FLAWS IN STEEL.

Hauraki Plains Gazette, Volume XXXVI, Issue 4795, 5 January 1925, Page 3

FLAWS IN STEEL.

THE X-RAY INDUSTRY.

OLD WOOD IN AN AEROPLANE.

How X-rays can be used for testing materials and detecting flaws in axles, aeroplane parts, guns motor tyres, etc., was described recently in London by Mr V. E. Pullin, director of Radiology in the research department oi Woolwich Arsenal, reports the London correspondent of the “Manchester Guardian." He jvas lecturing o'n “Radiology in Inspection" at the Royal Society of Arts before the Institute of Engineering Inspection.

J t was vitally necessary, said Mr Puilin, that the results obtained bv research workens should be accepted industrially. X-rays should be used in industry as a routine method of chemical analysis and of testing materials. It would not be necessary to employ highly trained physicists. Unskilled workmen could do the work, but it is most important that the Xray apparatus should be specially designed for special work, and that every precaution should be taken to ensure the safety of the worker. If this were done there would not be the slightest risk of injury.

Bridges, wheels and axles of railway engines and carriages, should be subjected to radio-analysis, and every single part of an aeroplane should be examined before assembling. The question was not whether British industry could afford to use X-rays in this manner, but whether it could afford not to do so. This special work had been started at Woolwich, and they were now able, by means of Xrays, to peer into solid steel of'between 3)-2 to 3% inches thick. Theie was no theoretical reason why they should not be able to deal with steel eight or nine inches thick. The services are now regularly using this metbou and finding it very satisfactory from, the economic standpoint. The world flight had been delayed by a defective engine casing. Why was it not X-rayed before starting ? In time legislation would insist upon the Xray examination of aeroplanes. INSTRUMENT OF PRECISION.

The X-ray was an instrument of precision and pf wonderful adaptability', and could be used with extraordinary accuracy by a workman. The use of X-rays in chemical analysis had net been developed, but it would be .specially useful in industrial concerns where chemical analysis was a matter of routine. Every element when X-rayed threw a different pattern on a photographic plate, and impurities could be detected by tliis me.ais. With the X-ray spectrometer it was possible to detect what happened to the atoms of a metal in a temperature change, and to detect the direction of cleavage planes.

Railway bridges, railway lines, the axles of buses and trains, had to be taken down because of the alteration of the crystal size of the metals, but With a tiny' piece knocked off the nic-tal and photographed by X-rays it was possible to- discover any alteration and appreciate any deterioration from this cause.

The lecturer showed a series of photographs illustrating the use o>. X-rays at Woolwich Arsenal to detect the flaws in machinery. These were of extraordinary interest. The penetrativeness of the rays was proved by one photograph taken through three inches of steel. The letters R. D., written in lead paint on the other side of the metal, were startlingly distinct. Another photograph of a metaT casting before the finishing process showed a number of .holes in the metal which were localised. Some ingots of brass intended to be used for cartridges were X-rayed and were shown to contain many' flaws.

The extreme value of the method was shown in the photograph of a turbine wheel designed to perform 10.000 revolutions a minute. This was found to have a crack right through the spindle. The workmen who made the important wooden part of an aeroplane which was supposed to be of new wood had* not reckoned on the canvas-covered wood being Xrayed. Inspection shoyved old screw ho’es, a conclusive proof that old wood had been used.

Another important investigation of two long , pieces of-metal welded together discovered the fact that the soldering held at the edges, and instead of.solid yvelding there was a crack nearly down all the length. The breaking up of enemy' bulletis of unknown composition resulted in accidents until X-ray photographs were taken and the explosive located. Sometimes a costly gun might show a slip.ht crack on the surface. Photographic films were placed inside, and the photograph taken showed .whether the crack yvas merely a surface mark or structural.

Turning to less deadly things, Mr Pullin showed how with X-rays it was possible to detect the crinkling of canvas in a motor tyre, which diminishes its wearing quality, and suggested strongly that this method should be adopted in industry. It was not yet possible, he said, to get the best o'ut of X-rays financially, “but,” he added, “we have got tso far with X-rays, and tlie chief result is that we know tlie lines on which to develop.”