Failure analysis of piano strings

In this paper we studied the failure cause of two types of piano strings. The numerous problems which make it difficult to quantify the string life are systematically analyzed. The strings in question, made of spring steel (cold drawn wires with different thickness), are bass strings and acute strings of a piano concert. SEM analysis and Energy dispersive X-ray analysis (EDS) were made.Related questions were taken into account:
• the connection of the string at the “tuning pin”;
• string wear produced in its anchor point “agraffe”;
• the bending in the compression points;
• the environment where the piano is located, the relative humidity and the strings corrosion phenomena that might trigger stress-corrosion cracking;
• the surface finish of the cold drawn string. Besides these factors, it is necessary to consider the different tuning performed on a concert grand piano.

► Were taken into consideration bass and acute strings of a grand piano concert broken up.
► The mechanisms leading to rupture the strings are examined.
► Critical points: tuning pin, agraffe, compression points, environment, tuner.