, and the chip disposability was bad. As a result, in the quenched and tempered condition, L6(ESC) shows better chip disposability when compared with L6, and H13 is the worst. 3.3. Drilling machinability Standard deviation of current measurements were obtained by a current sensor and used to assess the drilling machinability. An increase in standard deviation of the current implies that the cutting resistance is higher and tool wear is greater. Fig. 10 shows the motor current for the motor idling without drilling. The standard deviation for this baseline condition is about 0.031. Fig. 11 shows the standard deviation of the motor current for the drilling of both the annealed steels and the quenched and tempered steels. In the annealed condition, the standard deviation for H13 showed the lowest value and L6(ESC) was higher than L6. In quenched and tempered condition,
Fig. 8. Chip morphology at two different cutting speeds for annealed condition.
658
Y.H. Moon et al. / Journal of Materials Processing Technology 153–154 (2004) 654–659
Fig. 9. Chip morphology at two different cutting speeds for quenched and tempered condition.
L6(ESC) and L6 had nearly identical values while H13 had the highest. Therefore, the drilling machinability of L6(ESC) is judged to be similar with that of forged L6. 4. Conclusions The machinability of electroslag cast steel was measured using lathe turning and drilling. The results obtained are summarized as follows:
Fig. 10. Idling graph for the time.
(1) For the annealed steels, the cutting force of L6(ESC) is higher than L6 while H13 requires the highest value. In contrast for the quenched and tempered condition, L6(ESC) is lower than L6 and H13 has the lowest value. (2) In the lathe turning test, L6(ESC) exhibits better chip morphology for disposability than L6, whereas H13 is the worst. The chips produced at the cutting speed of 37.7 m/min from the quenched and tempered materials are regular continuous chips making chip disposability bad. (3) The drilling machinability of L6(ESC) is similar to forged L6. (4) The overall machining characteristics of L6(ESC) is judged to be good when compared to other hot-working tool steels. References
Fig. 11. Comparison of standard deviation with time.
[1] B.I. Medovar, G.A. Boyko, Electroslag Technology, Springer-Verlag, New York, NY, USA, 1990. [2] B.E. Paton, B.I. Medovar, G.A. Boiko, Electroslag Casting, Naukova Dumka Publisher, Kiev, Russia, 1981.
Y.H. Moon et al. / Journal of Materials Processing Technology 153–154 (2004) 654–659 [3] R.G. Baligidad, U. Prakash, A.R. Krishna, Effect of carbon addition on structure and mechanical properties of electroslag remelted Fe–20 wt.% Al alloy, Mater. Sci. Eng. A249 (1998) 97– 102. [4] P.L. Tso, An investigation of chip types in grinding, J. Mater. Process. Technol. 53 (1995) 521–532. [5] B. Worthington, The effect of rake face configuration on the curvature of the chip in metal cutting, Int. J. Mach. Tool Des. Res. 15 (1975) 223–239. [6] J. Roberg, A. Ber, R. Wertheim, Chip control in cut-off tools, Ann. CIRP 40/1 (1991) 73–77.
659
[7] G.E. Dieter, Mechanical Metallurgy, 3rd ed., McGraw-Hill, New York, NY, USA, 1987. [8] L.H. Van Vlack, Elements of Materials Science and Engineering, 5th ed., Addison-Wesley, New York, NY, USA, 1984. [9] T.Y. Kim, J.W. Kim, Adaptive cutting force control for a machining center by using indirect cutting force measurements, Int. J. Mach. Tools Manuf. 36 (1996) 925–937. [10] J. Fei, I.S. Jawahir, A new approach for chip-form characterization in metal machining, in: Proceedings of the First S.M. Wu Symposium on Manufacturing Science (1994) 11–17.