Tomo-o Sato and To-oru Furukawa
In aqueous solution of 10 wt%H2SO4 (30°) and 40 wt%HNO3 (boiling), corrosion tests were carried out on 17%Cr and 7%Ni PH stainless steel samples containing 0.73%Al cold-rolled to 50 and 70% reduction in thickness and then aged at 300∼600° for various hours. The following results were obtained; (1) Against 10%H2SO4 solution, the corrosion resistance of the samples cold-rolled 50% was almost the same as that of 18-8 stainless steel (Fig. 1). (2) Against the same solution, the corrosion resistance of this steel cold-rolled to 50 and 70% and aged at 400°×20 hr, 450°×3 hr and 500°×1 hr showed the minimum values. These aging times are somewhat shorter than that required for obtaining the maximum hardness at the respective aging temperature. (3) In 40%NO3 solution, the corrosion loss of the cold-rolled and aged samples of 17-7 steel was almost the same as that of 18-8 steel.
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