40Mn2, alloy structural steel, standard GB/T 3077-1999
【 Main Features 】
This is a medium carbon quenched and tempered manganese steel with high strength, plasticity, and wear resistance. It also has good machinability and heat treatment process performance. The critical quenching diameter in oil is 8.5-23mm, and in water it is 20-42mm; But it has tempering brittleness and overheating sensitivity, and is prone to cracking during quenching. This steel has white spot sensitivity, low cold deformation plasticity, and poor weldability. It needs to be preheated to 100-425 ℃ before welding.
[Application Example]
Generally used in the quenched and tempered state, it can be used to manufacture parts that work under heavy load conditions, such as shafts, crankshafts, axles, piston rods, worms, levers, connecting rods, load-bearing bolts, screws, reinforcement rings, springs, and other quenched and tempered parts. When used for small section important parts with a diameter less than 50mm, this steel has a static strength and fatigue performance equivalent to 40Cr steel, so it can be used as a substitute steel for 40Cr.
【 Chemical Composition 】 (mass fraction) (%)
Manganese Mn: 1.40-1.80
Phosphorus P: ≤ 0.030
Sulfur S: ≤ 0.030
Chromium Cr: ≤ 0.30
Nickel Ni: ≤ 0.30
Copper Cu: ≤ 0.25
Mechanical properties
Tensile strength (σ b/MPa): ≥ 885
Yield point (σ s/MPa): ≥ 735
Post fracture elongation (δ 5/%): ≥ 12
Sectional shrinkage rate (ψ/%): ≥ 45
Impact absorption energy (Aku2/J): ≥ 55
Brinell hardness (HBS100/3000)