Material Name: 70 spring steel
Standard: GB / T 1222-1984
● Features and application:
65 gauge steel with similar performance, flexibility and strength slightly higher, for the manufacture of small cross-section, less demanding strength, general machine round, square coil spring, such as cars, tractors or trains to withstand mechanical vibration on the flat circular spiral spring, and spring.
● Chemical Composition:
Carbon C: 0.65 ~ 0.75 Si Si: 0.17 ~ 0.37
Manganese Mn: 0.50 ~ 0.80
Sulfur S: ≤ 0.035
Phosphorus P: ≤ 0.035
Chromium Cr: ≤ 0.25
Ni-Ni: ≤ 0.25
Copper Cu: ≤ 0.25
● Mechanical Properties:
Tensile strength σb (MPa): ≥ 1029 (105)
Yield strength σs (MPa): ≥ 833 (85)
Elongation δ10 (%): ≥ 8
Reduction of area ψ (%): ≥ 30
Hardness: hot, ≤ 285HB; cold-drawn + heat treatment, ≤ 321HB
● Heat treatment and microstructure specifications:
Standard heat treatment: quenching 830 ℃ ± 20 ℃, oil cooling; tempering 480 ℃ ± 50 (special needs, ± 30 ℃).
Microstructure: fine pearlite + small amount of proeutectoid ferrite.
● Delivery status: hot-rolled steel to heat treatment or heat treatment delivery, cold-drawn steel with heat treatment delivery.
Standard: GB / T 1222-1984
● Features and application:
65 gauge steel with similar performance, flexibility and strength slightly higher, for the manufacture of small cross-section, less demanding strength, general machine round, square coil spring, such as cars, tractors or trains to withstand mechanical vibration on the flat circular spiral spring, and spring.
● Chemical Composition:
Carbon C: 0.65 ~ 0.75 Si Si: 0.17 ~ 0.37
Manganese Mn: 0.50 ~ 0.80
Sulfur S: ≤ 0.035
Phosphorus P: ≤ 0.035
Chromium Cr: ≤ 0.25
Ni-Ni: ≤ 0.25
Copper Cu: ≤ 0.25
● Mechanical Properties:
Tensile strength σb (MPa): ≥ 1029 (105)
Yield strength σs (MPa): ≥ 833 (85)
Elongation δ10 (%): ≥ 8
Reduction of area ψ (%): ≥ 30
Hardness: hot, ≤ 285HB; cold-drawn + heat treatment, ≤ 321HB
● Heat treatment and microstructure specifications:
Standard heat treatment: quenching 830 ℃ ± 20 ℃, oil cooling; tempering 480 ℃ ± 50 (special needs, ± 30 ℃).
Microstructure: fine pearlite + small amount of proeutectoid ferrite.
● Delivery status: hot-rolled steel to heat treatment or heat treatment delivery, cold-drawn steel with heat treatment delivery.
