Abstract: Duplex stainless steel pipes were all-position welded by different welding procedure.Microstruetures,mechanical and corrosion properties of the welded joints were investigated on condition of different heat inputs.The test results show heat input is an important factor which has effect on phase ratio.It will lead to more transformation of aus-tenite with higher heat input.Meanwhile,phase ratio also has influence on the mechanical properties such as tension,impact toughness of the welded joints.The corrosion surface morphology and crystallographiccharacteristics of crevice corrosion pit were investigated by scanning electron microscope (SEM).SEM observation reveals that ferrite is corroded preferentially and tubular austenite is uncovered.The occurrence of corrosion is due to the disparity in the electrochemical potentials of ferrite and anstenite.