1045 Hot Rolled Medium Carbon Steel
Comprehensive technical specification for 1045 hot rolled medium carbon steel, covering Canadian stock sizing, machinability, common defects, and handling guidelines for fabrication and machining operations.
Material Overview & Common Uses
1045 hot rolled medium carbon steel is a widely used grade in Canadian manufacturing, offering a balance of strength, hardness, and machinability. It contains approximately 0.45% carbon, providing higher tensile strength than low-carbon steels like 1018, while remaining weldable with proper preheat. Common applications include shafts, gears, bolts, studs, spindles, machine parts, and structural components where moderate wear resistance is required. The hot rolled finish (mill scale) is typical and often removed via machining or blasting before final use.
Core Technical Properties & Sizing
| Property | Value (As‑Rolled) | Notes |
|---|---|---|
| Tensile Strength | 570–700 MPa | Typical range |
| Yield Strength | ~310 MPa | |
| Hardness | 163–190 HB | Brinell |
| Elongation | 16% in 50 mm | |
| Density | 7.85 g/cm³ |
| Standard Canadian Stock Sizes (Imperial) | Dimensions | Length |
|---|---|---|
| Plate thickness | 1/8", 3/16", 1/4", 3/8", 1/2", 5/8", 3/4", 1", 1‑1/4", 1‑1/2" | 48" x 96" or 48" x 120" |
| Round bar diameter | 1/4" to 12" | 12' or 20' |
| Flat bar (thickness x width) | 1/4" x 1" up to 2" x 6" | 20' |
| Square bar | 1/4" to 4" | 20' |
| Hex bar | 1/4" to 2" | 12' |
| Dimensional Tolerances (ASTM A36 / A830) | Range | Tolerance |
|---|---|---|
| Plate thickness (≤ 1/4") | ±0.010" | |
| Plate thickness (1/4" – 1/2") | ±0.015" | |
| Plate thickness (> 1/2") | ±0.020" | |
| Round bar diameter (< 1") | ±0.005" | |
| Round bar diameter (1" – 4") | ±0.010" | |
| Flat bar width (< 2") | ±0.015" | |
| Flat bar width (2" – 6") | ±0.030" | |
| Flat bar thickness (< 1/2") | ±0.010" | |
| Flat bar thickness (1/2" – 1") | ±0.015" | |
| Length tolerance (stock lengths) | +1/4" / -0" |
Machinability, Tooling & Feeds
| Parameter | Recommendation |
|---|---|
| Machinability Rating | 55–60% of 1212 free‑machining steel |
| Turning – SFM (roughing) | 200–300 SFM, 0.010–0.020 IPR feed, carbide C2/C5 |
| Milling – SFM | 250–350 SFM, 0.004–0.008 IPT, carbide C2/C5 |
| Drilling – SFM | 150–250 SFM, 0.005–0.015 IPR, HSS with coolant |
| Cutting Fluid | Sulfur‑based oil or water‑soluble coolant at 5–10% concentration |
| Preheating (for welding) | 200–300°F to avoid cracking |
| Stress Relieving | 1100–1300°F after rough machining for dimensional stability |
Common Defects & Quality Control
| Defect / Item | Description / Check |
|---|---|
| Mill Scale | Surface oxide layer – causes tool wear; remove via blasting or machining |
| Decarburization | Surface carbon loss (0.005–0.015" deep) – soft spots; verify with hardness test |
| Seams & Laps | Longitudinal cracks from rolling; reject if deeper than 5% of thickness |
| Warpage | Especially in thin plates from residual stresses – check flatness |
| Incoming Inspection | Check surface cracks, excessive scale, dimensional compliance, hardness (Rockwell B 80–95) |
| Hardness Verification | Use portable hardness tester or file test |
| Rejection Criteria | Visible laminations, deep seams exceeding 5% of thickness |
Storage, Handling & Racking Guidelines
Store 1045 hot rolled steel indoors in a dry, covered area to minimize rust. Rack flat bars and plates on edge in vertical racks with wooden or rubber separators to prevent scratching and bending. Round bars should be stored in horizontal racks with multiple support points (max 4 ft spacing) to avoid sagging. Use a first-in-first-out (FIFO) system to prevent long-term oxidation. Apply light oil or rust inhibitor if storage exceeds 3 months. For outdoor temporary storage, cover with tarps and elevate off ground using dunnage. Handle with nylon slings or padded clamps to avoid surface damage. Keep material tagged with heat number and date received for traceability.