成分和微观组织结构对430不锈钢耐点蚀性能的影响OA

To address the issue that the pitting corrosion resistance of commercial 430 stainless steel varies significantly without systematic clarification on the root cause,cold-rolled 430 stainless steel sheets from four different steel mills(A,B,C,D)were selected in this study.Their pitting corrosion resistance was sys-tematically compared using immersion tests,critical pitting temperature(CPT)measurements,and pitting potential tests,combined with chemical composition and microstructural characterization.This investigation not only evaluated the theoretical predictability of the pitting resistance equivalent number(PREN),but also emphasized the decisive role of the actual microstructure on corrosion performance.Results show that A-430SS exhibits the best pitting corrosion resistance,with the highest average pitting potential(40.7 mV)in 3.5%NaCl solution and the highest CPT(57.3℃)in Cl⁻ solution of mass fraction 50×10⁻6,followed by B-430SS,while C-430SS and D-430SS show the poorest performance.Although B-430SS possesses the highest PREN value(17.61)due to its relatively high mass fraction of Cr(16.78%)and N(0.052%),its actual corrosion resistance is not optimal.Microstructural analysis reveals that A-430SS has excellent cleanliness with only 5 type-D inclusions,much lower than 23 in C-430SS and 20 in D-430SS,and a fully recrystallized,uniform and band-free microstructure,which effectively inhibits pitting nucleation.In contrast,the large number of inclusions and banded structure caused by incomplete recrystallization in B-430SS greatly weakens its com-positional advantage of high PREN.This study clarifies that microstructural defects can dominate the pitting corrosion resistance of commercial 430 stainless steel,invalidating the composition-based PREN prediction,and provides an important basis for the processing optimization and material selection of high-performance ferritic stainless steels.