Influence of grain boundary carbides and phosphorus segregation on the low-temperature intergranular embrittlement of type 316 stainless steel

In this chapter, a mathematical model for rate of formation of chromium carbides near the grain boundary, which is a pre-cursor to chromium depletion and corresponding sensitization behavior in stainless steels, is presented. This model along with the diffusion equation for chromium in the grain has been used to obtain chromium depletion profiles at various time and temperature conditions. Finite difference method has been used to solve the above equations in the spherical co-ordinate system and the results of time-temperature-sensitization diagrams of four different types of alloys have been compared with those of experiment from literature. For the problem of low temperature sensitization and corresponding inter-granular corrosion in austenitic stainless steel, it is very difficult to carry out experiment at higher temperatures and justify its validity at lower operating temperatures by extrapolation. The development of predictive models is highly useful in order to design the structures for prevention of corrosion of the material in aggressive environments.

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Investigation on the formation of serrated grain boundaries with grain boundary characteristics in an AISI 316 stainless steel

Journal of Nuclear Materials ◽

10.1016/j.jnucmat.2009.06.011 ◽

2009 ◽

Vol 393 (2) ◽

pp. 249-253 ◽

Cited By ~ 11

Author(s):

K.J. Kim ◽

H.U. Hong ◽

S.W. Nam

Keyword(s):

Stainless Steel ◽

Grain Boundary ◽

Grain Boundaries ◽

316 Stainless Steel ◽

Aisi 316 Stainless Steel ◽

Grain Boundary Characteristics ◽

Aisi 316 ◽

Boundary Characteristics

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Radiation-Induced Segregation in 316 and 304 Stainless Steels Irradiated at Low Dose Rate

MRS Proceedings ◽

10.1557/proc-650-r2.4 ◽

2000 ◽

Vol 650 ◽

Author(s):

T. R. Allen ◽

J. I. Cole ◽

J. Ohta ◽

K. Dohi ◽

H. Kusanagi ◽

...

Keyword(s):

Stainless Steel ◽

Grain Boundary ◽

Dose Rate ◽

Stainless Steels ◽

Low Dose ◽

Bulk Composition ◽

304 Stainless Steel ◽

316 Stainless Steel ◽

Low Dose Rate ◽

Radiation Induced

ABSTRACTAs part of the shutdown of the EBR-II reactor, structural materials were retrieved to analyze the effects of long-term irradiation on mechanical properties and microstructure. In this work, the effect of low dose rate irradiation (10−7 to 10−8 dpa/s) on grain boundary composition in 316 and 304 stainless steels was analyzed. Samples were taken from surveillance specimens and subassemblies irradiated in the reflector region of EBR-II at temperatures from 371-390°C to maximum doses of 30 dpa. The effects of dose, dose rate, and bulk composition on radiation- induced segregation are analyzed. In 316 stainless steel, changes in grain boundary chromium and nickel concentrations occur faster than changes in iron and molybdenum concentrations. In 304 stainless steel, decreasing the dose rate increases the amount of grain boundary segregation. For a dose of 20 dpa, chromium depletion and nickel enrichment are greater in 304 stainless steel than in 316 stainless steel, the difference most likely due to dose rate. In both 304 and 316 stainless steels, the presence of a grain boundary precipitate significantly changes the composition of the adjacent grain boundary.

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