SCM421 material name: gear steel SCM421 performance standards: JIS G4053-2003 

 ● Features and Scope: SCM421 thermal processing good performance, good cutting performance after normalizing, quenching and tempering after the good mechanical properties and low temperature impact toughness, higher after carburization bending strength and wear resistance However, poor welding performance, proper warm-up before welding, after welding should be promptly tempering. SCM421 commonly used in the manufacturing requirements of high surface hardness, good wear resistance important carburized parts such as gears, cam shaft connecting rod, pins, etc. 
 SCM421 steel gears 
 ● Chemical Composition: C: 0.17 ~ 0.23 Si Si: 1.15 ~ 1.35 Manganese Mn: 0.70 ~ 1.00 S S: to allow the residual phosphorus content ≤ 0.030 P: ≤ 0.030 to allow the residual content of chromium Cr: 0.90 ~ 1.20 Ni: to allow the residual content ≤ 0.25 Copper Cu: Mo to allow the residual content ≤ 0.030 Mo: 0.215 ~ 0.25 
 ● Mechanical Properties: Tensile σb (MPa): ≥ 1175 (120) yield strength σs (MPa): ≥ 885 (90) Elongation δ5 (%): ≥ 10 Reduction of ψ (%): ≥ 45 impacts Power Akv (J): ≥ 55 impact toughness αkv (J/cm2): ≥ 69 (7) Hardness: ≤ 217HB sample size: the sample blank standard size 15mm ● Heat treatment and microstructure: heat treatment specifications: quenching 850 ℃, oil-cooling; tempering 200 ℃, water, air-cooled. Microstructure: martensite. 
 ● Delivery status: to heat treatment (normalizing, annealing, or tempering) or heat treatment delivery, delivery status should be indicated in the contract