Recent Advances in the Analysis, Measurement, and Properties …
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protection not only against high speed impact of tank cars, but also against various
types of ballistic [12] and blast threats [13]. Composite metal foams made from heavy
metals such as iron, tungsten, and vanadium can offer reliable radiation shielding
against variety of sources from X-ray [14], to neutron [15], and Gamma ray [16],
but with the advantage of low density and great mechanical properties. S-S CMF
is proved to be able to offer a reduction in heat transfer compared to bulk stainless
steel due to the presence of air trapped within the spheres [8, 17]. These pockets of
air within the composite metal foam help disrupt flow of heat through the material
resulting in a 15 mm S-S CMF successfully passing the simulated pool fire testing
with a large margin [17, 18].
The testing in this study was performed in general accordance with the simulated
torch fire test specified in 49 CFR Part 179, Appendix B [19]. The specification
requires a sample to be subjected to a high velocity jet fire with a gas temperature
of 1204 ± 55.6°C (2200 ± 100°F) and velocity of 17.9 ± 4.5 m/s (40 ± 10 mph)
at the sample location. The full-scale torch fire test requires a 1.22 m × 1.22 m (48
in. × 48 in.) sample; however, due to the limitations in manufacturing composite
metal foam panels in larger scale, a scaled-down version of the test was developed
to provide initial data on the thermal protection performance of the material in the
torch fire set up using 30.2 × 30.2 cm panels.
This paper provides a description of the scaled-down version of the torch fire test
setup and the resulting data. Testing was performed to characterize the jet burner gas
temperature and velocity flow field, and a calibration fire test was conducted using
steel only as required by the test specification. Torch fire tests were then performed
on two different thickness composite metal foam panels to quantify the thermal
protection performance of the material. The microstructure of the SS-CMF is also
investigated using scanning electron microscope (SEM) analysis to correlate the
performance of the material against torch fire to its microstructure.
Experimental Procedure
Materials and Processing
Three panels of 30.2 × 30.2 × 1.59 cm steel-steel composite metal foam (S-SCMF)
were manufactured using stainless steel hollow spheres embedded in a 316L stainless
steel powder matrix and processed using powder metallurgy technique previously
developed [6, 9]. Hollow steel spheres with an average outer diameter of 2 mm and
a wall thickness of 100 µm were manufactured by Hollomet GmbH in Dresden,
Germany using lost core technique [20, 21]. Hollow stainless steel spheres were
shaken into a random-loose packing arrangement within a steel mold and surrounded
with a 316L stainless steel powder from North American Höganas with an average
particle size of 44 µm. The mold is then heated within a vacuum hot press and
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protection not only against high speed impact of tank cars, but also against various
types of ballistic [12] and blast threats [13]. Composite metal foams made from heavy
metals such as iron, tungsten, and vanadium can offer reliable radiation shielding
against variety of sources from X-ray [14], to neutron [15], and Gamma ray [16],
but with the advantage of low density and great mechanical properties. S-S CMF
is proved to be able to offer a reduction in heat transfer compared to bulk stainless
steel due to the presence of air trapped within the spheres [8, 17]. These pockets of
air within the composite metal foam help disrupt flow of heat through the material
resulting in a 15 mm S-S CMF successfully passing the simulated pool fire testing
with a large margin [17, 18].
The testing in this study was performed in general accordance with the simulated
torch fire test specified in 49 CFR Part 179, Appendix B [19]. The specification
requires a sample to be subjected to a high velocity jet fire with a gas temperature
of 1204 ± 55.6°C (2200 ± 100°F) and velocity of 17.9 ± 4.5 m/s (40 ± 10 mph)
at the sample location. The full-scale torch fire test requires a 1.22 m × 1.22 m (48
in. × 48 in.) sample; however, due to the limitations in manufacturing composite
metal foam panels in larger scale, a scaled-down version of the test was developed
to provide initial data on the thermal protection performance of the material in the
torch fire set up using 30.2 × 30.2 cm panels.
This paper provides a description of the scaled-down version of the torch fire test
setup and the resulting data. Testing was performed to characterize the jet burner gas
temperature and velocity flow field, and a calibration fire test was conducted using
steel only as required by the test specification. Torch fire tests were then performed
on two different thickness composite metal foam panels to quantify the thermal
protection performance of the material. The microstructure of the SS-CMF is also
investigated using scanning electron microscope (SEM) analysis to correlate the
performance of the material against torch fire to its microstructure.
Experimental Procedure
Materials and Processing
Three panels of 30.2 × 30.2 × 1.59 cm steel-steel composite metal foam (S-SCMF)
were manufactured using stainless steel hollow spheres embedded in a 316L stainless
steel powder matrix and processed using powder metallurgy technique previously
developed [6, 9]. Hollow steel spheres with an average outer diameter of 2 mm and
a wall thickness of 100 µm were manufactured by Hollomet GmbH in Dresden,
Germany using lost core technique [20, 21]. Hollow stainless steel spheres were
shaken into a random-loose packing arrangement within a steel mold and surrounded
with a 316L stainless steel powder from North American Höganas with an average
particle size of 44 µm. The mold is then heated within a vacuum hot press and