Carbon Steel 1045 CNC Machining —
Medium Carbon · Lowest Cost · Through-Hardenable
AISI/SAE 1045 is the workhorse medium-carbon steel — cheap, predictable, and through-hardenable to 55 HRC. We machine all conditions: hot-rolled, cold-drawn, normalized, quenched & tempered, and induction-hardened.
Why Choose Carbon Steel 1045?
1045 is the steel you pick when cost matters most and corrosion can be handled with a coating. It carries 0.43–0.50% carbon — enough to through-harden, weld with preheat, and accept induction hardening, but not so much that machinability suffers. For high-volume structural parts where budget rules, no other steel comes close on price.
The trade-off is corrosion. Bare 1045 flash-rusts in humid air within hours, so every part needs a finish: oil, zinc, phosphate, paint, or powder coat. When corrosion is a hard requirement (food, medical, marine), step up to 304 stainless. When fatigue and shock load matter more than cost, step up to 4140 chrome-moly.
Ginwate machines 1045 across all five conditions in-house. We stock cold-drawn round bar from Ø8 to Ø150 mm in S45C grade (the JIS designation, fully equivalent to AISI 1045 and DIN C45), and we run heat-treatment partners next door for water quench and induction hardening with 24-hour turnaround.
Carbon Steel 1045 vs Alternatives
Head-to-head against the two steels engineers most often cross-shop, plus stainless for visitors arriving from the material selector.
1045 Supply Conditions
1045 is available in five common conditions. Pick the right one before quoting — it determines machining cost, achievable tolerance, and final properties.
| Condition | Hardness | Tensile Strength | Machinability | Best For | Typical Uses |
|---|---|---|---|---|---|
| Hot-Rolled | 163–179 HB | 565–625 MPa | Good | Heavy roughing, weldable structural | Brackets, weldments, base plates |
| Cold-Drawn | 179–219 HB | 625–700 MPa | Excellent | Tight tolerance, smooth finish | Shafts, pins, precision turned parts |
| Normalized | 192–235 HB | 690–825 MPa | Good | Uniform grain, post-weld stability | Forgings, gear blanks |
| Quenched & Tempered | 28–32 HRC | 850–1100 MPa | Moderate | High strength, moderate ductility | Axles, connecting rods, machine keys |
| Induction Hardened | 55–58 HRC surface | Core: 600 MPa | Difficult | Selective wear resistance | Gear teeth, bearing journals, cam lobes |
Machining Specifications
Standard capabilities for 1045 carbon steel CNC milling and turning at Ginwate.
| Property | Value |
|---|---|
| Standard Tolerance | ±0.01 mm |
| High-Precision Tolerance | ±0.005 mm |
| Max Part Size (Milling) | 600 × 400 × 300 mm |
| Max Part Size (Turning) | Ø300 × 1000 mm |
| Surface Finish (as-machined) | Ra 1.6 μm |
| Surface Finish (fine) | Ra 0.4 μm |
| Density | 7.87 g/cm³ |
| Young's Modulus | 200 GPa |
| Max Hardness Achievable | 55 HRC (through-hardened) |
| Material Standards | AISI 1045 / DIN C45 / JIS S45C / EN 1.0503 |
Surface Finishes for 1045 Steel
1045 rusts fast. Always specify a finish — even "oil dip" is a finish. These eight are what 95% of customers ask for.
As-Machined
Ra 1.6–3.2 μm direct from the machine. 1045 rusts within hours of exposure — apply an oil dip or shipping coating before packing.
Black Oxide
Mild corrosion protection with a flat black appearance. Minimal dimensional change (< 2 μm). Common for fasteners, jigs, and tooling.
Zinc Plating
Economical galvanic corrosion protection (5–15 μm). Clear or yellow chromate passivation. Standard finish for hardware-store-grade structural parts.
Manganese Phosphate
Dark grey conversion coating that improves paint adhesion and reduces friction during break-in. Required by many automotive specs.
Oil Dip
Cheapest rust prevention for short-term storage and shipment. Wipe down with mineral oil; lasts weeks indoors, not for outdoor service.
Powder Coat
Tough, abrasion-resistant decorative finish — 60–100 μm thickness. Apply over phosphate or zinc primer for outdoor durability.
Wet Paint
Two-pack epoxy or urethane systems for heavy industrial and marine atmospheres. Surface prep is everything — blast to SA 2.5 first.
Induction Hardening
Selective surface hardening to 55–58 HRC on gear teeth, journals, and wear surfaces while keeping the core tough.
Design Tips for 1045 Steel Machining
Most 1045 problems come from picking the wrong condition or forgetting the corrosion finish. These six tips catch the common mistakes.
Specify the supply condition (hot-rolled, cold-drawn, normalized, or Q&T) on your drawing before quoting — it changes machining cost by up to 30% and determines what tolerances are realistic.
Plan for corrosion. 1045 will flash-rust on bare surfaces within hours of cleaning. Always specify a finish (oil, zinc, phosphate, paint) unless the part is sealed inside an oiled assembly.
For parts that need heat-treatment after machining, leave 0.2–0.4 mm stock on critical surfaces to accommodate distortion and allow finish grinding.
Inside-corner radii in pockets should be ≥ 1.0 mm in hot-rolled stock, ≥ 1.5 mm in normalized, and ≥ 2.0 mm in Q&T condition to avoid tool breakage.
Welding 1045 requires preheat (150–260 °C) and post-weld stress relief — its medium carbon content makes it prone to heat-affected-zone cracking otherwise.
For shafts that need both fatigue strength and a wear-resistant bearing surface, induction-harden the journals only and leave the body normalized. Cheaper and tougher than through-hardening the whole part.
Carbon Steel 1045 CNC Applications
1045 parts from Ginwate ship into general engineering, agricultural equipment, power transmission, construction machinery, and automotive aftermarket.
Explore Other Materials
4140 Alloy Steel
Step up from 1045 when you need higher fatigue resistance, better through-hardening in thick sections, or pre-hardened P/H supply.
Stainless Steel
Step up from 1045 when corrosion can't be solved with coatings — 304, 316L, 17-4 PH for food, medical, marine.
Aluminum 6061
Step sideways from 1045 when weight matters more than strength — 1/3 the density, naturally corrosion-resistant.
Need Precision 1045 Steel Parts?
Upload your CAD files and get a detailed 1045 steel quote in 24 hours. Prototypes to production runs — no minimum order, no setup fees on simple parts.
