EFFECT OF FLASH BUTT WELDING PARAMETERS ON THE WELD PROPERTIES OF HIGH STRENGTH LOW ALLOY STEELS

Abstract

In the present investigation, study has been carried out on the weldability of a H.S.L.A.(SSAILNIA, 300) steel of cross section of 36 mm x 10 mm, using Flash Butt Welding Process. The influence of welding parameters such as dura-tion of current flow, upsetting distance, and the upsetting pressure on , the morphology and mechanical properties (hard- ness and toughness) of HAZ has been studied. The results of the study reveals that the above parameters have significant influence; on the morphology of HAZ and thereby in controlling the properties of the welds. With the increase in duration of current flow wi4th of the HAZ has been found to increase,.with increase in upsetting 'distance the width of HAZ first decreases then increases. The upsetting pressure increase within the applied range show-ed no significant influence on the width of HAZ. Morphologically finer ferrite plates/needles with bainite structure goes coarser with the increase in the dura-tion of current flow. With a particular current flow time a band with different microstructure formed at the central region of HAZ. The increase in upsetting distance causes coarse ferrite/bainite plates to refine. The . structure of HAZ change to a WWdmanstattan structure with increasing up setting pressure. Hardness survey across the weld reveals, the peak hardness increases with the increase in duration of current flow, upsetting distance and upsetting pressure. The charpy V-notch impact energy at -400C found to increase with the increase in duration of current flow. However,the variation in upsetting distance and upsetting pressure do not cause marked variation in absorbed energy.