OTEVA

  1. OTEVA 101 SC
    Suzuki Garphyttan www.suzuki-garphyttan.com

    OTEVA 101 SC

    Oil tempered SiCrVMoW-alloyed ultra-high tensile clutch and transmission spring wire for surface nitriding

    OTEVA® 101 SC is a Super Clean steel, especially intended for the manufacture of clutch and transmission springs and other springs requiring high fatigue properties and good relaxation properties at increased working temperatures.

    Manufactured as standard in shaved condition in sizes from Ø 2.00 mm to 5.00 mm or in egg or elliptical shape corresponding to round cross section 2.50 mm to 5.00 mm. Other wire sizes on request.

    Chemical composition

    C (%) Si (%) Mn (%) P max. (%) S max. (%) Cr (%) V (%) Mo (%) W (%)
    0.50 - 0.70 2.10 - 2.40 0.30 - 0.70 0.020 0.030 1.10 - 1.40 0.05 - 0.25 0.05 - 0.25 0.05 - 0.25

    Cleanliness in steel

    The presence of non-metallic inclusions in the wire rod is inspected for every heat in accordance with the Suzuki Garphyttan method by the steel supplier.

    Before release for production, Suzuki Garphyttan performs non-metallic inclusion inspection for every fifth heat. The criteria for supplier inspection and releasing inspection are the following;

    For wire rod samples: Inclusion size max. 15 µm down to 1 mm below surface. Inspection area 1 000 mm2.  

    Inclusion size, surface 5–10 > 10–15 >15 µm
    Max. number of inclusions 50 7 0

    As stated by IVSWMA, International Valve Spring Wire Manufacturers Association, it is likely to find occasional inclusions  in  valve  spring  quality  steel of  a  size  larger  than 30 µm.

    Mechanical properties

    For round wire

    Diameter (mm) Tolerance (± mm) Tensile Strength (N/mm²) Torsions (l=300 mm, min. revs) Reduct. of area (min. %)
    2.00 - 2.50 0.020 2100 - 2200 2 40
    2.51 - 3.20 0.020 2100 - 2200 2 40
    3.21 - 4.00 0.025 2100 - 2200 2 40
    4.01 - 5.00 0.025 2100 - 2200 2 40

    Surface conditions

    Surface condition

    Surface condition – non-destructive testing
    In the standard size range 2.00 - 5.00 mm the wire is tested continuously in Eddy Current equipment to a surface level of > 40 microns. Other wire sizes on request.

    Surface condition – end sample test
    The wire is end sample tested by means of etch testing and binocular inspection as well as microscopical inspection of the material structure. Max. permissible depth of partial surface decarburization and surface defects, 0.5% x wire diameter. No complete decarburization allowed.

    Physical properties

    Recommendations

    Heat treatment

    As soon as possible after coiling, the springs should be stress relieved. Depending on nitriding temperature used later in the spring manufacturing process, this temperature may be decreased.

    Hot presetting

    After shot peening, the springs should be hot preset or stress relieved. In order to reach optimum fatigue and relaxation properties, the springs must be preset at an appropriate stress.

    Soft shot peening

    Before the nitriding process a soft shot peening process shall be applied in order to remove the oxide layer on the spring wire surface.

    Nitriding

    Springs of OTEVA® 101 SC must be nitrided to obtain optimum fatigue and relaxation properties. Our recommendation is gas nitriding.

    Shot peening

    In order to obtain optimum fatigue properties, the process time should be adjusted to get a complete treatment. Size of shots should be adapted to wire dimension, pitch and shot peening equipment.

    For nitrided springs with an extremely hard surface zone, it is important to use a shot peening media with high hardness.

    Shot peening of the inside of the spring coils is particularly critical.

    Spring Conditions For Tests

    Spring conditions for fatigue and relaxation tests (specially designed test spring) Diagrams 1 and 2:
    Wire diameter Ø 3.85 mm
    Diameter external 26.95
    Spring length, I0 53.0
    N active 4.15
    Spring index 6.0
    Stress relieving
    Temperature 450°C (790 ±10 °F)
    Time 30 minutes
    Soft shot peened
    Speed 20-30 m/s
    Time 5 min
    Shot size 0.8 mm
    Nitriding Gas nitriding
    Temperature 450-470°C
    Time 5-20 hours
    Aim for surface hardness Min. 850 Hv
    Aim for core hardness Min. 610 Hv
    Compound (white) layer Max. 1 µm.
    Shot peening (triple shot peening for nitrided springs)
    1st treatment Pressure 0.3 MPa with RCW shoot size 0.6 mm (hardness 800 Hv) for 20 minutes.
    2nd treatment Pressure 0.3 MPa with RCW shoot size 0.25 mm (hardness 800 Hv) for 10 minutes.
    3rd treatment Pressure 0.2 MPa with fine shoot size (hardness 700 HV) for 10 minutes.
    Aim for Almen arc-height 0.55 – 0.60 mm
    Hot presetting 1500 N/mm2 (nitrided springs)
    (theoretically set) 1300 N/mm2 (not nitrided springs)
    Temperature 200°C (max. 250°C)
    Time 10 minutes

     

    Relaxation And Fatigue Properties

    In diagram 1 the fatigue properties of this grade are illustrated in a Goodman-diagram, based on a special test spring design.

