ニッケルおよびニッケル合金の溶接割れに関する研究 ＩＩ ニッケルおよびモネルの溶接割れにおよぼすＳｉの影響

Abstract

In previous report (the 1st report), it was made clear that nickel and monel welding electrodes had to contain a little Al and Ti in their weld metals for prevention of porosity in weld metals, improvement of their mechamical propertis and prevention of micro cracking with decreasing ductility.Increased Al and Ti in the welding electrodes, however, promote the occurrence of hot cracking in nickel weld metals, because the content of Si in weld metals is increased by reducing reaction of Al and Ti with the silicates (SiO2) of the coating flux.In this paper, the authors investigate the relations between SiO2 content in the coating flux and Si content in weld metals, effect of Si content on weld crackings of nickel and monel weld metals.The results are summarized as follows:1) Si content in nickel and monel weld metals increases owing to the increase of SiO2 content in coating flux of the welding electrodes.2) Hot cracking of nickel weld metals aggravates remarkably due to the increase of Si content in the weld metals.3) Effect of Si content on hot cracking of monel weld metals was less than that of nickel weld metals. In overlaying monel on carbon steels, however, hot cracking of monel weld metals is remarkable owing to the increase of Fe in the weld metals caused by the penetration of Fe in the steels.4) In case of increased Si content in nickel weld metals, it is possible to prevent micro cracking of nickel weld metals when Al and Ti contents in the weld metals are more than three times Si content in the weld metals.5) It is clear that micro cracking of monel weld metals is not influenced by Si content in the weld metals.