Induction Flame Hardening
Flame hardening is similar to induction hardening, in that it is a surface hardening process. Heat is applied to the part being hardened, using an oxy- acetylene (or similar gas) flame on the surface of the steel being hardened and heating the surface above the upper critical temperature before quenching the steel in a spray of water.
The result is a hard surface layer ranging from 0.050" to 0.250" deep. As with induction hardening, the steel component must have sufficient carbon (greater than 0.35%). The composition of the steel is not changed; therefore core mechanical properties are unaffected. Flame hardening produces results similar to conventional hardening processes but with less hardness penetration. Applications for flame hardening are similar to those for induction hardening, although an advantage of flame hardening is the ability to harden flat surfaces. Flat wear plates, and knives can be selectively hardened using this process.
Flame hardening is a surface-hardening method that involves heating a metal with a high-temperature flame, followed by quenching. It is used on medium carbon, mild or alloy steels or cast iron to produce a hard, wear-resistant surface.
Flame hardening uses direct impingement of an oxy-gas flame onto a defined surface area. The result of the hardening process is controlled by four factors
Typical flame-hardening applications include:
Corrosionpedia explains Flame Hardening
Flame hardening is a rapid, economical method for selectively hardening specific areas on the surface of a part. This process is applied to selected metal surfaces of carbon and alloy steels, cast and ductile irons and some stainless steels, followed by an appropriate quenching method.
Flame hardening in its simplest form is the heating up of steel to its hardening temperature by a flame and then quenching in water or oil. It is used to produce a hard case on the surface of a wide range of mechanical components.
There are four types of flame hardening:
The gas used for the heating process is a mixture of oxygen and acetylene, although occasionally propane is employed. When the surface reaches the austenizing temperature, the part is immediately quenched to produce a locally hardened surface. Typical surface hardness range is 55-60 HRC in medium carbon steels. It is used on parts such as:
The benefits of flame-hardening include:
Flame hardening can be employed in various applications. Various shapes-curved/straight, varying lengths, widths, and thickness, can be flame hardened in selective areas that are subject to excessive wear.