    Diagram 2 shows the relaxation properties (loss of load) of nitrided springs made from OTEVA® 101 SC wire subjected to static compression at different temperatures, nitrided/not nitrided.

    Standards

    EN 10270-2

  2. OTEVA 70 SC, OTEVA 70 SC PLUS
    Suzuki Garphyttan www.suzuki-garphyttan.com

    OTEVA 70 SC, OTEVA 70 SC PLUS

    Oil tempered SiCr-alloyed valve spring wire

    OTEVA® 70 SC is a Super Clean steel, especially intended for the manufacture of clutch/ transmission springs with extremely high fatigue properties and good relaxation properties at moderately increased working temperature. The wire is manufactured in shaved or unshaved condition (Ø 6.50 – 14.00 mm in unshaved condition subcontracted) in sizes from Ø 0.50 mm to 6.50 mm, or in egg or elliptical shape corresponding to round cross section 2.50 mm to 6.50 mm Other wire sizes and shapes on request.

    OTEVA® 70 SC PLUS is intended for manufacture of valve springs and other springs requiring extremely high fatigue properties and good relaxation properties at increased working temperatures. Further information about the approval process for OTEVA SC PLUS is found here.

    Chemical composition

    C (%) Si (%) Mn (%) P max. (%) S max. (%) Cr (%)
    0.50 - 0.60 1.20 - 1.60 0.50 - 0.80 0.025 0.020 0.50 - 0.80

    Cleanliness in steel

    The presence of non-metallic inclusions in the wire rod is inspected for every heat of OTEVA® 70 SCin accordance with the Suzuki Garphyttan method by the steel supplier.

    Before release for production, Suzuki Garphyttan performs non-metallic inclusion inspection for every fifth heat. The criteria for supplier inspection and releasing inspection are the following;

    For wire rod samples: Inclusion size max. 15 µm down to 1 mm below surface. Inspection area: 1 000 mm2.

    Inclusion size, surface 5-10 µm >10-15 µm >15 µm
    Max. number of inclusions 50 7 0

    For OTEVA 70 SC PLUS, every heat is inspected including a SEM-EDS analysis of inclusions > 10µm to verify a Super Clean composition.

    As stated by IVSWMA, International Valve Spring Wire Ma­nu­­fac­turers Association, it is likely to find occasional inclusions  in  valve  spring  quality  steel of  a  size  larger  than 30 µm.

    Mechanical properties

    1) Other wire sizes on request.
    2) Ovality, i. e. the difference between the largest and smallest dimension of a cross section, is maximum half the tolerance range.
    3) Conversion from tensile strength to hardness values can be calculated in standard ISO EN 18265. The tensile strength Rm within one coil does not vary more than 50 N/Mm2.
    4) Torsion test is carried out for assessing deformability. The fracture of the torsion test piece shall be smooth and perpendicular to the wire axis. The rupture shall show no longitudinal cracks.

    For round wire

    Diameter (mm) Tolerance (± mm) Tensile Strength (N/mm²) Torsions (l=300 mm, min. revs) Reduct. of area (min. %)
    0.50 - 0.80 0.010 2080 - 2210 6
    0.81 - 1.30 0.015 2080 - 2210 5 50
    1.31 - 1.40 0.015 2080 - 2210 5 50
    1.41 - 1.60 0.020 2080 - 2210 5 50
    1.61 - 2.00 0.020 2010 - 2160 5 50
    2.01 - 2.50 0.020 1960 - 2060 5 50
    2.51 - 3.00 0.020 1910 - 2010 4 50
    3.01 - 3.20 0.020 1910 - 2010 4 45
    3.21 - 3.50 0.025 1910 - 2010 4 45
    3.51 - 4.50 0.025 1860 - 1960 4 45
    4.51 - 5.00 0.025 1810 - 1910 3 45
    5.01 - 5.60 0.030 1810 - 1910 3 40
    5.61 - 6.00 0.035 1760 - 1860 3 40
    6.01 - 6.50 0.035 1760 - 1860 40

    Yield point

    The proof stress Rp0.2 is min. 0.9 x tensile strength of the wire.

    Surface conditions

    Surface condition

    Surface condition – non-destructive testing
    In the standard size range 2.00 - 6.00 mm the wire is tested continuously in Eddy Current equipment to a surface level of  > 40 microns. Other wire sizes on request.

    Surface condition – end sample test
    The wire is end sample tested by means of etch testing and binocular inspection as well as microscopical inspection of the material structure.

