If you’re an engineer, buyer, or manufacturer looking for a reliable medium-carbon steel, 1045 cold rolled steel is likely on your radar. This versatile material balances strength, machinability, and cost—making it a top choice for everything from shafts to automotive parts. In this guide, we’ll break down its key properties, fabrication tips, industry uses, and how to source it smartly.
1. Material Properties & Grades: What Makes 1045 Cold Rolled Steel Unique?
1045 cold rolled steel is a medium-carbon alloy defined by its precise chemical composition and global equivalent grades. Let’s start with the basics:
Chemical Composition
The “45” in 1045 refers to its carbon content (0.45%) —a sweet spot that gives it more strength than low-carbon steels (like 1018) without sacrificing too much machinability. Here’s a full breakdown:
| Element | Content Range | Role |
|---|---|---|
| Carbon (C) | 0.42–0.48% | Boosts strength and hardness |
| Manganese (Mn) | 0.60–0.90% | Improves tensile strength and toughness |
| Phosphorus (P) | Max 0.035% | Controlled to avoid brittleness |
| Sulfur (S) | Max 0.040% | Enhances machinability (free-cutting) |
Global Equivalent Grades
If you source from international suppliers, you’ll encounter these alternatives to AISI 1045 CR:
- DIN 1.1191 (Germany)
- JIS S45C (Japan)
- GB 45# (China)
- EN C45E (Europe)
- UNS G10450 (USA)
Key Material Traits
- Microstructure: Fine ferrite-pearlite mix (from cold rolling), which improves surface finish and dimensional accuracy.
- Density: Standard for steel at 7.85 g/cm³ —easy to calculate weight for design.
- Machinability Rating: ~70 (vs. 100 for 1215 steel)—excellent for turning, milling, and drilling without excessive tool wear.
- Weldability: Moderate—preheating to 200–300°C (392–572°F) prevents cracking, making it suitable for welded machine parts.
2. Mechanical & Physical Properties: Data You Can Trust for Design
When engineering components like axles or bolts, you need precise mechanical data. Below is a table of typical properties for cold rolled 1045 steel (annealed condition):
| Property | Value | Test Standard |
|---|---|---|
| Tensile Strength | 600–700 MPa (87–102 ksi) | ASTM A370 |
| Yield Strength | 420–500 MPa (61–73 ksi) | ASTM A370 |
| Elongation at Break | 15–20% | ASTM A370 |
| Reduction of Area | 40–50% | ASTM A370 |
| Hardness (HRB) | 80–90 | ASTM E18 |
| Hardness (HRC) | 17–22 (after quenching) | ASTM E18 |
| Modulus of Elasticity | 200 GPa (29,000 ksi) | ASTM E111 |
| Poisson’s Ratio | 0.29 | ASTM E111 |
Real-World Example
A manufacturer of hydraulic piston rods uses 1045 CR because its high tensile strength (650 MPa) resists bending under pressure, while its low residual stresses after cold rolling ensures the rods stay straight during use. The surface finish (Ra 0.8–1.6 μm) also reduces friction with seals—extending the rod’s lifespan by 30% compared to hot-rolled alternatives.
Other Critical Traits
- Impact Toughness: 20–30 J at room temperature (ASTM A370)—enough for non-extreme environments like agricultural machinery.
- Fatigue Strength: 250–300 MPa (36–44 ksi) for 10^6 cycles—ideal for rotating parts like gears and pinions.
- Dimensional Tolerances: Typically h9/h11 (ISO 286)—critical for parts that need tight fits, such as jigs and fixtures.
3. Processing & Fabrication Techniques: How to Work With 1045 Cold Rolled Steel
1045 cold rolled steel responds well to most fabrication methods, but proper techniques ensure optimal results. Here’s what you need to know:
Primary Fabrication Methods
- Cold Rolling: The initial process that creates a smooth surface and tight tolerances. Unlike hot rolling, it’s done at room temperature—no scaling or warping.
- Machining:
- Turning/Milling: Use high-speed steel (HSS) or carbide tools with cutting speeds of 15–25 m/min (50–80 ft/min) for best results.
- Drilling: Pre-drill small pilot holes to prevent work hardening (common in medium-carbon steels).
- Heat Treatment:
- Annealing: Heat to 815–845°C (1500–1550°F), hold 1–2 hours, cool slowly. Softens the steel for easier machining.
- Quenching & Tempering: Heat to 830–860°C (1525–1580°F), quench in water/oil, then temper at 200–600°C (392–1112°F). Increases hardness to HRC 30–40 for high-wear parts like mining tools.
- Stress Relieving: Heat to 550–650°C (1022–1202°F) to reduce residual stresses after welding or machining.
Surface Finishing & Coatings
- Grinding: Centerless grinding achieves Ra 0.4 μm for precision parts like spindles.
- Coatings: Zinc plating (for corrosion resistance) or black oxide (for aesthetics) are common. A manufacturer of fasteners uses zinc-plated 1045 CR bolts for outdoor construction—they last 5+ years without rust.
