Loading page
Should I use 1018 or 1045 steel?
Use 1018 for pins, spacers, fixtures and welded parts: it is cheaper, welds without preheat, and carburizes for a hard case. Use 1045 for shafts, axles and gears that need more strength or an induction-hardened surface: cold drawn, it runs about 91 ksi (625 MPa) tensile versus 64 ksi (440 MPa) for 1018, roughly 40% stronger.
Steel 1018 (cold drawn)
Steel 1045 (cold drawn)
By the numbers
Priced on the same representative part: plate, cnc machining, 50 pcs.
Tensile strengthMPa
1018
440
1045
625
Yield strengthMPa
1018
370
1045
530
Densityg/cm³
1018
7.87
1045
7.87
Elongation%
1018
15
1045
12
Raw material cost$/kg
1018
2.2
1045
2.4
Which should you pick?
Pick 1018 when
- The part is welded
- Loads are light to moderate
- The plan is a carburized 58–62 HRC case over a tough core
- Lowest material and machining cost matter
Pick 1045 when
- Shafts, axles or spindles carry bending or torsion
- You want an induction or flame-hardened surface of 55–60 HRC without carburizing
- The part is forged
- Gear or sprocket teeth need hardening
Key differences
| 1018 | 1045 | |
|---|---|---|
| Carbon | 0.15–0.20% | 0.43–0.50% |
| Welding | No preheat in most sections | Preheat to 300–500 °F (150–260 °C) with low-hydrogen filler |
| Surface hardening route | Carburize for a 58–62 HRC case | Induction or flame harden to 55–60 HRC |
| Through-hardening | Not meaningful | Thin sections only; over about 1 in (25 mm) will not harden to the core |
| Forging use | Occasional | One of the most common closed-die forging steels |
| Common stock | Cold drawn round, square, flat and hex | Cold drawn bar plus turned, ground and polished shafting |
Questions
Is 1045 harder than 1018?
Yes. As cold drawn, 1045 runs about 179 HB versus 126 HB for 1018. Induction hardening takes 1045 to 55–60 HRC at the surface; 1018 reaches 58–62 HRC only in a carburized case.
Can 1045 steel be welded?
With care. Preheat to 300–500 °F (150–260 °C), use low-hydrogen filler, and cool slowly. Without preheat, the heat-affected zone can form brittle martensite and crack. 1018 welds without that procedure.
Should I use 1045 or 4140 for a shaft?
1045 covers moderately loaded and induction-hardened shafts at lower cost. Move to 4140 for sections over about 1 in (25 mm) that need through-hardness, for high fatigue or shock loads, or to use pre-hard 28–32 HRC bar.
Try both on your part.
The builder prices the same geometry in every suitable process and material, with DFM for each.