A process of producing a duplex stainless steel tube comprises the steps of: a) producing an ingot or a continuous casted billet of said duplex stainless steel; b) hot extruding the ingot or the billet obtained from step a) into a tube; and c) cold rolling the tube obtained from step b) to a final dimension thereof. The outer diameter D and the wall thickness t of the cold rolled tube is 50-250 mm respectively is 5-25 mm, and, for the cold rolling step, R and Q are set such that the following formula is satisfied: Rp0.2target=416.53+113.26·log Q+4.0479·R+2694.9·C %−82.750·(log Q)2−0.04279·R2−2.2601·log Q·R+16.9·Cr %+26.1·Mo %+83.6·N %+Z  (1) wherein Rp0.2target is targeted yield strength and is 800-1100 MPa and 0