4. Applications & Industries: Where 1045 Cold Rolled Steel Shines
Thanks to its balanced properties, 1045 cold rolled steel is used across industries. Below are the most common applications, with real-world use cases:
| Industry | Applications | Why 1045 CR? |
|---|---|---|
| Automotive | Shafts, gears, bolts | High strength + good weldability |
| Construction Equipment | Hydraulic piston rods, conveyor rolls | Resists bending + wear |
| Agriculture | Tractor axles, plow parts | Toughness for heavy loads |
| Machinery | Jigs, fixtures, die holders | Tight tolerances + machinability |
| Robotics | Arm components, fasteners | Dimensional stability |
Case Study: Automotive Gears
A leading car manufacturer switched from 1018 steel to 1045 cold rolled bar for transmission gears. The 0.45% carbon content increased gear hardness by 25%, reducing wear and extending the transmission’s lifespan from 150,000 to 200,000 km. The cold-rolled surface also eliminated the need for extra grinding—cutting production time by 10%.
5. Standards, Certifications & Quality Control: Ensuring You Get High-Quality Material
To avoid subpar steel, always check for compliance with global standards and quality certifications:
Key Standards
- ASTM A108: Specifies cold-finished carbon steel bars (includes 1045 cold finish).
- ASTM A29: Covers hot-rolled carbon steel bars (base material for cold rolling).
- EN 10277: European standard for cold-finished steel (includes EN C45E).
- JIS G4051: Japanese standard for carbon steel for mechanical structures (includes JIS S45C).
Quality Certifications
- MTR (Mill Test Report): Verifies chemical composition and mechanical properties—ask suppliers for this.
- EN 10204 3.1: A third-party certificate confirming compliance (critical for aerospace or medical parts).
- ISO 9001: Ensures the supplier follows quality management systems.
- RoHS/REACH Compliance: Mandatory for parts sold in the EU (restricts hazardous substances).
Quality Control Tests
- Ultrasonic Testing: Detects internal defects (e.g., cracks) in thick 1045 cold rolled plate.
- Magnetic Particle Inspection: Finds surface cracks in shafts or axles.
- Dimensional Checks: Verify straightness limits (max 1 mm/m) and tolerances (per ASTM A484).
6. Market & Procurement Insights: How to Source 1045 Cold Rolled Steel
Sourcing 1045 cold rolled steel wisely saves time and money. Below are key tips for buyers:
Pricing & MOQs
- Price per kg: $1.50–$3.00 (varies by size, quantity, and region). For example, a 1045 cold rolled bar (20mm diameter) costs ~$2.20/kg in the USA, vs. ~$1.80/kg from Chinese suppliers.
- Price per meter: $5.00–$15.00 (depends on diameter/thickness).
- MOQ (Minimum Order Quantity): Most suppliers require 100–500 kg for standard sizes; custom cuts may have higher MOQs.
Global Suppliers
- USA: Nucor, Steel Dynamics (domestic mills with fast lead times: 1–2 weeks).
- China: Baosteel, Wuhan Iron and Steel (low-cost options, lead times: 3–4 weeks).
- Europe: ArcelorMittal, Thyssenkrupp (compliant with EN standards, lead times: 2–3 weeks).
Sourcing Tips
- Stock Sizes: Choose standard sizes (e.g., 10mm, 15mm, 20mm bars) to avoid custom fees.
- Packaging: Ask for anti-rust oil and export packaging (wooden crates) to prevent damage during shipping.
- Incoterms: Use FOB (Free On Board) for cost control, or CIF (Cost, Insurance, Freight) for hassle-free delivery.
- Tariff Codes: HS 7228.50 (cold-rolled carbon steel bars) —check local tariffs to avoid surprises.
Yigu Technology’s Perspective
At Yigu Technology, we recommend 1045 cold rolled steel for customers needing a cost-effective, high-performance medium-carbon solution. Its machinability and strength make it ideal for custom machine components—we’ve used it to manufacture precision shafts and die holders for automotive clients, reducing their production costs by 15% vs. using higher-grade steels. We also prioritize suppliers with EN 10204 3.1 certification to ensure consistency, and offer custom cut-to-length services to meet small-batch needs.
FAQ
- Is 1045 cold rolled steel suitable for outdoor applications?
Yes, but it requires corrosion protection (e.g., zinc plating or painting). Uncoated 1045 CR will rust in moist environments, so we recommend coatings for outdoor parts like construction fasteners. - Can 1045 cold rolled steel be heat-treated to increase hardness?
Absolutely. Quenching and tempering can raise its hardness to HRC 30–40, making it suitable for high-wear parts like gears and mining tools. Annealing, by contrast, softens it for easier machining. - What’s the difference between 1045 cold rolled and hot-rolled steel?
Cold-rolled 1045 has a smoother surface (Ra 0.8–1.6 μm), tighter tolerances (h9/h11), and higher strength. Hot-rolled 1045 is cheaper but has a rough surface and looser tolerances—best for non-precision parts like structural brackets.
