STEEL NORMALIZING TREATMENT
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The Normalizing heat treatment process is applied to ferrous materials. The objective of the normalizing heat treatment is to enhance the mechanical properties of the material by refining the microstructure.
The ferrous metal is heated to the austenite phase above the transformation range. It is then subsequently cooled in still air at room temperature. The normalizing heat treatment balances the structural irregularities and makes the material soft for further working.
The cold working operations such as forging, bending, hammering hardens the materials and make it less ductile. Same goes for the heat-affected area near the welded portion.
The normalizing heat treatment can regain the ductility and softness of this material. This treatment is also used as before any subsequent surface hardening to improve response to the desired hardening.
The Normalizing Heat Treatment Process
The metal is heated in a normalizing furnace to begin the normalizing heat-treatment process.
The normalizing heat treatment temperature of the furnace is kept between 750-980 °C (1320-1796 °F). This is depending upon the carbon content in the material.
The material is kept at the austenite temperature for 1-2 hours until all the ferrite converts into austenite. The material is cooled to room temperature in still air or Nitrogen. Material can also be run in the vacuum furnace at less than 1 bar pressure.
The solubility of carbon in iron is higher in the austenite phase. The normalizing treatment produces a uniform carbide size. This aids in further heat treatment operations and results in a more consistent final product.
During the normalizing heat treatment process, the metal is heated from a temperature between 1320 to 1796 degrees Fahrenheit. The metal is then kept in this condition for some time and is then cooled to ambient room temperature in still air.
Carbon Steel Normalizing
Carbon steel contains carbon in the range of 0.12 to 2%. As the percentage of carbon content increases, the steel becomes harder, tougher, and less ductile. Low carbon steels usually do not need normalizing. However, they can be normalized on the requirement.
The Normalizing Temperature For Carbon Steel
Carbon steel products are heated to the steel normalizing temperature of 55 °C (131 °F) above the austenitic temperature. Ac3, (Lies between 750-980 °C / 1320-1796 °F) is also known as holding temperature.
The period of holding temperature is one hour per 25 mm (0.984 in) thickness. The process ensures that all the steel transforms into austenite. Steel is then cooled down to ambient temperature in still air.
What Is The Purpose Of The Normalizing Heat Treatment For Steel
This process produces a fine pearlite structure which is more uniform. Pearlite is a layered structure of two phases i.e. cementite (iron carbide) and α-ferrite. This process is different from annealing, this is because in the annealing process the heated metal is cooled slowly at a specified rate inside the furnace.
The normalizing heat treatment helps remove impurities and improves toughness and ductility. Normalized steel has greater strength and hardness than annealed steel, and the process is more economical due to cooling directly with air.
Steel Annealing Services
There are a variety of industrial processes that require or are enhanced by using annealed steel or metals. Annealing can restore durability and even strengthen metal that has been superheated through high-intensity machining processes.
Whether it's a hot chamber die casting manufacturing process or a specific die cast part, full annealing/heat treating is a great cost-effective way to get the most out of your parts and materials.