    Max. permissible depth of partial surface decarburization and surface defects, 1 % x wire diameter. In shaved condition; for diameters <=2 .00 mm 10 µm, for diameters > 2.00 mm 0.5% x d.

    Physical properties

    E and G modulus of elasticity

    206 kN/mm²

    kN/mm²

    E and G modulus of shear

    79.5 kN/mm²

    kN/mm²

    Recommendations

    Heat treatment

    As soon as possible after coiling, the springs should be stress relieved.

    Hot presetting

    After shot peening, the springs should be hot preset or stress relieved. In order to reach optimum fatigue and relaxation properties, the springs must be preset at an appropriate stress.

    Shot peening

    In order to obtain optimum fatigue properties, the process time should be adjusted to get a complete treatment. Size of shots should be adapted to wire dimension, pitch and shot peening equipment.

    Shot peening of the inside of the spring coils is particularly critical.

    Spring Conditions For Tests

    Spring conditions for fatigue and relaxation tests (specially designed test spring) Diagrams 1 and 2:
    Wire size Ø 4.00 mm
    Diameter external 28.00 mm
    Spring length, l0 59.5 mm
    N active 4.80
    Spring index 6.0
    Shot peening Speed 48 m/sec. for 20 minutes, size of shots 0.8 mm
    Hardness of Shot-peening grit (shot): 610-670 Hv
    Aim for Almen arc-height Min. 0.40-0.45 mm
    Hot presetting (theoretically set) 1200 N/mm2
    Temperature 200°C (max. 250°C)
    Time 10 minutes

    Relaxation And Fatigue Properties

    In diagram 1 the fatigue properties of this grade are illustrated in a Goodman-diagram, based on a special test spring design.

    Diagram 2 shows the relaxation properties (loss of load) of springs made from OTEVA® 70 SC wire subjected to static compression at different temper-atures.

    Additional

    Additional information

    Delivery forms
    See separate sheet.

    Nearest equivalent steel grades

    EN VDSiCr, SIS 142090-05

    Standards

    EN 10270-2, ASTM A877 A, BS 2803 685A55HD, JIS G3561 SWOSC-V

  3. OTEVA 75 SC, OTEVA 75 SC PLUS
    Suzuki Garphyttan www.suzuki-garphyttan.com

    OTEVA 75 SC, OTEVA 75 SC PLUS

    Oil tempered SiCrV-alloyed high tensile valve spring wire

    OTEVA® 75 SC is a Super Clean steel, especially intended for the manufacture of clutch/ transmission springs with extremely high fatigue properties and good relaxation properties at moderately increased working temperatures.

    Manufactured as standard in shaved condition in sizes from Ø 1.60 mm to 6.50 mm, or in egg or elliptical shape corresponding to round cross section 2.50 mm to 6.50 mm. Other wire sizes and shapes on request.

    OTEVA® 75 SC PLUS is intended for manufacture of valve springs and other springs requiring extremely high fatigue properties and good relaxation properties at increased working temperatures.

    Chemical composition

    C (%) Si (%) Mn (%) P max. (%) S max. (%) Cr (%) V (%)
    0.50 - 0.70 1.20 - 1.65 0.50 - 0.80 0.020 0.020 0.50 - 1.00 0.05 - 0.20

    Cleanliness in steel

    The presence of non-metallic inclusions in the wire rod is inspected for every heat of OTEVA® 75 SC in accordance with the Suzuki Garphyttan method by the steel supplier.

    Before release for production, Suzuki Garphyttan performs non-metallic inclusion inspection for every fifth heat. The criteria for supplier inspection and releasing inspection are the following;

    For wire rod samples: Inclusion size max. 15 µm down to 1 mm below surface. Inspection area: 1 000 mm2.

    Inclusion size, surface 5-10 µm >10-15 µm >15 µm
    Max. number of inclusions 50 7 0

    For OTEVA 75 SC PLUS, every heat is inspected including a SEM-EDS analysis of inclusions > 10µm to verify a Super Clean composition.

    As stated by IVSWMA, International Valve Spring Wire Manufacturers Association, it is likely to find occasional inclusions in valve spring quality steel of a size larger than 30 µm.

    Mechanical properties

    For round wire

    Diameter (mm) Tolerance (± mm) Tensile Strength (N/mm²) Torsions (l=300 mm, min. revs) Reduct. of area (min. %)
    1.60 - 2.00 0.020 2160 - 2260 5 45
    2.01 - 2.50 0.020 2110 - 2210 5 45
    2.51 - 3.20 0.020 2060 - 2160 5 45
    3.21 - 4.00 0.025 2010 - 2110 4 45
    4.01 - 5.00 0.025 1960 - 2060 3 45
    5.01 - 5.60 0.030 1910 - 2010 3 40
    5.61 - 6.00 0.035 1910 - 20100 3 40
    6.01 - 6.50 0.035 1910 - 2010 35

    Yield point

    The proof stress Rp0.2 is min. 0.9 x tensile strength of the wire.

