Flame Surface Hardening
Flame surface hardening is a process that involves heating small portions of a metal surface to high temperatures beyond its austenite transformation temperature and then cooling it quickly. It is used to harden a select surface area, but not the entire metal part. It works well because of the fact that it can be applied to local areas that need to be hardened without having to try and harden the entire metal part.
Flame surface hardening is used in a variety of metalworking processes. It is often used for components that need to be more resistant to abrasion, fatigue, adhesion and wear. Flame hardening is a minimally destructive process and allows for very precise control of the hardening process.
The flame hardening process is relatively simple. It requires a flame, usually an oxy-fuel flame or an air-fuel flame, that is roughly two to three times hotter than the metals melting point. Once these two items are present, the metal can then be heated until the austenite transformation temperature is reached. At this temperature, the metal is heated for a certain amount of time which then alters its crystalline structure, creating a hardened surface.
Once the metal is heated to its transformation temperature and is allowed to cool down, it will enter a martensitic structure, producing a hardened surface. This hardened surface has higher wear resistance, fatigue strength and abrasion resistance than the original metal.
The end result of flame surface hardening is improved part functioning due to the increased surface wear and fatigue strength. This process is often employed for certain parts that need to undergo a lot of wear and tear. It also increases the durability of metal parts that may be exposed to a corrosive environment.
The process has several advantages over other alternative surface hardening processes. One of the main advantages is that flame hardening is a process that is relatively low cost. Secondly, it is a localized process which means that only the surface that needs to be hardened is affected. No further structural or chemical changes occur, which is often the case with other hardening processes.
Finally, flame hardening is a relatively quick process. It takes only a few minutes to heat the metal to its transformation temperature and then cool it, resulting in a hardened surface. This compared to other alternative processes which can take hours or days to completely harden a metal.
Overall, flame surface hardening is an economical and efficient process for hardening metal objects. It has a number of advantages compared to other hardening processes, which makes it a popular choice for certain applications.
