30CrMnSiNi2A

alloy structural steel trademark:30CrMnSiNi2A features and use scope: After heat treatment can get higher intension, good plasticity and toughness ,good antifatigue and fracture toughness , low fatigue crack extend speedly .Good hardenability ,good test for machinability of weldability,but it is sensltive for gap and hydrogen embrittlement (includ surrounding of hydrogen embrittlement ).It used to making parts of important stress of hightensile combined parts and oxis . Chemical composition: C :0.27 0.34 Si:0.90 1.20 Mn:1.00 1.30 S :≤0.020 P :≤0.020 Cr:0.90 1.20 Ni:1.40 1.80 mechanical properties: tensile strength σb (MPa):1)1767; 2)1627 yield strength δ5 (%):1)12;2)13 extensibility ψ (%):50 notched bar impact strengthαku (J/cm2):1)79;2)90 specimen size:bar material heat treatment regime and metallurgical structure: heat treatment regime :1)890 900°C oil hardening,200 300°C backfire,air cooling ;2)890 900°Cheat up,put 210 280°Cmid- tempetature of salprunella groove 1h,air cooling ,after 200 300°C backfire ,air cooling. metallurgical structure:1)after hot rolled or cold rolled use high-temperature backfire to pearlite;2)normalizing add high- temperature backfire is tempered sorbite ; 3)After annealing is lamellar pearlite and ferrite;4)normalizing is martensite and bainite ; 5)When using is backfire