Low-alloy wire electrode for GMA (MIG/MAG) welding of Cr-Mo alloyed creep resistant boiler and pipe steels subjected to operating temperatures up to 570°C. Contains high level of deoxidizing (Mn and Si) elements to control porosity during welding. Welds are of X-ray quality. Also suitable for joining C-Mn steels to be postweld heat treated. Observe directions as to pre and post weld heat treatment of base material. CO2 or mixed shielding gases can be used depending on the thickness of the base metal. A thin and homogeneous copper coating increases electrical conductivity and protects the wire from rusting.