Speed of Sound in Steel
| Value | 5,900 m/s |
| Status | Measured: ± 100 m/s (0.017 relative) |
| Source | ASM Handbook / ASNT Nondestructive Testing Handbook |
| Categories | Material PropertiesEngineering & Trade |
| millimeter per year | 186,189,840,000,000 mm/yr |
| millimeter per day | 509,760,000,000 mm/day |
| millimeter per hour | 21,240,000,000 mm/h |
| inch per day | 20,069,291,000 in/day |
| foot per day | 1,672,440,900 ft/d |
| inch per hour | 836,220,470 in/h |
| meter per day | 509,760,000 m/d |
| millimeter per minute | 354,000,000 mm/min |
| meter per hour | 21,240,000 m/h |
| inch per minute | 13,937,008 in/min |
| millimeter per second | 5,900,000 mm/s |
| foot per minute | 1,161,417.3 ft/min |
| centimeter per second | 590,000 cm/s |
| meter per minute | 354,000 m/min |
| inch per second | 232,283.46 in/s |
| kilometer per hour | 21,240 km/h |
| foot per second | 19,356.955 ft/s |
| mile per hour | 13,197.924 mph |
| knot | 11,468.683 kn |
| meter per second | 5,900 m/s |
| mach (sea level) | 17.337949 Ma |
| kilometer per second | 5.9 km/s |
| speed of light | 0.000019680282 c |
Learning zone
There is no single speed of sound in a solid, and this is the constant people most often get wrong. A long thin bar carries extensional waves at √(E/ρ) = √(200e9/7850) = 5050 m/s. A bulk medium, where lateral contraction is prevented, is stiffer and carries longitudinal waves at about 5900 m/s. Shear (transverse) waves, which have no analogue in fluids, travel at √(G/ρ) ≈ 3230 m/s. Ultrasonic thickness gauges are calibrated on the 5900 m/s bulk longitudinal value, and using the bar value would read 14 % thin.
The practical uses follow from the mode. Bulk longitudinal speed does UT thickness and flaw detection; shear speed does angle-beam weld inspection; bar speed governs impact and vibration in slender members. Steel's high wave speed is also why structure-borne noise travels so far in a building — a pump vibration reaches a distant room through the piping and framing long before it arrives through the air, and why isolators and flexible connectors, not more air-side attenuation, are the fix.