If you work in manufacturing, construction, or automotive engineering, pickled and oiled steel (PO steel) is a game-changer for projects needing clean, rust-resistant, and easy-to-process metal. Unlike rough hot-rolled steel, PO steel has a smooth, scale-free surface—making it ideal for stamping, welding, or painting. This guide breaks down everything you need to know to choose, use, and source PO steel effectively.
1. Pickled & Oiled Steel Products: Forms for Every Project
PO steel comes in versatile shapes tailored to different industrial needs. Knowing which product to pick saves time and reduces waste. Here’s a breakdown:
| Product Type | Key Features | Common Uses |
|---|---|---|
| Hot rolled pickled and oiled steel coil | Continuous rolls (width 100–2000mm), cost-effective | Mass production (e.g., automotive chassis parts) |
| Pickled and oiled steel sheet | Flat, cut to standard sizes (1m×2m, 2m×4m) | Storage tank panels, agricultural equipment parts |
| Pickled and oiled steel plate | Thick (6–50mm), durable | Structural components for heavy machinery |
| Pickled and oiled steel strip | Narrow (width <100mm), precise | Pipe fittings, small stamped parts |
| Slit pickled and oiled steel coil widths | Custom-slit coils (e.g., 50mm, 75mm) | Automotive trim, electrical enclosures |
Real Example: A tractor manufacturer uses pickled and oiled steel sheet for its machine bodies. The smooth surface accepts paint evenly, and the oil coating prevents rust during storage—cutting rework costs by 15%.
2. Pickling & Oil-Coating Process: How PO Steel Is Made
The PO steel process transforms rough hot-rolled steel into a high-quality material in 5 key steps. Each stage ensures a clean, flat, and protected surface:
- Hot-Rolled Steel Preparation: Start with hot-rolled steel (from a blast furnace), which has a thick, flaky oxide layer (“scale”) on its surface.
- Acid Pickling Line: The steel is dipped in a bath of either hydrochloric acid or sulfuric acid (30–40% concentration) at 60–80°C. This dissolves the scale—hydrochloric acid works faster (10–15 minutes vs. 20–25 for sulfuric) and leaves a smoother surface.
- Rinsing & Drying: After pickling, the steel is rinsed with water to remove acid residue (prevents pitting) and dried with hot air.
- Tension Leveling: The steel passes through rollers under tension to fix warping. This step ensures improved flatness—critical for stamping or welding.
- Oil Coating: A thin layer of rust preventive oil (e.g., mineral oil or eco-friendly ECO oil) is applied via spraying or rolling. The oil creates a barrier against moisture, keeping the steel rust-free for 3–6 months in storage.
- Edge Trimming (Optional): For sheets or strips, edges are trimmed to remove irregularities and ensure consistent width.
Pro Tip: Hydrochloric acid is better for automotive-grade PO steel (needs ultra-smooth surfaces), while sulfuric acid is more cost-effective for construction parts.
3. Surface Quality & Properties: Why PO Steel Outperforms Hot-Rolled
PO steel’s unique properties solve common problems with hot-rolled steel (like scale or rust). Here are its most valuable traits:
- Scale-Free Surface: Pickling removes all oxide scale, so there’s no need for grinding or sandblasting before painting/welding. This saves 20–30% on prep time.
- Improved Flatness: Tension leveling eliminates warping—PO steel sheets lie flat, making assembly easier (e.g., for storage tanks).
- Uniform Oil Film Thickness: The oil coating is 5–10 μm thick (consistent across the surface), so no area is unprotected from rust.
- Enhanced Paint Adhesion: The clean, slightly porous surface (from pickling) lets paint bond better. Tests show paint on PO steel lasts 2x longer than on untreated hot-rolled steel.
- Reduced Oxide Pitting: Acid pickling removes deep scale, preventing pitting that can weaken parts (critical for pressure vessels).
