Effect of Heat Treatment Applied Potential on the Caustic Stress Corrosion Cracking of Inconel 600

CORROSION ◽  
1985 ◽  
Vol 41 (9) ◽  
pp. 540-553 ◽  
Author(s):  
K. H. Lee ◽  
G. Cragnolino ◽  
D. D. Macdonald
2010 ◽  
Vol 438 ◽  
pp. 155-162 ◽  
Author(s):  
Panayotis Spathis ◽  
Efthimios Papastergiadis ◽  
Georgios Stalidis ◽  
Georgios Papanastasiou

Aim of the present work is the study of corrosion and stress corrosion cracking behaviour of 1050 Al-Alloy anodised in a 3M H2SO4 anodising bath with the presence in it of malonic acid, in various concentrations and anodising current densities. The investigation was carried out by SCC (Stress Corrosion Cracking) tests and electrochemical measurements. The influence of applied potential on SCC behaviour was also examined. The corrosion and SCC behaviour of anodised 1050 Al-Alloy was found to vary with malonic acid concentration, anodising conditions, applied potential and stress level. In SCC conditions all prepared coatings protected the bare alloy, with better protective properties in the case of 0.015M concentration of malonic acid prepared with a 6 A.dm-2 anodising current density. The coating prepared in these conditions had better mechanical properties as indicated from the increased protection at a high stress level and also the better behaviour in corrosion, without stress, conditions of coatings prepared in different conditions of malonic acid concentration and anodising current density. For the interpretation of the results, properties of the anodic coatings as thickness, packing density, coating ratio, roughness, were also studied. The anodic coating formed in a electrolytic bath of 0.015M concentration of malonic acid and a 6 A.dm-2 anodising current density was found to be less porous, more compact and rough, with better oxide structure. Prepared coatings were found to increase protective properties in an area of applied potentials slightly more anodic than the free corrosion potential values.


Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6115
Author(s):  
Marina Cabrini ◽  
Sergio Lorenzi ◽  
Cristian Testa ◽  
Francesco Carugo ◽  
Tommaso Pastore ◽  
...  

Laser bed powder fusion (LPBF) is an additive manufacturing technology for the fabrication of semi-finished components directly from computer-aided design modelling, through melting and consolidation, layer upon layer, of a metallic powder, with a laser source. This manufacturing technique is particularly indicated for poor machinable alloys, such as Alloy 625. However, the unique microstructure generated could modify the resistance of the alloy to environment assisted cracking. The aim of this work was to analyze the stress corrosion cracking (SCC) and hydrogen embrittlement resistance behavior of Alloy 625 obtained by LPBF, both in as-built condition and after a standard heat treatment (grade 1). U-bend testing performed in boiling magnesium chloride at 155 and 170 °C confirmed the immunity of the alloy to SCC. However, slow strain rate tests in simulated ocean water on cathodically polarized specimens highlighted the possibility of the occurrence of hydrogen embrittlement in a specific range of strain rate and cathodic polarization. The very fine grain size and dislocation density of the thermally untreated specimens appeared to increase the hydrogen diffusion and embrittlement effect on pre-charged specimens that were deformed at the high strain rate. Conversely, heat treatment appeared to mitigate hydrogen embrittlement at high strain rates, however at the slow strain rate all the specimens showed a similar behavior.


2005 ◽  
Vol 297-300 ◽  
pp. 993-998 ◽  
Author(s):  
Chun Bo Huang ◽  
Guang Fu Li ◽  
Zhan Peng Lu ◽  
Jian Min Zeng ◽  
Wu Yang

The effects of cold working and heat treatment on caustic stress corrosion cracking (SCC) of mill annealed (MA) alloy 800M in boiling solution of 50%NaOH+0.3%SiO2+0.3%Na2S2O3 were investigated by means of microstructure examination, tensile test, X-ray stress analysis, SCC testing of C-rings, Auger electron spectroscopy (AES), scanning electron microscopy (SEM) and metallography. The microstructure of alloy 800M under tested conditions was austenite. With a train of 25% by cold working, the grains of alloy 800M became longer, yield strength (YS) and ultimate tensile strength (UTS) increased, elongation (δ ) decreased, residual stress and the susceptibility to SCC increased. With increasing temperature of heat treatment of alloy 800M with cold working, the grains became bigger , residual stress, YS and UTS decreased and δ increased, the susceptibility to SCC of alloy 800M decreased. In boiling caustic solution, SCC cracks on the surfaces of C-ring specimens polarized potentiostatically at –20mV/SCE initiated from pitting and propagated along grain boundaries. AES analysis indicated that the surface films on MA alloy 800M were enriched in nickel and depleted in iron and chromium.


CORROSION ◽  
1973 ◽  
Vol 29 (11) ◽  
pp. 442-450 ◽  
Author(s):  
DAVID A. VERMILYEA

Abstract Stress corrosion cracking (SCC) of iron and nickel base alloys in aqueous solutions at 289 C (552 F) has been studied using a straining electrode apparatus. Cracking susceptibility decreases in the order sensitized stainless steel, cold worked stainless steel containing martensite, sensitized Inconel 600, annealed stainless steel, and annealed or cold worked Inconel 600 and alloy AL 326. High cracking susceptibility usually occurs when conditions result in the development of thick reaction products. Acid conditions and chromium depletion favor thick reaction products and enhance susceptibility.


CORROSION ◽  
1977 ◽  
Vol 33 (1) ◽  
pp. 20-26 ◽  
Author(s):  
G. J. THEUS

Abstract Modified Streicher and 288 C (550 F) electrochemical caustic stress corrosion tests were performed on Alloy 600 to determine the relationship between acid intergranular attack susceptibility and caustic stress corrosion cracking (SCC) susceptibility. Mill annealed and solution annealed materials with and without a subsequent 621 C (1150 F) heat treatment (simulated stress relief) were evaluated. Susceptibility to attack in the Streicher test was greatest for material that had received a 621 C (1150 F) heat treatment, whereas this heat treatment caused the same material to be least susceptible to cracking in the electrochemical tests. The conclusions drawn from these results are: (1) stress relieving Alloy 600 does improve its resistance to caustic SCC, and (2) resistance of Alloy 600 to acid intergranular attack does not imply resistance of Alloy 600 to caustic SCC. Therefore, the results demonstrate the need for selecting corrosion qualification tests which are relevant to service conditions.


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