22 2 A method of continuous annealing for cold-rolled 22Cr duplex stainless steel

摘要

PURPOSE: A continuous annealing heat treatment method of cold rolled 22Cr duplex stainless steel is provided which is capable of securing superior pickling property and corrosion resistance as preventing widthwise creep deformation of the cold rolled steel. CONSTITUTION: In a continuous annealing method of the cold rolled 22Cr duplex stainless steel capable of securing superior pickling property and corrosion resistance as preventing widthwise creep deformation of the cold rolled material after cold rolling 22Cr duplex stainless steel consisting austenitic and ferritic phases in which 20 to 27 wt.% of chromium (Cr), 4.0 to 8.0 wt.% of nickel (Ni), 2.0 to 5.0 wt.% of molybdenum (Mo), 0.08 to 0.3 wt.% of nitrogen (N) and 0.0005 to 0.0025 wt.% of calcium (Ca) and 0.0010 to 0.0035 wt.% of boron (B) particularly for improving hot working formability are included, and a balance of Fe and elements contained as inevitable impurities is included, the continuous annealing heat treatment method of cold rolled 22Cr duplex stainless steel is characterized in that the cold rolled 22Cr duplex stainless steel is heat treated in the annealing time range of 30 to 60 seconds by maintaining an excessive oxygen amount of the annealing furnace atmosphere of continuous annealing to 6 to 8%, maintaining temperature of the continuous annealing steel material to 1,045 to 1,060 deg.C and controlling tensile stress applied to the steel material to 0.3 to 0.55 kgf/mm¬2.