Grade: 20CrMo

Standard: GB / T 3077-1988

Corresponds to the standard: JIS G4053: 2003

ASTM A29M: 2005

ISO 683-18:1996

Unified digital code: A30202

● Features and application:

High hardenability, no temper brittleness, very good weldability, cold cracking tendency to form small, cutting and cold can be a good strain plasticity. General case hardening in quenched state or used for the manufacture of non-corrosive medium and temperature lower than 250 ℃, the medium containing a mixture of nitrogen and hydrogen in high pressure pipe work and a variety of fasteners, higher carburizing parts such as gears and shafts.

● Chemical Composition:

Carbon C: 0.17 ~ 0.24

Si Si: 0.17 ~ 0.37

Manganese Mn: 0.40 ~ 0.70

Sulfur S: promised to the residual content of ≤ 0.035

Phosphorus P: agreed residual content of ≤ 0.035

Chromium Cr: 0.80 ~ 1.10

Ni: to promise the residual content of ≤ 0.030

Copper Cu: agreed residual content ≤ 0.030

Mo Mo: 0.15 ~ 0.25

● Mechanical Properties:

Tensile strength σb (MPa): ≥ 885 (90)

Yield strength σs (MPa): ≥ 685 (70)

Elongation δ5 (%): ≥ 12

Reduction of area ψ (%): ≥ 50

Impact energy Akv (J): ≥ 78

Impact toughness αkv (J/cm2): ≥ 98 (10)

Hardness: ≤ 197HB

Sample size: Sample size is 15mm rough

● Heat treatment and microstructure specifications:

Standard heat treatment: quenching 880 ℃, water, oil cooling; tempering 500 ℃, water-cooled, oil-cooling.

● Delivery status: to heat treatment (normalizing, annealing, or tempering) or heat treatment delivery, delivery status should be indicated in the contract.