THREE PHASES PROTECTIVE GAS MIXTURE FOR ARC WELDING OR ARC FILLING OF ALLOY STEEL AND ARC WELDING OR ARC FILLING METHOD THAT USE SAID GAS MIXTURE

摘要

Ternary gas mixt. providing protection during the arc-welding or -resurfacing of alloy steels, where the gas contains by vol. 2.5-3.5% CO2, 0.8-1.2% H2, remainder argon. The pref. gas mixt. (A) is 96% Ar, 3% CO2, 1% H2. The gas is pref. used to protect a consumable alloy steel electrode wire and the molten weld pool formed by the arc, esp. where the transfer of the molten wire is made by:- (1) sprayed drops, known as the "Spray-Arc" (RTM) method; (2) repeated short circuits between the wire and the bath using short arces and the process "Short Arc" (RTM); or (3) controlled pulses by the process known as "Arc-Pulse" (RTM). When welding by method (2), the workieces are pref. 0.5-1.5mm thick. The gas may also be used in welding or resurfacing austenitic steels, which may contain a small amt. of ferrite, e.g. Ni-Cr steels. The presence of CO2 permits the transfer of metal in a finely divided state, thus avoiding projections, and the H2 exerts a pickling action so correct wetting is obtd. without porosity; the gas also prevents an increase in the % C in the weld deposit and the expensive gas He is not used in the mixt.