    Surface conditions

    Surface condition

    Surface condition – non-destructive testing
    In the standard size range 2.00 - 6.00 mm the wire is tested continuously in Eddy Current equipment to a surface level of > 40 microns. Other wire sizes on request.

    Surface condition – end sample test
    The wire is end sample tested by means of etch testing and binocular inspection as well as microscopical inspection of the material structure.
    Max. permissible depth of partial surface decarburization and surface defects, 1 % x wire diameter. In shaved condi-tion; for diameters <=2 .00 mm 10 µm, for diameters > 2.00 mm 0.5% x d.

    Physical properties

    E and G modulus of elasticity

    206 kN/mm²

    kN/mm²

    E and G modulus of shear

    79.5 kN/mm²

    kN/mm²

    Recommendations

    Heat treatment

    As soon as possible after coiling, the springs should be stress relieved.

    Hot presetting

    After shot peening, the springs should be hot preset or stress relieved. In order to reach optimum fatigue and relaxation properties, the springs must be preset at an appropriate stress.

    Shot peening

    In order to obtain optimum fatigue properties, the process time should be adjusted to get a complete treatment. Size of shots should be adapted to wire dimension, pitch and shot peening equipment.

    Shot peening of the inside of the spring coils is particularly critical.

    Spring Conditions For Tests

    Spring conditions for fatigue and relaxation tests (specially designed test spring) Diagram 1 and 2:
    Wire size Ø 4.00 mm
    Diameter external 28.00 mm
    Spring length, l0 59.5 mm
    N active 4.80
    Spring index 6.0
    Stress relieving
    Temperature 420 ±5°C (790 ±10 °F)
    Time 30 minutes
    Shot peening (double shot peening)
    1st treatment Speed 56 m/sec. for 20 minutes, size of shots 0.8 mm
    2nd treatment Speed 30 m/sec. for 10 minutes, size of shots 0.8 mm
    Hardness of Shot-peening grit (shot): 610-670 Hv
    Aim for Almen arc-height Min 0.45 mm
    Hot presetting
    (theoretically set)
    1300 N/mm2
    Temperature 200°C (max. 250°C)
    Time 10 minutes

    Relaxation And Fatigue Properties

    In diagram 1 the fatigue properties of this grade are illustrated in a Goodman-diagram, based on a special test spring design.

    Diagram 2 shows the relaxation properties (loss of load) of springs made from OTEVA® 75 SC wire subjected to static compression at different temperatures.

    Nearest equivalent steel grades

    EN VDSiCrV

    Standards

    ASTM A877 B

  4. OTEVA 90 SC, OTEVA 90 SC PLUS
    Suzuki Garphyttan www.suzuki-garphyttan.com

    OTEVA 90 SC, OTEVA 90 SC PLUS

    Oil tempered SiCrVNi-alloyed ultra-high tensile valve spring wire for
    surface nitriding

    OTEVA® 90 SC is a Super Clean steel, especially intended for the manufacture of clutch/transmission springs with extremely high fatigue properties and good relaxation properties at increased working temperatures.

    Manufactured as standard in shaved condition in sizes from Ø 2.00 mm to 6.00 mm, or in egg or elliptical shape corresponding to round cross section 2.50 mm to 6.00 mm. Other wire sizes on request.

    OTEVA® 90 SC PLUS is intended for manufacture of valve springs and other springs requiring extremely high fatigue properties and good relaxation properties at increased working temperatures.

    Chemical composition

    C (%) Si (%) Mn (%) P max. (%) S max. (%) Cr (%) V (%) Ni (%)
    0.50 - 0.70 1.80 - 2.20 0.70 - 1.00 0.020 0.020 0.85 - 1.05 0.05 - 0.15 0.20 - 0.40

    Cleanliness in steel

    The presence of non-metallic inclusions in the wire rod is inspected for every heat of OTEVA® 90 SC in accordance with the Suzuki Garphyttan method by the steel supplier.

    Before release for production, Suzuki Garphyttan performs non-metallic inclusion inspection for every fifth heat. The criteria for supplier inspection and releasing inspection are the following;

    For wire rod samples: Inclusion size max. 15 µm down to 1 mm below surface. Inspection area: 1 000 mm2.

    Inclusion size, surface 5-10 µm >10-15 µm >15 µm
    Max. number of inclusions 50 7 0

    For OTEVA 90 SC PLUS, every heat is inspected including a SEM-EDS analysis of inclusions > 10µm to verify a Super Clean composition.

    As stated by IVSWMA, International Valve Spring Wire Manufacturers Association, it is likely to find occasional inclusions  in  valve  spring  quality  steel of  a  size  larger  than 30 µm.

    Mechanical properties

    1) Other wire sizes on request.
    2) Ovality, i. e. the difference between the largest and smallest dimension of a cross section, is maximum half the tolerance range.
    3) Conversion from tensile strength to hardness values can be calculated in standard ISO EN 18265. The tensile strength Rm within one coil does not vary more than 50 N/mm2.
    4) Torsion test is carried out for assessing deformability. The fracture of the torsion test piece shall be smooth and perpendicular to the wire axis. The rupture shall show no longitudinal cracks.

