38CrMoAlA

Alloy Steel

38CrMoAlA

(GB/T 3077). Nominal values—confirm mill certificate.

Chemical Composition (%)

C0.35
CR0.7
MO0.7
AL0.7
P0.035
S0.035

Mechanical Properties

Tensile:≥835 MPa;Yield:≥635 MPa;Elong:≥12%;RA:≥45%

Chinese Standard

T 3077 38CrMoAlA

Available Forms

Bar,Plate

Uses

Nitriding steel that develops an extremely hard, wear- and corrosion-resistant surface after nitriding with minimal distortion. Aluminium (≈0.9%) forms hard AlN nitrides, giving the highest surface hardness. Used for crankshafts, cylinder liners, screws, valves, die blocks and precision machine components.

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. Quench & temper first to ≈30–40 HRC, then gas/nitride at 480–540 °C for 10–60 h; no further quench needed — minimal distortion.

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). Machine the core stock before surface hardening; leave grinding allowance for the hardened case.

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