40CrMnMo
Alloy Steel40CrMnMo
(GB/T 3077). Nominal values—confirm mill certificate.
Chemical Composition (%)
| C | 0.37 |
|---|---|
| SI | 0.17 |
| MN | 0.9 |
| CR | 0.9 |
| MO | 0.2 |
| P | 0.035 |
| S | 0.035 |
Mechanical Properties
Tensile:≥980 MPa;Yield:≥785 MPa;Elong:≥10%;RA:≥45%
Chinese Standard
T 3077 40CrMnMo
Available Forms
Bar,Plate
Uses
Low-alloy engineering steel with enhanced hardenability and strength from alloying elements. Chromium (≈1.05%) improves hardenability, wear and corrosion resistance. Molybdenum (≈0.25%) raises high-temperature strength and prevents temper embrittlement. 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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