Porosity in aluminum welds generates primarily due to rejection of hydrogen on solidification of weld bead. Hydrogen dissolved in the liquid weld metal will try to escape as the aluminum solidifies, and trapped hydrogen will result in weld porosity which is often extensive. The most common sources of hydrogen are hydrocarbons and moisture from contaminants on the aluminum base metal and on the filler wire surface.

Potential causes and remedial measures are shown in table below:

Reference: The welding of aluminum and its alloys, Gene Mathers

Keep reading, happy welding

Thank you,

KP Bhatt

Duty Cycle means “how long something will work for before it overheats”.

Duty cycle is a welding equipment specification which defines the number of minutes, within a 10 minute period, during which a given welder can safely produce a particular welding current.

For example: a 250 amp. Welding machine with a 30% duty cycle must be “rested” for at least 7 minutes after 3 minutes of continuous welding.

Formula for the Estimation of Duty Cycle other than rated outputs:

Example: 200 Ampere Power Source rated at 60% Duty Cycle and operated at 250 Ampere (as far as permitted):

This means that the power source has to be operated maximum 3.8 minutes with a current of 250 Ampere (according to the 10 minute cycle).

Formula for the Estimation others than rated output currents at a specified Duty Cycle:

Example: The maximum output current at a duty cycle of 100% (according to 10 minutes duty cycle) can be calculated by:

Reference: AWS Welding Handbook 9th Edition – Welding Processes Part 1 Volume 2.

Keep reading, happy welding

Thank you,

KP Bhatt