4125
Alloy Steel4125
AISI/SAE 4125 carbon / alloy steel.
Chemical Composition (%)
| C | 0.25 |
|---|---|
| CR | 0.5 |
| MO | 0.12 |
| P | 0.03 |
| S | 0.03 |
Applications
International high-end steel grade for aerospace, oil & gas, defense or engineering machinery.
Available Forms
Bar, plate, sheet, tube, forgings, strip, wire, powder
Uses
Low-alloy engineering steel with enhanced hardenability and strength from alloying elements. Chromium (≈0.725%) improves hardenability, wear and corrosion resistance. Molybdenum (≈0.21%) 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
Weldable with standard procedures; preheat may be needed for thick sections or higher-carbon/ alloy grades. Protect from decarburization during heating (controlled atmosphere or protective coating).
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