This paper provides a review of recent developments in the field of Mg corrosion and puts those into context. This includes considerations of corrosion manifestations, material influences, surface treatment, anodization, coatings, inhibition, biodegradable medical applications, stress corrosion cracking, flammability, corrosion mechanisms for HP Mg, critical evaluation of corrosion mechanisms, and concluding remarks. There has been much research recently, and much research continues in this area. This is expected to produce significantly better, more-corrosion-resistant Mg alloys.

Review of Recent Developments in the Field of Magnesium Corrosion

This review aims to provide a foundation for the safe and effective use of magnesium (Mg) alloys, including practical guidelines for the service use of Mg alloys in the atmosphere and/or in contact with aqueous solutions. This is to provide support for the rapidly increasing use of Mg in industrial applications, particularly in the automobile industry. These guidelines should be firmly based on a critical analysis of our knowledge of SCC based on (1) service experience, (2) laboratory testing and (3) understanding of the mechanism of SCC, as well as based on an understanding of the Mg corrosion mechanism.

A Critical Review of the Stress Corrosion Cracking (SCC) of Magnesium Alloys

Much of our understanding of the Mg corrosion mechanism is based on research using aggressive chloride based solutions like 3% NaCl, which are appropriate for understand the corrosion for applications such as auto construction. The chloride ions tend to cause break down of the partly protective surface film on the Mg alloy surface. The corrosion rate increases with exposure time until steady state is reached, which may take several weeks. An overview is provided of the aspects which determine the corrosion of Mg alloys: (i) measurement details; (ii) impurity elements Fe, Ni, Cu and Co; (iii) second phases; (iv) surface films and surface condition and (v) stress corrosion cracking (SCC). This understanding is used to help understand Mg corrosion for Mg as a biodegradable implant for medical applications. Solutions that elucidate these applications tend to form surface films and the corrosion rate tends to decrease with immersion time.

Corrosion mechanism applicable to biodegradable magnesium implants

Hydrogen embrittlement in different materials: A review

The opportunity to give an invited presentation to the Gordon Research Conference - Aqueous Corrosion in 2006 and reflections on the discussion at the conference were used to review our understanding of Mg corrosion mechanism, to generate new insights, to identify gaps in our knowledge and to identify research opportunities.

Recent Insights into the Mechanism of Magnesium Corrosion and Research Suggestions

This paper presents a new testing apparatus for stress corrosion research. In this linearly increasing stress test (LIST) method, plain un-notched specimens are simultaneously exposed to an environment and subjected to an applied stress increasing linearly at a controlled rate. Experiments are repeated at various applied stress rates and the parameters measured include SCC initiation stress (the stress at which stress corrosion cracks start to propagate), fracture stress and average crack velocity. The LIST test is similar to the constant extension rate test (CERT) test, with the essential difference that the LIST test is load-controlled whereas the CERT test is displacement-controlled. The LIST test is particularly aimed at service conditions of loaded parts and structures; that is, service conditions described as load-controlled. This paper describes the design, construction and operation of the test apparatus and some typical results are given to illustrate its performance. Experiments have been conducted using as-quenched 3.5Ni-Cr-Mo-V turbine rotor steel specimens in aerated distilled water at 90 degrees C at stress rates varying from 0.00034 MPa s-1 to 2.08 MPa s-1.

https://iopscience.iop.org/article/10.1088/0957-0233/4/11/017/pdf

C.C. Brosnan

Papers

Linearly increasing stress test (LIST) for SCC research

A new impinging jet test rig used to identify the important parameters in service erosion-corrosion in bayer liquor and to study the damage morphology