38CrA

Alloy Steel

38CrA

Aircraft-quality chromium steel (GJB 1951 structural bar).

Chemical Composition (%)

C0.34
SI0.17
MN0.5
CR0.8
P0.025
S0.025

Mechanical Properties

Tensile Strength:≥930 MPa;Yield Strength:≥785 MPa;Elongation:≥12%

Chinese Standard

GJB 1951 38CrA

Equivalent Standards

~AISI 5140

Applications

Aircraft structural bars, shafts.

Available Forms

Bar, Forging

Uses

Low-alloy engineering steel with enhanced hardenability and strength from alloying elements. Chromium (≈0.95%) improves hardenability, wear and corrosion resistance. 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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