Chemical composition:
Chemical Composition
C Si Mn P S Ni Cr Cu
≤
25Mn 0.22 ~ 0.29 0.17 ~ 0.37 0.70 ~ 1.00 0.035 0.035 0.30 0.25 0.25
30Mn 0.27 ~ 0.34 0.17 ~ 0.37 0.70 ~ 1.00 0.035 0.035 0.30 0.25 0.25

Mechanical properties:
Grades blank sample
Size
/ mm heat treatment process of the mechanical properties of the steel hardness delivery status
/ HBS
Normalizing quenching and tempering σb / MPa σs / MPa δ5 (%) ψ (%) Ak / J ≤
≥ No heat annealed steel
25Mn 25 900 870 600 490 295 22 50 71 207
30Mn 25 880 860 600 540 315 20 45 63 217 187

Characteristics and Uses:
25Mn 20Mn steel strength steel and are higher than the 25th, and the 25th other performance steel and 20Mn steel similar to carburizing and welding parts, such as camshafts, gears, couplings, hinges, pins, tow bars and so on.
30Mn strength and hardenability corresponding high carbon steel, welding performance medium, when the cold plastic deformation is still good, good cutting performance, there is a tendency to temper brittleness, after forging to tempering immediately. Usually in the normalized state. For the manufacture of bolts, nuts, screws, levers, brake pedal, with cold-drawn steel small parts in high-stress work.