Material Sound Velocities

Ultrasonic Thickness Gauge Tutorial

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 gauges. 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 gauging, 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 or 68 °F)
0.0580
1480
Zinc
0.1640
4170
Zirconium
0.1830
4650

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