non-destructive measurement of hardness penetration depthhardening of steel is a common process to...
TRANSCRIPT
Replacing Destructive Measurement of HPD
Hardening of steel is a common process to increase life time especially of strongly loaded contact areas of critical parts, like many kinds of bearings, rails or railway wheels. The hardness penetration depth (HPD) is crucial for the quality control. State-of-the-art are destructive testswhere samples need to be cut in pieces for optical- and Vickers-tests. Laser Ultrasound (LUS) is an exciting alternative to state-of-the-art methods as it is a non-destructive and even non-contact technology, which allows to analyze samples still hot from the thermal treatment.
the most common hardening process is aheat treatment followed by quenching, whichchanges the microstructure at the surface ofthe steel down to a certain depth. it is ofgreat interest for the quality control of themanufactured part to know this hPD. thestate-of-the-art procedure to determine hPDis destructive, i.e. cutting the part to get access to the cross section, grinding and polishing the surface and then doing eitheran optical microstructure analysis or a classical hardness determination accordingto vickers or brinell. the result is hPD at oneposition of the cut cross section – only!
For many cases this destructive procedure can be replaced by LUS!
in principle, lus is similar to commonlyknown ultrasonic techniques with piezo transducers. but it is fully contactless, broadband and delivers stable signals in industrial environment. both, excitation and detection, are conducted by lasers. the advantages are obvious: a distance of several centimetres is possible, which allowsfor automation but also enables measure-ment on still hot samples. thus, this technique is very appropriate for the determi-nation of the hPD: every single measurement
gives an hPD value which enables a fast process for a complete volume!
fig. 1 shows an etched micrograph image of a crankshaft (top) in comparison to a lus result (bottom), which shows a very cleartransition from the hardened area to the untreated material.
TECHNOLOGYOFFER
Non-Destructive Measurementof Hardness Penetration Depth
Facts/Key-Values/Features & Benefits� non-contact → no couplant
necessary� automatable due to possible
stand-off distances� broadband signals for each
measurement� applicable for most smooth surfaces
Potential UsersFields of Application� Determination of the hPD of crank -
shafts, bearings, metal wheels, …� microstructure evolution during
thermal treatment
Status – what do we offer?� measurements and analysis in
RecenDt-labs� Development of methods to solve
your specific problems� Development of customized
measurement systems for your lab or fab
Contact data
Robert [email protected]+43 732 2468 4602
ReseaRch centeR foR non-DestRuctive testing gmbh (RecenDt)science PaRk 2/2.og, altenbeRgeR stRasse 69, 4040 linz, austRia, +43 732 2468-4600, [email protected], www.RecenDt.at
Fig. 1 Comparison of a stitched and etched micrographof an inductively hardended crankshaft (top) and the respective laser ultrasound result (bottom).
ReseaRch centeR foR non-DestRuctive testing gmbh (RecenDt)science PaRk 2/2.og, altenbeRgeR stRasse 69, 4040 linz, austRia, +43 732 2468-4600, [email protected], www.RecenDt.at