Product Overview
Spring steel round bars are alloy and carbon steel grades engineered with high yield strength, elastic limit, and resistance to permanent deformation under cyclic mechanical loads. Manufactured through electric arc furnace (EAF) smelting and ladle refining (LF+VD) to minimize non-metallic inclusions, these bars provide uniform fatigue performance for high-stress industrial components.
Technical Specifications
|
Parameter |
Specification Details |
|
Common Grades |
AISI 6150, AISI 5160, SUP9, SUP10, EN42J, 65Mn, 55SiCr |
|
Execution Standards |
ASTM A29, EN 10089, JIS G4801, GB/T 1222 |
|
Size Range |
Diameter 10mm to 300mm (Hot Rolled); Diameter 10mm to 80mm (Cold Drawn / Peeled) |
|
Supply Condition |
Hot Rolled (HR), Spheroidize Annealed (A), Quenched & Tempered (Q&T), Peeled / Turned & Polished (P+T) |
|
Dimensional Tolerance |
h11, h9, or customized per ASTM A29 / EN 10260 |
|
Surface Quality |
Black, Peeled, Turned, Ground; Free from visible seams, laps, and rolling cracks (100% MPI/Eddy Current tested upon request) |
Product Advantages
High Elastic Limit:
Withstands extreme bending and torsional stress without suffering permanent plastic deformation.
Controlled Hardenability:
Uniform chemistry across the bar cross-section ensures predictable hardening response during component heat treatment.
Low Decarburization Limits:
Controlled rolling parameters minimize surface carbon loss, preserving fatigue endurance in final springs.
Internal Soundness:
Assessed via ultrasonic testing (UT) per SEP 1921 Class C/c to guarantee freedom from internal voids and porosity.
Applications
Automotive Suspension: Leaf springs, coil springs, torsion bars, and stabilizer bars.
Industrial Drive Systems: Heavy-duty clutch plates, retaining rings, and mechanical springs.
Tools & Hardware: Agricultural tines, industrial knives, hand saws, and cold chisels.
Customization & Processing
Centerless grinding and rough turning to achieve tight diameter tolerances for automated CNC machining lines.
In-house spheroidize annealing to lower initial hardness levels, optimizing machinability prior to final forming.
Custom length cutting, chamfering, and physical stamping of melt heat numbers onto bar ends.
Quality Control & Inspection
Chemical Verification: Direct-reading spectrometer testing conducted per melt heat to confirm carbon, chromium, silicon, and manganese percentages.
Mechanical Testing: Tensile strength, yield strength, elongation percentage, and Brinell hardness (HBW) verification.
Metallographic Analysis: Grain size determination (ASTM E112) and micro-inclusion rating (ASTM E45).
Surface Integrity: Automated eddy current testing or magnetic particle inspection (MPI) for surface defect detection.
Compliance Documentation: Mill Test Certificates (MTC) issued in strict accordance with EN 10204 3.1.
Packaging & Shipping
Bundling: Mechanically strapped with high-strength steel bands, segregated and bundled strictly by melt heat number to ensure material traceability.
Surface Protection: Anti-rust corrosion inhibitor applied to bare steel surfaces; waterproof heavy-duty woven wrapping provided for containerized ocean freight.
Identification: Weatherproof metal tally tags displaying steel grade, heat number, dimensions, net/gross weight, and mill identification.
FAQ
Q: What is the primary difference between AISI 5160 and AISI 6150 spring steel round bars?
A: AISI 5160 is a chromium alloy steel providing high toughness and shock resistance, utilized extensively in heavy-duty leaf springs. AISI 6150 incorporates a vanadium addition, which refines the austenitic grain structure, improves resistance to fatigue failure, and enhances wear characteristics under sustained loads.
Q: Are the bars supplied in an annealed condition to facilitate machining?
A: Yes. Stock bars can be delivered in the spheroidize annealed condition, lowering the hardness matrix to support cold sawing, turning, and forming operations prior to final quenching and tempering.
Q: What is the maximum allowable surface decarburization depth?
A: Decarburization is maintained within strict compliance limits per EN 10089 or ASTM specifications, typically capped at a maximum of 1% to 1.5% of the bar diameter depending on the grade. Completely decarb-free peeled and turned options are available upon order.
Q: Can independent third-party inspection reports be arranged?
A: Yes. Witnessed testing and third-party verification by organizations such as SGS, Bureau Veritas, or TUV can be scheduled prior to cargo release based on project terms.
Q: What is the Minimum Order Quantity (MOQ) for non-standard grades or custom sizes?
A: For non-stock chemical compositions or custom diameter rollings, the standard mill production MOQ is 5 metric tons per heat/size.
Q: How is full material traceability maintained from melt shop to delivery?
A: Every individual bar or bundle is physically stamped or tagged with a unique melt heat number. This identifier links directly back to the furnace melt logs, spectrometer analysis sheets, and mechanical test results recorded in the MTC.
Request a Quote
Submit your required Steel Grade, Diameter / Tolerance, Supply Condition, and Total Tonnage to obtain an immediate technical and commercial proposal.
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