In which type of welding flame is oxygen proportion more compared to acetylene proportion?

Explanation:

Oxidising Welding Flame

Definition: An oxidising welding flame is a type of flame used in oxy-acetylene welding where the proportion of oxygen is higher compared to the proportion of acetylene. This flame is characterized by a hissing sound and a shorter, more pointed inner cone.

Working Principle: In oxy-acetylene welding, the flame is produced by burning a mixture of oxygen and acetylene gas. The oxidising flame has an excess of oxygen, which means that the ratio of oxygen to acetylene is greater than 1:1. This causes the flame to have a higher temperature and a more intense burning characteristic. The excess oxygen reacts with the metal, causing oxidation.

Advantages:

• Higher flame temperature, which can be beneficial for cutting operations and welding certain metals that require higher heat input.
• Improved penetration and faster welding speeds due to the intense flame.

Disadvantages:

• Excess oxygen can cause oxidation of the weld metal, leading to brittleness and potential defects in the weld.
• Not suitable for welding non-ferrous metals, as the oxidation can adversely affect the material properties.

Applications: Oxidising welding flames are often used in cutting operations and welding ferrous metals where the higher temperature and intense flame can provide better results. However, it is essential to control the flame to avoid excessive oxidation of the weld metal.

Important Information:

Reducing Welding Flame:

Also known as a carburising flame, it has a higher proportion of acetylene compared to oxygen. This flame produces a softer, cooler flame and is used for welding metals that are prone to oxidation, such as aluminium and lead.

Carburising Welding Flame:

Similar to the reducing welding flame, it has an excess of acetylene. This flame is used to add carbon to the weld pool, which can be beneficial for welding high-carbon steels and cast iron.

Neutral Welding Flame:

This flame has a balanced ratio of oxygen and acetylene (1:1). It produces a clean, stable flame without any excess oxygen or acetylene. It is the most commonly used flame for general welding purposes, providing a good balance of heat and minimal oxidation.