Research On High Efficiency Welding Technology And Welding Deformation Control Of Luxury Cruise Ship Thin Sheet

In this thesis Aiming at the urgent demand of luxury cruise ship construction for high-efficiency welding process and welding deformation control of thin sheet,according to the requirements of welding procedure qualification standard of shipbuilding industry,the thin sheet welding process,welding deformation and control,welding efficiency of thin sheet are studied by three kinds of welding procedure qualification tests of thin wire submerged arc welding,twin wires MAG welding and laser arc hybrid welding.From the perspective of welding process effect,through the analysis of welding joint morphology characterization and mechanical properties test,the characteristics of high-efficiency welding process of the three welding methods were studied,and the differences of the three welding methods were compared and analyzed.Laser arc hybrid welding can realize one-sided welding,two-sided forming and one-time filling forming of weld.Ceramic back is used in twin wires MAG welding to force one-sided welding,two-sided forming and one-time filling forming of weld.Thin wire submerged arc welding cannot realize one-sided welding and two-sided forming of weld.The welding speed of the three welding methods from high to low are laser arc hybrid welding,thin wire submerged arc welding and twin wires MAG welding.The welding heat input from low to high is laser arc hybrid welding,twin wires MAG welding and thin wire submerged arc welding.From the microstructure and mechanical properties of the welded joint,the welds formed by the three welding processes are all good,and all meet the requirements of welding standards.The weld formed by laser arc hybrid welding is better than that of thin wire submerged arc welding and twin wires MAG welding.Thin wire submerged arc welding and twin wire MAG welding are typical microstructure characteristics of arc welding.The microstructure of laser arc hybrid top welding joint is similar to that of thin wire submerged arc welding and twin wires MAG welding and the microstructure of weld is coarse dendrite growing perpendicular to the weld pool wall towards the center.The microstructure of coarse grain zone is mainly composed of granular bainite,ferrite and martensite,while the microstructure of fine grain zone is mainly composed of ferrite and granular bainite.The mechanical properties such as tensile strength,bending strength,Vickers hardness and impact toughness of the welded joints prepared by the three welding processes are qualified,and there is no obvious difference among them,and all meet the requirements of industry standards.From the point of view of welding deformation,the influence of three welding processes such as thin wire submerged arc welding,twin wires MAG welding and laser arc hybrid welding on the welding deformation of thin sheet is studied,and the control methods of welding deformation are put forward.For the laboratory test panel,the order of deformation from large to small is twin wires MAG welding,thin wire submerged arc welding and laser arc hybrid welding.For field products,the deformation of laser arc hybrid welding is less than that of thin wire submerged arc welding.Heat input has the greatest influence on welding deformation,and welding sequence and number of welds passes also have an important influence on welding deformation.From the point of view of welding production efficiency,the influence of two welding methods on the welding deformation of actual products is compared between SAW and laser arc hybrid welding.The actual productivity of three kinds of welding methods including thin wire submerged arc welding,twin wires MAG welding and laser arc hybrid welding was studied.Laser arc hybrid welding takes the least time to complete the 100 m thin sheet welding,twin wires MAG welding is the second,and submerged arc welding takes the most time.In terms of welding assembly requirements,laser arc hybrid welding has the highest assembly requirements and the most time consumed before welding,twin wires MAG is the second,and thin wire submerged arc welding has the lowest requirements.In terms of the number of production processes,thin wire submerged arc welding is the most,twin wire MAG welding is the second,laser arc hybrid welding is the least,and the time consumed after welding is the least.The higher the tolerance of the welding process to the preparation before welding,the less time is consumed in the preparation before welding;The less welding process,the less welding total time is consumed.From the above research,in terms of the quality of welding joint,sheet welding deformation,or welding efficiency,laser arc hybrid welding shows excellent effect,which is more suitable for luxury cruise ship sheet welding.With the gradual implementation of the "Made in China 2025" and "One Belt One Road" development strategy,the demand for automation and intelligent production mode is becoming more and more urgent.As the front-end technology of automatic manufacturing,laser arc hybrid welding will play an important role in the coming luxury cruise manufacturing industry in our country.