Materials science and metallurgy of the Caribbean steel drum - Part I - Fabrication, deformation phenomena and acoustic fundamentals

Steel-drum fabrication, especially the sinking of the drum head (also refer red to as the "pan") by hand with a hammer, has been examined in detail uti lizing light metallography (LM) and transmission electron microscopy (TEM) to characterize residual microstructures corresponding to reductions in thi ckness of up to 50% at the bottom of the drum head. Dislocation densities i n the low-carbon (0.01-0.05 wt % C), ferritic steels can exceed 10(10) cm(- 2). Simulations of simple, ideal, free circular notes utilizing 316 stainle ss-steel plates (0.05 wt % C), cold rolled to reductions up to 40%, reveale d that deformation (per cent cold reduction) has an important effect on the acoustic spectrum, especially harmonic spectra. Harmonic-node splitting wa s observed for thin circular plates (0.076 cm thick); the frequency differe nce was 60 Hz at 20% cold reduction and 160 Hz at 40% cold reduction. These dispersion effects, due to deformation-induced microstructures, as well as irregularities in the note geometries and thicknesses, point to the comple x and non-linear acoustic features that contribute to the unique sounds of the Caribbean steel drum. (C) 1999 Kluwer Academic Publishers.