Abstract: A wire for gas metal arc welding containing 0.01 to 0.06 wt % of C, 0.10 to 0.60 wt % of Si, 0.9 to 3.1 wt % of Mn, 0.7 to 2.0 wt % of Cr, 0.005 to 0.06% of Ti, not greater than 0.08 wt % of Al and if necessary, 0.05 to 0.30 wt % of Cu, and the balance of Fe and unavoidable impurities. This wire improves the selective corrosion resistance and the low temperature toughness of the resulting weld metal, and is particularly suitable for circumferential welding of line pipes for transporting CO.sub.2 -containing petroleum, natural gases or CO.sub.2.

Abstract: The present invention relates to a method of reducing an amount of welding deformation in the case where steel plates to be welded are butted and subjected to tack-welding and then the tack-welded portion is subjected to one side welding for joining the plates.In the present invention, not less than 3 welding electrodes are used and a welding condition is determined so that the parameter P shown by the expression of ##EQU1## can be a predetermined value. In this case, Qi is the heat input of each electrode determined by a current, voltage and speed, and Li is a distance from the first electrode to each electrode, and H is the maximum value of the height of a tack-welded bead, wherein the height H is made to be a value not more than half of the wall thickness of the steel plates to be welded.

Abstract: In a method of automatically welding rails, welding of bottom portions of the rails is carried out as root pass welding of a first layer according to CO.sub.2 gas shielded arc weld technique, and as continuous multilayer welding of layers above the first layer according to CO.sub.2 gas shielded arc weld technique without discontinuing the welding of a second layer and upper layers. In welding of ankle portions (R2) of the rails, a flux is rapidly added to promptly shift to electroslag weld. Then, welding is conducted to head surfaces (R5) of the rails by continuing electroslag weld technique. This automatic welding method enables high efficiency field welding of rails, obviating the need for any complicated switching operation of the electric power source and use of several kinds of welding materials.

Abstract: A welding flux which forms a weld metal simultaneously satisfying low-oxygen, low-nitrogen, and low-hydrogen contents, gives weld beads in good form, and joins given metal pieces without entailing weld defects is obtained by formulating the flux in a composition such that a four-component system used therein is formed of CaO, MgO, Al.sub.2 O.sub.3, and SiO.sub.2 in the following proportions based on the total amount of the system taken as unity (100%),CaO: 10 to 60%MgO: Not more than 30%Al.sub.2 O.sub.3 : 20 to 70%SiO.sub.2 : 5 to 40%that the total amount of the four components accounts for not less than 35% of the total weight of the flux less the CO.sub.2 component thereof, that the composition incorporates therein CaF.sub.2 in an amount of from 25 to 65% of the total weight of the flux less the CO.sub.