Corrosion behavior of 17–4 PH stainless steel in simulated marine environment

Abstract

The corrosion behavior of 17–4 precipitation hardened (PH) stainless steel in 3.5 wt% NaCl solution was investigated in the present research by both electrochemical experiments and constant strain rate tensile tests. Electrochemical experiments revealed that corrosion behavior of PH steel was mainly controlled by cathodic reactions. The double‐stage aging process exhibited poor corrosion resistance with a corrosion current density (icorr) of 1.18 × 10−5 A/cm2 in comparison to single‐stage aging and adding intermediate treatments. Scanning electron microscopy (SEM) images suggested that cracks in the samples were deeper and wider, whereas transmission electron microscopy (TEM) images expounded that the precipitation of carbides occurred at grain boundaries. The adding intermediate treatment process yielded the lowest SCC susceptibility (Iscc) with the lowest icorr of 4.98 × 10−6 A/cm2. Furthermore, it was found that anodic dissolution (AD) dominated the stress corrosion cracking (SCC) mechanism of 17–4 PH stainless steel; however, under the same process, applied strain rates also increased the values of Iscc. Therefore, among all factors, heat treatment processes manifested greater effects on Iscc as compared to applied strain rates and loading times.

Influence of scanning strategies on microstructure, residual stress, and corrosion behavior of 17-4 PH stainless steel fabricated by selective laser melting

“…Therefore, the defects and porosity present in the strip alternate and rectangular alternate scan strategies samples act as passivation pitting potential sites in the samples. A similar observation was also reported by Wang et al 21…”

“…Therefore, the defects and porosity present in the strip alternate and rectangular alternate scan strategies samples act as passivation pitting potential sites in the samples. A similar observation was also reported by Wang et al 21 Potentiodynamic polarization test. The open-circuit potential tests were done for all the samples for 600 min, and OCP values are shown in Figure 9(a).…”

“…They reported that islands act as stress releasing zones for island scanning strategy. Wu et al 21 reported that corrosion behavior is influenced by cathode reactions and microstructure for 17-4 precipitation hardened stainless steel (PH SS) fabricated by SLM. Swaroop et al 22 reported that the pitting corrosion of 17-4 PH SS SLM occurred at delta ferrite regions for as-built samples and this delta ferrite phase in the matrix acts as a strong pit initiator.…”

Investigation of tribological and corrosion performance of electroplated hard chromium coating on 17-4 PH steel

“…The corrosion rate calculated using theoretical density of Cr (7.19 g cm −3 ) was 9.2 × 10 −3 mpy (mils per year; 1 mils = 25.4 μm) which clearly shows excellent corrosion resistance of the electroplated hard chromium in 3.5 wt% NaCl medium. Previously, Wu et al [31] have reported corrosion behavior of 17-4 PH stainless steel under different aging conditions in 3.5 wt% NaCl solution at RT and obtained E corr value in the range of −400 mV vs. SCE and corrosion current density in the range 1.18 × 10 −5 A cm −2 to 4.98 × 10 −6 A cm −2 as shown in inset of Figure 12(a). It shows superior corrosion resistance of electroplated chromium in comparison to 17-4 PH stainless steel in 3.5 wt% NaCl solution.…”

Hydrogen induced cracking and stress corrosion cracking behavior of the weld metals in 17‐4 precipitation hardening stainless steel after double over aging treatment

“…Therefore, the decrease in sensitivity to these types of corrosion is highly important. It is reported that applying over aging treatment can effectively reduce the hardness and strength and coarsen the precipitates [9][10][11][12][13]. In the weld metal of the 17-4 precipitation hardening stainless steels, reversed austenite increased by over aging treatment and improved the toughness of the joints [14].…”