Inspection & Measurement Systems

Thickness Gage Tutorial

Material Sound Velocities

Material Sound Velocities

The table below lists typical longitudinal wave ultrasonic velocities in a variety of common materials that can be measured with ultrasonic thickness gages. Note that this is only a general guide. The actual velocity in these materials may vary significantly due to a variety of causes such as specific composition or microstructure, grain or fiber orientation, porosity, and temperature. This is especially true in the case of cast metals, fiberglass, plastics, and composites. For best accuracy in thickness gaging, the sound velocity in a given test material should always be measured by performing a velocity calibration on a sample of known thickness.

Ultrasonic Velocities in Common Materials

Material V (in./µsec) V (m/sec)
Acrylic (Perspex) 0.1070 2730
Aluminum 0.2490 6320
Beryllium 0.5080 12900
Brass 0.1740 4430
Composite,
graphite/epoxy
0.1200 3070
Copper 0.1830 4660
Diamond 0.7090 18000
Fiberglass 0.1080 2740
Glycerin 0.0760 1920
Inconel® 0.2290 5820
Iron, Cast (soft) 0.1380 3500
Iron, Cast (hard) 0.2200 5600
Iron oxide (magnetite) 0.2320 5890
Lead 0.0850 2160
Lucite® 0.1060 2680
Molybdenum 0.2460 6250
Motor oil 0.0690 1740
Nickel, pure 0.2220 5630
Polyamide 0.0870 2200
Nylon 0.1020 2600
Polyethylene,
high density (HDPE)
0.0970 2460
Polyethylene,
low density (LDPE)
0.0820 2080
Polystyrene 0.0920 2340
Polyvinylchloride, (PVC) 0.0940 2395
Rubber, polybutadiene 0.0630 1610
Silicon 0.3790 9620
Silicone 0.0580 1485
Steel, 1020 0.2320 5890
Steel, 4340 0.2300 5850
Steel, 302 austenitic stainless 0.2260 5740
Tin 0.1310 3320
Titanium 0.2400 6100
Tungsten 0.2040 5180
Water (20°C) 0.0580 1480
Zinc 0.1640 4170
Zirconium 0.1830 4650
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