Porosity Formation Mechanism And Control Method Research On CO₂Laser Deep Penetration Welding Low Carbon Steel

As power of industry high-powered optical maser power rise ceaselessly,and the constant improvement of the beam quality, deep penetration laser welding technology has been widely promoted in industrial production. But in the process of CO2deep penetration laser welding especially imperviously, porosity which affects the quality of welding is easy to form.This paper takes the20g boiler steel which quality requirements is strict in industrial production as the research object.researches the influence of process and parameters to the formation mechanism of porosity during the high-powered CO2laser deep penetration imperviously, to inhibit or control the porosity of the goal.First based on orthogonal test method taking porosity number as indicators to research the laser power(P), welding speed(v), laser beam Angle(θ) and focus(f) for the four factors, draw the best test combination: P=4.5Kw, v=1.4m/min.9=22.5°, f=6mm. Then the formation mechanism of the porosity in deep penetration laser welding were discussed and analyzed.Combined with the orthogonal experiment results and forming mechanism of porosity, welding experiments research the protective gas flow, beam angle, laser power and welding speed on the influence of porosity rate. The study found increased porosity of the gas flow at first and then decreased in the process, flow of35L/min, the lowest porosity; with the laser beam angle appears to increase porosity of the table after the first cut by the trend, is a negative angle of37.5°and7.5°when the angle of the lowest porosity;3Kw laser power when the porosity is high, continue to increase the low porosity and little change; low welding speed in0.75m/min get a better stomatal inhibition.Finally, special process method to suppress porosity, the results show that the test changing speed repeated welding, CO? protection, and the whole surface oxidation to improve porosity defects have little effect, suitable space and changing power repeated welding can make a better effect to inhibit the porosity defects.