High-strength and high-tenacity basic flux cored wire

The invention discloses a high-strength and high-tenacity basic flux cored wire. The high-strength and high-tenacity basic flux cored wire comprises a sheath and a basic flux core with which the sheath is filled. The sheath adopts a mild-carbon steel strip and is obtained through the three working procedures of rolling, folding and drawing. The pH value of the basic flux core ranges from 2.1 to 3.5. The basic flux core comprises, by weight, 3%-7% of ZrO2, 1%-5% of Na2SiF6, 1.5%-6% of KAlSi3O8, 2%-5% of TiO2, 12%-25% of CaF2, 2%-6% of CaCO3, 1%-3% of Al-Mg alloy, 25%-35% of metal powder, and the balance iron powder. During welding of the high-strength and high-tenacity basic flux cored wire, CO2 gas is adopted as protective gas, the welding arc is stable, the amount of spatter and smog is small, deslagging is easy, welding joints are attractive in appearance, the strength of the welding joints can reach more than 830 MPa, the good low-temperature toughness is achieved, and the high-strength and high-tenacity basic flux cored wire is applicable to all-position welding of 830 Mpa grade high-strength steel.