High-strength dual-phase stainless steel tube and preparation method thereof

The invention discloses a high-strength dual-phase stainless steel tube, wherein the microstructure is martensite and ferrite; the high-strength dual-phase stainless steel tube comprises the chemical elements by mass percent: 0.05% or less of C, 0.05-0.80% of Si, 0.05-0.60% of Mn, 0.001-0.100% of Al, 1.5-3.5% of Mo, 16-20% of Cr, 3-6% of Ni, 0.01-0.05% of N, 0.3% or less of Nb, V and Ti, the balance of Fe and other inevitable impurities; and E% is greater than -5. The invention also discloses a preparation method of the high-strength dual-phase stainless steel tube. The preparation method comprises the steps of 1) smelting and casting; 2) preparing a tube blank; 3) annealing and then heating the tube blank; 4) preparing a pierced billet; 5) quenching; and 6) tempering. The high-strength dual-phase stainless steel tube and the preparation method thereof disclosed by the invention have the advantages that 1) the strength can be up to 110ksi or more; 2) the decay resistance is good; and 3) the production cost is low.