10 鋼材の熔接性に及ぼす砒素の影響に就て(第2報)

At the 1st report, the authors described that shock values of the weld metal obtained with electrode core steels containing arsenic decrease with the increase of arsenic contents of core steels. Then it is important problem to adopt any device which is available for the prevention of such deterioration of properties. In this report, the authors investigated the relation between deoxidizing abilities of coatings and shock values of weld metals.<BR>And from the experimental results, following facts were concluded.<BR>(a) Low shock values and low elongations of weld metals obtained by welding of mild steel without arsenic with coated electrodes, which are made of low carbon core steels containing various quantities of arsenic, are remarkably improved if suitable deoxidizers are added in the coating.<BR>(b) When we are abliged to use core steels containing remarkably much amount of arsenic, Mn-Si alloy and metallic Chromium ought to be added rather than Fe-Mn alloy as deoxidizers in the coating. The improvement of the weld metal by such deoxidizers seems to be due to the following reasons.<BR>i) If the weld metal is well deoxidized, oxides of arsenie decrease and inclusions consisted of the oxide decrease and for this reason the solidified weld metal becomes tougher.<BR>ii) In consequence of the deoxidation of fused metal, arsenic vaporizes and after solidification the arsenic content of ferrite decreases. And the ferrite-matrix of weld metal becomes softer and the deformability of weld metal increases.<BR>That is to say, owing to these two tendencies, the shock value and elongation of the weld metal are improved, and the decrease of cracking tendency of weld metal are expected.