Medium and high carbon steels have large concentrations of a secondary phase in steel known as iron carbide (Fe3C). Iron carbide precipitates out in dark lamellar plates like in FIG 1. These plates increase strength and reduce formability by acting as barriers to dislocation movement during stamping, rolling, pressing, and bending- which can lead to fracturing.
FIG 1- 100% Pearlite
To increase formability, a specialized heat treatment in Steel Warehouse’s bell-shaped batch annealing furnaces slowly transforms the plate-like carbide structure into spherical particles.
FIG 2- 50% Pearlite/50% Spheroidized Carbide
With time and temperature, the process reduces boundary area and creates more space for microstructural movement during forming operations. FIG 2 and FIG 3 exhibit the evolution of pearlite (iron carbide and ferrite) to spheroidized carbide.
FIG 3- 100% Spheroidized
Customers request this heat treatment on medium and/or high carbon steels for tough forming operations where fracturing and equipment wear are of the highest concern.