    For round wire

    Diameter (mm) Tolerance (± mm) Tensile Strength (N/mm²) Torsions (l=300 mm, min. revs) Reduct. of area (min. %) Tensile strength after heat treatment 480C 1h (N/mm²)
    2.00 - 2.50 0.020 2180 - 2280 5 45 -
    2.51 - 3.20 0.020 2130 - 2230 5 45 5 -
    3.21 - 4.00 0.025 2080 - 2180 4 45 -
    4.01 - 5.00 0.025 - 2130 3 45 -
    5.01 - 5.60 0.030 - 2080 3 40 -
    5.61 - 6.00 0.035 - 2080 3 40 -

    Yield point

    The proof stress Rp0.2 is min. 0.8 x tensile strength of the wire. The proof stress will rise above 0.9 x tensile strength after stress relieving the springs.

    Surface conditions

    Surface condition

    Surface condition – non-destructive testing
    In the standard size range 2.00 - 6.00 mm the wire is tested continuously in Eddy Current equipment to a surface level of > 40 microns. Other wire sizes on request.

    Surface condition – end sample test
    The wire is end sample tested by means of etch testing and binocular inspection as well as microscopical inspection of the material structure.
    Max. permissible depth of partial surface decarburization and surface defects, 1 % x wire diameter. In shaved condi-tion; for diameters <=2 .00 mm 10 µm, for diameters > 2.00 mm 0.5% x d.

    Physical properties

    E and G modulus of elasticity

    206 kN/mm²

    kN/mm²

    E and G modulus of shear

    79.5 kN/mm²

    kN/mm²

    Recommendations

    Heat treatment

    As soon as possible after coiling, the springs should be stress relieved. Depending on nitriding temperature used later in the valve spring manufacturing process, this temperature may be decreased.

    Hot presetting

    After shot peening, the springs should be hot preset or stress relieved. In order to reach optimum fatigue and relaxation properties, the springs must be preset at an appropriate stress.

    Soft shot peening

    Before the nitriding process a soft shot peening process shall be applied in order to remove the oxide layer on the spring wire surface.

    Nitriding

    Springs of OTEVA® 90 SC should be nitrided to obtain optimum fatigue and relaxation properties. Our recommendation is gas nitriding.

    Shot peening

    In order to obtain optimum fatigue properties, the process time should be adjusted to get a complete treatment. Size of shots should be adapted to wire dimension, pitch and shot peening equipment.

    For nitrided springs with an extremely hard surface zone, it is important to use a shot peening media with high hardness.

    Shot peening of the inside of the spring coils is particularly critical.

    Spring Conditions For Tests

    Spring conditions for fatigue and relaxation tests (specially designed test spring) Diagrams 1 and 2:
    Wire size Ø 3.85 mm
    Diameter external 26.95 mm
    Spring length, l0 53.0 mm
    N active 4.15
    Spring index 6.0
    Stress relieving  
    Temperature 450 ±5 °C (840 ±10 °F) min. 420 °C (790 ±10 °F) for nitriding
    Time 30 minutes
    Soft shot peened  
    Speed 20-30 m/s
    Time 5 min
    Shot size 0.8 mm
    Nitriding Gas nitriding
    Temperature 450-470°C
    Time 5-20 hours
    Aim for surface hardness Min. 800 Hv
    Aim for core hardness Min. 560 Hv
    Compound (white) layer Max. 1 µm.
    Shot peening (triple shot peening for nitrided springs)  
    1st treatment Pressure 0.3 MPa (~60m/s)* with RCW shot size 0.6 mm (hardness 800 Hv) f or 20 minutes.
    2nd treatment 3rd treatment

    Aim for Almen arc-height
    Pressure 0.3 MPa (~60m/s)* with RCW shot size 0.25 mm (hardness 800 Hv) f or 10 minutes. Pressure 0.2 MPa (~40m/s)* with fine shot size (hardness 700 Hv) for 10 minutes. 0.55 – 0.60 mm
    Hot presetting
    (theoretically set)
    1500 N/mm2 (nitrided springs) 1300 N/mm2 (not nitrided springs)
    Temperature 200°C (max. 250°C)
    Time 10 minutes

    * Pressure setting for an air blast system and the approximate corresponding shot speed for a centrifugal blast wheel (in brackets). Try to solve the new Formula Cube! It works exactly like a Rubik's Cube but it is only $2, from China. Learn to solve it with the tutorial on rubiksplace.com or use the solver to calculate the solution in a few steps. (Please subscribe for a membership to stop adding promotional messages to the documents)

    Relaxation And Fatigue Properties

    In diagram 1 the fatigue properties of this grade are illus-trated in a Goodman-diagram, based on a special test spring design.

