Shock-absorbent Sturdy Cold-drawn Round Bar 65Mn Spring Steel for Bicycle Brake Springs

● General Carbon Steel: Q195, Q215, Q235, Q355. These grades are ideal for low-to-medium stress applications due to their good weldability and cost-effectiveness. Q235, for instance, is widely used in bicycle frames and auxiliary components, while Q355 offers higher tensile strength (≥345MPa) for heavier-duty structural parts.​

● High-Quality Carbon Steel: 20#, 35#, 45#. Characterized by precise carbon content control, these grades balance machinability and strength. 45# steel (carbon content 0.42%-0.50%) is suitable for parts requiring moderate hardness (HRC 19-25 after annealing) and wear resistance, such as bicycle pedal shafts, while 20# steel (low carbon, 0.17%-0.24%) excels in cold forming and welding for lightweight components.​

● Alloy Structural Steel: 20Cr, 40Cr, 20CrMo, 35CrMo, 42CrMo. These grades are reinforced with chromium, molybdenum, or other alloys to enhance hardenability and fatigue resistance. 40Cr steel (chromium content 0.80%-1.10%) is a top choice for high-torque parts like bicycle crankshafts, while 42CrMo (with molybdenum addition) delivers exceptional high-temperature strength, making it suitable for industrial machinery springs and automotive components.​

● Free-Cutting Steel: 1215, 12L14, 1144. Designed for easy machining, these grades contain lead, sulfur, or phosphorus to reduce cutting resistance. 12L14 steel, for example, can be quickly turned or drilled into small precision parts like bicycle brake adjusters, minimizing production time and costs.​

● Specialized Spring Steel: Gr15, 60Si2Mn, 65Mn. These grades are engineered for superior elasticity and fatigue life. Gr15 (high-carbon chromium bearing steel) offers excellent wear resistance for high-speed rotating parts, while 60Si2Mn (silicon-manganese spring steel) provides higher yield strength (≥1275MPa) than 65Mn, making it suitable for heavy-duty bicycle suspension springs. 65Mn, as the flagship grade for brake springs, strikes the perfect balance between elasticity, cost, and processability—its manganese content (0.70%-1.00%) enhances hardenability, while controlled carbon (0.62%-0.70%) ensures it retains shape after thousands of compression cycles.​

● Diameter Range: 3mm - 120mm. This broad spectrum covers almost all common use cases for round bars. For bicycle brake springs, the most popular diameters are 3mm - 8mm—thin enough to maintain flexibility for shock absorption, yet sturdy enough to withstand braking stress. Larger diameters (20mm - 120mm) cater to industrial needs, such as heavy machinery springs (30mm - 50mm) or structural supports (80mm - 120mm). Each diameter is manufactured with tight dimensional tolerance (ISO h9 standard: for a 10mm diameter bar, the tolerance is ±0.036mm), ensuring precise fitting with other components.​

● Length Customization: Available on demand. Whether you need short segments (e.g., 1m bars for small-batch bicycle spring production) or long lengths (up to 12 meters for continuous manufacturing lines), we can cut the round bars to your exact specifications. This eliminates material waste—you only order what you need—and simplifies downstream processing, as pre-cut bars require no additional trimming.​

● Surface Finish: All cold-drawn bars feature a smooth surface (Ra ≤ 0.8μm) thanks to the cold-drawing process, which eliminates the rough texture of hot-rolled steel. For enhanced corrosion resistance, optional surface treatments are available: galvanization (zinc coating thickness ≥8μm), electrophoresis (paint film thickness 15μm - 25μm), or oil coating (anti-rust oil for temporary storage). These treatments extend the service life of the bars, especially for outdoor or humid environments (e.g., bicycle components exposed to rain).​

● Tensile Strength: 980MPa - 1180MPa​

● Yield Strength: ≥785MPa​

● Elongation After Fracture: ≥8%​

● Hardness: HRC 35 - 45​

● MOQ: 2 Tons. This threshold balances the needs of small bicycle workshops (which may require 2 - 5 tons for quarterly production) and large suppliers (ordering 50+ tons for annual stock). For high-value alloy grades (e.g., 42CrMo), we can negotiate MOQ on a case-by-case basis to accommodate specialized projects.​

● Delivery Time: 7 - 15 working days for standard materials (Q235, 45#, 65Mn) and 15 - 25 working days for customized grades or large diameters. We work with leading logistics providers (Maersk, COSCO) to offer door-to-door delivery, with cargo insurance covering loss or damage during transit.​

● Payment Terms: We accept T/T (30% advance, 70% against B/L), L/C at sight, or Alibaba Trade Assurance for secure transactions—giving global clients peace of mind, especially for large orders.​

● Bicycle Industry: Beyond brake springs, 40Cr steel for crankshafts, 12L14 for adjusters, and Q235 for frames—providing a one-stop material solution for bicycle manufacturers.​

● Automotive Industry: 20CrMo for engine valves, 35CrMo for suspension springs, and 42CrMo for drive shafts.​

● Industrial Machinery: 60Si2Mn for heavy-duty springs, Gr15 for bearing rings, and Q355 for structural supports.​

● Electrical Equipment: 20# steel for transformer cores, 1144 for terminal blocks, and free-cutting grades for small precision parts.​

● ASTM (American Society for Testing and Materials): A227 (spring steel), A36 (carbon steel), A519 (mechanical tubing steel).​

● DIN (Deutsches Institut für Normung): 17221 (spring steel), 17100 (carbon structural steel), 1654 (free-cutting steel).​

● GB/T (Chinese National Standard): 1222 (spring steel), 700 (carbon structural steel), 3077 (alloy structural steel).​

● ISO (International Organization for Standardization): ISO 683-1 (carbon steels for springs), ISO 898-1 (mechanical properties of fasteners).​

•Cold-drawn round steel

material