Skip to content
METAFERRUMSteeltech Pvt. Ltd.

Stage 02 · Structure

A long, controlled heat-and-cool cycle that re-arranges the steel from the inside.

Overview

Annealing is the stage you cannot see in the finished wire — and the one that decides how it behaves in your press. In an electrical bell furnace, a charge of coils is heated, held and slowly cooled. The cycle softens the steel, relieves stresses from rolling and drawing, and for alloy and higher-carbon grades changes the shape of the carbides inside.

FurnaceElectrical bell type
Heating≈ 8 hours
Cooling≈ 7 hours
Temperature700 – 980 °C, by grade

The cycle

A bell furnace cycle, stage by stage.

Phase

Charge

Charge temperature

30 °C

Schematic. Temperatures shown are illustrative; the actual cycle is set per grade within 700 – 980 °C.

By grade

Choose a grade family to see its typical anneal type and temperature zone.

020040060080010000 h4 h8 h12 h16 hPLANT RANGE 700 – 980 °CHEAT ≈ 8 hSOAKCOOL ≈ 7 h

Alloy / case hardening

Spheroidise anneal

SAE 4140 · 16MnCr5 · Boron

Typical zone

720 – 780 °C

Indicative, from general metallurgy references. The actual cycle is set per grade and charge.

Structure changing

Structure

Lamellar pearlite

As rolled, carbon sits in thin plates of iron carbide. Plates act like tiny blades — under cold heading, cracks start at their edges.

Illustration of the mechanism, not a micrograph of our material.

Why it matters

01

Softer steel forms better

Cold heading squeezes the wire hard. Annealed wire needs less force, cracks less and wears the tooling less.

02

Spheroidising

In medium-carbon and alloy grades, pearlite’s plate-like carbides become small, round particles. Round carbides let the steel flow instead of crack.

03

Uniform through the coil

A bell furnace heats the whole charge evenly and cools it slowly, so the inside and outside turns of a coil behave the same.

Step by step

  1. 01

    Charge

    Coils are stacked on the furnace base and the inner cover is placed over them.

  2. 02

    Bell down

    The heating bell is lowered over the stack by crane.

  3. 03

    Heat

    The charge is brought up to temperature — about 8 hours, to 700–980 °C depending on grade.

  4. 04

    Soak

    Held at temperature so every turn of every coil reaches the same structure.

  5. 05

    Cool

    The heating bell is lifted and the charge cools under cover — about 7 hours.

  6. 06

    Discharge

    Coils are unloaded, checked and sent to the drawing line.

Enquiries

We come back with availability and a quotation — usually the same working day.

Request a quote+91 94229 27509