Data Comparison: PO Steel vs. Untreated Hot-Rolled Steel
| Property | Pickled and Oiled Steel | Untreated Hot-Rolled Steel |
|---|---|---|
| Surface Condition | Scale-free, smooth | Rust-prone, scaly |
| Paint Adhesion | Excellent | Poor (needs sanding) |
| Storage Rust Resistance | 3–6 months | 1–2 weeks (without oil) |
4. Applications & End-Use Industries: Where PO Steel Shines
PO steel’s versatility makes it a staple in industries needing clean, easy-to-work metal. Here are its top uses:
- Automotive: Automotive chassis components (PO steel) (e.g., frame rails, control arms) rely on its flatness for precise welding and its scale-free surface for corrosion-resistant coatings.
- Pipe & Tube: Pipe and tube manufacturing (PO steel) uses coils—its smooth surface ensures seamless welding, and the oil coating prevents rust during tube forming.
- Agricultural: Tractor bodies, plow blades, and harvester parts use PO steel sheets—its durability resists dirt and impact, and the oil coating protects it during outdoor storage.
- Stamping: Stamping and deep drawing (PO steel) is ideal for complex shapes (e.g., metal buckets, automotive brackets)—its ductility and smooth surface prevent cracking during forming.
- Storage & Pressure Vessels: Storage tanks and pressure vessels (PO steel) need a scale-free surface to avoid weak points—pickling ensures the steel can handle high pressure without leaking.
5. Grades, Standards & Specifications: Ensuring Quality
Using certified PO steel avoids defects and ensures compliance with industry rules. Here are the key standards and grades to know:
| Standard/Grade | Origin | Key Characteristics | Common Uses |
|---|---|---|---|
| ASTM A1011 | USA | Covers hot-rolled PO steel for general use | Construction beams, storage tanks |
| SAE 1008/1010 PO steel | USA | Low-carbon, high ductility | Stamped parts, automotive trim |
| JIS G3131 SPHC-PO steel | Japan | Commercial quality, good formability | Electrical enclosures, small brackets |
| EN 10111 DD11 pickled and oiled | Europe | Low-carbon, suitable for bending | Pipe fittings, agricultural parts |
| Structural grade A36 PO steel | USA | High strength (250 MPa yield), durable | Heavy machinery frames, construction columns |
Certification Tip: Always request a Mill Test Report (MTR) to confirm the steel meets your grade—this document verifies pickling process, oil type, and surface quality.
6. Coatings & Post-Treatments: Extending PO Steel’s Lifespan
PO steel can be further treated to boost rust resistance, improve paint adhesion, or fit specific project needs. Here are the most common options:
- Oiled vs. Dry Pickled Steel: Oiled PO steel has rust protection for storage; dry pickled steel (no oil) is better for projects where oil could contaminate processes (e.g., food-grade tanks).
- Pre-Primed Pickled and Oiled Steel: A factory-applied primer is added to the oiled surface—saves time on-site, as the steel is ready to paint.
- Thin Organic Coating: A polymer layer (e.g., epoxy) is applied over the oil—ideal for outdoor parts (e.g., construction framing) that need long-term rust resistance.
- Rust-Preventive Oil Types: Mineral oil is cost-effective for indoor storage; ECO oil is biodegradable (better for environmentally sensitive projects, like marine equipment).
- Wax-Coated Pickled and Oiled Steel: A thick wax layer provides 12+ months of rust protection—used for long-term storage or shipping to humid regions.
Yigu Technology’s Perspective
At Yigu Technology, we recommend pickled and oiled steel for clients needing efficient, low-waste manufacturing. For automotive projects, we supply SAE 1008/1010 PO steel—its ductility ensures smooth stamping, and our hydrochloric pickling process delivers a paint-ready surface. For construction clients, we offer A36 PO steel with ECO oil, aligning with sustainability goals. We also provide custom-slit coils to match project widths, reducing material waste by up to 10%.
FAQ
- Do I need to remove the oil from PO steel before welding?
Yes—oil can burn during welding, creating porous welds. Wipe the surface with a degreaser (e.g., acetone) before welding to ensure strong joints. - How long does the oil coating on PO steel last?
Standard rust preventive oil lasts 3–6 months in indoor storage. For outdoor or humid conditions, choose wax-coated PO steel (12+ months) or zinc-plate it for permanent protection. - Can PO steel be used for food-grade applications?
Yes—but use dry pickled steel (no oil) and ensure it meets food-safe standards (e.g., ASTM A240 for stainless steel PO variants). The scale-free surface prevents bacteria buildup.
