Fatigue and Low Temperature Characteristics of Tungum Alloy Tube

As would be expected of a material originally developed for use in the hydraulic control systems of aircraft, Tungum Alloy has excellent fatigue resisting properties.

Today, pulsing pressures and vibration are recognised as being a major factor infl uencing the integrity and performance of all hydraulic systems irrespective of the application.

In practice, tubing is often used after bending. In this operation the outer wall of the tube becomes thinner and the inner wall thicker. The severity of this depends on the radius of curvature and the angle encompassed by the bend. The tube also becomes oval due to the forming operation.

The radius of the bend, the angle of the bend, the ovality of the tube and obviously properties of the tubing material, all influence its fatigue life. The relationship between the maximum stress, calculated for straight and circular Tungum Alloy tubing, and the number of stress repetitions to cause failure is shown below. The graphs are based on the results of tests carried out in controlled conditions and are reproduced for guidance purposes only.

Tungum Alloy satisfies many low temperature and cryogenic applications. The mechanical properties of the Alloy all improve with reducing temperatures down to as low as - 196°c. The impact resistance also remains substantially unchanged over the same temperature range.

The table compares the properties of solid, hard as drawn Tungum alloy at 15°c and -196°c.

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