Figure 3 - uploaded by G.M. Scamans
Content may be subject to copyright.
All-aluminum 17,000 ton research vessel 'ALCOA SEAPROBE', 1971. Vessels hull fabricated using 5456-H117 and Alcoa's latest welding specifications for marine applications (21).
Similar publications
Citations
... The Mg 2 Al 3 phases are anodic to the Al-matrix and it can be easily dissolved in an aqueous environment, this leads to the intergranular corrosion of the material [2,3]. N.J.H. Holroyd and G.M. Scamans [4] discussed all the corrosion-related issues on Al-Mg alloys. Despite their excellent properties, such as good weldability, formability, lightweight and moderate strength, 5xxx series alloys are highly susceptible to stress corrosion cracking and intergranular corrosion. ...
... Such a distinct potential plateau in the anodic region of AA5083 indicates a limited passivation behaviour and pitting occurred at −784 mV. Pitting corrosion occurred due to the dissolution of anodic beta phase precipitates (Al 8 Mg 5 ) present at grain boundaries of AA5083 [4]. As observed from the PDP curves, all the coated samples shift the cathodic region to a low current density region and at the same time, the anodic region of all the coated samples showed better passivation behaviour than the substrate. ...
Cermet coatings were fabricated on AA5083 by D gun coating technique using three different combinations of powder feedstock namely WC–Co, WC–Co–Cr, and Cr3C2–NiCr. The effect of powder combinations on coatings’ phase composition, surface morphology, and cross-sectional microstructure were investigated using XRD, SEM, and EDS. Major findings revealed that WC–Co and WC–Co–Cr powders produced higher thickness with considerable surface defects compared to a coating that was produced by Cr3C2–NiCr powders. Moreover, a smooth compact and a uniform coating was obtained by using Cr3C2–NiCr powders. Electrochemical corrosion results showed that the OCP values of all the coated samples were shifted to a higher value than substrate and sample coated with Cr3C2–NiCr powder showed a stable OCP and more positive value than other coated samples. Similarly, the PDP curve of sample coated with Cr3C2–NiCr also showed lower corrosion current density at the cathodic region and better passivation behaviour in the anodic region.
... Corrosion is one of the main failure forms of aluminum alloys, and Al-Zn-Mg-Cu alloys are strongly susceptible to the localized corrosion [10,11] , such as pitting, intergranular corrosion (IGC), stress corrosion cracking (SCC) and so on. The poor corrosion resistance limits the applications of Al-Zn-Mg-Cu alloys [12][13][14][15][16] . In the past several decades, some investigations have been carried out to study the relationships between the heat treatment, microstructural evolution and properties of Al-Zn-Mg-Cu alloys [17][18][19][20][21][22] . ...
In order to study the effects of aging treatment on the intergranular corrosion (IGC) and stress corrosion cracking (SCC) of 7003 aluminum alloy (AA7003), the intergranular corrosion test, electrochemical test and slow strain rate test (SSRT), combined with optical microscopy (OM) and scanning electron microscopy (SEM) as well as transmission electron microscopy (TEM) observations have been carried out. The IGC and electrochemical test results showed that the IGC resistance of AA7003 for peak aged (PA) temper is the lowest, with double peak aged (DPA) the moderate, and retrogression and re-aging (RRA) the highest among three tempers, which is attributed to the continuous feature of precipitation on grain boundary of PA temper and the interrupted feature of precipitation on grain boundary of DPA and RRA tempers, as well as the wide precipitation free zones (PFZ) of RRA temper. In addition, the SSRT results indicated that all three tempers AA7003 are susceptible to SCC in IGC solution, and the change tendency of SCC susceptibility (ISCC) of AA7003 for three tempers follows the order: ISCC(RRA)<ISCC(DPA)<ISCC(PA).
... Several investigators chemically charged the AL alloys to introduce H into the metal (Holroyd & Scamans, 2016;Holroyd et al., 2017). Their idea is to substantiate that these AL alloys fail in chemical environment due to H. ...
... Inert behavior (Type 1) is common for lab air and in vacuum. Type 2 has been observed in 5083 alloys under H-charging and in applied potentials (Takemoto & Okamoto, 1984;Holroyd & Scamans, 2016;Holroyd et al., 2017) conditions and in 8090 type of alloys (Ghosh et al., 2007). Type 3 has been observed in 4340 (Frohmberg et al., 1954) steel with H-charging. ...
Stress corrosion characteristics of three alloys, AL-3Li, AL-2Li-3Cu, and 5083, were analyzed. All three alloys have anodic grain boundary (GB) precipitates (ppts) (δ, T1, and β, respectively) that show different corrosion rates with respect to the lattice H diffusion. These GB phases grow with heat treatment time. These phases affect room-temperature fracture toughness in AL-3Li and AL-2Li-3Cu alloys but not in 5083 alloy. When exposed to NaCl solution, all three GB phases dissolve. Under an applied stress, the resulting stress corrosion threshold stress intensity K1scc varies inversely with size and spacing, when the local crack tip environmental condition is established. The mechanism involved is mostly anodic dissolution with a secondary effect from hydrogen.
