Effect Nitrogen On Microstructure And Toughness Of C-Mn Steel Weld Metals Containing Tatanium And Boron

Effects of nitrogen on microstructure and toughness of C-Ma steel weld metals containing titanium and boron have been studied using dilatometry in combination with transmission electron microscopy (TEM) associated with microanalysis techniques, i.e. energy dispersive X-ray analysis (EDXA) and electron energy loss spectroscopy (EELS). Results of this investigation show that acicular ferrite which gives good impact toughness could be maximized by combined effect of To inclusions which act as potent substrate for nucleation of acicular ferrite and soluble B which retards grain boundary ferrite formation. It is concluded that a certain addition of N to Ti-B type weld metals can give a beneficial effect and should be considered of equal importance as microalloying elements themselves. Key words : acicular ferrite, austenite to ferrite transformation, inclusion and toughnes