In the case of the electrodes of less refractory coatings, or lower arc voltage; the electrode tip takes the form as shown in Fig. 3b and no particles are generated from the tip, so the material transference occures always accompanying the mechanical contact between electrode and the base metal at ordinary arc length. In the case of the electrodes of gas generating type, this mechanical contact accompanies mostly electrical short circuit (Photo. No. 56), but in slug type electrode, electrical short circuit does not always occures. (Photo. No. 61).
The 182nd picture of Photo. No. 61 shows the abrupt change of the are foot in the electrode side, and we can see the corresponding abrupt arc voltage rise from the accompanying oscillogram. The cause of the above mentioned phenomena is supposed to be explained by Fig. 29. In general there are two types in the abrupt change of the arc voltage, as shown in Fig. 30 (a) and (b). Fig. 30 (a) shows the abrupt change occured by the lengthening of the arc length. due to the magnetic arc blow, and the trapezoidal. wave form of voltage is its characteristic. Fig. 30 (b) is due to the abrupt change of the arc foot simillar to Photo. No. 61 and is likely to occur in the coated electrodes. Some examples are shown in Fig. 31-34 (Fig. 31 and 32 are the case of overhead welding)
As the bridging path between the electrode and the base metal has some electrical conductivity, a part of the welding current flows in this bridge parallel to the arc as illustrated in Fig. 36 So in the case of a. c. the current (i in Fig. 36) from the source flows only in the bridge path for a small interval of current zero phase, and the wave form of the terminal voltage becomes like P Q in Fig. 35 (b), and differs from the wave form of the ordinary arc with no bridge. (Fig. 35 a). An example is shown in Photo. No.62 and its corresponding oscillogram, and the picture A correspond to the point P in the oscillogram.

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一般に熔着鋼の破面に於て線状組織と稱せられてゐるものは其の性質上線状破面と謂ふべきであつて,之は熔着鋼が完全に固化してよりA₃變態點(?)に至るまでの龜裂所謂高温龜裂部の破面である.高温龜裂が空氣中に裂開してをれば著しく着色したる線状破面を現はし,然らざれば殆ど着色せられすして金屬光澤を有する線状破面を示す.線状破面部は次層のビードの熔込に依て其の一部又は全部を消失する.Si,Ti,Ni,Cr,Mn及Al等の特殊成分が熔着鋼中増加すれば高温龜裂を生じ易くなり從つて線状破面を生することが多くなる.熔接電流が過大なる場合にはビードが比較的に薄くなり,共の結果線状破面を生じ易くなる.壷が潔くなるやうな蓮棒法又は熔接棒を用ふれば線状破面の出方も多い.

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