Method for manufacturing austenitic stainless steel strip
A method for manufacturing an austenitic stainless steel strip comprises: hot-rolling a material having a component composition containing, in % by mass, more than 20.0% and 30.0% or less of Ni, more than 15.0% and 18.0% or less of Cr, 1.0 to 2.0% of Mo, 3.5% or more and less than 5.0% of Al, more than 1.0% and 2.0% or less of Nb+Ta, 0.3% or less of Ti+V, 1.0% or less of Si, 2.0% or less of Mn, 0.01 to 0.3% of Zr, 0.005 to 0.045% of C, 0.001 to 0.03% of B, and also containing at least one element selected from Y, La, Ce and Hf in an amount such that the content of Y+La+Ce+Hf+Zr can become 0.01 to 0.5% with the remainder comprising Fe and unavoidable impurities; cold-rolling the strip; and heating the strip, then maintaining the strip at that temperature, and rapid-cooling the strip.
1 . A method for manufacturing an austenitic stainless steel strip, which obtains an austenitic stainless steel strip having a sheet width of 120 mm or more and a sheet thickness of 3 mm or less, the method comprising:
a hot rolling step of performing hot rolling on a hot rolling material to form a hot-rolled steel strip, wherein the hot rolling material has a component composition including, in % by mass,
Ni: more than 20.0% and 30.0% or less,
Cr: more than 15.0% and 18.0% or less,
Mo: 1.0 to 2.0%,
Al: 3.5% or more and less than 5.0%,
Nb+Ta: more than 1.0% and 2.0% or less,
Ti+V: 0.3% or less, including 0%,
Si: 1.0% or less, including 0%,
Mn: 2.0% or less, including 0%,
Zr: 0.01 to 0.3%,
C: 0.005 to 0.045%,
B: 0.001 to 0.03%, and
as necessary, at least one of Y, La, Ce, and Hf in a range of 0.01 to 0.5% of Y+La+Ce+Hf+Zr, with the remainder comprising Fe and unavoidable impurities;
a cold rolling step of performing cold rolling on the hot-rolled steel strip after the hot rolling step to form a cold-rolled steel strip;
a polishing step of removing an oxide layer and a nitride layer formed during the hot rolling step on a rolled steel strip surface between the hot rolling step and the cold rolling step or during the cold rolling step; and
a solution treatment step of performing heating and maintaining the cold-rolled steel strip after the cold rolling step in a non-oxidizing atmosphere free of nitrogen at 1,000 to 1,150° C. for 0.1 to 30 minutes and then rapid cooling at a cooling rate of 5° C./s or faster,
wherein the austenitic stainless steel strip obtained after the solution treatment step has an average austenite grain size of 30 to 100 μm.