The oxy-fuel process is a method of thermal cutting that uses the rapid oxidation (rusting) of steel at elevated temperatures to sever the material. It is a two-stage process involving preheating the metal and then introducing a stream of pure oxygen to sustain a chemical reaction. 

Here is a technical breakdown of the gas cutting process: 

• Preheat Flame: First, a cutting torch generates a preheat flame by combining a fuel gas (like acetylene or propane) with oxygen. You apply this flame to the surface of the steel plate, heating a small area to its ignition temperature, which is typically around 870°C (1600°F). The steel glows a bright cherry-red at this point. 
• Oxygen Jet: Once the ignition temperature is reached, you trigger a high-pressure stream of pure oxygen, known as the oxygen jet, through a central orifice in the cutting torch tip. This stream of commercially pure oxygen is directed at the preheated spot. 
• Oxidation Reaction: The pure oxygen immediately initiates and sustains an exothermic oxidation reaction with the iron in the steel. This reaction creates iron oxide, more commonly known as slag. The heat generated by this chemical reaction is substantial and becomes the primary source of energy for cutting, continuing the process through the entire thickness of the plate. 
• Molten Metal Removal: The high-pressure oxygen jet serves a dual purpose. It not only fuels the oxidation but also forcefully blows away the molten slag from the cut path, or "kerf." This action clears the way for the reaction to progress, allowing the cut to move forward along the desired path. 

This process is highly effective for carbon steel because the melting point of its iron oxide (slag) is lower than the melting point of the steel itself. This allows the slag to be easily removed while the base metal remains solid. Conversely, materials like stainless steel and aluminum form oxides with very high melting points, which prevents the oxygen jet from clearing the kerf and stopping the cut.