Consumable electrode type gas shield arc welding method and arc welding portion

Abstract

The present invention provides a consumable electrode type gas shield arc welding method for performing arc welding of two steel sheets using a welding torch having a consumable electrode. The consumable electrode type gas shield arc welding method includes performing arc welding while a shielding gas having an oxygen potential α which is indicated by the following Expression (1) and ranges from 1.5% to 5% is supplied from the welding torch toward the consumable electrode, and blowing an oxidation promotion gas having an oxygen potential β which is indicated by the following Expression (2) and ranges from 15% to 50% at a flow velocity ranging from 1 to 3 m/sec over a weld bead and a weld toe portion which are formed by arc welding and are in a state of 700° C. or higher,α=100×([(O)]+[(CO)]/5)/([()]+[(O)]+[(CO)])  Expression (1)β=100×[(O)]/([()]+[(O)]+[(CO)])  Expression (2) here, [V(X)] is a mixing ratio (volume %) of an inert gas included in the shielding gas, [V(O)] is a mixing ratio (volume %) of oxygen included in the shielding gas, [V(CO)] is a mixing ratio (volume %) of carbon dioxide included in the shielding gas, [V(X)] is a mixing ratio (volume %) of an inert gas included in the oxidation promotion gas, [V(O)] is a mixing ratio (volume %) of oxygen included in the oxidation promotion gas, and [V(CO)] is a mixing ratio (volume %) of carbon dioxide included in the oxidation promotion gas.