    Diagram 2 shows the relaxation properties (loss of load) of springs made from OTEVA® 90 SC wire subjected to static compression at different temperatures, nitrided/not nitrided.

    Standards

    ASTM A877 C

  5. OTEVA 91 SC
    Suzuki Garphyttan www.suzuki-garphyttan.com

    OTEVA 91 SC

    Oil tempered SiCrVMo-alloyed ultra-high tensile valve spring wire for surface nitriding

    OTEVA® 91 SC is a Super Clean steel, especially intended for the manufacture of clutch/transmission springs with extremely high fatigue properties and good relaxation properties at increased working temperatures.
    Manufactured as standard in shaved condition in sizes from Ø 2.00 mm to 6.00 mm, or in egg or elliptical shape corresponding to round cross section 2.50 mm to 6.00 mm. Other wire sizes on request.

    OTEVA® 91 SC PLUS is intended for manufacture of valve springs and other springs requiring extremely high fatigue properties and good relaxation properties at increased working temperatures.

    Further information about the approval process for OTEVA SC PLUS is found here.

    Chemical composition

    C (%) Si (%) Mn (%) P max. (%) S max. (%) Cr (%) V (%) Mo (%)
    0.50 - 0.70 1.80 - 2.20 0.30 - 0.60 0.020 0.025 0.80 - 1.00 0.05 - 0.15 0.05 - 0.15

    Cleanliness in steel

    The presence of non-metallic inclusions in the wire rod is inspected for every heat of OTEVA® 96 SC in accordance with the Suzuki Garphyttan method by the steel supplier.

    Before release for production, Suzuki Garphyttan performs non-metallic inclusion inspection for every fifth heat. The criteria for supplier inspection and releasing inspection are the following;

    For wire rod samples: Inclusion size max. 15 µm down to 1 mm below surface. Inspection area: 1 000 mm2.

    Inclusion size, surface 5-10 µm >10-15 µm >15 µm
    Max. number of inclusions 50 7 0

    For OTEVA 91 SC PLUS, every heat is inspected including a SEM-EDS analysis of inclusions > 10µm to verify a Super Clean composition.

    As stated by IVSWMA, International Valve Spring Wire Manufacturers Association, it is likely to find occasional inclusions  in  valve  spring  quality  steel of  a  size  larger  than 30 µm.

    Mechanical properties

    1) Other wire sizes on request.
    2) Ovality, i. e. the difference between the largest and smallest dimension of a cross section, is maximum half the tolerance range.
    3) Conversion from tensile strength to hardness values can be calculated in standard ISO EN 18265. The tensile strength Rm within one coil does not vary more than 50 N/mm2.
    4) Torsion test is carried out for assessing deformability. The fracture of the torsion test piece shall be smooth and perpendicular to the wire axis. The rupture shall show no longitudinal cracks.

    For round wire

    Diameter (mm) Tolerance (± mm) Tensile Strength (N/mm²) Torsions (l=300 mm, min. revs) Reduct. of area (min. %)
    2.00 - 2.50 0.020 2180 - 2280 5 45
    2.51 - 3.20 0.020 2130 - 2230 5 45
    3.21 - 4.00 0.025 2080 - 2180 4 45
    4.01 - 5.00 0.025 2030 - 2130 3 45
    5.01 - 5.60 0.030 1980 - 2080 3 40
    5.61 - 6.00 0.035 1980 - 2080 3 40

    Yield point

    The proof stress Rp0.2 is min. 0.8 x tensile strength of the wire. The proof stress will rise above 0.9 x tensile strength after stress relieving the springs.

    Surface conditions

    Surface condition

    Surface condition – non-destructive testing
    In the standard size range 2.00 - 6.00 mm the wire is tested continuously in Eddy Current equipment to a surface level of > 40 microns. Other wire sizes on request.

    Surface condition – end sample test
    The wire is end sample tested by means of etch testing and binocular inspection as well as microscopical inspection of the material structure.
    Max. permissible depth of partial surface decarburiza-tion and surface defects, 1 % x wire diameter. In shaved condition; for diameters <=2 .00 mm 10 µm, for diameters > 2.00 mm 0.5% x d.

    Physical properties

    E and G modulus of elasticity

    206 kN/mm²

    kN/mm²

    E and G modulus of shear

    79.5 kN/mm²

    kN/mm²

    Recommendations

    Oil tempered SiCrVMo-alloyed ultra-high tensile valve spring wire for surface nitriding

    Heat treatment

    As soon as possible after coiling, the springs should be stress relieved. Depending on nitriding temperature used later in the valve spring manufacturing process, this temperature may be decreased.

    Hot presetting

    After shot peening, the springs should be hot preset or stress relieved. In order to reach optimum fatigue and relaxation properties, the springs must be preset at an appropriate stress.

    Soft shot peening

    Before the nitriding process a soft shot peening process shall be applied in order to remove the oxide layer on the spring wire surface.

