Method of automatically welding rails

In a method of automatically welding rails, using both CO.sub.2 gas shielded arc weld technique and electroslag weld technique, characterized in that:

• 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 after the welding of the first layer;
• welding of leg portions of the rails is conducted by rapidly adding a flux at an adding speed of over 200 g/min and below 1 kg/min to thereby promptly shift to electroslag weld;
• then, welding is conducted to head surfaces of the rails by continuing electroslag weld technique;
• during these continuous welding operations, CO.sub.2 gas and the flux are automatically supplied using copper shoes and an outer sleeve of a nonconsumable electrode nozzle while a slag and a molten metal are prevented from flowing out;
• and
• d.c. current having a constant voltage characteristic, a welding filler wire having a radius 1.2 to 2.0 mm, and as the flux a low melting point and low viscosity fused type flux are used, the flux containing major components of CaF.sub.2 --SiO.sub.2 --TiO.sub.2 :
• 25 to 40 wt. % of CaF.sub.2 ;
• 20-35 wt. % of SiO.sub.2 ;
• and 5-15 wt. % of CaF.sub.2 +SiO.sub.2 being contained at an amount of at least 50 wt. %.