Hot Rolled Steel Round Bar for General Machining Blanks and Structural Applications — Factory Direct Supply with Custom Cutting

For the last twelve years, Tianjin Youcheng Technology Co., Ltd, a professional steel stockist, distributor and exporter, has supplied hot rolled steel round bar, bright round bar, peeled round bar and polished round steel bar to customers across Kuwait, Russia, Brazil, Belgium, Kenya and many other regions.

Available grades include Q235B, Q355B, 45#, S235JR, S355JR, and A36. Diameter ranges from Φ10mm to 250mm. Surface options include black hot-rolled mill scale, peeled, and polished finishes. Mill Test Certificates (MTC) are provided for every shipment.

What Is This Product?

Our hot rolled steel round bar, also known as black round bar, is a standard carbon steel solid bar formed by hot rolling process. It is widely used for structural fabrication, forging work, and as raw blanks for general machining. It comes with natural mill scale surface and standard rolling tolerances, ideal for projects that do not require tight precision directly from stock.

Beyond hot rolled black bar, we also provide cold finished, centerless ground and peeled round bar. These finishing processes remove dimensional irregularities, decarburised layers and surface scale from hot rolled base material. Depending on the finishing method, the surface roughness can reach Ra values between 0.2 and 0.8 μm. Strict dimensional tolerance control reduces extra preparation work before CNC machining or assembly.

Our precision-grade bright, peeled and polished round bars are perfect for precision shafts, fastener blanks and CNC-machined components. Consistent diameter and scale-free surface help reduce collet interference and extend cutting tool service life.

Product Specifications

Key Technical Properties

Our standard hot rolled steel round bar (black round bar) is supplied to standard hot rolling tolerances, with mill scale surface, designed for structural fabrication, forging and general machining blanks.

For projects requiring higher dimensional accuracy, we provide secondary peeling and centerless grinding services on hot rolled base stock. Finished peeled bar meets ISO h8–h11 tolerances. Extra centerless grinding can reach h7 or h6 for automotive and hydraulic parts needing tight fits.

Straightness of peeled and ground bars is ≤0.5 mm per metre, ideal for rotating parts and close-clearance assemblies. Peeling removes decarburised surface layers for better dimensional consistency and machinability versus raw as-hot-rolled bar.

Hot-dip galvanized (HDG) finish is available as an anti-corrosion option for outdoor structural use. Zinc coating alters outer dimension, so HDG is not suitable for precision tolerance applications.

For grades such as 45# medium carbon steel, surface finishing will not change the base material chemistry. Core mechanical performance depends on the steel grade itself, not post-processing.

Surface Finish Options Explained

You have three finish and coating conditions available for your galvanized steel round bar production:

• Black hot-rolled finish — supplied as the as-rolled base bar for structural fabrication where close tolerances and surface quality are not critical; can be used directly where a protective coating is applied downstream.
• Peeled surface — removes the outer decarburized layer, improving dimensional uniformity and machinability and providing a clean, consistent base for a uniform zinc coating.
• Galvanized (zinc-coated) surface — hot-dip or electro-galvanized for superior corrosion resistance, delivering a bright, uniform zinc layer suited to outdoor, marine and long-service applications. Coating thickness is controlled to your specified coating mass and standard, making galvanized round bar a functional choice for components exposed to moisture, weather or corrosive environments.

For reference, galvanized steel round bar keeps tight dimensional accuracy on its peeled or drawn base, so the zinc layer protects the part while machinability and size tolerance remain dependable for fabrication and contact applications.

Applications

Polished Round Steel Bar is utilised in a wide variety of industrial applications where the surface quality and dimensional precision are important for further processing or component performance.

Precision Shafting: Precision shafting is used for electric motors, hydraulic cylinders and pump assemblies to provide a uniform surface finish that ensures reliable contact with seals and decreases wear at the contact point.

CNC MACHINING: A scale-free bar of uniform diameter avoids collet interference during automated machining cycles and prolongs the life of carbide cutting tools.

Mechanical Part Blanks Suitable for shaft raw material, bolt forging stock, fastener blanks. Grades like as 45# offer a good balance of machinability and core strength for mechanical components.

Structural and Architectural Applications Polished bars give a satisfactory surface finish with less surface preparation in visible or corrosion controlled situations.

Quality Control Process for Hot Rolled Steel Round Bar

Each batch undergoes a standardized inspection procedure before shipment: Dimensional Verification: Calibrated micrometers and calipers check diameter tolerances along the full length of the hot rolled steel round bar.

• Surface Inspection: Eddy current testing identifies surface cracks, laps and seams. Visual examination confirms the surface condition of hot rolled round steel, complying with standard hot rolled finish requirements.
• Straightness Check: Total Indicator Reading measured via dial indicators on a leveling bed, tolerance ≤0.5mm/m for hot rolled steel round bar.
• Mechanical and Chemical Testing: Tensile test, hardness test and spectroscopic chemical analysis confirm the material satisfies specified steel grade requirements.

All test data is documented in the Mill Test Certificate to EN 10204 3.1. Every shipment of hot rolled steel round bar is supplied with valid MTC and Certificate of Compliance.

Customization and Supply Capability

Standard lengths are available and fixed length cutting per customer specifications. We supply shaft blanks and pin parts with turning and machining. Special dimensions, surface conditions or material grades not beyond the regular OEM and ODM support range. Products can be supplied to GB,ASTM or EN standards as required by the project.

Currently we have about 200 tonnes of Polished Round Steel Bar in stock. Lead time is 7 to 10 days for production. Packing: Steel strapped bundles with export packing for seaworthy. Finished surface protected with anti rust oil and VCI wrapping throughout maritime freight.

Packaging & Delivery

Global Clients Visit Our Steel Supplier Factory

FAQ

Q: What is the product commonly used for ?

A: It is widely utilised for precision shaft blanks, CNC machining feed stock, bolt forging stock and structural component fabrication in industries where dimensional accuracy and surface condition affect the part performance.

Q: What grades do you teach?

A: Structural purposes are served by Q235B and Q355B. 45# medium carbon steel is used for machined mechanical parts, where a balance of strength and machinability is essential. S235JR, S355JR and A36 are available to customers working to EN or ASTM standards.

Q: Are you providing set length cutting?

A: Yes. We can also provide custom set length cuts on all diameters.

Q: What is the difference between polished steel and bright steel?

A: A brilliant bar is on the order of up to Ra 1.6–3.2μm. A fine finish on the bar is aimed at Ra 0.8μm or better, suited for precision fittings and surfaces where dimensional accuracy is a functional requirement.

Q: Does polishing method alter core mechanical properties?

A: No, polishing is a surface finishing method The fundamental mechanical qualities are functions of the grade of base material and any preceding heat treatment.

Q: How is marine freight protected against corrosion?

A: The bar surface is coated with anti-rust oil, and it is packed with VCI plastic wrapping or wooden box packing to avoid oxidation in transit.

Contact Us

Do you have more questions about Polished Round Steel Bar? Send your inquiry or request a quote by emailing sales@youchengkjsteel.com.