20MnB

Alloy Steel

20MnB

Mn quench & temper steel. (GB/T 3077; equiv GB 40Mn2 / DIN 42Mn6). Nominal values—confirm mill certificate.

Chemical Composition (%)

C0.38
MN1.3

Mechanical Properties

Tensile:≥885 MPa;Yield:≥735 MPa

Chinese Standard

T 3077 20MnB

Equivalent Grades

GB 40Mn2 / DIN 42Mn6

Applications

锰调质钢。,"Bar

Available Forms

Forging"

Uses

Medium-carbon grade for machine parts such as gears, crankshafts, axles, connecting rods, spindles and forgings that need a balance of strength, toughness and machinability. Commonly supplied as bar, plate, sheet, tube and forging.

Heat Treatment

Austenitize at 820–870 °C (oil or water quench depending on section) and temper at 400–650 °C to the required strength/toughness balance.

Precautions

Preheat and control interpass temperature when welding; post-weld heat treatment or stress relief is recommended to avoid hard-zone cracking. Use low-hydrogen electrodes. Protect from decarburization during heating (controlled atmosphere or protective coating).

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