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.