Shimpei Tokuda

The effects of applied stress on the pitting of sensitized Type 304 stainless steel were investigated in 4 M MgCl2 immersion test. Regardless of whether stress was applied, pitting was initiated at inclusions at sensitized grain boundaries. In the absence of applied stress, the occurrence of pitting decreased when the area exposed to the solution decreased, and not all the inclusions acted as initiation sites. However, pitting was observed independent of the exposed area under applied stress. Th

The effect of sensitization on the pitting potentials at MnS and CrS inclusions in Type 304 stainless steels was assessed. For Type 304 containing MnS inclusions, MnS dissolution was observed approximately 0.3 V, and the pitting potential at MnS was in the passive region and decreased by sensitization. Based on the pit morphology, the pit initiation at MnS inclusions is thought to be caused by the transition from passive to active state of the steel matrix. In contrast, the pitting potential at

MnS inclusions in Type 304 stainless steel were mainly transformed into oxide/oxysulfide inclusions by heat-treatment at 1673 K. In 0.1 M MgCl2 under both the no-stress and stress conditions, the pitting potential of the steel heat-treated at 1673 K was higher than the steel heat-treated at 1373 K. The pitting potential of the stainless steel heat-treated at 1673 K did not decrease due to applied stress. For the steel heat-treated at 1673 K, the dissolution current of oxide/oxysulfide inclusions

Electrochemical measurements with and without stress were conducted to clarify the effect of applied stress on pitting corrosion behavior. In potentiodynamic polarization, the increase of the chloride ion concentration led to the formation of shallower pits. In immersion tests with and without stress in the 4 M MgCl2 solution at pH 5, the pit was formed slightly earlier under applied stress. However, there is no or little effect of stress on the corrosion potential before and after the pit initi

Stainless steels are widely used in structural applications due to their superior corrosion resistance. However, stainless steels sometimes suffer from pitting corrosion and stress corrosion cracking in chloride environments. It was reported that applied stress promoted pitting corrosion and changed the morphology of pitting corrosion 1 . Moreover, it is known that stress corrosion cracking is often initiated at pits in stress environment 2 . Elucidating the effect of applied stress on pitting c

Stainless steels are widely used due to their excellent corrosion resistance. In actual applications, stainless steels tend to suffer from localized corrosion such as pitting, crevice corrosion, and stress corrosion cracking (SCC) in chloride environments. Among others, SCC is dangerous because its growth rate is often rapid and SCC readily causes material failure due to a combination of a material and a corrosive environment under tensile stress. Pitting corrosion is well known to be the initia

In this report, various properties of ks-2, such as resistance of corrosion and cavitation-erosion, mechanical properties, weldability and corrosion fatigue strength are described with test results on an actual blade. In addition, the result on a propeller in an actual ship test is also included.