INCLUSIONS IN STEEL COATED ELECTRODES WELDS OF CAR BODY

The goal of this project (BK-284/RT1/2007) is to chose the proper method of car body welding. SMAW could be treated as the main method used in the transport industry. Properties of metal weld deposits depend on many conditions. This paper attempts to study first of all the role of oxide inclusion sites on the transformation austenite-*acicular ferrite in steel weld metal deposits and their toughness. Properties of metal weld deposits depend on the amount of acicular ferrite in them. For good toughness over a range of temperatures, metal weld deposits should have a high amount of acicular ferrite. Different basic and rutile electrodes were used in order to obtain different as-deposited weld compositions. Impact toughness tests of various deposits were carried out. The microstructure of the welds with different oxygen levels, the inclusion size distribution and approximate chemical composition of inclusions are characterized. Most observations and measurements were done with a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer. The result of the present study implies that it is advantageous to keep oxygen contents in basic and rutile deposits as low as possible when well-developed microstructures of acicular ferrite are desired.