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The purpose of this paper is to study the effect of surface salt spray duration on the fretting wear and electrochemical corrosion behaviors of Inconel 690 alloy.

A high-temperature steam generator was applied to salt spray test samples, a fretting wear rig was used to realize the damage behavior tests, an electrochemical workstation was applied to analysis the changes of each sample’s corrosion dynamic response before and after fretting wear.

The thickness of the oxide film that formed on sample surface was increased with the salt spray duration, and somewhat it could act as lubrication during the fretting wear process; however, the corrosive chloride would accelerate the fretting mechanical damage behavior.

In a salt steam spray condition, the fretting tribo-corrosion behaviors of Inconel 690 alloy surface was studied.

Fretting corrosion—a surface damage occurring between two closely fitting surfaces subject to slight vibrational movement—has caused trouble in machinery ever since the first closely fitting machined parts were put together. It is something different from ordinary wear or rusting of the usual chemical nature, and it is not always recognised as fretting corrosion by users of equipment in which it occurs. ‘Friction oxidation,’ ‘wear oxidation,’ ‘false brinelling,’ ‘chafing,’ ‘bleeding’ and ‘cocoa’ are some of the names that have been applied to the phenomenon. One of the results of work carried out by the Mechanical Engineering Research Laboratory of the D.S.I.R., briefly described in CORROSION TECHNOLOGY, May 1954, is that it is possible to correlate the degree of damage with such variables as total number of oscillations, load or atmospheric humidity. In the United States, too, much work has been done on fretting corrosion and ways of combating it. So that as many as possible could benefit from this research, the American Society for Testing Materials organised a Symposium in which leading experts gave their findings. The Symposium has recently been published as a booklet. Here are shortened versions of two of the papers presented.

The study aims to analyze the fretting phenomenon, manifested at the taper junctions of modular total hip prostheses (THP). Modularity of prostheses implies the micro-movement occurrence. Fractures can arise as a result of the fretting cracking of the prostheses components, affecting durability of modular THPs. Fretting corrosion is associated with the decrease in the clinical acceptance of hip modular implants.

Starting from the fretting phenomenon influence on modularity, monoblock THPs and prostheses with modular femoral head recovered from some review surgeries were investigated. Modular prostheses have a taper junction femoral head – femoral stem neck. Investigation consisted in the analysis of fretting wear and fretting corrosion, of the femoral heads’ taper and of the femoral stems’ trunnions.

The main result was that the micro-movement that provokes the fretting of the femoral head-femoral stem taper junction analyzed does not have the same direction. It is manifesting in the direction of the axis of the femoral head taper, around this axis or as a composed movement. The authors suspect that this is due to the different design of the taper. In this way, the inclination of the stem’s trunnion into the head hole has a different angular misalignment and may cause greater damages of the taper.

This result can be a starting point from the improvement of the future taper junctions design that will improve the quality, durability and modularity of THPs.

The Presidential Address to the Liverpool Engineering Society by Mr. Farthing (the salient points of which are reproduced in this issue) has particular bearing upon lubrication and especially on young lubrication engineers. Mr. Farthing stressed the very wide field open to young engineers and the difficulties associated with training in order to cover as wide a field as may be necessary. It is usually so important to gain a wide knowledge before one can specialise and this is certainly the case with lubrication engineers. One cannot begin to fully appreciate the intricacies of a lubrication system with all its accessory components lubricating and guarding, for example, a large motive power plant or rolling mill, until one has more than a mere working knowledge of the plant itself, the duties it must perform, how it performs them and the snags that arise which might be overcome by correct lubrication. In view of the fact that lubrication systems are just as important in a textile mill as in a power station or a large brick works, the almost impossible‐to‐achieve‐range of knowledge that would simplify the work of a lubrication engineer is very obvious. Fortunately, lubricating principles apply to most cases and knowing how to apply one's knowledge from basic principles is the key to success in this difficult profession.

Corrosion cracking A metal fails due to corrosion fatigue if it cracks while being subjected to repeated or alternating tensile stresses in a corrosive environment. If the corrosive environment is removed, the metal will not fail through fatigue, even after a very high number of cycles, providing the tensile stress is below the fatigue limit.

DALIC‐PLATING, the technique by which electrodeposits are made from electrolytes held in absorbent materials attached to portable electrodes, is of growing industrial importance; not least in the prevention of corrosion problems, particularly fretting corrosion. The high current densities employed enable the process to be carried out very quickly. The Dalic equipment and solutions are supplied in Britain by Metadalic Ltd., of Gatwick Road, Crawley, Sussex.

Introduction There is no need to emphasize the problems that corrosion can cause. It is like a cancer cell, sometimes slowly developing for many years undetected and then once observed it is too late to eliminate. The best course of action at that stage being to try and contain it. Corrosion is a very complex chemical action involving a metal with its environment and it is rare for all the various circumstances to repeat themselves, resulting in an identical corrosion situation.

FRETTING AND FRICTION AT THE N.E.L. Engineering materials cannot be used efficiently unless the designer knows the stresses to which components made from them will be subjected in service, and how the material will behave under those stresses. The National Engineering Laboratory, East Kilbride, Glasgow, is adding considerably to the sum of this knowledge and its report for 1958 covers mechanical engineering aspects of corrosion as well as properties and strength of materials and other basic research.

Solutions to the many corrosion problems of industry are being sought in the laboratories of the Department of Scientific and Industrial Research and its affiliated research associations. These investigations range from the fundamental work at the Chemical Research Laboratory to studies on the special problems of industry, such as the protection of coil springs against corrosion. Here is a summary of results achieved and future plans as recorded in the 1952–53 report of the D.S.I.R. which appeared recently.