Soldering of mild steels: functional joints

In recent years, adhesive joints have replaced numerous soldered joints, especially in applications where electrical conductivity is not required from the members of the joint. Nevertheless, soldered joints are still used in applications ranging from electronics to high-technology components. The present work seeks to demonstrate that soldered joints, which can be considered as functional joints, have very good mechanical properties and can provide more than acceptable levels of leak tightness. Hence, microstructural characterisation studies have been carried out on the filler metals used to solder mild steel, the surface preparation required to achieve the best final properties has been assessed, the joints characterised by means of radiography and the mechanical properties of the joints determined. The results obtained for soldered joints have been compared with those obtained from adhesive and hybrid joints. y, scanning electron microscopy has been performed on the fracture surfaces of the soldered joint.