Pickled and Oiled Steel Plate

Pickling Plate, the full name of which is hot rolled pickled and oiled sheets and coils, is a type of steel product manufactured from premium hot rolled thin coils. The raw material runs through a complete pickling line to strip off surface mill scale, followed by edge trimming, finishing and other finishing procedures.

Compared with ordinary hot rolled steel, it boasts better surface condition, tighter dimensional tolerance and superior stamping performance. Meanwhile, pickled and oiled steel plate comes at a much lower cost than cold rolled steel sheet. For this reason, it is recognized as an ideal cost-saving substitute that “replaces cold rolled steel with hot rolled material”.

Pickled and oiled steel plate has found extensive applications across automobile manufacturing, machinery production, home appliance fabrication, light industry and hardware sectors. PO steel plate holds particularly vital usage in the production of auto chassis parts, wheel hubs, compressor housings and other key components.

Critical Control Points in Our Pickling Process

Edge Trimming Precision: We apply side-trimming with a slit width tolerance of ±0.5mm to eliminate work-hardened edges. This prevents edge cracking during deep drawing of wheel hubs—a common failure if using untrimmed HRC.

Oiling Weight Control: Post-pickling, we apply anti-rust oil at 1.0-2.0 g/m² (both sides). For customers using robotic welding, we can adjust this to 0.5-0.8 g/m² upon request to avoid weld spatter and porosity—this is a specific pain point we’ve solved for automotive Tier-1 suppliers.

Surface Roughness (Ra): Unlike standard HRPO which offers ~Ra 1.5-2.5μm, we offer a fine-finished variant at Ra ≤ 1.2μm for applications requiring direct painting without intermediate sanding.

Comparison Between Pickled Steel Sheet and Cold Rolled Steel Sheet

Principle of Steel Pickling

Pickling relies on the chemical dissolving power of acids.

In our industrial continuous pickling lines, we predominantly utilize high-concentration hydrochloric acid (HCl) at 18-22% concentration, coupled with a proprietary corrosion inhibitor. This specific formulation effectively removes magnetite (Fe₃O₄) scale while preventing hydrogen-induced blistering on the steel substrate—a critical control point that distinguishes professional picklers from general processors.

These acids trigger chemical reactions with oxides and contaminants covering the surface on pickled and oiled steel plate, dissolving such substances and stripping them off the steel base.

Reference of Pickled Steel Sheet Applications, Common Grades & Specifications

When to Substitute HRPO for Cold Rolled Steel?

Real-case Reference 1

Cost Down Project for a German Agricultural Machinery OEM

Challenge: The client was using 2.0mm CR4 cold-rolled steel for harvester cabin brackets, with material cost accounting for 34% of total part cost. They needed an alternative without retooling their existing stamping dies.

Our Intervention: After analyzing their drawing (bending radius R=6mm, thickness tolerance ±0.08mm), we recommended substituting with 2.0mm SPHC-PO. We adjusted the oiling weight to 0.6 g/m² to ensure their robotic welding line (Fronius brand) had zero porosity issues.

Outcome: 22% material cost saving (saving €0.85 per bracket × 180,000 pcs/year = €153,000 annual saving). Zero splitting or surface defects after powder coating (curing at 200°C for 20 min). The client has now rolled this substitution to 3 additional part numbers.

Application Scenarios and Material Grade Selection Recommendations

Advantages of Pickled and Oiled Plate

Excellent dimensional accuracy: ±0.05mm thickness tolerance (verified by on-site ultrasonic thickness gauge, inspection report attached to each coil)

Great mechanical properties: Yield strength 235-345 MPa, elongation ≥ 38% (per JIS Z 2241 tensile test, sample taken from every heat number)

Outstanding workability: Successful deep drawing up to draw ratio 2.2 (validated in our in-house press lab before mass production)

Quality Assurance & Supply Chain Traceability

Mill Source: Our coils originate from Baosteel, Shougang, and HBIS (with full mill test certificates EN 10204 Type 3.1).

Third-Party Inspection: SGS/BV inspection accepted at loading port. We provide in-process pickling bath concentration logs upon request.

Anti-Rust Warranty: Under indoor storage (RH < 60%, temp 15-25°C), we guarantee no red rust for 6 months (extended from standard 3 months via our VCI oiling option).

FAQ

Q1: What is the difference between pickled and oiled steel plate and cold rolled steel sheet?

A1: PO (Pickled & Oiled) Steel Plate is based on hot rolled steel with pickling treatment, with lower cost. Cold rolled steel has ultra-smooth surface and thinner thickness down to 0.3 mm for high-precision parts. PO plate fits medium-precision structural pieces, while cold rolled sheet targets high-standard appearance components with strict tolerance demands.

Q2: Can PO steel plate be used for outdoor products directly?

A2: No. The anti-rust oil on surface only provides short-term temporary protection during storage and processing. For long-term outdoor exposure, you need subsequent surface treatments such as painting, galvanizing or powder coating to boost anti-corrosion capacity.

Q3: What thickness range can you offer for PO steel plate?

A3: Our standard thickness range covers 1.0mm to 6.0mm, customizable width from 800mm to 2000mm and length from 1000mm to 6000mm according to clients’ drawing demands.

Q4: How long can PO steel stay rust-free under normal storage?

A4: Stored in a dry indoor warehouse without humid air or chemical gas, the anti-rust oil can protect the steel surface for 3-6 months. Avoid open-air stacking to prevent premature oxidation.