    Nitriding

    Springs of OTEVA® 91 SC should be nitrided to obtain optimum fatigue and relaxation properties. Our recommendation is gas nitriding.

    Shot peening

    In order to obtain optimum fatigue properties, the process time should be adjusted to get a complete treatment. Size of shots should be adapted to wire dimension, pitch and shot peening equipment.

    For nitrided springs with an extremely hard surface zone, it is important to use a shot peening media with high hardness. Shot peening of the inside of the spring coils is particularly critical.

    Spring Conditions For Tests

    Spring conditions for fatigue and relaxation tests (specially designed test spring) Diagrams 1 and 2:
    Wire size Ø 3.85 mm
    Diameter external 26.95 mm
    Spring length, l0 53.0 mm
    N active 4.15
    Spring index 6.0
    Stress relieving  
    Temperature 450 ±5 °C (840 ±10 °F) min. 420 °C (790 ±10 °F) for nitriding
    Time 30 minutes
    Soft shot peened  
    Speed 20-30 m/s
    Time 5 min
    Shot size 0.8 mm
    Nitriding Gas nitriding
    Temperature 450-470°C
    Time 5-20 hours
    Aim for surface hardness Min. 800 Hv
    Aim for core hardness Min. 560 Hv
    Compound (white) layer Max. 1 µm.
    Shot peening (triple shot peening for nitrided springs)  
    1st treatment Pressure 0.3 MPa (~60m/s)* with RCW shot size 0.6 mm (hardness 800 Hv) for 20 minutes.
    2nd treatment 3rd treatment

    Aim for Almen arc-height
    Pressure 0.3 MPa (~60m/s)* with RCW shot size 0.25 mm (hardness 800 Hv) for 10 minutes. Pressure 0.2 MPa (~40m/s)* with fine shot size (hardness 700 Hv) for 10 minutes. 0.55 – 0.60 mm
    Hot presetting
    (theoretically set)
    1500 N/mm2 (nitrided springs) 1300 N/mm2 (not nitrided springs)
    Temperature 200°C (max. 250°C)
    Time 10 minutes

    * Pressure setting for an air blast system and the approximate corresponding shot speed for a centrifugal blast wheel (in brackets).

    Relaxation And Fatigue Properties

    In diagram 1 the fatigue properties of this grade are illustrated in a Goodman-diagram, based on a special test spring design.

    Diagram 2 shows the relaxation properties (loss of load) of springs made from OTEVA® 91 SC wire subjected to static compression at different temperatures, nitrided/not nitrided.

    Standards

    ASTM A877 D

  6. OTEVA 96 SC, OTEVA 96 SC PLUS
    Suzuki Garphyttan www.suzuki-garphyttan.com

    OTEVA 96 SC, OTEVA 96 SC PLUS

    Oil tempered SiCrVMo-alloyed ultra-high tensile valve spring wire for
    surface nitriding

    OTEVA® 96 SC is a Super Clean steel, especially intended for the manufacture of clutch/transmission springs with extremely high fatigue properties and good relaxation properties at increased working temperatures.

    Manufactured as standard in shaved condition in sizes from Ø 2.00 mm to 6.00 mm, or in egg or elliptical shape corresponding to round cross section 2.50 mm to 6.00 mm. Other wire sizes on request.

    OTEVA® 96 SC PLUS is intended for manufacture of valve springs and other springs requiring extremely high fatigue properties and good relaxation properties at increased working temperatures.

    Chemical composition

    C (%) Si (%) Mn (%) P max. (%) S max. (%) Cr (%) V (%) Mo (%)
    0.60 - 0.70 2.00 - 2.20 0.30 - 0.60 0.020 0.025 0.90 - 1.00 0.10 - 0.15 0.10 - 0.15

    Cleanliness in steel

    The presence of non-metallic inclusions in the wire rod is inspected for every heat in accordance with the Suzuki Garphyttan method by the steel supplier.

     Before release for production, Suzuki Garphyttan performs non-metallic inclusion inspection for every fifth heat. The criteria for supplier inspection and releasing inspection are the following;

    For wire rod samples: Inclusion size max. 15 µm down to 1 mm below surface. Inspection area 1 000 mm2.

    Inclusion size, surface 5-10 µm >10-15 µm >15 µm
    Max. number of inclusions 50 7 0

    For OTEVA 96 SC PLUS, every heat is inspected including a SEM-EDS analysis of inclusions > 10µm to verify a Super Clean composition.

    As stated by IVSWMA, International Valve Spring Wire Manufacturers Association, it is likely to find occasional inclusions in valve spring quality steel of a size larger than 30 µm.

    Mechanical properties

    1) Other wire sizes on request.
    2) Ovality, i. e. the difference between the largest and smallest dimension of a cross section, is maximum half the tolerance range.
    3) Conversion from tensile strength to hardness values can be calculated in standard ISO EN 18265. The tensile strength Rm within one coil does not vary more than 50 N/mm2.
    4) Torsion test is carried out for assessing deformability. The fracture of the torsion test piece shall be smooth and perpendicular to the wire axis. The rupture shall show no longitudinal cracks.

