By Eric Lundin, Contributing Editor
If you need to sort through a small pile of metal scrap to separate steel items from aluminum, or if you need to figure out if a stray tube is carbon
steel or stainless steel, a magnet is the way to go.
However, if you need to identify an alloy and quantify its chemical composition (elemental content),
you need something more sophisticated. This is
where X-ray fluorescence (XRF) can be helpful.
The XRF process bombards the object under test
with X-rays, imparting energy to a sample of atoms
in the object. When that energy is released just milliseconds later, it gives off a series of distinctive signatures. The XRF detector evaluates these signatures
and, in doing so, determines the specific elements
and the relative quantities of each in the alloy.
This branch of science is XRF spectroscopy, which
studies the interactions between matter and electromagnetic radiation, but you don’t need a science
degree or a fancy title (“spectroscopist”) to use this
technology. To analyze the spectrum given off by
the object under test, you just pull the trigger and
the tool does the rest.
Let’s say you have an alloy consisting of 80 per-
cent copper, 11. 5 percent lead, 6. 5 percent tin, and 1
percent each of zinc and nickel. That’s a tin bronze,
which goes by the Copper Development Association
(CDA) designation 936 copper. An iron-based alloy
that has 0.15 percent carbon, 0.60 percent manga-
nese, 0.040 percent phosphorus, and 0.050 percent
sulfur is a low-carbon steel, designated 1018 by the
American Iron and Steel Institute (AISI). A similar al-
loy that has a little less carbon, 0.10 percent, and
another element, silicon, at 0.10 percent, is an old
friend, 1010 carbon steel.
XRF analyzers have been available for decades, so
they’re nothing new, but according to Mark Lessard,
a market development manager for Thermo Fisher
Scientific, industry needs them now more than ever.
Review, Repair, or Replace
It’s commonly known that manufacturers rely on
XRF to identify incoming material and scrap dealers
use the technology to segregate material, but these
are just two of many applications.
“We see significant growth potential for mission-critical applications,” Lessard said, referring to catastrophic events. “In the petrochemical industry, using the wrong alloy can result in an explosion. The
implications are much more severe if materials get
mixed up in a nuclear power plant or at an aerospace component manufacturing facility,” he said.
Sometimes the hazard isn’t as abrupt, but it can
be devastating nonetheless.
“Much of the pressure is regulatory in doing re-
pairs or in reviewing a construction project,” he
said. “Using the wrong material can lead to corro-
sion, and corrosion can lead to failure.”
Of course, some applications aren’t mission-criti-
cal, but mixups can have huge cost implications.
“For about 100 years, the automotive industry
relied on steel,” Lessard
said. “These days the industry is using aluminum,
magnesium, and titanium.” Verifying that the
right alloy showed up at
the receiving dock is an
ideal use for an XRF detector, as is keeping the
incoming raw materials
and the scrap from production segregated every
time they’re handled. The
pressure is on to improve
fuel efficiency, and one
of the tactics is to use the
possible. As the material’s
weight drops, the cost increases. Nobody wants to
make thousands of parts
from the wrong alloy.
An XRF analyzer also can
be used to check a coating
thickness, including pas-
sivation or conversion coatings, which is an impor-
tant step when preparing a steel surface for a bond-
ing agent, Lessard said.
“Auto manufacturers have been using adhesives
for years and their use is only going to grow,” he
said. “When using an adhesive, it’s critical that the
coating thickness is correct to ensure the structural
integrity of the bond.”
The Pace of Technology
Technologies are ever-changing—compare a digital camera or a computer or a cell phone of today
with one from a decade ago—and this includes XRF
analyzers. According to Lessard, the company’s latest unit, model XL5, is much more capable than its
“The unit has about three times better the level
of detection than previous units,” he said, stating
that the latest unit can detect the presence of some
elements down to single-digit parts per million. As
recently as five years ago, this level of detection
(LOD) was available only with laboratory-grade analyzers, not hand-held units, Lessard said. This has
the potential to benefit any industry that relies on
“It’s often a matter of what is not supposed to be
in the metal as what is supposed to be in it,” he said.
The risk of contaminating known metals with tramp
metals—so-named because they are as unwelcome
as tramps, vagrants, and other ne’er-do-wells who
tend to show up uninvited—is more prevalent than
ever due to growing recycling efforts. A low LOD is
necessary for any scrap dealer that guarantees the
furnace melt chemistry content of the scrap, as the
top-tier recyclers do.
Not just for analyzing metals anymore
XRF analyzer suitable for evaluating oils, troubleshooting machinery
Photo courtesy of Thermo Fisher Scientific, Tewksbury, Mass.