Numerical and experimental study on keyhole and melt flow dynamics during laser welding of aluminium alloys under subatmospheric pressures

•The boiling points of 5A06 alloy under various ambient pressures were calculated.•Wider and deeper keyhole with less humps was obtained under subatmospheric pressures.•Weakened vortices and larger melt flow velocity was produced under subatmospheric pressures.•The keyhole stability and porosity def...

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