Normalização do Aço - Telecurso 2000

Understanding Steel Preparation Processes

The Importance of Thermal Processes in Steel Preparation

• The preparation of steel for machining involves various thermal processes, not just subcritical annealing. Normalization at temperatures above the critical zone is crucial.

• Higher temperatures accelerate the growth of austenite grains; prolonged exposure to slightly elevated temperatures can exacerbate this effect.

Transformation During Cooling

• Upon cooling, austenite transforms into different phases: ferrite, cementite, and pearlite. The size of these grains is influenced by the dimensions of the original austenite grains.

• Coarse grain structures lead to brittleness in materials and alter their mechanical properties, making them more susceptible to crack propagation.

Normalization Process Explained

• To mitigate issues related to coarse grain structures, normalization is employed. This process involves heating steel above the critical zone (between 750°C and 950°C).

• After approximately three hours in the furnace, the steel transforms entirely into austenite before being slowly cooled on a bench, resulting in an improved final structure.