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THIS paper shows briefly the origins and development of a comparatively new and certainly important branch of engineering science. For many years the alloys of the light metals, particularly of aluminium and magnesium, have been developed, until the term “light alloys” has come to be generally accepted as indicating the alloys of the light metals or any metallic alloy having a density of less than about 3·8. Towards the other end of the density scale are now being developed alloys of the heavy metals, mainly tungsten and tantalum. The techniques of production and manufacture of these two groups are very different: whereas the light alloys are produced and manipulated mainly by melting, casting, annealing, and forging, the heavy alloys are produced by various processes of powder metallurgy, resulting in substances with densities of 15 or more.

A review is made of existing and likely future aircraft materials and their choice for use on airframes is discussed in relation to the problems of advanced aircraft design. Both technological and production problems arc included and it is finally suggested that urgent governmental action is required to remedy Great Britain's grave lack of suitable capital equipment.

IN replying to the discussion on one of his many excellent papers to the Institute of Metals, the late Dr. Rosenhain once made a statement to the effect that it took industry approximately ten to fifteen years to develop for commercial use the advances in knowledge which resulted from the researches of such Institutions as the National Physical Laboratory. Whatever may have been the shortcomings of industry ten years ago, the outstanding feature in the world of light alloys during the past two or three years has been the tremendous increase in manufacturing capacity and the modernization of all methods of production. This has been a necessity, caused on the one hand by the progressive increase in size of engines and planes, and on the other hand by the Rearmament Programme, which has been necessary owing to the unsettled condition of world affairs.

D.T.D. Aluminium and Light Alloys † 18C Light Alloy Forgings and Stampings.

131A Aluminium Alloy Sand or Die Castings (suitable for Pistons, etc.).

WHEN the use of metals in the construction of the more important parts of aircraft of the heavier‐than‐air type superseded the use of timber, a large number of practical problems were encountered, as might reasonably be expected. The reasons for the popularity of metal structures are readily appreciated by those who have had experience of wooden structures. An important property in any material employed in aircraft construction is that of permanence. So far as materials employed in marine aircraft are concerned, the task of supplying alloys to give the desired degree of permanence, together with the necessary mechanical properties, is not by any means an easy one. The corrosion‐resistance, in particular, is a property vitally affecting the suitability of a particular metal or alloy for use in marine aircraft. Most industrial metals corrode—i.e., enter into chemical reactions, the result of which is in effect the conversion of some of their mass into non‐metallic matter—on exposure to a normal inland atmosphere, and as a rule the rate of corrosion is much greater in marine atmospheres or in contact with sea water.

FOR the welding of light alloys, the flame should be adjusted to a fairly distinct cone having a light aura which indicates a small excess of acetylene. Under no circumstances should there be an excess of oxygen, as this would burn the material. With the longer types of job, the blowpipe should be cooled as often as possible in cold water and the flame should be frequently re‐adjusted.

THE considerations involved in the successful machining of aluminium and its alloys have sprung into particular prominence during the last year or so with the greatly increased use of these materials under the armaments expansion programme. Numerous firms who have hitherto confined their attentions to steels and non‐ferrous metals like brass and copper arc now engaged in the mass production of parts machined from extruded, rolled and cast aluminium and aluminium alloys. These light metals are by no means difficult to machine but their particular properties require a special technique if full advantage is to be taken of the economy resulting from the high speed at which they may be worked.

In this article a resume is given of the principal obsevations made during the course of exposure in a natural atmosphere during some twenty years, while choosing the most characteristic examples. The following points will be examined: Resistance to spray and mist of aluminium‐magnesium, aluminium‐magnesium‐silicon, aluminium‐ zinc‐magnesium, and aluminium‐copper magnesium rolled alloys, and of cast alloys; Behaviour of welds, and of contacts with steel and cement; Behaviour during immersion in the sea, and corrosion by differential aeration; Protection by anodisation. These observations have been made during exposure at the experimental stations of the Pechiney Group, in marine atmospheres at Salin‐de‐Giraud (Mediterranean), Saint‐Jean‐de‐Luz, Biarritz and Ostend, and in an industrial atmosphere at Aubervilliers.

The purpose of the present paper is to develop a new technology for producing magnesium alloy twin-rib aircraft brackets by the forging method.

An overall description of magnesium alloys is given, with particular emphasis placed on magnesium wrought alloys that are used in the aircraft industry. Methods for producing ribbed brackets are discussed and the location of these parts in aircraft structure is described. The forging process for producing AZ31 magnesium alloy twin-rib brackets was modelled numerically, and selected results of the simulations performed are presented. The simulation results were then verified under laboratory conditions using a three-slide forging press equipped with three movable working tools. It was assumed that the use of this machine would allow for obtaining twin-rib aircraft brackets with improved both functional and strength properties compared to the production methods used so far.

The results demonstrate that the method developed by the present authors permits the production of twin-rib brackets. Positive theoretical results and preliminary experimental results prove that it is justified that the research on magnesium alloys used in the aircraft industry be continued.

The production of twin-rib aircraft brackets from magnesium alloys by the technology developed by the present authors would lead to enhanced product quality with simultaneous reduction in production costs (reduced labour costs and material consumption as well as increased process efficiency). At present, magnesium alloy aircraft parts, mainly obtained from semi-finished products imported to Poland, are produced by casting and machining methods. They exhibit, however, much worse properties than elements produced by metal forming methods. In addition to that, the application of machining in the production of these part leads to higher production costs.

The originality of this study stems from the presentation of an innovative metal forming technology for producing twin-rib brackets. This method is unique on a global scale, and its basic assumptions have been granted patent protection. Also, the originality of the study stems from the fact that brackets are made from magnesium alloys, as these light metals are considered the future of structural materials used in the aircraft industry. Given the above, the research on developing the technology for producing parts made from these alloys using a three-slide press is justified.