Product Overview
Our alloy steel hexagonal bars are produced via hot rolling or cold drawing, followed by controlled heat treatment to meet demanding mechanical requirements for heavy-duty components. Primarily utilized in CNC machining and automatic lathe production, these bars provide high tensile strength, wear resistance, and uniform machinability. Every production batch is backed by certified mill test reports (MTR) confirming chemical composition and mechanical properties per ASTM, AISI, or EN/DIN standards.
Technical Specifications
|
Parameter |
Specification Details |
|
Available Grades & Equivalents |
AISI 4140 (EN 1.7225 / 42CrMo4), AISI 4340 (EN 1.6580 / 34CrNiMo6), AISI 8620 (EN 1.6523 / 20NiCrMo2), AISI 5140 (EN 1.7035 / 41Cr4) |
|
Size Range (Across Flats) |
10 mm to 100 mm (Cold Drawn); 30 mm to 200 mm (Hot Rolled) |
|
Length Options |
3m, 5.8m, 6m, or custom cut-to-length per project requirements |
|
Dimensional Tolerance |
Cold Drawn: h11 / h9; Hot Rolled: ASTM A29 / DIN EN 10060 |
|
Delivery Condition |
Annealed, Normalized, or Quenched and Tempered (Q&T) |
|
Surface Finish |
Cold drawn, peeled, centerless ground, or black hot-rolled |
|
Inspection Standards |
ASTM A29, EN 10204 3.1 Mill Test Certificate |
Product Advantages
Uniform Hardenability:
Controlled alloy element addition (Cr, Mo, Ni) ensures consistent hardening depth across heavy cross-sections during heat treatment.
Tight Dimensional Control:
Cold drawn variants maintain strict tolerance bands (+/- 0.05 mm to +/- 0.10 mm), reducing setup time in automatic CNC Swiss lathes.
Optimized Microstructure:
Electric arc furnace (EAF) melting followed by ladle refining (LF) and vacuum degassing (VD) minimizes non-metallic inclusions and center porosity.
Straightness Precision:
Multi-roll straightening processes limit camber to under 1.5 mm per 1000 mm, preventing vibration and spindle wear during high-speed machining.
Applications
Fasteners & Studs: High-tensile bolts, anchor studs, and socket head cap screws exposed to heavy cyclic loads.
Hydraulic Systems: Valve bodies, fittings, and hydraulic cylinder components requiring pressure containment and wear resistance.
Automotive & Powertrain: Transmission shafts, spline shafts, gears, and steering components.
Industrial Machinery: Heavy-duty pins, shafts, couplings, and structural brackets.
Customization & Processing
Manufacturing and processing capabilities align with exact production line requirements:
In-house quenching, tempering, and annealing furnaces adjust hardness and tensile strength to specific project blueprints (e.g., HB 280-320 or specific tensile tiers).
High-speed band saws execute precise cut-to-length services with square ends, eliminating in-house prep work.
Centerless grinding removes surface decarburization layers and achieves Ra surface roughness values down to 0.8 um.
Quality Control & Inspection
Production adheres to strict metallurgical and dimensional verification protocols prior to release:
Chemical Spectrometry: Direct-reading optical emission spectrometers (OES) verify elemental composition (C, Mn, Cr, Mo, Ni) for every heat.
Mechanical Testing: Tensile testing machines measure yield strength, elongation, and reduction of area; Brinell and Rockwell testers verify hardness distribution.
Non-Destructive Testing (NDT): Ultrasonic testing (UT) per ASTM A388 detects internal cracks, voids, and inclusion clusters in bars over 50 mm.
Traceability: Heat numbers are hard-stamped and color-coded on bar ends, linking directly to the EN 10204 3.1 MTR supplied with the shipment.
Packaging & Shipping
Bundling: Securely bundled with heavy-duty steel strapping at regular intervals to prevent bending during transit.
Surface Protection: Anti-rust oil coating applied to bare steel surfaces; optional waterproof plastic wrapping or woven textile outer layers available.
End Protection: Plastic caps fitted on bar ends for cold-drawn, precision-ground finishes to prevent impact damage.
Transport: Loaded into 20ft/40ft containers with wooden dunnage or secured in break-bulk vessels for large mill quantities.
FAQ
Q: What is the minimum order quantity (MOQ) for non-standard alloy grades or sizes?
A: Standard inventory grades (such as AISI 4140 and 8620) have an MOQ of 1 metric ton per size. Custom rolling or special heat-treatment batches typically require an MOQ of 3 to 5 metric tons depending on the steel mill scheduling.
Q: Do you provide EN 10204 3.1 Mill Test Reports with every shipment?
A: Yes. Every shipment includes a traceable 3.1 test certificate detailing exact ladle analysis, heat treatment parameters, grain size, and mechanical test results.
Q: What is the difference between hot-rolled and cold-drawn alloy steel hex bars?
A: Hot-rolled bars have a scaled surface, wider dimensional tolerances, and are supplied in larger diameters. Cold-drawn bars offer tighter dimensional tolerances, higher yield strength, a smooth surface finish, and better straightness, making them ideal for direct CNC machining.
Q: Can you supply alloy steel hex bars in a pre-hardened condition?
A: Yes. Bars can be supplied in a quenched and tempered condition with specified hardness ranges (typically 28-32 HRC or 32-36 HRC) to eliminate the need for post-machining heat treatment on finished components.
Q: How do you prevent rust during ocean freight?
A: Bars are coated with a solvent-based rust preventive oil. For extended sea voyages or high-humidity destinations, VCI (Volatile Corrosion Inhibitor) bags and desiccants can be added inside container linings.
Q: What are your standard delivery lead times?
A: Ex-stock standard sizes ship within 7 to 10 days. Mill production orders for custom sizes or specific heat-treatment requirements typically require 35 to 45 days.
Request a Quote
Submit your complete technical specifications to receive a formal quotation with mill lead times and freight estimates.
Please specify in your inquiry:
Steel Grade: (E.g., AISI 4140 / EN 1.7225)
Size: Across-flats dimension (mm or inches)
Length: Cut length or standard length (3m / 5.8m / 6m)
Condition & Finish: (E.g., Cold Drawn, Quenched & Tempered, Centerless Ground)
Quantity: Metric tons or total pieces
Destination Port: For accurate freight calculation
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