The relationship between plasma optic signal and penetration depth during partial-penetration laser welding

At some process condition,the weld fusion area increase linearly with heat input,and for the two common parameters of laser power and weld speed,laser power has more influence on penetration while weld speed has more influence on weld width.The plasma optic signal at 400nm~600nm corresponds to variation of the weld penetration,and the signal's RMS value increases with the penetration in a quadratic curve mode.The inherent relation between plasma optic signal and penetration is also analyzed.The results provide theoretical and practical guidance for real-time penetration monitor and prediction in partial-penetration laser welding.