20XH4GA

Alloy Steel

20XH4GA

Ni-Cr-Mo ultra-high-strength steel. (GOST 4543; equiv GB 40CrNiMoA / DIN 36CrNiMo4 / JIS SNCM439). Nominal values—confirm mill certificate.

Chemical Composition (%)

C0.38
SI0.15
MN0.6
NI1.65
CR0.7
MO0.2

Mechanical Properties

Tensile:≥1080 MPa;Yield:≥930 MPa;Elong:≥12%

Chinese Standard

GOST 4543 20XH4GA

Equivalent Grades

GB 40CrNiMoA / DIN 36CrNiMo4 / JIS SNCM439

Applications

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Available Forms

Forging"

Uses

Low-alloy engineering steel with enhanced hardenability and strength from alloying elements. Chromium (≈0.8%) improves hardenability, wear and corrosion resistance. Molybdenum (≈0.25%) raises high-temperature strength and prevents temper embrittlement. Nickel (≈1.825%) 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 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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