4340VAR

Alloy Steel

4340VAR

Specialty steel grade. ; equiv AMS 6414 / E4340 VAR). 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

AMS 6414 4340VAR

Equivalent Standards

AMS 6414 / E4340 VAR

Applications

镍铬钼超高强钢。,Bar

Available Forms

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.

Uses

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

Heat Treatment

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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