軟鋼溶着金属中の酸素量(第1報)

Abstract

Oxygen in weld metal is one of the causes of porosity during solidification and afect the mecha-nical properties of weld metal forming oxide inclusions in the solidified weld metal. In theprevious reports, the authors investigated the shapes, compositions and formation process of oxide inclusions in mild steel weld metals. In this report, oxygen contents in mild steel weld metals, deoxidation ability of coating fluxes and slag-metal interactions during weld process are investigated.Oxygen content in weld metal is afected mainly by the chemical compositions of coating flux, because the composition of core wire is almost difinite. The author proposes the value of 'deoxidation tendency' (R1-1/2R2-A) calculated from the contents of deoxidizers, organic matters andoxidizers in coating flux. The relation between deoxidation tendency of flux and [O] in weld metal is as follows: on the cases of the same coating type electrodes using Fe-Mn as deoxidizer, the results are stand in a curve and on the case of basic type (low hydrogen type) electrodes using Fe-Mn, Fe-Si and Fe-Mn-Fe-Si as deoxidizer, the results are stand in a curve. These results prove the utility of 'deoxidation ten-dency'. It is shown that, the reaction of Mn-deoxidation (onthe cases of every type of electrode) and Si-deoxidation (on the case of bafic types electrodeonly) are seemed a rapid one and organic matters act as deoxidizer equal to Fe-Mn or Fe-Si.On the other hand, oxygen content in molten metal is affected the composition of slag. Relation between [O] in weld metal and (FeO) in slag shows two lines, one is on the case of basic type (lowhydragen type) and the other is on the acidic types (several types except low hydrogen). These results show that, reaction of (FeO)=[Fe]+[O] is a rapid one during weld process. Distribution of Mn between weld metal and slag shows two lines, on the cases of acidic and basic types. It is shown that the reaction of (FeO)+[Mn]=[Fe]+ (MnO) is a rapid one during weld process. But distribution of Si between weld metal and slag is not shows a line on the case of acidic type and is showd a line on basic type. From these results, it is, shown that the reaction of 2(FeO)+[Si]=2[Fe]+(SiO2) is a rapid one only on the case of basic type electrode.