Abstract：CCD camera and infrared radiation monitoring system are used to systematically study the influences of the heat input on the relative intensities of the infrared radiation and the area of molten pool during laser welding of TC4. The results show that the relative intensities of the signal can be obviously divided into three phases for the whole weld seam: the starting state of welding, the quasi-stable state, and the arc suppressing of welding. When the laser power keeps constant with welding speed decreasing, the area of molten pool increases, meanwhile the relative intensity of infrared radiation signal increases. Results indicate that there are the same varying rules existing between molten pool and relative intensities of infrared radiation.Thereby, changes about the area of molten pool can be monitored quite exactly, and the stability of welding process can be monitored by using infrared radiation signal.
2011, 
