What is Protective Atmosphere Normalizing in Heat Treatment?

12 October 2020

Metals typically undergo various heat treatment processes to alter their overall properties and characteristics. Generally, heat treatment is a group of industrial, thermal, or metalworking processes that are utilised to change the physical or chemical properties of a material. Aside from metals, other materials like glass can also maximise the benefits of different heat treatment processes.

There are a lot of processes that are under heat treatment. Some of these processes include annealing, case hardening, carburising, precipitation, strengthening, tempering, and quenching. A wide variety of properties, such as ductility and toughness, that is found on a specific material can be easily modified by one or more of the mentioned heat treatment processes.

Heat Treatment Processes for Metals

Metals such as steels and other alloys are hugely utilised in the manufacturing industry. Their versatility, durability, and longevity have encouraged a lot of manufacturers to maximise them and fabricate them into different equipment, appliances, devices, and other products.

The fabrication of metals has been carried out through different heat treatment processes. One of the most common heat treatment processes for metals is annealing. This heat treatment process heats and slowly cools metal to eradicate stress and makes it softer. Annealing likewise modifies the structure and ductility of the metal. Precipitation hardening, on the other hand, subjects the metal at elevated temperatures to increase its yield or even high-temperature strength.

Carburising is another heat treatment process that adds carbon to the surface of the metal by heating it below the melting point and exposing it with carbon-rich elements. This process helps the metal gain a harder surface and withstand abrasion. Quenching, alternatively, is a heat treatment process that cools the metal by immersing it into water or oil. This is done to fix the whole metal structure in a solidified state.

Protective Atmosphere Normalising

Another heat treatment process or technique that can be utilised by manufacturers would be a protective atmosphere normalising. The purpose of undergoing this heat treatment process is to refine the grain size of the metal and subsequently improve the uniformity of its microstructure. This process can also enhance the overall machinability of the metal.

Protective atmosphere normalising is carried out by heating the metal under suitable temperature and subsequently still-air cooling it to eliminate the heat or thermal influence from hot rolling or forging. The metals under this process are typically heated about 37°C above the upper critical temperature, which is around 900°C. They are then held at the given temperature so that all their parts are evenly heated before cooling them in air.

Cold worked metals are expected to soften when normalised, while metals that have undergone annealing will become reinforced when subjected under this heat treatment process. The microstructure that is produced by this heat treatment process can be pearlite, pearlite in a ferrite matrix, or pearlite in a commentate matrix.

Materials that have been welded, segregated in castings, and forged can all utilise the refinements of protective atmosphere normalising, especially when it comes to their microstructure and grain size.

Optimized by: Netwizard SEO