    For round wire

    Diameter (mm) Tolerance (± mm) Tensile Strength (N/mm²) Torsions (l=300 mm, min. revs) Reduct. of area (min. %)
    2.00 - 2.50 0.020 2180 - 2280 5 45
    2.51 - 3.20 0.020 2130 - 2230 5 45
    3.21 - 4.00 0.025 2080 - 2180 4 45
    4.01 - 5.00 0.025 2030 - 2130 3 45
    5.01 - 5.60 0.030 1980 - 2080 3 40
    5.61 - 6.00 0.035 1980 - 2080 3 40

    Yield point

    The proof stress Rp0.2 is min. 0.8 x tensile strength of the wire. The proof stress will rise above 0.9 x tensile strength after stress relieving the springs.

    Surface conditions

    Surface condition

    Surface condition - non-destructive testing
    In the standard size range 2.00 - 6.00 mm the wire is tested continuously in Eddy Current equipment to a surface level of > 40 microns. Other wire sizes on request.

    Surface condition - end sample test
    The wire is end sample tested by means of etch testing and binocular inspection as well as microscopical inspection of the material structure. Max. permissible depth of partial surface decarburization and surface defects, 1 % x wire diameter. In shaved condi-tion; for diameters <=2 .00 mm 10 µm, for diameters > 2.00 mm 0.5% x d.

    Physical properties

    E and G modulus of elasticity

    206 kN/mm²

    kN/mm²

    E and G modulus of shear

    79.5 kN/mm²

    kN/mm²

    Recommendations

    Heat treatment

    As soon as possible after coiling, the springs should be stress relieved. Depending on nitriding temperature used later in the valve spring manufacturing process, this tem-perature may be decreased.

    Hot presetting

    After shot peening, the springs should be hot preset or stress relieved. In order to reach optimum fatigue and relaxation properties, the springs must be preset at an appropriate stress.

    Soft shot peening

    Before the nitriding process a soft shot peening process shall be applied in order to remove the oxide layer on the spring wire surface.

    Nitriding

    Springs of OTEVA® 96 SC should be nitrided to obtain optimum fatigue and relaxation properties. Our recommendation is gas nitriding.

    Shot peening

    In order to obtain optimum fatigue properties, the process time should be adjusted to get a complete treatment. Size of shots should be adapted to wire dimension, pitch and shot peening equipment.
    For nitrided springs with an extremely hard surface zone, it is important to use a shot peening media with high hardness.
    Shot peening of the inside of the spring coils is particularly critical.

    Spring Conditions For Tests

    Spring conditions for fatigue and relaxation tests (specially designed test spring) Diagrams 1 and 2:
    Wire size Diameter external Spring length, l0 N active Ø 3.85 mm 26.95 mm 53.0 mm 4.15
    Spring index 6.0
    Stress relieving  
    Temperature 450 ±5 °C (840 ±10 °F) min. 420 °C (790 ±10 °F) for nitriding
    Time 30 minutes
    Soft shot peened  
    Speed 20-30 m/s
    Time 5 min
    Shot size 0.8 mm
    Nitriding Gas nitriding
    Temperature 450-470°C
    Time 5-20 hours
    Aim for surface hardness Min. 800 Hv
    Aim for core hardness Min. 560 Hv
    Compound (white) layer Max. 1 µm.
    Shot peening (triple shot peening for nitrided springs)  
    1st treatment Pressure 0.3 MPa (~60m/s)* with RCW shot size 0.6 mm (hardness 800 Hv) for 20 minutes.
    2nd treatment 3rd treatment
    Aim for Almen arc-height
    Pressure 0.3 MPa (~60m/s)* with RCW shot size 0.25 mm (hardness 800 Hv) for 10 minutes. Pressure 0.2 MPa (~40m/s)* with fine shot size (hardness 700 Hv) for 10 minutes.. 0.55 – 0.60 mm
    Hot presetting
    (theoretically set)
    1500 N/mm2 (nitrided springs) 1300 N/mm2 (not nitrided springs)
    Temperature 200°C (max. 250°C)
    Time 10 minutes

    * Pressure setting for an air blast system and the approximate corresponding shot speed for a centrifugal blast wheel (in brackets). Try to solve the new Formula Cube! It works exactly like a Rubik's Cube but it is only $2, from China. Learn to solve it with the tutorial on rubiksplace.com or use the solver to calculate the solution in a few steps. (Please subscribe for a membership to stop adding promotional messages to the documents)

    Relaxation And Fatigue Properties

    In diagram 1 the fatigue properties of this grade are illustrated in a Goodman-diagram, based on a special test spring design.

    Diagram 2 shows the relaxation properties (loss of load) of springs made from OTEVA® 96 SC wire subjected to static compression at different temperatures, nitrided/not nitrided.

    Standards

    EN 10270-2