I. Product Description

Round steel refers to solid, long steel bars with a circular cross-section. Produced through hot rolling, forging, or cold drawing, it features a smooth surface, high dimensional accuracy, and stable mechanical properties. It can be cut, bent, welded, or machined as needed. It is a fundamental steel type used in machinery manufacturing, construction engineering, metalworking, and other fields.

II. Materials

Round steel is categorized into several types based on its intended use and performance requirements. Carbon steel and alloy steel are the primary core materials:

Carbon Structural Steel:

Q235 Steel: The most commonly used low-carbon steel, with a carbon content of 0.14%-0.22% and a yield strength of 235 MPa, offers excellent ductility and toughness, superior weldability, and a low price. It is suitable for general load-bearing structures (such as building rebar and general machinery parts). 45 steel: Medium carbon steel, containing 0.42%-0.50% carbon. High strength (tensile strength ≥600 MPa). Quenching and tempering enhances hardness and wear resistance. Suitable for mechanical parts subject to medium loads (such as shafts and gear blanks).

Alloy structural steel:

40Cr steel: Chromium alloy structural steel, containing 0.8%-1.1% chromium. Heat treatment significantly enhances strength, toughness, and hardenability. Suitable for high-strength transmission parts (such as automotive axles and machine tool spindles).

20CrMnTi steel: Case-hardened steel containing chromium, manganese, and titanium. After carburizing, it achieves a high surface hardness (HRC 58-62) and excellent core toughness. Suitable for parts subject to impact and wear (such as gears and bearing sleeves).

Special Purpose Steels:

Stainless Steel (e.g., 304, 316): Contains elements such as chromium and nickel, offering excellent corrosion resistance and suitable for use in humid, acidic, and alkaline environments (e.g., chemical equipment and food processing machinery parts).

Tool Steel (e.g., T8, T10): High-carbon steel with high hardness and strong wear resistance, suitable for making simple tools (e.g., chisels and wrenches).

III. Dimensions

Round steel dimensions are centered around diameter. Common specifications range from small-diameter precision parts to large structural components, as follows:

Diameter Range:

Hot-rolled round steel: Diameters range from 5mm to 300mm (common specifications include 10mm, 12mm, 16mm, 20mm, 25mm, 30mm, and 50mm, with increments of 5mm).

Cold-drawn round steel: Diameters range from 3mm to 100mm, offering higher dimensional accuracy (tolerances can be controlled within ±0.02mm), suitable for precision parts. Forged round steel: Diameters can be customized to over 500mm, used for load-bearing components of large machinery (such as generator shafts).

Length Specifications:

Hot-rolled round steel is typically available in fixed lengths (6m, 9m, and 12m) and can be cut to order. Cold-drawn round steel offers flexible lengths (1m-6m), suitable for small-batch customization.

Precision Levels:

Normal Precision: For general structures, diameter tolerance ±0.5mm;

High Precision: For machining, diameter tolerance ±0.1mm-±0.3mm.

IV. Applications

Low-carbon steel round steel (such as Q235) is used as rebar for reinforcement in concrete structures (such as beams, columns, and floor slabs). Ties or welding create a skeleton to enhance the tensile strength of concrete.

Large-diameter round steel (≥50mm) is used for embedded components and support columns in buildings to withstand vertical loads.

Mechanical Manufacturing:

Medium-carbon steel and alloy steel round bars (such as 45# steel and 40Cr) are processed through cutting, forging, and heat treatment into shafts (motor shafts, machine tool spindles), gears, bolts, pins, and other transmission or connecting parts.

Cold-drawn round bars (high-precision) are used for guide rods and piston rods in precision instruments to ensure smooth movement.

Metal Processing:

Small-diameter round bars (≤10mm) are used as raw materials to be drawn into steel wire, or bent and welded into metal mesh, guardrails, shelves, and more.