特殊鋼熔接の基礎的研究(第5報)
不安定大洲田組織を含む鋼を心線とする被覆棒をもつて,強靭鋼を熔接する場合の熔着鋼の硬度に及ぼす被覆剤中の黄血塩の影響について
1950 年 19 巻 10-11 号 p. 214-221
詳細
1950 年 19 巻 10-11 号 p. 214-221
In this research, the authors made many kinds of arc-welding electrode by applying coating-materials containing or not containing potassium ferocYanide on core-rods made of Ni-Cr stainless steel or Mn-Cr steel which consisted of an unstable austenitic structure or a ferritic and martensitic structure. Using these electrodes, they welded a V-shaped groove between two plates made of Mn-Cr-Mo alloy steel, and measured the hardnesses of the weld metals, and made chemical analysis of them. In this way, the following results were obtaind.
(1) When a V-shaped butt joint of alloy steel was welded with electrodes having coating which contained potassium ferrocyanide, the weld metal obtained was softer than that obtained with electrodes which had the coating containing the same constituents excepting potassium ferrocyanide.
(2) Such a tendency was remerkable in the first layer of the V-shaped butt joint. And the authors considered these phenomena as follows :
When there is potassium ferrocyanide in the coating of an electrode, the atmosphere of CN gas is produced in the vicinity of the electric arc at the end of the electrode by decomposition of K4Fe(CN)6, and gas thus produced excludes the air from the surrounding place of the arc.
Consequently at the time of deposition by electric arc, the degree of decrease of easily oxidizable special elements such as Mn and Cr are insignificant, and nitrogen-content of weld metal is great. As a result of this tendency, the weld metal contains more austenitic structure and the austenitic structure is stabilized by the same tendency. Accordingly the hardness of weld metal decreases.
But when the content of potassium ferrocyanide in coating is more than 30%, much gas is produced at the time of electric arc-welding and the atmosphere of a workshop becomes bad for health. Therefore, when applying this method, precautionary measures such as opening of the workshop windows, etc. must be taken for the maintenance of healthy conditions for the workers.
