The compressional speed for steel is approximately 19,700 feet per second, while the shear speed is approximately 10,600 feet per second. Acoustic waves propagate in steel at two different speeds: longitudinal, or compressional wave velocity and transverse, or shear wave velocity. However, these approximate values may significantly differ from the actual speed due to several factors, including fiber or grain alignment, composition, temperature or permeability.
Acoustic waves are produced as a result of vibrating or oscillating particles within a medium, which can be solids, liquids or gases. The propagation of these waves is greatly influenced by the density and elastic characteristics of the material where the waves are traveling. The relationship between velocity, density and elasticity can be mathematically expressed in the equation V = sqrt (Cij/d), where "V" denotes the velocity, "Cij" indicates the elastic constant and "d" represents the density.
In solids, the molecules are condensed and tightly packed together, while in liquids and gases, the molecules are more dispersed. Sound waves travel readily along solid materials, while they propagate less in liquid or gaseous substances. Elasticity pertains to the ability of a material to return to its normal shape and withstand deformation after being stretched or compressed. Rigid materials, such as steel, have higher tendencies to resist distortion. Less elastic media allows sound waves to propagate faster compared to more elastic materials.