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CHROMIUM‐PLATED STEEL BOLTS Fatigue strength after saline immersion. An article in Werkstoffe und Korrosion, October 1964, by F. Bollenrath, reports the effects of a 3% saline solution on tensile fatigue strength of bolts made from two special steels, the bolts being either chromium plated or non‐plated. Tensile fatigue strength was measured after 10 × 106 load cycles with a nominal mean stress of σm = 20 kg/mm2 (see graphs below). Both steels, known as IK 1 and IK 2, have a low carbon content; steel IK 2 has higher contents of C, Si, Mn, Cu and Ti than IK 1.

SOME faulty castings of aluminium—and magnesium—alloys were partly statically loaded and partly dynamically loaded in imitation of operational conditions, up to the point of rupture. From the test results it was possible to obtain some basic facts for the estimation of casting faults.

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the U.S. National Advisory Committee for Aeronautics, and publications of other similar research bodies as issued

MOST previous methods for predicting moments of resistance of beams subjected to pure bending beyond the limit of proportionality involve somewhat complicated and cumbersome calculations and are usually confined to specific materials and cross‐sections.

SOME kinds of chrome‐molybdenum steels widely employed in the construction of aeroplanes, the chrome‐manganese‐silicon steels introduced comparatively recently and even some carbon steels with a higher content than 0·2 per cent. carbon show minute cracks after welding with oxy‐acctylene, even when the actual operation of welding is carried out faultlessly. This tendency is described as “weld‐crackability,” cracking occurring at high temperatures. At first, micro‐fractures form, causing in turn the formation of cracks that are visible at a temperature still high enough to cover their surface with a dark bluish flux. These cracks occur not only in the weld itself but also in the whole of the region affected by the thermic influence of the flame. It is characteristic that welding by an electric are does not produce this phenomenon.

THE METHODS available for the application of chromium coatings are listed in Table 2. Until recently most chromium coatings have been applied either by electrodeposition or chemical vapour deposition. Vacuum and powder‐coating techniques are breaking through in strip‐coating, and electrodeposition has also been investigated extensively since steel, having a thin ‘flash‐coating’ of chromium, can compete successfully with tin‐plate.

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the U.S. National Advisory Committee for Aeronautics and publications of other similar research bodies as issued

THE importance of control surface mass balancing does not need to be emphasized, and it is well known that the faster aeroplanes fly, the greater is the care and attention which the designer must give to this question.

LIST No. 6 APPLICATIONS for the supply of copies of translations mentioned below should be addressed to the Under‐Secretary of State, Air Ministry (R.T.P.), Berkeley Square House, W.1, and will be supplied, free of charge, as far as availability of stocks permit. Suggestions concerning new translations will be considered in relation to general interest and facilities available.

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Committee, Reports and Technical Notes of the U.S. National Advisory Committee for Aeronautics and publications of other similar research bodies as issued