Corrosion creep magnesium alloys

E. M. Gutman, A. Eliezer, Ya. Unigovski, E. Abramov, Mechanoelectrochemical behavior and creep corrosion of magnesium alloys. Material Set Eng. A, A302 (2001) 63-67. 

It may be felt that the initiation of a stress-corrosion test involves no more than bringing the environment into contact with the specimen in which a stress is generated, but the order in which these steps are carried out may influence the results obtained, as may certain other actions at the start of the test. Thus, in outdoor exposure tests the time of the year at which the test is initiated can have a marked effect upon the time to failure as can the orientation of the specimen, i.e. according to whether the tension surface in bend specimens is horizontal upwards or downwards or at some other angle. But even in laboratory tests, the time at which the stress is applied in relation to the time at which the specimen is exposed to the environment may influence results. Figure 8.100 shows the effects of exposure for 3 h at the applied stress before the solution was introduced to the cell, upon the failure of a magnesium alloy immersed in a chromate-chloride solution. Clearly such prior creep extends the lifetime of specimens and raises the threshold stress very considerably and since other metals are known to be strain-rate sensitive in their cracking response, it is likely that the type of result apparent in Fig. 8.100 is more widely applicable. 

Sivaraj D, McCune R, Mallick P K and Mohanty (2006), Aqueous corrosion of experimental creep-resistant magnesium alloys , 2006 SAE World Congress, SAE Paper No. 2006-01-0257. 

Corrosion creep and fatigue behavior of magnesium (Mg) alloys... 

Key words magnesium alloys, corrosion creep, corrosion fatigue, buffer solution, NaCl, Na2S04. 

The synergistic effect of corrosion and stress on the creep behavior of magnesium and diecast Mg alloys named corrosion creep has been investigated. We can conclude that at room temperature marked plasticization and fracture are observed in sodium tetraborate buffer solution even under stresses less than 40% of TYS as compared with common low-temperature creep in air almost... 

Anodized Mg alloys reveal a significantly longer creep life than uncoated diecast alloys. Pure magnesium shows transgranular fracture in corrosion creep tests against the ordinary intergranular fracture of alloys in corrosive media. 

Small alloy additions are made to zinc to improve grain size, give work hardening, and improve properties such as creep resistance and corrosion resistance. There are a number of proprietary compositions available containing additions of copper, manganese, magnesium, aluminum, chromium, and titanium. 

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