Deformation Effects on Intragranular Carbide Precipitation and Transgranular Chromium Depletion in Type 316 Stainless Steels

CORROSION ◽  
1991 ◽  
Vol 47 (12) ◽  
pp. 939-947 ◽  
Author(s):  
A. H. Advani ◽  
L. E. Murr ◽  
D. G. Atteridge ◽  
R. Chelakara ◽  
S. M. Bruemmer
Keyword(s):  
Stainless Steels ◽  
Carbide Precipitation ◽  
Chromium Depletion ◽  
Intragranular Carbide

Deformation effects on transgranular carbide precipitation in 304 stainless steels

1992 ◽  
Vol 50 (1) ◽  
pp. 260-261
Author(s):  
A.H. Advani ◽  
L.E. Murr ◽  
D.J. Matlock ◽  
W.W. Fisher ◽  
P.M. Tarin ◽  
...  
Keyword(s):  
Stainless Steels ◽  
True Strain ◽  
Carbide Precipitation ◽  
Material Research ◽  
Chromium Depletion ◽  
Engineering Strain ◽  
Twin Fault ◽  
Heat Treated ◽  
Strain Induced Martensite ◽  
The Relationship

Plastic deformation is a key variable producing accelerated intergranular (IG) carbide precipitation and chromium-depletion (sensitization) development in stainless steels. Deformation above 20% also produces transgranular (TG) carbides and depletion in the material. Research on TG carbides in SS is, however, limited and has indicated that the precipitation is site-specific preferring twin-fault intersections in 316 SS versus deformation-induced martensite and martensite lath-boundaries in 304 SS. Evidences indicating the relation between martensite and carbides were, however, sketchy.The objective of this work was to fundamentally understand the relationship between TG carbides and strain-induced martensite in 304 SS. Since strain-induced martensite forms at twin-fault intersections in 304 SS and the crystallography of the transformation is well understood, we believed that it could be key in understanding mechanisms of carbides and sensitization in SS. A 0.051% C, 304 SS deformed to ∽33% engineering strain (40% true strain) and heat treated at 670°C/ 0.1-10h was used for the research. The study was carried out on a Hitachi H-8000 STEM at 200 kV.

EM study of carbon content effects on carbide precipitation and chromium depletion in type 304 stainless steels

1993 ◽  
Vol 51 ◽  
pp. 1164-1165
Author(s):  
E.A. Trillo ◽  
A.H. Advani ◽  
L.E. Murr ◽  
W.W. Fisher
Keyword(s):  
Carbon Content ◽  
Stainless Steels ◽  
Test Methods ◽  
Carbide Precipitation ◽  
Valuable Insight ◽  
Chromium Depletion ◽  
Electrochemical Test ◽  
Heat Treated ◽  
Precipitation Characteristics ◽  
Type 304

Carbon content is the most critical compositional variable in carbide precipitation and sensitization development in stainless steels (SS). Quantitative electrochemical test methods have conclusively demonstrated that an increase in carbon content enhances the susceptibility of SS to sensitization development. The increase in sensitization has been considered to be caused by the influence of carbon on the thermodynamics of the precipitation-depletion process. This has been supported by limited TEM work. In this research, we are using electron microscopy to quantify the effects of carbon content on carbide precipitation and chromium-depletion development in SS. Initial observations that compare precipitation characteristics and depletion profiles in 0.011% C, 0.025% C, 0.051% C, and 0.07% C-containing, 304 SS heat treated at 775°C for 0.1-500 h are presented in this paper, and will be enhanced by a statistical analysis of carbon content effects on precipitate sizes, densities, and depletion profiles, to provide a valuable insight into the precipitation-depletion phenomena.

Strain-induced martensite effects on transgranular carbide precipitation in type 304 stainless steels

1991 ◽  
Vol 49 ◽  
pp. 604-605
Author(s):  
A.H. Advani ◽  
L.E. Murr ◽  
D. Matlock
Keyword(s):  
Heat Treatment ◽  
Grain Boundary ◽  
Stress Corrosion Cracking ◽  
Stainless Steels ◽  
Deformation Twin ◽  
Austenitic Stainless Steels ◽  
Carbide Precipitation ◽  
Strain Induced Martensite ◽  
Type 304

Thermomechanically induced strain is a key variable producing accelerated carbide precipitation, sensitization and stress corrosion cracking in austenitic stainless steels (SS). Recent work has indicated that higher levels of strain (above 20%) also produce transgranular (TG) carbide precipitation and corrosion simultaneous with the grain boundary phenomenon in 316 SS. Transgranular precipitates were noted to form primarily on deformation twin-fault planes and their intersections in 316 SS.Briant has indicated that TG precipitation in 316 SS is significantly different from 304 SS due to the formation of strain-induced martensite on 304 SS, though an understanding of the role of martensite on the process has not been developed. This study is concerned with evaluating the effects of strain and strain-induced martensite on TG carbide precipitation in 304 SS. The study was performed on samples of a 0.051%C-304 SS deformed to 33% followed by heat treatment at 670°C for 1 h.

