Carbon & Alloy Steel
Strong, economical steels for shafts, gears and structural components — heat-treatable for higher strength.
Carbon and low-alloy steels deliver high strength at low cost, making them the backbone of machinery, transmission and structural parts. They are readily heat-treated to tune hardness and strength, and weld easily.
1018 is a soft, weldable, easily machined low-carbon steel; 1045 is a medium-carbon grade for shafts and gears; 4140 and 4340 are chromoly alloy steels that heat-treat to high strength and toughness for highly stressed parts.
Material properties
| Density | 7.85 g/cm³ |
|---|---|
| Tensile strength (1045) | 565–625 MPa |
| Tensile strength (4340, HT) | up to 1280 MPa |
| Max service temp | ~400 °C |
| Corrosion resistance | Poor (requires coating) |
| Machinability | Good (1018/1045) |
| Relative cost | Low |
Typical values for reference; exact properties depend on grade, temper and heat treatment. Full material certification is provided on every order.
Machinability
Low- and medium-carbon steels machine predictably with good tool life. Alloy steels like 4140/4340 machine best in the annealed condition and are often hardened after machining. All carbon steels rust readily, so parts need oil, plating, black oxide or paint for protection.
Typical applications
Related engineering guides
Frequently asked questions
Will carbon steel rust?
Yes. Carbon steel has little corrosion resistance and must be protected with a coating such as black oxide, zinc or nickel plating, powder coat, or oil for indoor use.
What is the difference between 4140 and 1045?
4140 is a chromoly alloy steel that heat-treats to higher strength and toughness than the plain medium-carbon 1045, making it preferred for highly stressed parts.
Can these steels be hardened after machining?
Yes — 1045, 4140 and 4340 are commonly machined soft, then through-hardened or induction-hardened to final strength.