Stainless Steel Testing

Bruker® XRF Gun Takes 3 Seconds per Scan!

Stainless Shavings
Tested by Bruker Gun

Clearly, stainless is the queen of the steel alloys, the most durable and resistant, and correspondingly costlier than the others. Because they are specifically chosen for their superior properties, stainless alloys must be standards-compliant and accurately labeled. As steel testing experts we have often seen steel items marked “316L” that proved to be one of the lower, cheaper stainless steel grades, or to contain lower grade component parts. Though such situations can be due to fraud, most alloy grade errors are banal, caused by suppliers’ inadequate material management or reliance on inaccurate steel analysis equipment. Bruker’s handheld XRF guns for testing stainless steel offer an easy and reliable solution that efficiently solves the problem of steel grade mix-ups. (Note, however, that XRF is “blind” to carbon, so it won’t help you distinguish between 316 and 316L stainless steel, but it is able to differentiate the vast majority of stainless steel grades.) Please do not hesitate to contact us with questions about using a portable XRF solution for your stainless steel testing.

How Using a Bruker XRF Stainless Steel Tester Saves Money

As its name suggests, stainless steel is prized above all for its anti-rust, anti-corrosion properties. These are due to the relevant alloys’ elemental composition, chiefly to the presence of chromium, molybdenum, and sometimes copper. Stainless steel (known as “inox” or “inoxidizable” steel) is technically defined as any steel alloy containing at least 10.5% chromium content by mass. (Generally, stainless steel alloys contain from 12-25% Cr.) Additionally, all stainless steel alloys contain some nickel, which boosts resistance. Importantly, the stainless steel alloys retain their normal corrosion resistance and mechanical strength in temperatures of up to 800°C. (By contrast, the low alloy steels lose their strength and corrode rapidly in temperatures exceeding 650°C.)

Stainless steels are classified based on their properties. The stainless steel alloy groups are as follows.

Stainless steel is completely recyclable. Steelmaking is a lucrative industry dependent on to the availability of affordable stainless steel scrap. Interestingly, stainless steel objects and construction are today composed of an average 60% recycled steel, out of which amount some 40% is made up by recycled EOL (“end-of-life”) products, the other 60% provided by manufacturing processes.

A portable XRF stainless steel analyzer offers stainless scrap professionals quick ROI. A scrap sorter with a throughput of over 100 tons per month may recover the instrument’s cost in three months’ time. Here are some of the money saving benefits of using a Bruker XRF gun:

• Accurate Steel Grade Verification. There is a shortage of good stainless steel scrap. Top quality scrap costs the most, but the buyer must depend on stainless steel testing equipment to be certain that the scrap he is buying is the real deal.
• Scrap Upgrading. The steel mill pays for scrapper minimum guaranteed concentration. A pile of stainless steel scrap containing 304 with nickel content of 8-12% is resorted into two new piles, with 8-10% and 10-12% Ni respectively, the latter pile being priced based on 10% Ni, a substantial gain.
• Penalty Avoidance. “Tramp” elements in stainless steel may incur penalties for the seller. These can easily be detected and eliminated by resorting with the help a Bruker gun.

Stainless steel’s value arises mainly from its approximately 10% nickel content. Molybdenum content (typically at 2%)adds further to the value. Moreover, certain non-stainless steel scrap grades are also used in stainless steel production, namely, chromium steel and nickel steel scrap, carbon and low alloy steels, manganese steel scrap and nickel-alloy scrap. (Facing stainless steel testing challenges? Bruker Inc. is standing by to help you out. Click here to contact us now, it’s easy!)

Testing Stainless Steel for Impurities and“Tramp” Elements

A “tramp” or “trace” element is any chemical element included steel’s composition that was not added deliberately and is not easily removable. These impurities enter steel from ore and pig iron, via impurities in ferroalloy additions, refractories and, importantly, from scrap. Such common “tramps” presences in stainless steel that are not metallurgically reducible include phosphorus, vanadium, copper, tungsten, niobium, cobalt, tin, lead, and tantalum. Moreover, foundries are unable to reduce sulfur in stainless steel. All these elements must be rigorously scanned for. Luckily, a Bruker XRF stainless steel tester can “see” them all.) Today, professional steel scrap sorters by default rely on handheld XRF guns such as Bruker’s to identify and verify stainless steel grades. Reaching the steel mill, scrap is re-analyzed more meticulously. A steelmaker usually pre-sorts the material with an XRF gun and then tests a statistically significant sample from each scrap load with a bench top stationary spectrometer machine in a steel testing lab.

Here is a table showing the penalty limits on tramp elements in stainless steel material. Above these limits, scrap steel will most likely see a significant drop in price.

Needless to say, it isn’t all about scrap. Steel testing with handheld XRF has numerous other applications in industry. Please contact us for more information or to receive a quote from Bruker Inc.

More Information

If you have found this article useful, also browse our information pages concerning alloy steel testing and steel scrap testing. You may also be interested in carbon steel or/or low alloy steel testing issues.