Executive Standard: JIS G4051-2005
● Features and application:
S20C steel strength higher than 15, very little quenching, no temper brittleness. Cold plastic deformation is high, usually for bending, rolling, curved edges and hammer arch and other processing, and exposure to welding arc welding performance is good, gas welding when the thickness is small, form-critical or complex shape of the workpiece on the crack-prone. Machinability than the annealed cold-drawn or normalizing a good state of the state, S20C discontinuity generally used in the manufacture of large parts requiring high toughness.
(1) characteristics of cold extrusion, carburized hardened steel. The low-carbon steel is carbon steel, the steel low intensity, toughness, ductility and weldability are good. Yield strength ≥ 245MPa, Tensile strength ≥ 245MPa, elongation ≥ 28%. Normalizing can promote organizational goals, thinning large block-eutectoid ferrite, the improvement is less than 160HBS rough cutting.
(2) the state does not supply heat treatment state.
(3) chemical composition (mass fraction,%) C 0.18-023, Si 0.15-0.35, Mn 0.30-0.60, P ≤ 0.030, S ≤ 0.035.
(4) refer to the corresponding steel China GB / JB standard steel No. 20, China's Taiwan CNS standard steel S20C, the German DIN standard material number 1.0402, the German DIN standard steel CK22/C22, British BS standard steel IC22, France AFNOR standard steel CC20, the French NF standard steel C22, Italy UNI standard steel C20/C21, Belgium NBN standard steel No. C25-1, the Swedish standard steel SS 1450, Spain UNE standard steel F.112, U.S. AISI / SAE 1020 steel standard, Japanese JIS standard steel S20C/S22C.
(5) phase transition temperature (approximate) Ac1 = 720-845 ℃, Ar1 = 815-730 ℃
(6) cold rough handling practices softening temperature of 700-720 ℃, holding time 8-15h, to 50-100 ℃ / h of cooling rate, reduce the temperature of ≤ 550-600 ℃, baked air-cooled.
Prior to treatment hardness ≤ 143HBS, treatment, hardness ≤ 131HBS.
(7) normalizing standard temperature 870-920 ℃, baked air-cooled.
(8) standard annealing temperature of about 860 ℃, baked air-cooled.
(9) standard quenching temperature 910 ℃ ± 10 ℃, 10% NaCl brine cooling.
Properties and Applications
Slightly higher than the S15C steel strength, good weldability, no temper brittleness, can be improved machinability by water quenching.
Uses: used in the manufacture are not subjected to great stress and high toughness requirements of the various mechanical parts. In the general machinery and automobiles, agricultural machinery for the manufacture of high surface hardness of heart is not required by the Ministry carburizing and carbonitriding parts.