Overview
Spheroidize annealing converts the lamellar pearlite in as-rolled or drawn wire into rounded carbide particles in a ferrite matrix. The result is the lowest hardness and highest ductility the steel can reach — which is what a header needs to fill a deep socket, form a flange or upset a large head without cracking.
Indisteel anneals in PRECONS bell-type furnaces under a nitrogen atmosphere with vacuum purge, with every cycle SCADA-controlled. Annealing capacity is 700 MT per month. After discharge, every coil is tested for hardness, and the spheroidization percentage and decarburization depth are checked under the microscope before the coil is tagged and released.
Applications
- Feed wire for socket-head, flange and heavy cold-forged fasteners
- Multi-station cold forging of automotive parts
- Input for phosphated and drawn (SAP + PPD) wire
- Annealed coils for customers who phosphate and draw in-house
Frequently Asked
What is the difference between annealed and spheroidized annealed wire?
Ordinary (sub-critical or process) annealing relieves the work hardening from drawing. Spheroidize annealing is a longer, controlled cycle that also changes the carbide shape from plates to spheres, giving the softest possible wire. For heavy cold forming and medium-carbon or alloy grades, spheroidized wire is the standard.
How do you control decarburization during annealing?
The furnaces run under a nitrogen atmosphere after a vacuum purge, and the charge is inspected for decarburization depth by microscope after every cycle. Results are recorded coil-wise in our quality system.