Structure formation of the heat-affected zone of the permanent joint made by the automatic submerged arc welding with the use of the flux-cored wire with thermite filler

The specific feature of obtaining a permanent joint of elements produced from carbon alloys is the formation of mainly quenching structures in the heat-affected zone of the weld. Among the methods aimed at reducing this phenomenon, additional thermal methods of impact are widespread, consisting in preheating of the joint zone and slow cooling of the deposited metal. Such methods seem to be cost-intensive and the results are difficult to control. It determines the relevance to find solutions aiming at eliminating the quenching structures of the weld and heat-affected zone. To solve this problem a series of experimental studies has been carried out to form the structure and properties of the heat-affected zone of the weld made by automatic welding with the help of flux-cored wire with thermite filler. The specific feature of using this wire is weld formation when the heat enters the joint zone of the elements simultaneously both from the electric arc and exothermic process, due to the aluminothermic component. As the result of the study, permanent joints made of St3 steel and 45 steel have been obtained; their structures and stress-strain properties are also presented.