Study On Welding Process Of Flame Heated Friction Stir Welding Of Steel

Steel materials,due to their rich in natural resources,stable quality,favorable comprehensive mechanical performance,are the most widely used engineering materials in the human society.With the development of modern science and technology, steel welding technology is also constantly improving and enhancing.The existing heat fusion welding methods can not fully meet the requirements of modern products, therefore, choosing a more suitable welding method is crucial.Friction stir welding is a new technology of solid state joining process which was invented by the Welding Institute of England in1991,which is called "a revolution of welding after laser welding",and is recognized as the most potential and application prospect of advanced connection method.Therefore, it has a broad prospect in the fields of aerospace,shipbuilding,nuclear industry,transportation and other industrial manufacturing fields.Compared with friction stir welding of aluminum, copper and other soft metals, the research of friction stir welding steel is relatively few.In order to solve the problem of friction stir welding of steel better, an auxiliary flame heating method of friction stir welding is proposed.Firstly,friction stir welding heat source model under the condition of auxiliary flame heating was set up.The flame heat source model introduces the jet impact heat transfer model and the Gaussian distribution heat flux model.In addition,the tool heat source includes the friction heat source model for shoulder and the shear heat source model for the pin by using the method of calculus.Secondly, on the base of the heat source model,the influence of such flame heating friction stir welding process parameters,as the flame parameter, preheating time, tool dwell time, welding speed, rotational speed and pressure on the temperature field were analyzed by using the finite element software ANSYS.That is used as a basis to select the appropriate parameter value and then analyzed the temperature field on the combination process parameters,it will provide theoretical basis and guidance for the following experimental work.Finally,based on the results of finite element analysis,the experiment of friction stir welding of Q235steel was conducted.And the tool material was confirmed by observing the weld appearance and tool state of different materials tool after welding.Then,the micro structure of heat affected zone,heat-mechanical affected zone and stir zone were analyzed,as well as the hardness and tensile mechanical properties of the weld.