Study On Technology And Mechanism Of Laser-Arc Hybrid Welded SUS304 Stainless Steel

Laser-arc hybrid as a new type of welding method is the hotspot of word welding research which keeps the advantages of laser welding and arc welding and overcomes their shortcomings.It has the advantage of deeper penetration,higher welding speed and better welding gap adaptability.SUS 304 austenitic stainless steel is used widely in engineering and daily life because of its excellent corrosion-resistance and weldability.So the text chose SUS 304 austenitic stainless steel as base metal to study on the technology and mechanism of laser-arc hybrid welding.First of all,drop transfer in the laser-arc hybrid welding was observed by high-speed photography technology to research the influence of different process parameters on the mode of metal transfer and droplet diameter.Due to the introduction of the laser in laser-arc hybrid welding,the droplet is acted upon by reacting force of metal vapor and electromagnetic force of laser induced plasma except the force acted in arc welding.In laser-arc hybrid welding,when laser power is 1kW,the method of droplet transfer is projected transfer,with the laser power increasing,which became short circuiting transfer and the droplet diameter became larger.Frequency drop transition become higher with the distance between laser and arc.As the current increased,the method of droplet transfer is short circuiting transfer when the current changed from 150 A to 175 A.The method of droplet transfer is projected transfer when the current changed from 200 A to 225 A.When the current is 250 A,the method of droplet transfer is short circuiting transfer.When the current changed from 150 A to 250 A,droplet diameter became smaller and frequency drop transition become larger.After knowing the regular of droplet transfer in laser-arc hybrid welding,a series of welding process testing was made to study the influence of different process parameters on welding appearance.At first,the welding process testing was bead-on-plate welding and the result show that welding appearance of arc-leading is better than the laser-leading and the weld formation is the best when the distance between laser and arc is 2mm.Penetration depth and welding increased with the laser power and current increasing.The optimum process parameters of 8mm SUS 304 austenitic stainless steel mutual welding was acquired: laser power is 5kW,welding current is 200 A,welding speed is 1.68mm/min,arc leading and the distance between laser and arc is 2mm,defocusing amount is-5mm.When the welding gap is between 0mm and 1mm,beautiful welding appearance can be obtained.The microstructure of laser area is smaller than the arc zone in laser-arc hybrid welding microstructure and there are isometric crystal in laser area.The tensile strength of laser-arc hybrid welding is 699 MPa and elongation is 53.7% and the tensile strength of laser welding is 619 MPa,and elongation is 32%.