81НМА

Alloy Steel

81НМА

GOST (Russia) steel grade 81НМА

Chemical Composition (%)

C0.79
SI0.17
MN0.4
NI1
P0.04
S0.04

Applications

Russian state standard (GOST) steel grade.

Available Forms

Bar, plate, sheet, tube, forgings, strip, wire

Uses

Low-alloy engineering steel with enhanced hardenability and strength from alloying elements. Nickel (≈3%) increases toughness and impact strength at low temperature. Applied to gears, shafts, bolts, connecting rods, pressure parts and heavy forgings in automotive, energy and machinery sectors.

Heat Treatment

Austenitize at 760–820 °C and quench (oil/water) then temper at 150–400 °C for high hardness; spheroidize anneal (680–720 °C) improves machinability of the as-rolled bar.

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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