High Tensile SWRH72A Galvanized Wire Coil 3.0mm 1570MPa Spring Grade Wire

High tensile galvanized wire is bought on a different logic from fencing wire. A 1570 MPa coil in SWRH72A carries roughly three times the load of a soft 400 MPa binding wire at the same 3.0 mm diameter, which means fewer strands for the same working load in prestressing, spring forming, cable armouring and tensioned trellis systems. Getting that strength consistently is a metallurgical problem: carbon content, patenting temperature, drawing reduction sequence and the thermal history of the zinc bath all move the number, and a supplier who quotes 1570 MPa must be able to show it on every coil, not only on the first trial batch.

We produce this coil from 72A high carbon rod, patent the wire to refine pearlite, draw it in multiple passes with controlled reduction per pass, then hot dip galvanize at a temperature and dwell time that does not soften the core. The result is a coil that holds its tensile after galvanizing, which is the point where many cheaper coils quietly lose 100 - 150 MPa because the zinc bath annealed the wire.

• Verified strength after galvanizing: 1570 - 1770 MPa measured on the finished galvanized wire, not on the black wire before coating.
• Patented pearlite structure: fine, uniform pearlite from controlled patenting gives both high tensile and enough torsion ductility to survive forming.
• Torsion test record: minimum 20 turns without fracture, reported per lot, which is the practical indicator of drawing quality and internal defects.
• Adhesion under stress: the zinc layer withstands winding and forming without cracking, because coating thickness and bath chemistry are matched to the wire grade.
• Heavy coil options: 200 - 800 kg coils reduce changeover downtime on continuous spring and strand lines.
• Batch level traceability: every coil carries a heat number linked to tensile, torsion and coating test data.

Spring makers use it for tension springs and formed wire parts where the zinc provides corrosion protection without a post coating step. Prestressed concrete producers use galvanized high tensile wire where the strand will be exposed at slab edges or in marine structures. Cable and strand manufacturers use it as armouring and messenger wire. Trellis, vine training and greenhouse support systems use it because a 3.0 mm high tensile wire tensions further than a soft wire of the same diameter with less sag after two seasons. If your forming process includes tight radii, tell us the bend diameter before order: above roughly 1570 MPa the wire needs a forming radius about three times the wire diameter to avoid surface cracking, and we will recommend a slightly softer grade instead of letting you find out on the machine.

Testing covers tensile strength, yield, elongation, torsion, reverse bend, coating mass and coating adhesion, with sampling at both ends and the middle of each coil. Zinc bath chemistry is logged per shift and the coating mass is verified by the stripping method. We reject coils with laps, seams, slivers or any uncoated point, and we keep the rejected sample until the shipment closes so disputes can be settled on evidence. Mill test certificates are issued to ASTM A641 or the equivalent EN 10244-2 class, and third party inspection can be arranged before loading.

Heavy coils are strapped to wooden pallets or bundled horizontally with steel band, wrapped in VCI paper and plastic film, and labelled with coil number, net weight, heat number and tensile value. A 20 foot container takes about 25 tons; 500 - 800 kg coils load more efficiently than small coils. Lead time is 20 days after deposit. We ship with mill certificate, packing list, coating report and certificate of origin so the goods clear customs without a second document round.