Precipitation formation on ∑5 and ∑7 grain boundaries in 316L stainless steel and their roles on intergranular corrosion

2021 ◽  
pp. 116822
Author(s):  
Shao-Pu Tsai ◽  
Surendra Kumar Makineni ◽  
Baptiste Gault ◽  
Kaori Kawano-Miyata ◽  
Akira Taniyama ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Grain Boundaries ◽  
Intergranular Corrosion ◽  
316L Stainless Steel ◽  
Precipitation Formation

The Effect of Sigma Phase vs Chromium Carbides On the Intergranular Corrosion Of Type 316 and 316L Stainless Steel (Part 2—Laboratory Investigation)★

CORROSION ◽  
1959 ◽  
Vol 15 (5) ◽  
pp. 17-28 ◽  
Author(s):  
DONALD WARREN
Keyword(s):  
Stainless Steel ◽  
Intergranular Corrosion ◽  
Sigma Phase ◽  
316L Stainless Steel ◽  
Steel Part ◽  
Intergranular Attack ◽  
Acid Media ◽  
Chromium Carbides ◽  
Type 316L ◽  
Stainless Steel Part

Abstract A laboratory study was made of the intergranular corrosion behavior of Types 316 and 316L stainless steel in 14 different acid environments. Included were nitric, nitric-hydrofluoric, acetic, citric, sulfuric, lactic, oxalic, formic and phosphoric acids. Results of this study showed that sensitized or welded Type 316L had excellent resistance to intergranular attack in all of the acid media except nitric. This was true despite the presence of a continuous network of sigma phase in the grain boundaries of the sensitized steel. In contrast, Type 316 having a continuous grain boundary network of chromium carbides underwent severe intergranular corrosion in 12 of the 14 environments studied. 3.2.2

Mechanism of intergranular corrosion of 316L stainless steel in oxidizing acids

1980 ◽  
Vol 14 (11) ◽  
pp. 1175-1179 ◽  
Author(s):  
T.M. Devine ◽  
C.L. Briant ◽  
B.J. Drummond
Keyword(s):  
Stainless Steel ◽  
Intergranular Corrosion ◽  
316L Stainless Steel

The Effects of Sulfur and Phosphorus on the Intergranular Corrosion of 304 Stainless Steel

CORROSION ◽  
1980 ◽  
Vol 36 (9) ◽  
pp. 497-509 ◽  
Author(s):  
C. L. BRIANT
Keyword(s):  
Stainless Steel ◽  
Grain Boundaries ◽  
Intergranular Corrosion ◽  
304 Stainless Steel ◽  
Boundary Structure ◽  
Chromium Depletion ◽  
Grain Boundary Structure ◽  
The Matrix ◽  
Acid Test ◽  
Electrochemical Potentials

Abstract This paper reports a study of the effects of sulfur and phosphorus on the sensitization and intergranular corrosion of 304 stainless steel. It is shown that sulfur has little effect on the intergranular corrosion of the material, except at the high electrochemical potentials of the Huey test and oxalic acid test. At these potentials chromium sulfides precipitated at the grain boundaries and in the matrix are preferentially attacked. Phosphorus has little effect on intergranular corrosion as measured by the modified Strauss test, but it greatly accelerates intergranular corrosion in the Huey test. The magnitude of this effect depends on the extent of chromium depletion. It is also shown that in all of the alloys studied grain boundaries in a given sample corrode at varying rates. This variation appears to be a result of variation in grain boundary structure and hence in precipitation and segregation.

Study on Intergranular Corrosion of Sensitized 316L Stainless Steel

2013 ◽  
Vol 331 ◽  
pp. 391-395
Author(s):  
Yong Quan Li ◽  
Wen Jie Bai ◽  
Shao Qing Pu ◽  
Xu Meng Xie ◽  
Quan Duan
Keyword(s):  
Stainless Steel ◽  
Intergranular Corrosion ◽  
316L Stainless Steel ◽  
Rapid Development ◽  
Large Degree ◽  
Development Stage ◽  
Small Degree ◽  
Inspection Method ◽  
Time Extension ◽  
Material Grain Size

The results of experimental study on intergranular corrosion of sensitized 316L stainless steel by mass loss measurement and metallographic inspection method through boiling nitric acid experiments show that: the intergranular corrosion behavior of sensitized 316L stainless steel is mainly divided into three stages: initiation stage, stable stage and rapid development stage, the corrosion rate added with the experimental time extension; the degree of intergranular corrosion has a direct relationship with material grain size, large grain regions have a small degree of intergranular corrosion; and small grain regions have a large degree of intergranular corrosion, even leading to pitting corrosion.

scholarly journals Intergranular and Pitting Corrosion in Sensitized and Unsensitized 20Cr-25Ni-Nb Austenitic Stainless Steel

CORROSION ◽  
10.5006/3725 ◽  
2021 ◽  
Author(s):  
Ronald Clark ◽  
Choen Chan ◽  
W. Walters ◽  
Dirk Engelberg ◽  
Geraint Williams
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Pitting Corrosion ◽  
Intergranular Corrosion ◽  
Niobium Carbide ◽  
Ion Concentration ◽  
Kelvin Probe ◽  
The Matrix

Advanced gas-cooled reactor (AGR) oxide fuels used in the UK are clad in bespoke grade 20%Cr-25%Ni-Nb austenitic stainless steel. Electrochemistry was first applied to correlate the breakdown potential with chloride ion concentration, temperature and pH for this alloy. At near-neutral pH the unsensitized material exhibited a linear E<sub>b</sub> = A + B log10[Cl<sup>-</sup>] relationship, where A = 0.7 V (vs. SCE), and B = 0.098 V/decade. Scanning Kelvin probe force microscopy revealed grain boundary regions in the heat-treated material up to 65 mV less noble to the matrix, whereas un-dissolved niobium carbide (NbC) precipitates were up to 55 mV more noble to the matrix. In-situ time-lapse microscopy and post-corrosion observations confirmed that sensitized grain boundaries were susceptible to pitting corrosion, further developing along intergranular corrosion pathways. It has however been shown that micro galvanic coupling between the Nb precipitates and matrix and / or sensitized grain boundary regions is not a factor in corrosion initiation as all experiments were performed under external potential control. Post corrosion observations showed the presence of pits at NbC precipitates promoting grain boundary corrosion. It is postulated that corrosion initiates at NbC precipitates as a pit, and when in close vicinity to Cr-depleted grain boundaries, then propagates along grain boundaries as intergranular corrosion.

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