According to the International Institute of Welding (IIW) formula recommended by the carbon equivalent Ceq = C +1 / 6Mn +1 / 5 (Cr + Mo + V) +1 / 15 (Ni + Cu) (%) (1) When Ceq <0.40 %, the obvious tendency of hard steel, excellent weldability, welding without preheating can be directly welding; (2) When Ceq = 0.40 ~ 0.60%, the steel became clear tendency of the hard, yet weldability can, welding can be required to take appropriate preheating before welding, after welding and other processes slow cooling measures to control the welding heat input; (3) When Ceq> 0.60%, the strong tendency of hard steel, weldability is poor, are more difficult to weld steel, must take a higher preheat temperature and rigorous measures, select the appropriate welding materials. Been calculated, 35CrMo steel carbon equivalent value Ceq = 0.72%. Thus, poor weldability of this material, welding tend to be larger when its hard, heat-affected zone hot cracking and cold cracking tendency will be greater, especially in the quenched state welding, heat affected zone will tend to cold cracking appeared very prominent, so should select the appropriate welding materials, welding method, based on reasonable, preheating before welding to a high temperature, stringent process control measures and appropriate temperature conditions between layers in order to achieve the goal of welding products purposes. 

 Feature 
 35CrMo alloy steel, with high static strength, impact toughness and higher fatigue limit than the 40Cr high hardenability, high temperature under high 

 Creep strength and rupture strength, long-term working temperature up to 500 ℃; cold plastic deformation of the middle, poor welding. 

 Use 
 Used in high load of the important structural components, such as vehicle and engine transmission parts; turbine rotor, spindle, heavy load shaft, a large cross-section parts 

 Chemical composition 
 Carbon C: 0.32 ~ 0.40 

 Si Si: 0.17 ~ 0.37 

 Manganese Mn: 0.40 ~ 0.70 

 S S: to allow the residual content ≤ 0.035 

 Phosphorus P: allow the residual content ≤ 0.035 

 Chromium Cr: 0.80 ~ 1.10 

 Ni: to allow the residual content ≤ 0.030 

 Copper Cu: ≤ 0.030 to allow the residual content 

 Mo Mo: 0.15 ~ 0.25 

 Mechanical Properties 
 Tensile strength σb (MPa): ≥ 985 (100) 

 Yield strength σs (MPa): ≥ 835 (85) 

 Elongation δ5 (%): ≥ 12 

 Reduction of area ψ (%): ≥ 45 

 Impact energy Akv (J): ≥ 63 

 Impact toughness αkv (J/cm2): ≥ 78 (8) 

 Hardness: ≤ 229HB 

 Sample size: Sample size of 25mm rough 

 Microstructure and heat treatment specifications 
 Standard heat treatment: quenching 850 ℃, oil-cooling; tempering 550 ℃, water-cooled, oil-cooling. 

 Heat treatment and mechanical properties: 

 Steel: 35CrMo 

 Blank sample size / mm: 25 

 Heat Treatment | hardening | heating temperature / ℃ | first quenching: 850 

 Heat Treatment | hardening | heating temperature / ℃ | second quenching: - 

 Heat Treatment | hardening | Coolant: Oil 

 Heat Treatment | Tempering | heating temperature / ℃: 550 

 Heat Treatment | Tempering | Coolant: water, oil 

 Mechanical Properties | tensile strength σb / MPa | ≥: 980 

 Mechanical properties | yield point σs / MPa | ≥: 835 

 Mechanical properties | Elongation δ5 (%) | ≥: 12 [1] 

 Mechanical properties | area shrinkage ψ (%) | ≥: 45 

 Mechanical Properties | Impact absorbed energy AKV / J | ≥: 63 

 Delivery status hardness HBS | ≥: 229 

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