Material Name: High quality carbon structural steel 

 Grade: 70Mn 

 Standard: GB / T 699-1988 

 70MN Overview 
 Features and Scope 
 Hardenability of steel better than 70, obtained after heat treatment better than the strength of 70 steel, heat treatment with heat sensitivity and temper brittleness, easy to produce quenching cracks. Cold plastic deformation ability, poor welding. Withstand large stress, wear and tear under the conditions of working parts, such as the various coils of spring washers. Thrust ring. Locking ring. Clutch plate, for the manufacture of wear-resistant, planted a large load of mechanical parts, such as coil spring washer, thrust ring, clutch disc, locking ring, coil spring, etc. 

 Chemical Composition: 
 Carbon C: 0.67 ~ 0.75 

 Si Si: 0.17 ~ 0.37 

 Manganese Mn: 0.90 ~ 1.20 

 S S: ≤ 0.035 

 Phosphorus P: ≤ 0.035 

 Chromium Cr: ≤ 0.25 

 Ni-Ni: ≤ 0.25 

 Copper Cu: ≤ 0.25 

 Physical properties 
 Mechanical Properties: 
 Tensile strength σb (MPa): ≥ 785 (80) 

 Yield strength σs (MPa): ≥ 450 (46) 

 Elongation δ5 (%): ≥ 8 

 Reduction of area ψ (%): ≥ 30 

 Hardness: no heat treatment, ≤ 285HB; annealed steel, ≤ 229HB 

 Sample size: Sample size is 25mm 

 Heat treatment and microstructure specifications: 
 Heat treatment specifications: normalizing, 790 ℃. 

 ● Delivery status: no heat treatment or heat treatment (annealing, normalizing or tempering) the status of delivery. Requires heat treatment delivery should be specified in the contract, not indicated by no heat treatment delivery. 

 70mn density 
 ρ = 7.81 g / cc, the steel can be cold rolled into plate, strip and wire, making the spring. 70mnMn can also be produced such as the fitter of the chisel, stylus and other tools. 70Mn steel section size can be made generally about 8 ~ 15mm small flat spring as a variety of small, round spring, at the end of the spring pads, spring winding.