Stress corrosion crack initiation testing of high strength aluminium alloys using tuning fork type specimens

An experimental investigation was carried out into the applicability of various corrosive environments for stress corrosion crack initiation testing of high strength aluminium alloys using constant strain loaded tuning fork type specimens. The effect of surface preparation was also involved. The most important findings were that salt-chromate...

The Jominy end-quench test for investigation of corrosion properties and microstructure of high strength aluminium alloys

The Jominy end-quench test was applied to extruded rods of the aluminium alloys 2024 and 7075 to obtain a decreasing quench rate over the length of the rods. Subsequently the alloys were heat treated to the conditions: 2024-T4, 2024-T6, 7075-T73. A corrosion investigation and a transmission electron microscopy investigation were performed to...

Engineering property comparisons of the aluminium plate alloys 7050-T7365I, 7010-T7365I and 7010-T765I

The Al-Zn-Mg-Cu alloy 7050 produced by Alcoa is a typical plate and forging alloy because of its low quench sensitivity. In order to compare this alloy with the earlier tested plate alloy 7010 an experimental programme was performed involving tensile, fracture toughness, and fatigue testing. In addition stress corrosion crack initiation and...

Engineering properties of the recently developed aluminium alloy designated 7010

An experimental investigation.was performed on 80 mm thick plate material of 7OIO-T7651 and 7OIO-T73651 developed by Alcan Industries Ltd in U.K. The testing programme involved: tensile tests, fracture toughness, stress corrosion and fatigue tests. For comparison a similar investigation vas carried out on 7075-T7351 Alcoa plate material.

Heat treatment studies of aluminium alloy type 7050 forgings. Interim report no. 3: Corroded-specimen fatigue tests and SCC propagation tests

The influence of previous corrosion on the fatigue life was investigated. It was foimd that a slight corrosive attack could drastically reduce the fatigue life. The damaging effect of corrosion was greater for the alloy AA 7050 than for AZ 74.61. It could be established that fatigue cracks initiated from various corrosion pits. A second series...

Breukvlakonderzoek

In this report an attempt is made to give an overview of the various aspects involved in a fracture surface investigation, stating with a definition of fractography and why it is done. Then the equipment needed is discussed, including stereo-microscopes, optical microscopes, transmission and scanning electron microscopes, and micro-analysis...

Aluminium alloys for advanced structural applications in transport aircraft

This paper concisely reviews and discusses (1) metallurgically cleaner alloys like -2124, 2048 and 7475, (2) potential application of 7000 series alloys in tension panels, (3) development of high strength stress corrosion resistant thick section materials like 7010, 7049 and 705O, (4) powder metallurgy 7000 series alloys with high strength and...

De toepassing van schade-onderzoek in de luchtvaart

Following an introduction about the methods of failure smalysis the present paper illustrates by meaJis of actual case histories the role of service failure analysis in defining new inspection procedures and the adapting of existing ones. It appears that in some cases this leads to a different design or choice of material. The examples are all...

Heat treatment studies of aluminium alloy forgings of the AZ 74.61 type. Interim report no. 3: Fatigue crack propagation performance under manoeuvre spectrum loading

The fatigue crack propagation performance of the alloy AZ 74.61 under manoeuvre spectrum loading was studied. The crack propagation behaviour was also compared with that of the American forging alloy AA 7050, not only for simulated manoeuvre loading but also for simulated gust loading and programme loading. It was found that, at comparable...

A quantitative analysis of hydrogen-induced cracking

Internal hydrogen embrittlement, stress corrosion cracking and external hydrogen embrittlement of high strength steel are analysed. They are found to have lattice decohesion as a common source.

Study of the growth of stress corrosion cracks in the aluminum alloy 7075. Part III: Continuation of the investigation on the influence and the role of the corrosion potential and the halide anion

SEN specimens of 70T5 alloy loaded in bending have been used to determine time to failure and the crack propagation rate as a function of K, the stress intensity factor, and of the electrical potential in 3 wt % aqueous solutions of NaCl, NaBr and Nal with p values of 3 and 7. The SC tests were supplemented by potentio-kinetic polarization tests...

Heat treatment studies of aluminium alloy type 7050 forgings. Interim report no. 2: The effect of heat treatment on a variety of engineering properties

The effect of variety of heat treatments on various engineering properties was studied with the aim to derive an optimum heat treatment. The engineering properties comprised Vickers hardness, short-time tensile strength, fatigue crack propagation resistance, fracture toughness and stress corrosion resistance. The test results were compared with...

Heat treatment and SCC susceptibility of AU4SG type forged material

Material from forgings rejected after cracking in service was given a variety of heat treatments. Material aged to peak hardness was susceptible to SCC at all ageing temperatures. Overageing at temperatures around 160° C imparted a significant increase in SCC resistance while useful strength was retained. An additional one week ageing at 160° C...

Study of the growth of stress corrosion cracks in the aluminium alloy 7075: part II: investigation on the effect and the role of the corrosion potential