Research On TIG Surfacing Process And Interface Of Soft Iron/Copper Composite Elastic Band

The traditional elastic band material includes soft iron and copper.The copper itself is soft.The use of copper as the elastic band will cause a large amount of copper to remain in the cannon during the projectile launching,causing pollution.It is necessary to regularly clean the cannon while losing the copper band,and The poor shear resistance produces side slip,which makes the air-tightness of the projectile during the launch process worse,affecting accuracy and range.The hardness of the soft iron is higher,which solves the problem of the copper elastic band,but increases the friction between the elastic band and the twisted wire,so that the wear of the twisted wire is serious,which affects the life of the cannon.In order to optimize the performance of the elastic band,the subject adopts the automatic wire feeding and welding swing forced water-cooled TIG welding method to obtain the soft iron-copper composite project by the method of copper in front and soft iron in the back and first welding soft iron and then welding copper.band.The two kinds of elastic belts can be fully utilized,and the softness and high strength of the soft iron can be used to improve the rigidity of the elastic belt as a whole,thereby avoiding the slip phenomenon of the copper elastic belt and reducing the wear of the twisted wire.The residual copper can be taken out and the cannon can be cleaned.Using the TIG welding method,the welding of HS201 welding copper wire was carried out.The results show that the optimum process parameters for surfacing copper on the surface of 50# steel substrate are: welding current 140-160 A,wire feeding speed 1.3-1.5m/min,rotation period 1-1.5r/min,gas flow 10 L/min,swing 2mm.Through metallographic observation,the copper-steel interface is a brazed joint when the welding current is less than 160 A,and the diffusion of iron becomes more obvious as the current is larger,when the current reaches 170 A.The bulk iron begins to appear in the surfacing layer.It is known that the iron content in the surfacing layer is less than 2% when the current is less than 160 A.The process of soft iron welding is also explored.The best welding parameters are: weldment cleaning before welding,preheating,welding current 160-170 A,wire feeding speed 1.3-1.5m/min,rotation period 1-1.5r/min,The air flow rate is 10 L/min,the welding gun swing amplitude is 1.5 mm,and the air cooling is stopped after welding.According to the above parameters,the soft iron is first welded,and then the copper is laminated to obtain a composite elastic band.The microstructure and element distribution of the composite elastic band joint were analyzed.The base metal and soft iron surfacing layer experienced two thermal cycles.The first thermal cycle,the soft iron surfacing layer was organized as upper bainite and near-interface parent metal.The microstructure is quenched structure(pre-eutectoid cementite + lath martensite)and normalized structure(ferrite + pearlite).In the second thermal cycle,the soft iron surfacing layer is organized into Wei's structure,and the near-interface parent metal structure is lath martensite,and the grain size becomes smaller.The distal annealing zone of the interface is mainly organized into fine pearlite.The results of measuring the mechanical properties of the composite elastic band show that the copper/soft iron composite elastic band obtained by using the 165 A soft iron surfacing current and the 160 A copper surfacing current meets the basic requirements of the projectile launching,and can prevent the projectile when the soft iron band width reaches 4 mm.Side slip occurs during launch.The copper/soft iron composite elastic belt can reduce the hardness of the elastic belt as a whole while avoiding side slip,reduce the friction performance of the elastic belt,reduce the wear of the twisted wire,and prolong its service life.The copper/soft iron composite elastic belt can improve the plastic toughness of the soft iron elastic band in the composite elastic band after the second thermal cycle,and reduce the hardness and friction coefficient.The shear strength of the copper/soft iron composite elastic band can reach 500 MPa or more,and the hardness value The control is below 200 HV,the friction coefficient is below 1.0,and the overall performance is improved compared to the single elastic band.