What is a Weld Pool in Welding?

A weld pool is a localized volume of molten metal in a weld prior to its solidification as weld metal. The size and shape of the weld pool depend on a number of factors, including:

welding current,
electrode type and position,
shielding gas flow rate and composition,
and workpiece material.

As the weld pool cools and solidifies, the weld metal contracts and forms a strong joint between the workpieces.

Weld pools can be used to join metals of different thicknesses, shapes, and sizes. When welding thick materials, the weld pool may be several inches deep. Shallow weld pools are common when welding thin materials or when using small-diameter electrodes.

What causes weld pool?

The depth of the weld pool also affects the heat input to the workpiece. Deep weld pools can cause extensive heat damage to the workpiece, while shallow weld pools provide less heat input and are less likely to cause damage.

In some cases, it may be necessary to preheat the workpiece before welding to help control the depth of the weld pool. Preheating also reduces the risk of cracking and other defects.

How to control weld pools?

Weld pools can be controlled by various welding parameters, such as:

current,
electrode type and position,
shielding gas flow rate and composition,
and workpiece material.

By carefully controlling these parameters, welders can produce high-quality welds with minimal defects.

How hot is a weld pool?

The temperature of a weld pool can vary depending on the welding parameters used. In general, the higher the welding current, the hotter the weld pool will be.

Shielded metal arc welding

In SMAW, the weld pool is protected from oxygen and other atmospheric gases by a molten flux that forms a slag on top of the weld pool. The slag protects the weld pool from contamination and helps to control the depth of the weld pool.