Carbide precipitation and chromium depletion on coherent twin boundaries in deformed 304 stainless steels

1992 ◽  
Vol 50 (2) ◽  
pp. 1216-1217
Author(s):  
A.H. Advani ◽  
L.E. Murr ◽  
D.J. Matlock ◽  
W.W. Fisher ◽  
P.M. Tarin ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Stainless Steels ◽  
Interfacial Free Energy ◽  
Carbide Precipitation ◽  
Twin Boundaries ◽  
Invariant Structure ◽  
Heat Treated ◽  
Constant Structure ◽  
Cr Depletion

Coherent annealing-twin boundaries are constant structure and energy interfaces with an average interfacial free energy of ∼19mJ/m2 versus ∼210 and ∼835mJ/m2 for incoherent twins and “regular” grain boundaries respectively in 304 stainless steels (SS). Due to their low energy, coherent twins form carbides about a factor of 100 slower than grain boundaries, and limited work has also shown differences in Cr-depletion (sensitization) between twin versus grain boundaries. Plastic deformation, may, however, alter the kinetics and thermodynamics of twin-sensitization which is not well understood. The objective of this work was to understand the mechanisms of carbide precipitation and Cr-depletion on coherent twin boundaries in deformed SS. The research is directed toward using this invariant structure and energy interface to understand and model the role of interfacial characteristics on deformation-induced sensitization in SS. Carbides and Cr-depletion were examined on a 20%-strain, 0.051%C-304SS, heat treated to 625°C-4.5h, as described elsewhere.

Prevention of Corrosion in Austenitic Stainless Steel through a Predictive Numerical Model Simulating Grain Boundary Chromium Depletion

2017 ◽  
pp. 374-389
Author(s):  
M.K. Samal
Keyword(s):  
Mathematical Model ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Numerical Model ◽  
Low Temperature ◽  
Grain Boundary ◽  
Stainless Steels ◽  
Predictive Models ◽  
Chromium Depletion ◽  
Sensitization Behavior

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.

Intergranular Corrosion Behavior of 00Cr12 Ferritic Stainless Steels Containing Cerium

2013 ◽  
Vol 690-693 ◽  
pp. 133-138
Author(s):  
Ya Bo Li ◽  
Fu Ming Wang ◽  
Xiao Nong Cheng
Keyword(s):  
Grain Boundary ◽  
Corrosion Behavior ◽  
Stainless Steels ◽  
Intergranular Corrosion ◽  
Optical Microscope ◽  
Mechanism Analysis ◽  
Chromium Depletion ◽  
Ferritic Stainless Steels ◽  
Boundary Density ◽  
Grain Sizes

Intergranular corrosion behavior of 00Cr12 ferritic stainless steels with different amounts cerium was evaluated. For this evaluation, electrochemical measurements - polarization curves - were obtained for tested materials, and optical microscope was used to observe corrosive microstructure. Experimental results shows: cerium reduces grain sizes and improves intergranular corrosion resistance of test materials. Through mechanism analysis: cerium reduces grain sizes, increases grain boundary density, therefore might improve distribution aspects of carbides and nitrides, chromium depletion situation near grain boundary would be improved, this work worth further study.

METALLURGY AND PROCESSING OF STAINLESS STEEL FROM MILL TO FINISHED PRODUCT1

1974 ◽  
Vol 37 (12) ◽  
pp. 612-617
Author(s):  
Bruno Werra
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Stainless Steels ◽  
Carbide Precipitation ◽  
Free Iron ◽  
Surface Finishes ◽  
Welding Processes ◽  
Resistance Data

This paper discusses the relation of “Materials” to 3-A Standards; “Passivity” defined; corrosion resistance of stainless steels; “Free Iron”; “Austenite” defined; analyses; corrosion resistance data; corrosion phenomena; carbide precipitation affect; Galvanic Series; least “noble” (anodic), “active,” and sacrificial; most “noble” (cathodic), “least active,” and least readily sacrificial; welding processes; stainless steel finishes and surface finishes for sanitary food equipment; 3-A Standards resume and explanation of their intent: cleanliness for bacteriological and anti-corrosion reasons.

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