Coupled Multi-Electrode Investigation of Crevice Corrosion of 316 Stainless Steel and NiCrMo Alloy 625

Bocher, Florent; Presuel-Moreno, Francisco; Budiansky, Noah; Scully, John R.

doi:10.1149/1.2789220

Cited by 3 publications

(1 citation statement)

References 17 publications

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“…Other details of the array setup are presented elsewhere. 10,38,39 The compositions of the alloys AISI 316, 625, and 22 are given in Table I. Table II presents the experimental critical crevice temperature ͑CCT͒, 34 critical pitting temperature ͑CPT͒, 34 and the empirical pitting resistance equivalent number ͑PREN͒.…”

Section: Methodsmentioning

confidence: 99%

Investigation of Crevice Corrosion of AISI 316 Stainless Steel Compared to Ni–Cr–Mo Alloys Using Coupled Multielectrode Arrays

Bocher¹,

Presuel-Moreno²,

Scully³

2008

J. Electrochem. Soc.

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Close-packed coupled multielectrode arrays simulating a planar electrode were used to monitor the anodic current evolution as a function of position during initiation and propagation of crevice corrosion of AISI 316 stainless steel (UNS S31600) and Ni–Cr–Mo alloy 625 (UNS N06625). Scaling laws xcrit2 vs G and xcrit*2 vs G derived from polarization data in simulated crevice solutions guided the implementation of rescaled crevices with greater spatial resolution. xcrit and xcrit* are the distances from the mouth to the location where the potential reaches two different critical values, and G is the crevice gap. Scaling laws were also used along with anodic polarization data in simulated crevice solution to predict crevice corrosion behavior of alloy 22 (UNS N06022). Crevice corrosion of AISI 316 stainless steel in 0.6mol∕L NaCl at 50°C readily initiated close to the crevice mouth (i.e., xcrit≈0 ) at modest applied potentials (e.g., Eapp=0normalVSCE ) and spread both inward and outside the crevice with time. Crevice corrosion initiated farther inside the crevice (i.e., xcrit is large) and required higher applied potentials (e.g., Eapp=50mVSCE ) in the case of alloy 625. The local crevice current density increased dramatically over a short period of time to reach a limiting value in the case of AISI 316; while metastable dissolution behavior over a large area was observed for alloy 625. The ramification of the larger critical depth for Ni–Cr–Mo alloys toward crevice corrosion susceptibility in the case of crevice formers of finite length is discussed. Crevice corrosion shifts to the mouth of the crevice for the less corrosion-resistant materials in crevice solutions saturated in metal salts but remains confined at a distance xcrit for alloy 625 under the conditions tested.

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Section: Methodsmentioning

confidence: 99%